NISTIR 7338 

Evaluation of Fire Models for 

Nuclear Power Plant Applications 

Benchmark Exercise #3 

International Panel Report 

Compiled by Kevin McGrattan 

NISTIR 7338 

Evaluation of Fire Models for 

Nuclear Power Plant Applications 

Benchmark Exercise #3 

International Panel Report 

Compiled by Kevin McGrattan 

Fire Research Division 

Building and Fire Research Laboratory 

January 2007 

U.S. Department of Commerce 

Carlos M. Gutierrez, Secretary 

Technology Administration 

Robert Cresanti, Under Secretary of Commerce for Technology 

National Institute of Standards and Technology 

William Jeffrey, Director 

i

Abstract 

A series of full-scale fire experiments was conducted at NIST in 2003 to provide data for an 

international benchmarking exercise to assess the accuracy of fire models over a range of 

operating conditions expected within a variety of compartments in a nuclear power plant. 

Seven organizations from France, Germany, Britain, and USA exercised seven fire models 

as part of the International Collaborative Fire Modeling Project (ICFMP). This report documents the results of the individual modeling studies. 
ii

Content 

1 Introduction.............................................................................................1-1

1.1 Review of Previous NRC-Sponsored Experiments .............................1-2

1.1.1 Investigation of Twenty-Foot Separation Distance...................................1-2

1.1.2 Fire Tests in a Control Room Mock-Up ....................................................1-2

1.1.3 Fire Test in a Cable Room Mock-Up ........................................................1-3

1.2 Experimental Description of Benchmark Exercise #3 ........................1-3

1.3 The Benchmarking Process ..................................................................1-8

1.4 References ............................................................................................1-11

2 Simulations using Jasmine and CFAST (Stewart Miles, BRE)...........2-1

2.1 CFAST Input Parameters and Assumptions........................................2-1

2.2 JASMINE Input Parameters and Assumptions ....................................2-3

2.3 Comparison of CFAST Blind and Semi-Blind Predictions with 

Measurements ........................................................................................2-7

2.4 Comparison of JASMINE Blind and Semi-Blind Predictions with 

Measurements ......................................................................................2-24

2.5 Conclusions and Recommendations for CFAST and JASMINE ......2-50

2.6 References ............................................................................................2-53

3 Open Simulations using FLAMME_S (Laurence Rigollet, IRSN) .......3-1

3.1 FLAMME_S Input Parameters and Assumptions ................................3-1

3.2 Comparison of FLAMME_S with Measurements.................................3-1

3.2.1 Test 2 and 8: door closed and ventilation off............................................3-1

3.2.2 Tests 3 and 9: door opened and ventilation off ........................................3-3

3.2.3 Tests 3 and 10: door closed and ventilation on........................................3-4

3.2.4 Test 5: door opened and ventilation on ....................................................3-5

3.3 Conclusions and Recommendations for FLAMME_S.........................3-6

3.4 References ..............................................................................................3-7

4 Open Simulations using FATE (Fauske and Associates)...................4-1

4.1 FATE Input Parameters and Assumptions...........................................4-2

4.1.1 Room Geometry and Ventilation ..............................................................4-2

4.1.2 Cable Targets...........................................................................................4-4

4.1.3 Test Matrix and Fire Source .....................................................................4-5

4.2 Comparison of FATE Predictions with Measurements.......................4-5

4.2.1 BE-3 Case 1 FATE Open Benchmark Results.........................................4-5

4.2.2 BE-3 Case 2 FATE Open Benchmark Results.......................................4-20
iii

4.2.3 BE-3 Case 3 FATE Open Benchmark Results.......................................4-36

4.2.4 BE-3 Case 4 FATE Open Benchmark Results.......................................4-57

4.2.5 BE-3 Case 5 FATE Open Benchmark Results.......................................4-73

4.2.6 BE-3 Case 14, 15, and 18 FATE Open Benchmark Results ..................4-73

4.3 Conclusions and Recommendations for FATE .................................4-96

4.4 References ............................................................................................4-97

5 Simulations using COCOSYS (Walter Klein-Hessling, GRS) .............5-1

5.1 COCOSYS Input Parameters and Assumptions ..................................5-1

5.2 Comparison of COCOSYS Predictions with Measurements ..............5-7

5.2.1 First set of blind calculations for tests 2, 3 and 4......................................5-8

5.2.2 Open calculation of test 2, 3 and 4.........................................................5-40

5.2.3 Further blind calculations........................................................................5-47

5.3 Conclusions and Recommendations for COCOSYS.........................5-68

6 Open Simulations using CFX (Matthias Heitsch, GRS) ......................6-1

6.1 CFX Input Parameters and Assumptions.............................................6-1

6.2 Comparison of CFX Predictions with Measurements .........................6-3

6.2.1 Test 2........................................................................................................6-3

6.2.2 Test 3........................................................................................................6-4

6.2.3 Test 4........................................................................................................6-5

6.3 Conclusions and Recommendations for CFX .....................................6-7

7 Open Simulations using FDS (Kevin McGrattan, NIST) ......................7-1

7.1 FDS Input Parameters and Assumptions.............................................7-1

7.1.1 Compartment Geometry...........................................................................7-2

7.1.2 Fire ...........................................................................................................7-3

7.1.3 Radiation ..................................................................................................7-4

7.1.4 Output.......................................................................................................7-7

7.1.5 Summary ..................................................................................................7-8

7.2 Comparison of FDS Open Predictions with Measurements...............7-9

7.2.1 Gas Temperatures....................................................................................7-9

7.2.2 Heat Flux and Surface Temperature at the Walls, Ceiling and Floor .....7-22

7.2.3 Heat Flux and Surface Temperature at Cable Targets...........................7-34

7.2.4 Gas Species Concentrations..................................................................7-57

7.2.5 Smoke Concentration.............................................................................7-61

7.2.6 Compartment Pressure ..........................................................................7-64

7.2.7 Velocity...................................................................................................7-68

7.2.8 Energy Budget........................................................................................7-70
iv

7.3 FDS Sensitivity Analysis......................................................................7-71

7.3.1 Grid Sensitivity........................................................................................7-71

7.3.2 Sensitivity to Wall Material Properties ....................................................7-72

7.3.3 Radiation Parameters.............................................................................7-74

7.4 Conclusions and Recommendations for FDS ...................................7-75

7.5 References ............................................................................................7-77

8 Summary of Conclusions from Individual Contributions...................8-1

8.1 Modeling the Fire....................................................................................8-1

8.2 Fire Extinction.........................................................................................8-1

8.3 Heat Flux .................................................................................................8-2

8.4 Target Model ...........................................................................................8-2

8.5 Carbon Monoxide and Soot...................................................................8-2

8.6 Mechanical Ventilation...........................................................................8-3

8.7 Compartment Pressure..........................................................................8-3
v

Foreword 

This report documents the results of fire model calculations of Benchmark Exercise #3 of the 

International Collaborative Fire Model Project. The objective of this study was to provide 

participants in the project an opportunity to test their respective fire models, and to evaluate 

the capabilities of the fire models for fire safety analyses in nuclear power plants. The work 

of each organization participating in the exercise is included as a chapter in the main report. 

These chapters document the analyses conducted by the participating organizations, their 

assessment of the accuracy and capabilities of their models, and the insights gained from 

the validation exercise. These studies are the product of each organization. The chapters 

also discuss the considerations for developing input parameters and assumptions for the 

models, and a summary of the conclusions from the individual studies. No attempt has been 

made to provide code to code comparisons, or assess the performance of each model used. 

Each organization participating in the exercise will assess the performance of the models it 

exercised, and determine their specific applicability for the organization’s own use and benefit. This document is not intended to provide guidance to users of fire models. Guidance on 

the use of fire models is currently being developed by several national and international 

standards organizations, industry groups, and utilities. This document is intended to be a 

source and reference for technical information and insights gained through the analyses 

conducted, and provided by the experts participating in this project. This information may be 

beneficial to users of fire models, and developers of guidance documents or standards for 

the use of fire models in nuclear power plant applications. 
vi

Acknowledgments 

In addition to the analysts identified in the table of contents who performed the calculations 

for the benchmark exercise, several experts from various organizations contributed to this 

benchmark exercise in many ways. The test series used for this benchmark exercise was 

co-sponsored by the US Nuclear Regulatory Commission and the National Institute of Standards and Technology (NIST). Anthony Hamins and Alex Maranghides of NIST conducted 

the test series. Jonathan Barnett at Worcester Polytechnic Institute, USA, Olavi KeskiRahkonen and Simo Hostika at VTT, Finland, and James Oldham and Doug Brandes (retired) at Duke Energy, USA hosted the 7th, 8th and 9th ICFMP meetings where the benchmark 

exercise was planned and discussed, and also provided peer reviews and technical support. 

Marina Roewekamp at GRS, Germany and Chantal Casselman at IRSN, France provided 

project management and technical support to the ICFMP group. Alan Coutts at WSMS, USA, 

Jason Floyd at Hughes Associates, USA, Bijan Najafi and Francisco Joglar-Billoch at 

SAIC/EPRI, USA, Bernard Gautier and Laurent Gay at EdF, France, Peter Rew at WS Atkins Consultants, UK, Olaf Riese at iBMB, Germany, Jurgen Will at HHPBraunschweig, 

Germany, Walter Jones at NIST, USA, Bob Kassawara at EPRI, USA, Naeem Iqbal at 

NRC/NRR, USA, and Alan Wylie and Geoff Jones at HSE/NII, UK all contributed to this 

benchmark exercise either by providing peer comments, participating in meetings to discuss 

the test plan and results, or indirectly by sponsoring participants for the project. This benchmark exercise and document would not have been possible without the help and expertise of 

all the above. 
vii

Acronyms 

BFS Bundesamt fur Strahlenschutz 

BRE Building Research Establishment 

CFAST Consolidated Model for Fire and Smoke Transport 

CFD Computational Fluid Dynamics 

COCOSYS Containment Code System 

EdF Electricite de France 

EPRI Electric Power Research Institute 

FATE Facility Flow, Aerosol, Thermal, and Explosion Model 

FDS Fire Dynamics Simulator 

GRS Gesellschaft fuer Anlagen-und Reaktorsicherheit 

HGL Hot Gas Layer 

HRR Heat Release Rate 

HSE Health and Safety Executive 

ICFMP International Collaborative Fire Model Project 

iBMB Institut fuer Baustoffe, Massivbau und Brandschutz 

IRSN Institut de Radioprotection et de Surete Nucleaire 

JASMINE Analysis of Smoke Movement in Enclosures 

LOL Lower Oxygen Limit 

NII Nuclear Installations Inspectorate 

NIST National Institute of Standards and Technology 

NPP Nuclear Power Plant 

NRC Nuclear Regulatory Commission 

PRA Probabilistic Risk Analysis 

SAIC Science Applications International Corporation 

VTT Valtion Teknillinen Tutkimuskeskus 

WPI Worcester Polytechnic Institute 

WSMS Westinghouse Safety Management Solutions
viii
1-1

1 Introduction 

The US Nuclear Regulatory Commission (USNRC) has co-organized an International Collaborative Fire Model Project (ICFMP) to evaluate fire models for Nuclear Power Plant (NPP) 

applications. Five benchmarking exercises have been conducted as part of the ICFMP to 

evaluate the predictive capability and limitations of fire models (both zone and CFD). This 

report documents numerical simulations by ICFMP participants of a set of full-scale compartment fire experiments that were conducted at the National Institute of Standards and 

Technology (NIST) in 2003. These experiments are referred to throughout this document as 

ICFMP Benchmark Exercise (BE) #3. The other benchmarking exercises are: 

ICFMP BE #1: Hypothetical Cable Tray Fire Scenarios (no experiments) [Dey, 2002] 

ICFMP BE #2: Pool Fires in Large Halls [Miles, 2004] 

ICFMP BE #4: Large Fires in Compartments [Klein-Hessling, 2005] 

ICFMP BE #5: Flame Spread in Cable Tray Fires [Riese, 2005] 

The details of the BE #3 experiments are documented in Hamins et al. [2005]. This report 

provides a brief discussion of the design of the experiments and previous experiments. 

This report includes contributions from the BRE in the U.K. (Chapter 2), IRSN in France 

(Chapter 3), Fauske and Associates, a U.S. consulting firm specializing in nuclear issues 

(Chapter 4), GRS in Germany (Chapters 5 and 6), and NIST in the U.S. (Chapter 7). A 

chapter was originally submitted by the US NRC, but was withdrawn because it did not satisfy that organization’s internal review process. The models that were used in the withdrawn 

chapter, CFAST and FDS, are nevertheless applied in Chapters 2 and 7, respectively. In all, 

seven fire models are reviewed: the zone models CFAST, FLAMME_S, and FATE; the CFD 

models JASMINE, CFX, and FDS; and one “hybrid” model COCOSYS. 
1-2

1.1 Review of Previous NRC-Sponsored Experiments 

In the past, the US NRC sponsored three large-scale fire test series. Sandia National Laboratories (SNL) conducted an "Investigation of Twenty Foot Separation Distance as a Fire 

Protection Method as Specified in 10 CFR 50 Appendix R" [NRC, 1983]. SNL conducted two 

additional test series for the NRC; "Enclosure Environment Characterization Testing for the 

Base Line Validation of Computer Fire Simulation Codes" [NRC, 1987], and "An Experimental Investigation of Internally Ignited Fires in Nuclear Power Plant Control Cabinets" [NRC, 

1988]. The Laboratory on Research and Modeling of Fires, Institut de Radioprotection et de 

Sûreté Nucléaire, France, also conducted a single test. The test and results are described in 

"Probability Study on Fire Safety" [IRSN, 1997]. A brief description of each test series follows. 

1.1.1 Investigation of Twenty-Foot Separation Distance 

The tests were conducted at Underwriters Laboratories and the work reported in 1983. The 

primary purpose of these tests was to evaluate the effectiveness of the fire protection afforded by the separation of redundant safety related cables by a horizontal distance of 6.1 m 

(20 ft) with no intervening combustibles or hazards. The full-scale test compartment was 7.6 

m x 4.3 m x 3.0 m (25 x 14 x 10 ft). Construction was hollow core concrete blocks laid with 

mortar. The ceiling was of 12 mm inorganic board fastened to steel form and coated with a 

cementious mixture. There was a 4 ft x 8 ft opening. The fire was a 1 ft x 5 ft steel pan filled 

with five gallons of heptane. The pan was placed against the wall. The compartment contained two vertical trays with 43 cables, corresponding to a 12.5 % fill. The vertical trays 

were directly above the heptane pan. Two horizontal cable trays, also filled at 12.5 %, were 

located 20 ft from the fire. The horizontal trays were energized. Ventilation was free convective movement through the compartment opening. 

1.1.2 Fire Tests in a Control Room Mock-Up 

A series of fire experiments were conducted by researchers from Sandia National Laboratories (SNL), New Mexico, at the Factory Mutual Research Center (FMRC) in Rhode Island. 

The results were reported in March 1987 (US NRC, 1987, 1988). The primary purpose of 

these tests was to provide data for fire model validation. The test compartment was 18.3 m x 

12.2 m x 6.1 m (60 x 40 x 20 ft). Interior ceiling and walls were lined with marinate, a fireresistant insulating material often used in fire testing. The floor was a concrete slab. Fuels 
1-3

used were a gas burner, heptane pool, methanol pool, and solid polymethylmethacrylate 

(PMMA) with fires ranging from 500 kW to 2000 kW. Some of the tests were conducted in an 

empty enclosure; some with a control room mock-up. Forced ventilation was used during the 

tests ranging form one to ten room air changes per hour. Test variables included fire intensity, enclosure ventilation rate, and fire location. 

1.1.3 Fire Test in a Cable Room Mock-Up 

A single test was conducted at the Laboratory on Research and Modeling of Fires, IRSN, 

Cadarache, France. The objectives of this test were to provide quantitative information to 

safety analysts and contribute data to the qualification of the FLAMME_S fire model. The 

test was conducted on March 28, 1996 and reported in April 1997. The test was designed to 

simulate a cable room fire. Compartment construction was reinforced concrete with walls 

0.25 m thick. Compartment dimensions were 9 m x 6 m x 7.5 m. A forced ventilation system 

consisted of a floor blower, and an extractor located high on the wall. The ventilation flow 

rate was set at five air changes per hour. The compartment contained five bundles of 20 

cables mounted on a ladder-like support. Four were set horizontally with voltage supplied to 

them (two near the ceiling and two near the fire). One was vertical without any voltage applied. One electrical cabinet was also included (1 m x 0.3 m x 1.2 m) with metal plates inside 

to represent electrical equipment. One hundred liters of MOBIL DTE medium oil preheated 

to 250 oC were used for the fire that yielded a peak heat release rate of 940 kW. Temperature measurements were made along each cable run on either side of the bundle using 

2 mm diameter type K thermocouples. 

1.2 Experimental Description of Benchmark Exercise #3 

The experiments for Benchmark Exercise #3 of the International Collaborative Fire Model 

Project (ICFMP) were designed by staff members from the US NRC and NIST. A draft specification of the experiments was issued to participants on September 6, 2002, to solicit comments, further ideas, and suggestions. Written comments on the draft specification were 

received from participants. The draft specification was also presented at the 6th ICFMP 

meeting at British Research Establishment (BRE), UK on October 10-11, 2002, when verbal 

comments from participants in the meeting were received and documented. Appendix A of 

Hamins et al. [2005] provides the written and verbal comments received on the draft specification of the ICFMP Benchmark Exercise #3, including the resolution and disposition of the 

comments. 
1-4

The design of Benchmark Exercise #3 incorporated several lessons learned from previous 

NRC-sponsored large-scale fire tests described in the previous section. Most importantly, a 

considerable emphasis was placed on obtaining material properties, ventilation flow rates, 

leakage rates, and enough measurements to estimate the integrated heat losses through the 

walls and compartment opening. This information is vital for a model validation exercise. 

Benchmark Exercise #3 consisted of 15 large-scale experiments performed at NIST in June 

2003. Numerous measurements (350 per test) were made including gas and surface temperatures, heat fluxes and gas velocities. The experiments are documented in Hamins et al. 

[2005]. Only a brief description of the experiments is included here. 

The test compartment dimensions were 21.7 m x 7.1 m x 3.8 m high. An overview of the 

compartment is shown in Figure 1-1. The walls and ceiling were lined with two layers of 

marinate boards; the floor was covered with one layer of gypsum board on top of one layer of 

plywood. Thermo-physical properties of the marinite and other materials were provided to 

the participants. The compartment had one 2 m by 2 m door and a mechanical air injection 

and extraction system. Some of the tests were conducted with the door closed and no mechanical ventilation (Tests 2, 7, 8, 13, and 17), and in those tests the measured compartment leakage was an important consideration. Hamins et al. [2005] reports leakage area 

based on measurements performed prior to Tests 1, 2, 7, 8, and 13. 

The mechanical ventilation was used during Tests 4, 5, 10, and 16, providing about 5 air 

changes per hour. The door was closed during Test 4 and open during Tests 5, 10, and 16. 

The supply duct was positioned on the south wall, about 2 m off the floor. An exhaust duct of 

equal area to the supply duct was positioned on the opposite wall at a comparable location. 

The flow rates through the supply and exhaust ducts were measured in detail during breaks 

in the testing, in the absence of a fire. 

Ventilation conditions, the fire size, and fire location were the key parameters varied in the 

test series. Table 1-1 lists the fuel type, pan position and duration of the ramp-up, rampdown and steady burn periods. The fire pan was located at floor level in the center of the 

compartment for most of the tests (Tests 1-13, 16, and 17). In Test 14, the fire was centered 

1.8 m from the North wall. In Test 15, the fire was centered 1.25 m from the South wall. In 

Test 18, the fire was centered 1.55 m from the South wall. The fuel pan was 2 m long x 1 m 

wide and 0.1 m deep. The fuel used in 14 of the tests was heptane, while toluene was used 

for one test (Test 17). The HRR was determined using both the estimated fuel flow rate and 
1-5

oxygen consumption calorimetry. The uncertainty in the HRR measurement is described in 

Hamins et al. [2005]. The recommended uncertainty values were 17 % for all of the tests. 
1-6

3.82 m

21.7 m

7.04 m

1.9 m

10.0 m

2.2 m 2.7 m 3.2 m

10.9 m

2.0 m 1.0 m 1.3 m

2.96 m

1.05 m

9.83 m 8.33 m

10.7 m

0.75 m

2.05 m

1.35 m

0.50 m

Fuel Pans

F

BD

G

FB

D

Figure 1-1. Plan, side and perspective schematic drawings of the ICFMP BE #3 experimental arrangement. 

is at the top of the plan view. 
1-7

Table 1-1 Test matrix, including fuel type, pan position and duration of the ramp-up, ramp-down 

Steady HRR (kW) Ramp-up Steady 

Test Fuel Fuel Pan Position Based on Fuel Flow 

(NISTIR 1013) 

Based on 

Calorimetry 

(NISTIR 1013-1) 

(s) 

1 Heptane Center 390 410 148 122 Heptane Center 1140 1190 180 43 Heptane Center 1150 1190 178 124 Heptane Center 1150 1200 178 65 Heptane Center 1150 1190 178 126 test not conducted 7 Heptane Center 380 400 129 128 Heptane Center 1140 1190 176 49 Heptane Center 1120 1170 175 12

10 Heptane Center 1130 1190 176 611 test not conducted 12 test not conducted 13 Heptane Center 2220 2330 177 114 Heptane North 1130 1180 176 1215 Heptane South 1130 1180 180 1216 Heptane Center 2200 2300 177 217 Toluene Center 1070 1160 181 18 Heptane South-East 1130 1180 178 12
1-8

1.3 The Benchmarking Process 

Participants in the modeling exercise were invited to submit predictions for Tests 2, 3 and 4 

prior to the experiments to a non-participating third party. These results are referred to as 

“blind” throughout this report1

. The specified heat release rate for Tests 2, 3 and 4 was 

1000 kW. This HRR was to be achieved by calibrating the fuel flow rate into the pan prior to 

the tests. No flow meter was installed on the fuel line, but oxygen consumption calorimetry 

was performed during the tests. Following the tests, the originally targeted HRR of 1000 kW 

was adjusted to roughly 1150 kW based on the actual fuel flow to the pan, and these results 

were published in NISTIR 1013, January 2004. Those using the adjusted HRR have referred to their calculations as “semi-blind” because they were given the HRR, but not the gas 

phase measurements within the compartment. In 2005, the HRR estimate was re-evaluated 

based on the results of a study of the large fire exhaust hood at NIST, in which several of the 

BE #3 tests were repeated to reassess the HRR. The new estimate was a small increase 

over the older one (for example 1150 kW was increased to 1190 kW). The NIST report was 

re-issued as NISTIR 1013-1 and is cited here as Hamins et al. [2005]. All of the modeling 

studies described in this report were completed prior to the release of NISTIR 1013-1, and 

the difference between the HRR cited in NISTIR 1013 and NISTIR 1013-1 is well within the 

reported uncertainty of this measurement (17 %). 

The “blind” results reported in chapters 2 and 5 are based on the original specified HRR of 

1000 kW. These chapters also contain so-called “semi-blind” results. Chapters 3, 4, 6, and 

7 contain only “semi-blind,” or “open” results. Semi-blind calculations are those in which the 

modeler had knowledge of the measured HRR but not the measured compartment 

temperatures, heat fluxes, etc. The semi-blind set of calculations, along with those 

considered “open,” are based on the revised HRR estimates (1130 kW to 1150 kW for most 

 

1

 The use of the terms “blind” and “semi-blind” in this report differ from terms used in ASTM E 1355-

05a, “Standard Guide for Evaluating the Predictive Capability of Deterministic Fire Models.” According to the ASTM standard, “blind” means that the modeler is provided with “a basic description of the 

scenario,” and that the modeler “is responsible for developing appropriate model inputs, ... including 

additional details of the geometry, material properties, and fire description, as appropriate.” For the 

“blind” calculations described in this report, the modelers were given as much detail as was available, 

which according to the ASTM standard would more appropriately be characterized as “specified.” 
1-9

tests), the most appropriate HRR for comparing models with experiments. None of the 

studies included in this report made use of the calorimetry-based HRR values reported by 

Hamins et al. [2005] because the calculations documented in this report were done prior to 

the release of the final HRR values. The final HRR values are only slightly greater than the 

1130-1150 kW estimates. The two sets of HRR values are within the reported uncertainty of 

17 % and are shown in Table 1-1. 

To put this into perspective, consider the set of graphs shown in Figure 1-2. Tests 2, 3 and 

4 (the original blind simulation cases) were re-run with the CFD model FDS using HRR 

values of 1000 kW, 1150 kW, and 1190 kW. Notice that the HRR has little effect on the HGL 

(Hot Gas Layer) Height predictions, but it does have a noticeable effect on the HGL 

Temperature predictions. The difference between the 1150 kW and 1190 kW simulations is 

fairly small, and well within the uncertainty bounds of the HRR measurement itself. 

However, the 1000 kW simulations noticeably under-predict the HGL temperature. This is 

not surprising, because the HGL Temperature Rise is proportional to the two-thirds power of 

the HRR, according to the well-established MQH (McCaffrey, Harkleroad, Quintiere) 

correlation. Thus, a 15 % change in the input HRR will yield a 10 % change in the HGL 

Temperature Rise. 

The decision by NIST staff to increase the HRR estimates from the values reported in 

NISTIR 1013 to the values reported in NISTIR 1013-1 was not based on the predictions of 

FDS (the NIST CFD model) but rather a re-assessment of the intrumentation and 

procedures used during the 2003 experiments in the Large Fire Laboratory at NIST. In fact, 

the FDS predictions are slightly closer to the measurements, on average, when using the 

intermediate values of the HRR reported in NISTIR 1013, the same values used by the 

ICFMP participants and reported in this report. The goal of the experimentalists at NIST is to 

make the most accurate measurements possible, not to match fire model predictions. 

Neither the experiments nor the model was tweaked or tuned to improve agreement. 
1-10

Hot Gas Layer Temperature

ICFMP BE #3, Test 2

Time (min)

0 5 10 15 20 25 30

Temperature (C)

0

50

100

150

200

250

300

Experiment

FDS (1190 kW Fire)

FDS (1140 kW Fire)

FDS (1000 kW Fire)

Hot Gas Layer Height

ICFMP BE #3, Test 2

Time (min)

0 5 10 15 20 25 30

Height (m)

0

1

2

3

4

Experiment

FDS (1190 kW Fire)

FDS (1140 kW Fire)

FDS (1000 kW Fire)

Hot Gas Layer Temperature

ICFMP BE #3, Test 3

Time (min)

0 5 10 15 20 25 30

Temperature (C)

0

50

100

150

200

250

300

Experiment

FDS (1190 kW Fire)

FDS (1150 kW Fire)

FDS (1000 kW Fire)

Hot Gas Layer Height

ICFMP BE #3, Test 3

Time (min)

0 5 10 15 20 25 30

Height (m)

0

1

2

3

4

Experiment

FDS (1190 kW Fire)

FDS (1150 kW Fire)

FDS (1000 kW Fire)

Hot Gas Layer Temperature

ICFMP BE #3, Test 4

Time (min)

0 5 10 15 20 25 30

Temperature (C)

0

50

100

150

200

250

300

Experiment

FDS (1200 kW Fire)

FDS (1150 kW Fire)

FDS (1000 kW Fire)

Hot Gas Layer Height

ICFMP BE #3, Test 4

Time (min)

0 5 10 15 20 25 30

Height (m)

0

1

2

3

4

Experiment

FDS (1200 kW Fire)

FDS (1150 kW Fire)

FDS (1000 kW Fire)

Figure 1-2. Hot Gas Layer Temperature and Height for Tests 2, 3 and 4, showing the 

experimental measurements and three model predictions with three different 

heat release rates. 
1-11

1.4 References 

Dey, M., Ed., "International Collaborative Project to Evaluate Fire Models for Nuclear Power 

Plant Applications: International Panel Report on Benchmark Exercise # 1, Cable 

Tray Fires," U.S. Nuclear Regulatory Commission, NUREG-1758, June 2002. 

Klein-Hessling, W., M. Roewekamp and O. Riese, "Evaluation of Fire Models for Nuclear 

Power Plant Applications – Large Fires in Compartments, Benchmark Exercise 

#4, International Panel Report," Gesellschaft fur Anlagen-und Reaktorsicherheit 

(GRS) Report Number GRS-213, ISBN-Nr.: 3-931995-80-1, 2006. 

Hamins, A. et al. “Report of Experimental Results for the International Fire Model Benchmarking and Validation Exercise #3,” NIST Special Publication 1013-1, National 

Institute of Standards and Technology, Gaithersburg, Maryland, November 2003. 

Revised as 1013-1, June 2005. 

Institut de Radioprotection et de Sûreté Nucléaire (IRSN), France, “Probability Study Program on Fire Safety,” Laboratory on Research and Modeling of Fires, J. M. Such 

EF.30.15.R/96.442, April 1997. 

Miles, S., "International Collaborative Project to Evaluate Fire Models for Nuclear Power 

Plant Applications: International Panel Report on Benchmark Exercise # 2, Pool 

Fires in Large Halls," Building Research Establishment Ltd., BRE Report Number 

212214, May 2004. 

Riese, O., D. Hosser and M. Roewekamp, "Evaluation of Fire Models for Nuclear Power 

Plant Applications – Flame Spread in Cable Tray Fires, Benchmark Exercise #5, 

International Panel Report," Gesellschaft fur Anlagen-und Reaktorsicherheit 

(GRS) Report Number GRS-214, ISBN-Nr.: 3-931995-81-X, 2006. 

Riesemann, James M. Chavez, NUREG/CR-3192, SAND83-0306, RP, October 1983 

U.S. Nuclear Regulatory Commission, “An Experimental Investigation of Internally Ignited 

Fires in Nuclear Power Plant Control Cabinets,” J. M.Chavez, S. P. Nowlen, 

NUREG/CR-4527, SAND86-0336, Vol 2, November 1988. 

U.S. Nuclear Regulatory Commission, “Enclosure Environment Characterization Testing for 

the Base Line Validation of Computer Fire Simulation Codes,” S. P. Nowlen, 

NUREG/CR 4681, SAND86-1296, RP, March 1987. 
1-12

U.S. Nuclear Regulatory Commission, “Investigation of Twenty-Foot Separation Distance as 

a Fire Protection Method as Specified in 10 CFR 50, Appendix R,” Douglas D. 

Cline, Walter A von 
2-1

2 Simulations using Jasmine and CFAST (Stewart Miles, BRE) 

Blind, i.e. fully-blind (prior to the release of fuel mass loss and mechanical ventilation flow 

rates), and semi-blind (with knowledge of the above rates) calculations were performed with 

CFAST (zone model) version 3.1.6 and Jasmine (CFD model) version 3.2.3. These are also 

referred to as ‘stage 1’ and ‘stage 2’ calculations respectively. Tests 2, 3 and 4 were studied 

in both the CFAST and JASMINE work. 

For the blind calculations the geometry of the experimental rig was represented as closely a 

possible to that given in the problem specification [Maranghides et al, 2003] and the two 

subsequent small addendum documents. In the semi-blind calculations the experimentally 

measured fuel release and mechanical ventilation rates, and the estimated infiltration ventilation area (for the door-closed tests), [Hamins et. al., 2003a] were used. Comparisons between calculated results and the experimental measurements [Hamins et. al., 2003b] were 

made and are reported here. 

2.1 CFAST Input Parameters and Assumptions 

CFAST is a widely used zone model, available from the National Institute of Standards and 

Technology (NIST). It is a multi-room zone model, with the capability to model multiple fires 

and targets. The fuel pyrolysis rate is a pre-defined input, and the burning in the compartment is then modeled to generate heat release and allow species concentrations to be calculated. For most applications CFAST is used as a conventional two-zone model, whereby 

each compartment is divided into a hot gas upper layer and a cold lower layer. In the presence of fire, a plume zone/model transports heat and mass from the lower to upper layer 

making use of an empirical correlation [McCaffrey, 1983]. Flows through vents and doorways 

are determined from correlations derived from the Bernoulli equation. Radiation heat transfer 

between the fire plume, upper & lower layers and the compartment boundaries is included 

using an algorithm derived from other published work [Siegel and Howell, 1981]. Other features of CFAST relevant to the benchmark exercise include a one-dimensional solid phase 

heat conduction algorithm employed at compartment walls and targets and a network flow 

model for mechanical ventilation. 
2-2

For an in-depth description of CFAST, including its scientific and engineering background, 

the solved equations and the physical sub-models see the reference [Jones et al., 2000] and 

the later reference accompanying CFAST version 5 [Jones et al., 2004]. A summary of validation exercises that have been undertaken for the CFAST model is also included in [Jones 

et. al., 2004]. The panel report [Miles, 2004] and accompanying technical annexes for the 

second benchmark exercise include a number of examples where CFAST calculations have 

been compared to experimental measurement data for smoke filling inside a large hall. 

Information relevant to the application of CFAST to this benchmark exercise is given below. 

• Main geometry and thermal boundary conditions. Dimensions of room, and also the door 

in Test 3, were modeled as in the problem specification. Thermal properties of the walls, 

floor and ceiling were represented by creating a new user defined material with the required properties. Conduction losses to the room walls, ceiling and floor were included, 

using the one-dimensional heat conduction sub-model. 

• Leakage area for closed-door tests. A leakage area (vent) of width 0.17 m and height 

0.17 m, located at floor level, was used in the blind calculations. Some parametric calculations were undertaken using increased leakage vent dimensions of 0.34 m by 0.34 m. 

By contrast, for the semi-blind calculations the dimensions were fixed at 0.289 m by 

0.289 m. Note that as a consequence of the zone modeling assumptions employed there 

is no positional information attached to leakage vent location. 

• Mechanical ventilation. In Test 4 mechanical ventilation was defined. In CFAST, and 

zone models in general, the height of the vents above floor level is specified, but no further geometrical information is included, i.e. supply and extraction is to/from either the 

lower or upper layer, which by definition extends across the entire width and length of the 

room. However, initial attempts to specify a mechanical supply and a mechanical extract 

failed to produce converged solutions. The problem was by-passed by specifying a mechanical extract vent and a vertical natural vent (window), with the same dimensions and 

height above the floor. The natural vent allowed the inflow of replacement air for the mechanical extraction. 

• Fire specification. This was treated as a constrained fire (i.e. oxygen controlled) with 

area 2 m2

. The fuel was modeled as heptane, using a heat of combustion of 

4.5 x 107

 J kg-1. The pyrolysis rate was then set such that in the blind simulations the 

chemical energy release was exactly 1 x 106

 W and in the semi-blind simulations was 
2-3

adjusted to the suggested actual value. In all calculations a two-layer gas assumption 

was assumed inside the room and the 'ceiling jet' option was active. 

In the blind calculations the radiative fraction was set initially to 0.35, and then adjusted 

to 0.0 and 0.5 in various parametric analyses. For the semi-blind calculations the value 

was fixed at 0.44. In all calculations the lower oxygen limit (LOL) was fixed at 10%. However, the test was considered to be over once the oxygen concentration in the lower layer 

(where the measurement location was positioned) dropped to 15%. 

The choice of radiative fraction and heat of combustion requires careful scientific/engineering judgment. An appropriate choice of the radiative fraction in particular 

may have a significant bearing on the calculations for upper layer temperature. For a discussion of these parameters, see the panel report of the second benchmark exercise 

[Miles, 2004], where the terms and their meaning are reviewed. 

• Targets. A required approximation in CFAST is that cable targets are treated as rectangular slabs. Furthermore, heat conduction is modeled one-dimensionally, i.e. in the direction of the surface normal. In the calculations the cable targets were orientated such as 

to be exposed to the maximum thermal load. The appropriate choice of target location 

and orientation is highly important in a hazard analysis for applications such as nuclear 

power plant safety cases where cable damage is an important factor. 

2.2 JASMINE Input Parameters and Assumptions 

JASMINE [Cox & Kumar, 1987] solves the Reynolds-Averaged Navier Stokes (RANS) equations of fluid flow on a single-block Cartesian grid. The coupled set of equations for each of 

the three Cartesian velocity components, enthalpy (heat) and other scalars required by the 

various sub-models (e.g. fuel mass and mixture fractions for combustion) is approximated as 

a system of algebraic equations that are solved numerically on a discrete grid. This generates a solution value for each variable at each grid location. JASMINE uses the finite volume 

method, where the differential equations are first transformed into an integral form and then 

discretized on the control volumes (or cells) defined by the numerical grid. This solution procedure is coupled with a variant of the SIMPLE pressure-correction scheme [Patankar, 

1980]. 

In solving the RANS equations, the fluctuating components of the turbulent motion are not 

solved directly, but instead the effect of turbulence is included by means of a separate sub-
2-4

model. This saves computational effort, and for many industrial applications, including fire 

modelling, has been shown to produce reliable solutions provided a suitable turbulence 

mode is used. JASMINE employs a standard κ-ε turbulence model [Launder & Spalding, 

1974] with additional buoyancy source terms. An “effective turbulent viscosity” is calculated 

at each control volume, which can be considered as an increased viscosity to incorporate 

the effects of turbulence. Standard wall functions for enthalpy and momentum [Launder & 

Spalding, 1974] describe the turbulent boundary layer adjacent to solid surfaces. Transient 

solutions are generated by a first-order, fully-implicit scheme. 

The fire combustion process is generally modelled using an eddy break-up assumption 

[Magnussen & Hjertager, 1976] in which the fuel pyrolysis rate is specified as a boundary 

condition. Combustion is then calculated at all control volumes as a function of fuel concentration, oxygen concentration and the local turbulent time-scale (provided by the κ-ε model). 

A simple one-step, infinitely fast chemical reaction is assumed. The eddy break-up model is 

appropriate for turbulent diffusion flames characteristic of fire, where the rate of reaction is 

controlled by the comparatively slow mixing of fuel with oxygen. Complete oxidation of the 

fuel is assumed when sufficient oxygen is available. 

Radiant heat transfer is modelled with either the six-flux model [Gosman & Lockwood, 1973], 

which assumes that radiant transfer is normal to the co-ordinate directions or potentially 

more accurate discrete transfer method [Lockwood & Shah, 1981]. Local absorptionemission properties are computed using a mixed grey-gas model [Truelove, 1976], which 

calculates the local absorption coefficient as a function of temperature and gas species concentrations. 

Thermal conduction into solid boundaries may be included by means of a quasi-steady, 

semi-infinite, one-dimensional assumption, which is appropriate for many smoke movement 

applications. Alternatively, the solution of the one-dimensional heat conduction equation into 

the solid is also available. In both methods, the purpose of the solid-phase conduction calculation is to generate the solid surface temperature, at each control volume adjacent to a solid 

boundary at each time step, by balancing the convection, radiation and conduction heat 

fluxes. The surface temperature then provides the (thermal) boundary condition for the next 

time-step of the CFD solution. 

JASMINE has been successfully used to simulate fire and smoke movement in a wide variety of construction projects (e.g. atria, hospitals, sport stadia, warehouses, tunnels, etc.), as 

well as in other applications such as a nuclear containment cell, transportation vehicles and 
2-5

marine ships. The references [Cox et al., 1987], [Miles, 2000] and [Miles, 2001] provide 

some examples of JASMINE validation exercises. The panel report [Miles, 2004] and the 

BRE technical annex (Appendix H) for the second benchmark exercise report the comparison of JASMINE calculations and measurement data for the smoke filling of a large hall. 

Information relevant to the application of JASMINE to this benchmark exercise is given below. 

• Main geometry and thermal boundary conditions. Dimensions of room, and also the door 

in Test 3, were modeled exactly as in the problem specification. The thermal properties 

of the walls, floor and ceiling were included as specified. Conduction losses to the room 

walls, ceiling and floor were included, using the one-dimensional heat conduction submodel available in JASMINE. Radiative and convective fluxes from the radiation/gas 

fields were calculated at each solid surface cell face at each numerical time step. 

• Leakage area for closed-door tests. A leakage area (vent) of width 0.17 m and height 

0.17 m, located at floor level, was used in the blind calculations. For the semi-blind calculations the dimensions were increased to 0.289 m by 0.289 m, and the leakage vent was 

again located at floor level. 

• Mechanical ventilation. In Test 4 mechanical ventilation was included, with the supply 

and extract vents located as specified. For the blind calculations a fixed mass flow rate 

was imposed, corresponding to 5 air changes per hour at ambient temperature. Note 

here that as the gas temperature inside the room increases the air changes per hour will 

also increase according to the reduction in density. The mechanical ventilation rate was 

adjusted in the semi-blind calculations to 1.157 kg s-1 according to the information supplied [Hamins, 2003a]. 

In the blind calculations the air supply was directed normal to the wall surface. However, 

for the semi-blind calculations the supply angle was adjusted to 45° as indicated in the information supplied [Hamins, 2003a]. 

• Fire specification. Combustion was included using the eddy break-up sub-model, assuming a heptane fuel source and a simple one-step chemical reaction to yield CO2 and H2O. 

As in the CFAST calculations the heat of combustion to 4.5 x 107

 J kg-1. Again, in the 

blind predictions the chemical energy release rate was exactly 1 x 106

 W and in the 

semi-blind simulations was adjusted to the suggested actual value. The heptane was as-
2-6

sumed to pyrolyse as a pool fire with area 2 m2, meaning that the fuel spray itself was 

not modeled. 

Oxygen limitation was not applied in the calculations. However, the oxygen concentration 

at the measurement location was 'tracked' and the experiment was assumed to terminate 

once the level had reduced to 17 % by mass (assumed to be approximately equivalent to 

15% by volume), which occurred only in Tests 2 and 4. 

A main limitation of the fire modeling adopted is the absence of a soot generation and 

subsequent radiation process. For the blind calculations 30 % of the heat was removed 

at the source to represent that which could be expected to be 'lost' by radiation from the 

sooty flame region above the fuel source. The remainder of this heat is assumed to be 

convected into the rest of the compartment or, as a relatively small fraction, by radiation 

from the plume region due to CO2 and H2O. Note also that of the heat convected into the 

compartment, some of this may subsequently be radiated from the smoke gases (due to 

CO2 and H2O). In some parametric calculations the heat 'lost' by radiation from the sooty 

flame region was reduced to zero. In the semi-blind calculations the figure used was either 35 % and 0 %. 

The note made above under CFAST regarding the choice of radiative fraction (here the 

heat 'lost' by radiation) and heat of combustion applies equally to CFD modeling. 

• Targets. The response at the target gauges 3, 4, 5, 6, 9 and 10 was included. Here local 

gas temperature and incident radiation fluxes were calculated. Cable target temperature 

calculations were not performed with JASMINE. However, comparisons of predicted and 

measured gas temperatures at locations in close vicinity to the cable target measurement locations were performed. 

• Radiation. The six-flux radiation model was employed throughout. This provides a reasonable and efficient treatment for radiation exchange between the hot smoke gases and 

the compartment boundaries. Its primary limitation with respect to this benchmark exercise is that the radiation intensities are modeled in the Cartesian axial directions, and so 

important off-axis directional information may be missed. This may have a consequence 

for the target heating calculations. 

Emission/absorption due to the presence of the primary products of combustion, i.e. CO2

and H2O, was included, but not soot (which was not explicitly included in the JASMINE 

calculations). 
2-7

• Other settings. A numerical mesh of approximately 100,000 cells was employed, with a 

limited grid sensitivity for Test 2 using 800,000 cells (times 2 in each direction). The numerical time-step was fixed at 2 s throughout. For all calculations the κ-ε turbulence 

model with buoyancy modifications was employed. 

2.3 Comparison of CFAST Blind and Semi-Blind Predictions with Measurements 

Results are presented in this section primarily as graphs that directly compare calculated 

quantities (blind and semi-blind predictions) against measurements made in the experimental program (Tests 2,3 and 4). In the various figures, the terms 'stg1' (i.e. stage 1) and 'stg2' 

(i.e. stage 2) have been adopted for blind the semi-blind calculations respectively. In some 

cases the prediction data has been plotted only until the fire was predicted to have been 

terminated (due to the oxygen concentration dropping below 15 % by volume). Likewise, the 

experimental measurement data in Tests 2 and 4 is plotted until the fuel supply was terminated for safety reasons (oxygen concentration at O2-2 dropping below 15 %). 

A number of parametric calculations (runs) were performed for each test in the blind (stg1) 

stage and a couple of additional ones in the semi-blind (stg2) phase. Table 2-1 summarizes 

the main features of each of these calculations. 

Table 2-1 CFAST calculation runs 

Test No. Blind or semi-blind and Run No. Leakage vent size 

(Tests 2 & 4) 

Radiative fraction 

 2 blind (stg1) run 1 0.17 m x 0.17 m 0.35 

 2 blind (stg1) run 2 0.17 m x 0.17 m 0 

 2 blind (stg1) run 3 0.17 m x 0.17 m 0.5 

 2 blind (stg1) run 4 0.34 m x 0.34 m 0.35 

 2 semi-blind (stg2) run 1 0.289 m x 0.289 m 0.44 

 3 blind (stg1) run 1 n/a 0.35 

 3 blind (stg1) run 2 n/a 0 

 3 blind (stg1) run 3 n/a 0.5 

 3 semi-blind (stg2) run 1 n/a 0.44 

 4 blind (stg1) run 1 0.17 m x 0.17 m 0.35 

 4 blind (stg1) run 2 0.17 m x 0.17 m 0 

 4 blind (stg1) run 3 0.17 m x 0.17 m 0.5 
2-8

Figs. 2-1 to 2-5 compare the predicted and measured upper and lower layer gas temperatures, layer heights, pressures, species concentrations and target incident radiation fluxes 

for Test 2. In the plots of target incident radiation flux at gauge 3 CFAST values are provided 

in both the downward direction (as in the measurement) and for comparative purposes also 

in the upward direction. 

Fig. 2-6 compares he predicted and measured surface temperatures at various cable target 

locations for run 1 of the blind and semi-blind stages. As CFAST models the targets a rectangular 'slabs' with a one-dimensional heat conduction treatment at each face, the figure 

includes the surface temperature as calculates assuming various slab orientations. This is 

important when performing a hazard analysis in order that the most critical direction(s) are 

accounted for. 

Figs. 2-7 to 2-11 repeat the above for Test 3, except that lower gas layer temperature, pressure and oxygen concentration are not plotted as these are not significant hazard variables 

with the door open. Finally, Figs. 2-12 to 2-17 provide the information for Test 4. 

The main observations and findings from the CFAST calculations are summarized below: 

• While the size of the infiltration opening for Test 2 had a major effect on the pressure 

inside the compartment (see Fig. 2-3), it had little influence on other calculated quantities. CFAST calculations suggest that the infiltration leakage area in the experiment may 

have been just above a critical value, below which pressure inside the compartment may 

have been expected to rise significantly, i.e. the experimental leakage area was just 

above this critical value, and so the measured pressures were relatively low. 

• Tests 2, 3 and 4 all suggest that a radiative fraction of at lease 0.35 is appropriate. Using 

a value of zero consistently resulted in hot gas layer temperatures being too high. The 

results actually suggest a value closer to 0.5. However, care should be required in reaching such a conclusion as the influence of the heat of combustion, fuel supply rate and 

heat losses to the boundaries all have a bearing too. 

• The layer height predictions were judged to be good. The apparent discrepancy in Tests 

2 and 4, where the measurement data suggests that the layer did not descend to the 

floor, whereas CFAST calculations indicate that it did, is most likely due to the numerical 

data reduction method employed in calculating layer height from the measured temperature data. 
2-9

• In Test 3, where the open door condition provided a 'classical' room fire scenario, the 

CFAST predictions for gas temperatures, gas species and incident radiant fluxes and 

door flows were judged to be in good agreement with the experimental measurements. 

See the remark above about the appropriate choice of radiative fraction. Note also that 

given the correct gas temperature, the incident radiant fluxes should be reasonable. 

• Apart from CO, the gas species predictions were in reasonable agreement to the measured values. Not being a major product of combustion, calculation of CO concentration is 

significantly more difficult than for CO2, which is a major product. 

• A notable feature of the CFAST predictions was that the calculated incident radiant 

fluxes were, in each Test, largely independent of location or orientation. However, in 

Tests 2 and 4 the measurements indicate a significant location and/or orientation dependency on the incident fluxes. Hence the agreement between predicted and measured 

incident radiant flux was quite variable for Tests 2 and 4. One cause of discrepancy is 

the fact zone models such as CFAST do not model most of the three dimensional effects 

of a compartment fire. 

• Given the level of discrepancy between the predicted and measured incident fluxes, the 

target surface temperature predictions were judged to be in reasonable agreement with 

the measured values. 

• The method used to implement mechanical ventilation in Test 4 (mechanical extract vent 

and a vertical natural vent for make-up air) seemed to have no significant implication for 

the quality of the CFAST predictions. An under prediction of compartment pressure may, 

however, be one consequence. 

• In Tests 2 and 4 CFAST consistently predicted that the test would terminate (lower layer 

oxygen concentration dropping below 15%) earlier than was the case in the experiment. 
2-10

Test 2 Upper Layer Temperature

275

325

375

425

475

525

575

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

CFAST stg1 run 4

CFAST stg2 run 1

Test 2 Lower Layer Temperature

275

325

375

425

475

525

575

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

CFAST stg1 run 4

CFAST stg2 run 1

Fig. 2-1 Measured and CFAST predicted gas layer temperatures for Test 2 
2-11

Test 2 Layer Height

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 120 240 360 480 600 720

Time (s)

Layer height (m)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

CFAST stg1 run 4

CFAST stg2 run 1

Fig. 2-2 Measured and CFAST predicted hot gas layer height for Test 2 

Test 2 Pressure (relative to ambient)

0

500

1000

1500

2000

2500

3000

3500

4000

0 120 240 360 480 600 720

Time (s)

Pressure (Pa)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

CFAST stg1 run 4

CFAST stg2 run 1

Fig. 2-3 Measured and CFAST predicted static pressure for Test 2
2-12

Test 2 Oxygen Concentration

0

5

10

15

20

25

0 120 240 360 480 600 720

Time (s)

Volume fraction (%)

Experiment (O2-1)

CFAST stg1 run 1 (HGL)

CFAST stg1 run 2 (HGL)

CFAST stg1 run 3 (HGL)

CFAST stg1 run 4 (HGL)

CFAST stg2 run 1 (HGL)

Test 2 Carbon Dioxide Concentration

0

1

2

3

4

5

6

7

8

0 120 240 360 480 600 720

Time (s)

Volume fraction (%)

Experiment (CO2-4)

CFAST stg1 run 1 (HGL)

CFAST stg1 run 2 (HGL)

CFAST stg1 run 3 (HGL)

CFAST stg1 run 4 (HGL)

CFAST stg2 run 1 (HGL)

Test 2 Carbon Monoxide Concentration

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0 120 240 360 480 600 720

Time (s)

Volume fraction (%)

Experiment (CO-3)

CFAST stg1 run 1 (HGL)

CFAST stg1 run 2 (HGL)

CFAST stg1 run 3 (HGL)

CFAST stg1 run 4 (HGL)

CFAST stg2 run 1 (HGL)

Fig. 2-4 Measured and CFAST predicted gas concentrations for Test 2 
2-13

Test 2 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720

Time (s)

Heat flux (W m -2)

Experiment Rad 3 (dow n)

CFAST stg1 run 1 (B up)

CFAST stg1 run 1 (B dow n)

CFAST stg1 run 1 (E up)

CFAST stg1 run 1 (E dow n)

Test 2 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720

Time (s)

Heat flux (W m -2)

Experiment Rad 5 (north)

CFAST stg1 run 1 (B north)

CFAST stg1 run 1 (E north)

Test 2 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720

Time (s)

Heat flux (W m -2)

Experiment Rad 10 south)

CFAST stg1 run 1 (G south)

Fig. 2-5 Measured and CFAST predicted incicent fluxes for Test 2. 
2-14

Test 2 Target Surface Temperatures

275

325

375

425

475

525

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment E-TS-16

CFAST stg1 run 1 (E up)

CFAST stg1 run 1 (E dow n)

CFAST stg1 run 1 (E north)

CFAST stg2 run 1 (E up)

CFAST stg2 run 1 (E dow n)

CFAST stg2 run 1 (E north)

Test 2 Target Surface Temperatures

275

325

375

425

475

525

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment B-TS-14

CFAST stg1 run 1 (B up)

CFAST stg1 run 1 (B dow n)

CFAST stg1 run 1 (B north)

CFAST stg2 run 1 (B up)

CFAST stg2 run 1 (B dow n)

CFAST stg2 run 1 (B north)

Test 2 Target Surface Temperatures

275

325

375

425

475

525

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment VC-TS-33

CFAST stg1 run 1 (G south)

CFAST stg2 run 1 (G south)

Fig. 2-6 Measured and CFAST predicted target surface temperatures for Test 2 
2-15

Test 3 Upper Layer Temperature

275

325

375

425

475

525

575

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

CFAST stg2 run 1

Fig. 2-7 Measured and CFAST predicted upper gas layer temperatures for Test 3 

Test 3 Layer Height

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 240 480 720 960 1200 1440

Time (s)

Layer height (m)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

CFAST stg2 run 1

Fig. 2-8 Measured and CFAST predicted hot gas layer height for Test 3 
2-16

Test 3 Carbon Dioxide Concentration

0

1

2

3

4

5

6

7

8

0 240 480 720 960 1200 1440

Time (s)

Volume fraction (%)

Experiment (CO2-4)

CFAST stg1 run 1 (HGL)

CFAST stg1 run 2 (HGL)

CFAST stg1 run 3 (HGL)

CFAST stg2 run 1 (HGL)

Test 3 Carbon Monoxide Concentration

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0 240 480 720 960 1200 1440

Time (s)

Volume fraction (%)

Experiment (CO-3)

CFAST stg1 run 1 (HGL)

CFAST stg1 run 2 (HGL)

CFAST stg1 run 3 (HGL)

CFAST stg2 run 1 (HGL)

Fig. 2-9 Measured and CFAST predicted gas concentrations for Test 3 
2-17

Test 3 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 240 480 720 960 1200 1440

Time (s)

Heat flux (W m -2)

Experiment Rad 3 (dow n)

CFAST stg1 run 1 (B up)

CFAST stg1 run 1 (B dow n)

CFAST stg1 run 1 (E up)

CFAST stg1 run 1 (E dow n)

Test 3 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 240 480 720 960 1200 1440

Time (s)

Heat flux (W m -2)

Experiment Rad 5 (north)

CFAST stg1 run 1 (B north)

CFAST stg1 run 1 (E north)

Test 3 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 240 480 720 960 1200 1440

Time (s)

Heat flux (W m -2)

Experiment Rad 10 (south)

CFAST stg1 run 1 (G south)

Fig. 2-10 Measured and CFAST predicted incicent fluxes for Test 3 
2-18

Test 3 Target Surface Temperatures

275

325

375

425

475

525

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment B-TS-14

CFAST stg1 run 1 (B up)

CFAST stg1 run 1 (B dow n)

CFAST stg1 run 1 (B north)

CFAST stg2 run 1 (B up)

CFAST stg2 run 1 (B dow n)

CFAST stg2 run 1 (B north)

Test 3 Target Surface Temperatures

275

325

375

425

475

525

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment E-TS-16

CFAST stg1 run 1 (E up)

CFAST stg1 run 1 (E dow n)

CFAST stg1 run 1 (E north)

CFAST stg2 run 1 (E up)

CFAST stg2 run 1 (E dow n)

CFAST stg2 run 1 (E north)

Test 3 Target Surface Temperatures

275

325

375

425

475

525

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment VC-TS-33

CFAST stg1 run 1 (G south)

CFAST stg2 run 1 (G south)

Fig. 2-11 Measured and CFAST predicted target surface temperatures for Test 3 
2-19

Test 4 Upper Layer Temperature

275

325

375

425

475

525

575

0 120 240 360 480 600 720 840

Time (s)

Temperature (K)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

Test 4 Lower Layer Temperature

275

325

375

425

475

525

575

0 120 240 360 480 600 720 840

Time (s)

Temperature (K)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

Fig. 2-12 Measured and CFAST predicted gas layer temperatures for Test 4 
2-20

Test 4 Layer Height

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 120 240 360 480 600 720 840

Time (s)

Layer height (m)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

Fig. 2-13 Measured and CFAST predicted hot gas layer height for Test 4 

Test 4 Pressure (relative to ambient)

-60

-40

-20

0

20

40

60

0 120 240 360 480 600 720 840

Time (s)

Pressure (Pa)

Experiment

CFAST stg1 run 1

CFAST stg1 run 2

CFAST stg1 run 3

Fig. 2-14 Measured and CFAST predicted static pressure for Test 4 
2-21

Test 4 Oxygen Concentration

0

5

10

15

20

25

0 120 240 360 480 600 720 840

Time (s)

Volume fraction (%)

Experiment (O2-1)

CFAST stg1 run 1 (HGL)

CFAST stg1 run 2 (HGL)

CFAST stg1 run 3 (HGL)

Test 4 Carbon Dioxide Concentration

0

1

2

3

4

5

6

7

8

0 120 240 360 480 600 720 840

Time (s)

Volume fraction (%)

Experiment (CO2-4)

CFAST stg1 run 1 (HGL)

CFAST stg1 run 2 (HGL)

CFAST stg1 run 3 (HGL)

Test 4 Carbon Monoxide Concentration

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0 120 240 360 480 600 720 840

Time (s)

Volume fraction (%)

Experiment (CO-3)

CFAST stg1 run 1 (HGL)

CFAST stg1 run 2 (HGL)

CFAST stg1 run 3 (HGL)

Fig. 2-15 Measured and CFAST predicted gas concentrations for Test 4 
2-22

Test 4 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720 840

Time (s)

Heat flux (W m -2)

Experiment Rad 3 (dow n)

CFAST stg1 run 1 (B up)

CFAST stg1 run 1 (B dow n)

CFAST stg1 run 1 (E up)

CFAST stg1 run 1 (E dow n)

Test 4 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720 840

Time (s)

Heat flux (W m -2)

Experiment Rad 5 (north)

CFAST stg1 run 1 (B north)

CFAST stg1 run 1 (E north)

Test 4 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720 840

Time (s)

Heat flux (W m -2)

Experiment Rad 10 (south)

CFAST stg1 run 1 (G south)

Fig. 2-16 Measured and CFAST predicted incicent fluxes for Test 4 
2-23

Test 4 Target Surface Temperatures

275

325

375

425

475

525

0 120 240 360 480 600 720 840

Time (s)

Temperature (K)

Experiment B-TS-14

CFAST stg1 run 1 (B up)

CFAST stg1 run 1 (B dow n)

CFAST stg1 run 1 (B north)

Test 4 Target Surface Temperatures

275

325

375

425

475

525

0 120 240 360 480 600 720 840

Time (s)

Temperature (K)

Experiment E-TS-16

CFAST stg1 run 1 (E up)

CFAST stg1 run 1 (E dow n)

CFAST stg1 run 1 (E north)

Test 4 Target Surface Temperatures

275

325

375

425

475

525

0 120 240 360 480 600 720 840

Time (s)

Temperature (K)

Experiment VC-TS-33

CFAST stg1 run 1 (G south)

Fig. 2-17 Measured and CFAST predicted target surface temperatures for Test 4 
2-24

2.4 Comparison of JASMINE Blind and Semi-Blind Predictions with Measurements 

A number of parametric calculations (runs) were performed for each test in the blind (stg1) 

stage, followed by some additional runs in the semi-blind (stg2) phase. Table 2-2 summarizes the main features of each of these calculations. 

Table 2-2 JASMINE calculation runs 

Test No. Blind or semi-blind and Run No. Leakage vent size 

(Tests 2 & 4) 

Heat lost by soot 

radiation 

 2 blind (stg1) run 1 0.17 m x 0.17 m 30% 

 2 blind (stg1) run 2 0.17 m x 0.17 m 0 

 2 semi-blind (stg2) run 1 0.289 m x 0.289 m 35% 

 2 semi-blind (stg2) run 2 0.289 m x 0.289 m 0 

 3 blind (stg1) run 1 n/a 30% 

 3 blind (stg1) run 2 n/a 0 

 4 blind (stg1) run 1 0.17 m x 0.17 m 30% 

 4 blind (stg1) run 2 0.17 m x 0.17 m 0 

 4 semi-blind (stg2) run 1 0.289 m x 0.289 m 35% 

 4 semi-blind (stg2) run 2 0.289 m x 0.289 m 0 

Fig. 2-18 illustrates the single-block, Cartesian grid used in the JAMSINE calculations, which 

included approximately 100,000 cells. Note that the grid is refined at the fire source and 

vents, towards the walls and ceiling and at the locations of the target cables. The minimum 

cell dimensions were 0.075 m in the x direction (see Fig. 2-18), 0.04 m in the y direction and 

0.0425 m in the z direction. The maximum cell dimension inside the compartment was 0.2 m 

in each direction. 

Figs. 2-19 to 2-21 illustrate the development of gas temperatures over the first 12 minutes in 

the JASMINE calculations for Tests 2, 3 and 4 (stg1 run 1 in each case). 

Figs. 2-22 to 2-26 compare the predicted and measured gas temperatures (at selected 

measurement locations), pressures, species concentrations and target incident radiation 

fluxes for Test 2. In the plots of target incident radiation flux, predicted values are given for 
2-25

fluxes onto a surface with a normal in the specified direction and also, for comparative purposes, from in the opposite direction (identified in the captions as 'opp rad 3' etc), e.g. for 

cable radiation gauge 3 the specified direction is 'pointing down' so that the 'opp rad 3' surface normal is therefore 'pointing up'. 

While JASMINE calculations for the target cable temperatures were not performed, Fig. 2-27 

compares the predicted and measured gas temperatures of various cable target locations 

(actually in close vicinity to). Finally, Fig. 2-28 shows the principle calculated heat losses for 

a blind calculation (run 1) for Test 2. Here the convected heat to the solids is the heat transfer to the walls etc and the transfer to radiation is the heat removed from the gas phase to 

the radiation field, from where it is transferred mainly to the walls etc. 

Figs. 2-29 to 2-34 repeat the above for Test 3, except that pressure is not plotted as it is not 

a significant hazard variable with the door open. Also, the predicted and measured door 

mass flow rates are compared and the graphs showing the principle heat losses include a 

plot of the convected heat that passes through the open door. Finally, Figs. 2-35 to 2-41 provide the information for Test 4. 

The main observations and findings from the JASMINE calculations are summarized below: 

• As in the CFAST work, the assumed size of the leakage vent in Test 2 was found to be 

very sensitive (see Fig. 2-24). Furthermore, the calculations exhibited some convergence 

difficulties once the compartment pressure had increased significantly. In Test 4, increasing the area of the leakage vent to that suggested for the semi-blind calculations had a 

significant effect on the predicted pressure, bringing the value close to the measured 

value. It seems perhaps obvious that specifying a small opening to represent the total 

leakage/infiltration area has limitations. A better approach may be to distribute the leakage area over a entire wall (or walls) in some way. This requires further development. 

• The predicted quantities in Test 3 (with the open door) were, in the main, in reasonable 

agreement with the measured values. The gas temperatures were accurately captured in 

the run where 30% of the heat release rate was assumed to be removed due to soot radiation from the burning region. Where no heat removal was assumed the gas temperatures were then too high. 

The door flow rates were captured accurately in Test 3. There was, however, a notable 

discrepancy between predicted and measured incident radiant fluxes, with JASMINE 

tending to under predict the values. This is quite likely due to the six-flux radiation model 
2-26

used, which considers radiation transport in the three Cartesian directions. The more accurate discrete transfer radiation model, which traces rays in many directions, could be 

expected to provide more accurate predictions for target incident flux in scenarios such 

as the tests in this benchmark exercise. 

• In Tests 2 and 4 the predicted gas temperatures were, in general, in closer agreement to 

the measured values when 30% to 35% of the heat release rate was assumed to be removed due to soot radiation from the burning region (compared to where no heat was 

removed). 

While the gas temperatures were judged to be reasonable, there was a noticeable collapse of the thermal gradient (cooler lower down and hotter above) in the JASMINE predictions later in the simulations where there was a significant increase in compartment 

pressure. This was observed to a much lesser extent in the experiments. Note that in the 

semi-blind run for Test 4, where the pressure did not increase significantly, the thermal 

gradient did not collapse. 

• Gas species predictions were, in general, in reasonable agreement with the measured 

values. Furthermore, for Tests 2 and 4 the time predicted for the test to terminate (due to 

the lower layer oxygen concentration dropping below 15%) was generally similar to that 

in the experiment. However, in the runs for Test 4 where 30% to 35% of the heat release 

rate was assumed to be removed due to soot radiation the test was predicted to continue 

for its full duration, i.e. the oxygen level remained above the critical value. 

• As for Test 3, the predicted incident radiant fluxes in Tests 2 and 4 were generally lower 

than those measured. Again, a likely reason is the choice of the radiation sub-model. 

• The energy 'budgets' shown in Figs. 2-28, 2-34 and 2-41 are quite informative. For Test 

3 the JASMINE calculations indicate that approximately as much heat is 'lost' to radiation 

(due to the presence of CO2 and H2O) as is convected through the open door. Most of 

this radiated heat is subsequently transferred to the walls, ceiling and floor. The amount 

of heat transferred to the walls etc by convection is significantly less. 

• A general note from the JASMINE work is that the presence of soot, and the subsequent 

radiation absorption and emission, may have an important bearing on the gas temperatures predicted. This in turn influences the radiation fluxes significantly (bearing in mind 

the T4

 dependency on radiant intensity), which then has a major influence on the conduction into the walls and targets and their temperature rise. 
2-27

Fig. 2-18 JASMINE CFD grid 

outside compartment 
2-28

Fig. 2-19 JASMINE calculated temperature rise for Test 2, run 1 

T=240s

T=120s

T=360s

T=480s

T=600s

T=720s

T=240s

T=120s

T=360s

T=480s

T=600s

T=720s
2-29

Fig. 2-20 JASMINE calculated temperature rise for Test 3, run 1 

T=240s

T=120s

T=360s

T=480s

T=600s

T=720s

T=240s

T=120s

T=360s

T=480s

T=600s

T=720s

T=240s

T=120s

T=360s

T=480s

T=600s

T=720s
2-30

Fig. 2-21 JASMINE calculated temperature rise for Test 4, run 1 

T=240s

T=120s

T=360s

T=480s

T=600s

T=720s

T=240s

T=120s

T=360s

T=480s

T=600s

T=720s

T=240s

T=120s

T=360s

T=480s

T=600s

T=720s
2-31

Test 2 Tree 7 Temperature

275

325

375

425

475

525

575

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg1 run 1 T7.2

JAS stg1 run 1 T7.4

JAS stg1 run 1 T7.6

JAS stg1 run 1 T7.8

JAS stg1 run 1 T7.10

Test 2 Tree 7 Temperature

275

325

375

425

475

525

575

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg1 run 2 T7.2

JAS stg1 run 2 T7.4

JAS stg1 run 2 T7.6

JAS stg1 run 2 T7.8

JAS stg1 run 2 T7.10

Fig. 2-22 Measured and JASMINE predicted (blind) gas temperatures for Test 2 at Tree 7 
2-32

Test 2 Tree 7 Temperature

275

325

375

425

475

525

575

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg2 run 1 T7.2

JAS stg2 run 1 T7.4

JAS stg2 run 1 T7.6

JAS stg2 run 1 T7.8

JAS stg2 run 1 T7.10

Test 2 Tree 7 Temperature

275

325

375

425

475

525

575

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg2 run 2 T7.2

JAS stg2 run 2 T7.4

JAS stg2 run 2 T7.6

JAS stg2 run 2 T7.8

JAS stg2 run 2 T7.10

Fig. 2-23 Measured and JASMINE (semi-blind) gas temperatures for Test 2 at Tree 7 
2-33

Fig. 2-24 Measured and JASMINE predicted static pressure for Test 2 

Test 2 Static Pressure (relative to ambient)

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720

Time (s)

Pressure (Pa)

Experiment

JAS stg1 run 1

JAS stg1 run 2

JAS stg2 run 1

JAS stg2 run 2

Note that JASMINE exhibited some convergence difficulties due to pressure build up 
2-34

Test 2 Carbon Dioxide Concentration

0

1

2

3

4

5

6

7

8

0 120 240 360 480 600 720

Time (s)

Volume or mass fraction 

(%)

Experiment (CO2-4)

JAS stg1 run 1 (CO2-4)

JAS stg1 run 2 (CO2-4)

JAS stg2 run 1 (CO2-4)

JAS stg2 run 2 (CO2-4)

Fig. 2-25 Measured and JASMINE predicted gas concentrations for Test 2 

Test 2 Oxygen Concentration

0

5

10

15

20

25

0 120 240 360 480 600 720

Time (s)

Volume or mass fraction 

(%)

Experiment (O2-1)

JAS stg1 run 1 (O2-1)

JAS stg1 run 2 (O2-1)

JAS stg2 run 1 (O2-1)

JAS stg2 run 2 (O2-1)

Note this is a plot at O2-1 (upper layer) and that JASMINE data is a percentage by mass 
2-35

Test 2 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720

Time (s)

Heat flux (W m^-2)

Experiment Rad 3

JAS stg1 run 1 rad 3

JAS stg1 run 2 rad 3

JAS stg2 run 1 rad 3

JAS stg2 run 2 rad 3

JAS stg1 run1 opp rad 3

JAS stg1 run2 opp rad 3

JAS stg2 run1 opp rad 3

JAS stg2 run2 opp rad 3

Test 2 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720

Time (s)

Heat flux (W m^-2)

Experiment Rad 5

JAS stg1 run 1 rad 5

JAS stg1 run 2 rad 5

JAS stg2 run 1 rad 5

JAS stg2 run 2 rad 5

JAS stg1 run1 opp rad 5

JAS stg1 run2 opp rad 5

JAS stg2 run1 opp rad 5

JAS stg2 run2 opp rad 5

Test 2 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 120 240 360 480 600 720

Time (s)

Heat flux (W m^-2)

Experiment Rad 10

JAS stg1 run 1 rad 10

JAS stg1 run 2 rad 10

JAS stg2 run 1 rad 10

JAS stg2 run 2 rad 10

Fig. 2-26 Measured and JASMINE predicted incicent fluxes for Test 2 
2-36

Test 2 Target Gas Temperatures

275

325

375

425

475

525

575

625

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment T 4-8

JAS stg1 run 1 (T 4-8)

JAS stg1 run 2 (T 4-8)

JAS stg2 run 1 (T 4-8)

JAS stg2 run 2 (T 4-8)

Test 2 Target Gas Temperatures

275

325

375

425

475

525

575

625

0 120 240 360 480 600 720

Time (s)

Temperature (K)

Experiment T 2-5

JAS stg1 run 1 (T 2-5)

JAS stg1 run 2 (T 2-5)

JAS stg2 run 1 (T 2-5)

JAS stg2 run 2 (T 2-5)

Fig. 2-27 Measured and JASMINE predicted gas temperatures near cable targets for Test 2 
2-37

Test 2 Heat Losses

-8.0E+05

-7.0E+05

-6.0E+05

-5.0E+05

-4.0E+05

-3.0E+05

-2.0E+05

-1.0E+05

0.0E+00

0 120 240 360 480 600 720

Time (s)

Heat flow rate (W)

JAS stg1 run 1 (conv to solids)

JAS stg1 run 1 (transfer to radn)

JAS stg1 run 1 (total)

Fig. 2-28 JASMINE predicted heat losses for Test 2 
2-38

Test 3 Tree 7 Temperature

275

325

375

425

475

525

575

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg1 run 1 T7.2

JAS stg1 run 1 T7.4

JAS stg1 run 1 T7.6

JAS stg1 run 1 T7.8

JAS stg1 run 1 T7.10

Test 3 Tree 7 Temperature

275

325

375

425

475

525

575

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg1 run 2 T7.2

JAS stg1 run 2 T7.4

JAS stg1 run 2 T7.6

JAS stg1 run 2 T7.8

JAS stg1 run 2 T7.10

Fig. 2-29 Measured and JASMINE predicted (blind) gas temperatures for Test 3 at Tree 7 
2-39

Test 3 Carbon Dioxide Concentration

0

1

2

3

4

5

6

7

8

0 240 480 720 960 1200 1440

Time (s)

Volume or mass fraction 

(%)

Experiment (CO2-4)

JAS stg1 run 1 (CO2-4)

JAS stg1 run 2 (CO2-4)

Fig. 2-30 Measured and JASMINE predicted CO2 concentrations for Test 3 

Test 3 Door Mass Flow

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

0 240 480 720 960 1200 1440

Time (s)

Flow rate (kg s^-1)

Experiment door in

Experiment door out

JAS stg1 run 1 (door in)

JAS stg1 run 1 (door out)

JAS stg1 run 2 (door in)

JAS stg1 run 2 (door out)

Fig. 2-31 Measured and JASMINE door mass fkow rates for Test 3 
2-40

Test 3 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 240 480 720 960 1200 1440

Time (s)

Heat flux (W m^-2)

Experiment Rad 3

JAS stg1 run 1 rad 3

JAS stg1 run 2 rad 3

JAS stg1 run 1 opp rad 3

JAS stg1 run 2 opp rad 3

Test 3 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 240 480 720 960 1200 1440

Time (s)

Heat flux (W m^-2)

Experiment Rad 5

JAS stg1 run 1 rad 5

JAS stg1 run 2 rad 5

JAS stg1 run 1 opp rad 5

JAS stg1 run 2 opp rad 5

Test 3 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 240 480 720 960 1200 1440

Time (s)

Heat flux (W m^-2)

Experiment Rad 10

JAS stg1 run 1 rad 10

JAS stg1 run 2 rad 10

Fig. 2-32 Measured and JASMINE predicted incicent fluxes for Test 3 
2-41

Test 3 Target Gas Temperatures

275

325

375

425

475

525

575

625

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T 4-8

JAS stg1 run 1 (T 4-8)

JAS stg1 run 2 (T 4-8)

Test 3 Target Gas Temperatures

275

325

375

425

475

525

575

625

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T 2-5

JAS stg1 run 1 (T 2-5)

JAS stg1 run 2 (T 2-5)

Fig. 2-33 Measured and JASMINE predicted gas temperatures near cable targets for Test 3 
2-42

Test 3 Heat Losses

-8.0E+05

-7.0E+05

-6.0E+05

-5.0E+05

-4.0E+05

-3.0E+05

-2.0E+05

-1.0E+05

0.0E+00

0 240 480 720 960 1200 1440

Time (s)

Heat flow rate (W)

Experiment conv thru door

JAS stg1 run 1 (conv to solids)

JAS stg1 run 1 (transfer to radn)

JAS stg1 run 1 (conv thru door)

JAS stg1 run 1 (total)

Test 3 Heat Losses

-1.0E+06

-9.0E+05

-8.0E+05

-7.0E+05

-6.0E+05

-5.0E+05

-4.0E+05

-3.0E+05

-2.0E+05

-1.0E+05

0.0E+00

0 240 480 720 960 1200 1440

Time (s)

Heat flow rate (W)

Experiment conv thru door

JAS stg1 run 2 (conv to solids)

JAS stg1 run 2 (transfer to radn)

JAS stg1 run 2 (conv thru door)

JAS stg1 run 2 (total)

Fig. 2-34 JASMINE predicted heat losses for Test 3 
2-43

Test 4 Tree 7 Temperature

275

325

375

425

475

525

575

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg1 run 1 T7.2

JAS stg1 run 1 T7.4

JAS stg1 run 1 T7.6

JAS stg1 run 1 T7.8

JAS stg1 run 1 T7.10

Test 4 Tree 7 Temperature

275

325

375

425

475

525

575

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg1 run 2 T7.2

JAS stg1 run 2 T7.4

JAS stg1 run 2 T7.6

JAS stg1 run 2 T7.8

JAS stg1 run 2 T7.10

Fig. 2-35 Measured and JASMINE predicted (blind) gas temperatures for Test 4 at Tree 7 
2-44

Test 4 Tree 7 Temperature

275

325

375

425

475

525

575

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg2 run 1 T7.2

JAS stg2 run 1 T7.4

JAS stg2 run 1 T7.6

JAS stg2 run 1 T7.8

JAS stg2 run 1 T7.10

Test 4 Tree 7 Temperature

275

325

375

425

475

525

575

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T7.2

Experiment T7.4

Experiment T7.6

Experiment T7.8

Experiment T7.10

JAS stg2 run 2 T7.2

JAS stg2 run 2 T7.4

JAS stg2 run 2 T7.6

JAS stg2 run 2 T7.8

JAS stg2 run 2 T7.10

Fig. 2-36 Measured and JASMINE predicted (semi-blind) gas temperatures, Test 4 at Tree 

7 
2-45

Test 4 Pressure (relative to ambient)

0

25

50

75

100

125

150

175

200

0 240 480 720 960 1200 1440

Time (s)

Pressure (Pa)

Experiment

JAS stg1 run 1

JAS stg1 run 2

JAS stg2 run 1

JAS stg2 run 2

Fig. 2-37 Measured and JASMINE predicted static pressure for Test 4 
2-46

Test 4 Carbon Dioxide Concentration

0

1

2

3

4

5

6

7

8

0 240 480 720 960 1200 1440

Time (s)

Volume or mass fraction 

(%)

Experiment (CO2-4)

JAS stg1 run 1 (CO2-4)

JAS stg1 run 2 (CO2-4)

JAS stg2 run 2 (CO2-4)

JAS stg2 run 2 (CO2-4)

Fig. 2-38 Measured and JASMINE predicted gas concentrations for Test 4 

Note this is a plot at O2-1 (upper layer) and that JASMINE data is a percentage by mass 

Test 4 Oxygen Concentration

0

5

10

15

20

25

0 240 480 720 960 1200 1440

Time (s)

Volume or mass fraction 

(%)

Experiment (O2-1)

JAS stg1 run 1 (O2-1)

JAS stg1 run 2 (O2-1)

JAS stg2 run 2 (O2-1)

JAS stg2 run 2 (O2-1)
2-47

Test 4 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 240 480 720 960 1200 1440

Time (s)

Heat flux (W m^-2)

Experiment Rad 3

JAS stg1 run 1 rad 3

JAS stg1 run 2 rad 3

JAS stg2 run 1 rad 3

JAS stg2 run 2 rad 3

JAS stg1 run1 opp rad 3

JAS stg1 run2 opp rad 3

JAS stg2 run1 opp rad 3

JAS stg2 run2 opp rad 3

Test 4 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 240 480 720 960 1200 1440

Time (s)

Heat flux (W m^-2)

Experiment Rad 5

JAS stg1 run 1 rad 5

JAS stg1 run 2 rad 5

JAS stg2 run 1 rad 5

JAS stg2 run 2 rad 5

JAS stg1 run1 opp rad 5

JAS stg1 run2 opp rad 5

JAS stg2 run1 opp rad 5

JAS stg2 run2 opp rad 5

Test 4 Incident Radiation Fluxes

0

1000

2000

3000

4000

5000

6000

7000

8000

0 240 480 720 960 1200 1440

Time (s)

Heat flux (W m^-2)

Experiment Rad 10

JAS stg1 run 1 rad 10

JAS stg1 run 2 rad 10

JAS stg2 run 1 rad 10

JAS stg2 run 2 rad 10

Fig. 2-39 Measured and JASMINE predicted incicent fluxes for Test 4 
2-48

Test 4 Target Gas Temperatures

275

325

375

425

475

525

575

625

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T 4-8

JAS stg1 run 1 (T 4-8)

JAS stg1 run 2 (T 4-8)

JAS stg2 run 1 (T 4-8)

JAS stg2 run 2 (T 4-8)

Test 4 Target Gas Temperatures

275

325

375

425

475

525

575

625

0 240 480 720 960 1200 1440

Time (s)

Temperature (K)

Experiment T 2-5

JAS stg1 run 1 (T 2-5)

JAS stg1 run 2 (T 2-5)

JAS stg2 run 1 (T 2-5)

JAS stg2 run 2 (T 2-5)

Fig. 2-40 Measured and JASMINE predicted gas temperatures near cable targets for Test 4 
2-49

Test 4 Heat Losses

-8.0E+05

-7.0E+05

-6.0E+05

-5.0E+05

-4.0E+05

-3.0E+05

-2.0E+05

-1.0E+05

0.0E+00

0 240 480 720 960 1200 1440

Time (s)

Heat flow rate (W)

JAS stg2 run 1 (conv to solids)

JAS stg2 run 1 (transfer to radn)

JAS stg2 run 1 (conv thru vent)

JAS stg2 run 1 (total)

Fig. 2-41 JASMINE predicted heat losses for Test 4 
2-50

2.5 Conclusions and Recommendations for CFAST and JASMINE 

The main findings from both the CFAST and JASMINE work were reported in the previous 

sections. The main points raised, and some recommendations, are given below: 

• For both CFAST and JASMINE the results were judged to be encouraging when interpreted correctly and the limitations of the various modeling assumptions acknowledged. 

Test 3, with the open door, was relatively easy to model with both the zone and CFD approach. However, due to the ventilation restrictions, Tests 2 and 4 (closed compartment) 

were more difficult with both models and care was required when performing the calculations. 

• The predicted pressure rise, in Tests 2 and 4, was very sensitive to the size of infiltration 

opening used in the calculation. It was concluded that using a single opening to represent all the leakage paths may not be the best approach. It is clear that where a fire 

compartment is closed and the calculation of pressure is important that a sensitivity 

analysis is performed as the initial choice of leakage area may be close to the critical 

value in respect to any significant pressure effects. The level of numerical convergence 

needs to be considered when modeling closed compartments. This may be especially 

true of CFD models. 

• A radiative fraction of at least 0.3 in CFAST was found appropriate. A lower value resulted in calculated gas temperatures being too high. Indeed, a value of 0.5 provided the 

closest agreement between calculated and measured gas temperature. However, it 

should be recalled that the choice of the heat of combustion, the fuel supply rate and the 

heat losses to the boundaries may all have a significant bearing too. 

For JASMINE it was found that assigning 30 % to 35 % of the heat release to radiation 

from soot particles (in the 'plume') was an appropriate choice. This was borne out especially in Test 3 where a choice of 30 % yielded accurate gas temperature predictions. It 

should be noted that while radiation absorption and emission due to the presence of CO2

and H2O was included in the JASMINE calculations, and also the subsequent radiation 

heat transfer to the solid boundaries, the contribution due to soot particles was neglected. This may be important for target response predictions. 

As in previous benchmark exercises, see [US NRC, 2002] and [Miles, 2004], the appropriate choice of radiative fraction, or soot alternative modeling methodology, is consid-
2-51

ered to be a critical parameter for a reliable hazard analysis. For CFD models such as 

JASMINE the implementation of a reasonably simple, yet effective, soot modeling and 

radiation treatment is recommended. Earlier work in this area was performed by Magnussen and coworkers, e.g. [Magnussen et. al., 1979], here extending the concept of the 

eddy breakup combustion model. Some work on a more empirical approach to soot 

modeling for CFD applications has been reported recently [Lautenberger et. al., 2005]. 

• The choice of lower oxygen limit (LOL) in CFAST is another combustion related parameter that can have an important bearing on the hazard development. However, as the experiments were effectively terminated once the oxygen level had dropped below 15%, 

there was only limited scope to address this parameter in the current benchmark exercise. However, for Tests 2 and 4 CFAST predicted time to termination of the test (fuel 

supply) was notably earlier than in the experiment. By comparison, JASMINE tended to 

either predict about the right time for the duration of the experiment or a significantly 

longer time, e.g. in Test 4 with 30 to 35% of the heat release rate removed due to soot 

radiation the calculations indicated, in contrast to the actual experiment, that the test 

would not terminate. 

• The value in reducing the compartment space into an upper and lower gas layer is perhaps questionable for scenarios such as Tests 2 and 4 where there is significant mixing. 

Nonetheless, CFAST calculated that the layer interface height dropped to floor level 

within the first few minutes for both tests, and this can probably be interpreted as a correct behavior. 

While for Test 3 JASMINE predicted approximately the correct degree of thermal stratification, for Tests 2 and 4 it tended to under-predict the level of stratification, i.e. the calculated level of mixing was greater than that observed. This was particularly apparent in the 

later stage in those cases where the compartment pressure was predicted to rise significantly, where once the calculated pressure started to rise strongly the compartment became well mixed, i.e. no stratification. This may be due, in part at least, to numerical nonconvergence. The effect was not observed in the semi-blind calculations for Test 4 where 

the leakage area was increased to the recommended value. 

• Carbon monoxide predictions, using CFAST, were similar to the measurements only in 

the early stages of the tests. As each test proceeded the predicted level of CO was notably higher than that measured. This may have been due in part to the difficultly associated in modeling CO generation compared to the major products of combustion (CO2

and H2O). CO predictions were not made with JASMINE. 
2-52

• The method used to implement mechanical ventilation in the CFAST calculation for Test 

4 (mechanical extract vent and a vertical natural vent for make-up air) seemed to have 

no significant implication in terms of for the quality of the predictions. An under-prediction 

of compartment pressure may, however, be one consequence. 

• For the CFAST predictions the calculated incident radiant fluxes were, in each test, 

largely independent of location or orientation. However, in Tests 2 and 4 the measurements indicate a significant location and/or orientation dependency on the incident fluxes 

and so the agreement between predicted and measured incident radiant flux was quite 

variable for these tests. One cause of discrepancy is the fact zone models such as 

CFAST do not model most of the three dimensional effects of a compartment fire. 

JASMINE tended to under-predict incident radiant flux in all tests. This is likely due, in 

part at least, to the use of the six-flux radiation model which biases the radiant flux information in the three Cartesian directions. It may be due also to the absence of an explicit 

soot treatment. 

For both CFAST and JASMINE, the surface temperature calculations were judged to be 

reasonable given the accuracy of the incident fluxes. It can be argued that given reasonable incident flux predictions the surface (and interior) target temperatures may be expected to be reasonable provided the target structure is not too complicated. As in the 

previous benchmark exercises, it is recommended that further consideration be given to 

the most appropriate way to treat target response assessment, e.g. purely as a postprocess outside the primary fire model or more integrated into the fire simulation. 
2-53

2.6 References 

Cox G., Kumar S. & Markatos N.C. Some field model validation studies. Fire Safety Science 

– Proceedings of the First International Symposium, Hemisphere Publishing, pp. 

159 -171, 1986. 

Cox G. & Kumar S. Field modelling of fire in forced ventilated enclosures. Combustion. Science and Technology, vol. 52, pp. 7-23, 1987. 

Gosman A.D. & Lockwood F.C. Incorporation of a flux model for radiation into a finite difference procedure for furnace calculations. In Proceedings of the 14th Symposium 

(International) on Combustion, The Combustion Institute, pp. 661-671, 1973. 

Hamins, A. et. al. Report of test on experimental conditions and preliminary results for the 

International Fire Model Benchmarking and Validation Exercise # 3. July 2003a. 

Hamins, A. et. al. Report of experimental results for Tests 2,3 and 4 of the International Fire 

Model Benchmarking and Validation Exercise # 3. July 2003b. 

Jones, W.W. et. al. A Technical Reference for CFAST: An Engineering Tool for Estimating 

Fire and Smoke Transport. NIST TN 1431. April 2003. 

Jones, W.W. et. al. CFAST - Consolidated Model of Fire Growth and Smoke Transport (Version 5): Technical Reference Guide. NIST Special Publication 1030. October 

2004. 

Launder B.E. & Spalding D.B. The numerical computation of turbulent flows. Computer 

Methods in Applied Mechanics and Engineering, vol. 3, pp. 269-289, 1974. 

Lautenberger C.W. et. al. A simplified model for soot formation and oxidation in CFD simulation of non-premixed hydrocarbon flames. Fire Safety Journal, vol. 40, pp. 141-

176, 2005. 

Lockwood F.C. & Shah N.G. A new radiation solution method for incorporation in general 

combustion prediction procedures. In Proceedings of the 18th Symposium (International) on Combustion, The Combustion Institute, pp. 1405-1414, 1981. 
2-54

Magnussen B.F. & Hjertager B.H. On mathematical modelling of turbulent combustion with 

special emphasis on soot formation and combustion. In Proceedings of the 16th 

Symposium (International) on Combustion, The Combustion Institute, pp. 719 -

729, 1976. 

Magnussen B.F. et, al. Effects of turbulent structure and local concentrations on soot formation and combustion in C2H2 diffusion flames. In Proceedings of the 17th Symposium (International) on Combustion, The Combustion Institute, pp. 1383 -

1393, 1976. 

Maranghides, A. et al. Test plan for international fire model benchmarking and validation – 

exercise # 3. 11 March 2003. 

McCaffrey B.J. Momentum implications for buoyant diffusion flames. Combustion and Flame, 

vol. 52, p. 149, 1983. 

Miles S.D., Kumar S. & Cox G. Comparisons of ‘blind predictions’ of a CFD model with experimental data. Fire Safety Science – Proceedings of the Sixth International 

Symposium, IAFSS, pp. 543-554, 2000. 

Miles S. The predictive capability of CFD for fully developed fires. Fire and Explosion Hazards - Proceedings Third International Seminar, Windermere, UK, pp. 229-240, 

2001. 

Miles, S. International Panel Report: Benchmark Exercise # 2 - Pool Fires in Large Halls. 

May 2004. 

Patankar S.V. Numerical heat transfer and fluid flow. Hemisphere Publishing Co., 1980. 

Siegel R. & Howell J.R. Thermal Radiation Heat Transfer. Hemisphere Publishing Corporation, New York, 2nd ed., 1981. 

Truelove J.S. Mixed grey gas model for flame radiation. UK Atomic Energy Authority Report 

AERE HL 76/3448, 1976. 

U.S. Nuclear Regulatory Commission. International Collaborative Project to Evaluate Fire 

Models for Nuclear Power Plant Applications: Cable Tray Fires. Compiled by 

Dey, M., NUREG-1758, Washington, DC, June 2000. 
3-1

3 Open Simulations using FLAMME_S (Laurence Rigollet, IRSN) 

The two-zone fire model FLAMME_S v.2.3.2, developed by IRSN, was used for open simulations of Tests 2, 3, 4 and 5. The influence of the fire on the targets was not studied because the model is not accurate enough for this problem. 

3.1 FLAMME_S Input Parameters and Assumptions 

Most of input data were taken from the specifications. Some specific assumptions were: 

• The emissivity of all surfaces was assumed to be 0.95. 

• The convective heat transfer was assumed to be 10 W.m-2.K-1 inside the compartment and 6 W.m-2.K-1 outside. 

• The fire source was a pool of heptanes located at the center of the room with a heat 

release rate around 1 MW. 

• Most of the heptane properties are given in the SFPE handbook 0. 

• Complete combustion was assumed: C7H16 +11O2 →8 H2O + 7 CO2

• The pyrolysis rate was deduced from the measured heat release rate, specified in the 

report of experimental results. 

3.2 Comparison of FLAMME_S with Measurements 

3.2.1 Test 2 and 8: door closed and ventilation off 

This scenario was designed to determine the predictive capability of models for underventilated conditions. The nominal peak HRR was 1 MW with a heptane fire located in the 

center of the compartment. The door was closed during these tests and the mechanical ventilation was turned off with the supply and exhaust vents sealed. Several calculations were 
3-2

performed with varying input data like heat release rate and the area of leakage. Final results, presented in this report, used a maximum heat release rate of 1.3 MW corresponding 

to the upper bound of the experimental uncertainty, and with an opening simulating compartment leakage of 729 cm2

, which corresponds to an average value of experimental 

measurements 0. 

The FLAMME_S code calculates the fire extinguishment earlier than what was observed 

experimentally (see Figure 3-1). In this case, the fire extinguishes through lack of oxygen, for 

a value of the oxygen concentration around 12 %. But the experimental decrease of oxygen 

consumption is slower four minutes after the fire ignition than the calculated one (see Figure 

3-2). The difference between code and experiments may be due to two physical models: 

either the chemical reaction of combustion, which is imposed in the code, or the estimation 

of the flow rate through the leakage. In the input data, a complete reaction of combustion is 

supposed with only production of water and carbon dioxide. With this hypothesis of chemical 

reaction, the production of carbon dioxide seems to be well estimated by the code (see 

Figure 3-3). In order to verify if the flow rate through the leakage is well estimated by the 

code, the pressure measured during tests was compared to the code results (see Figure 

3-4). The calculated pressure shows that there is perhaps another oxygen contribution which 

is not modeled. In fact, the experimental pressure difference of the two tests is never equal 

to zero after the over-pressure which follows the fire ignition. 

The calculated layer height falls rapidly contrary to the one measured experimentally, during 

the two tests, which is stabilized around 0.8 m above the floor (see Figure 3-5). So, there is 

rapidly only one gas zone modeled. 

Four minutes after the fire ignition, the calculated gas temperature does not increase like the 

measured temperatures (see Figure 3-6). The difference between the code and experiments 

can be due to the uncertainties on the heat release rate or to an over-estimation of the heat 

transfer between gas and walls. 

For the two experiments 2 and 8, the heat release rate is not measured but it is estimated to 

be equal to 1140 kW ± 15 % 0. The calculations were performed with the maximum value of 

the heat release rate, i.e. 1.3 MW (see Figure 3-1). Even with this upper value, the gas temperature is under-estimated. The fire energy which heats the compartment surfaces is estimated experimentally (see Figure 3-7). The rate of heat loss to surfaces increases during the 

fire and reaches 1.3 MW. So if we consider that the energy loss to the walls surfaces repre-
3-3

sents 70 % or 80 % of the fire energy, the experimental heat release rate may be experimentally under-estimated. 

Calculated and measured energy loss to compartment surfaces was compared. The calculated energy loss to the side walls (north/south; east/west - see Figure 3-8) and to the ceiling 

(see Figure 3-9) are in good agreement with experimental estimations. But the calculated 

energy loss to the floor is overestimated (see Figure 3-9). In this case, the heat transfer is 

between the one gas zone modeled and the floor, and the calculated temperature is greater 

than the experimental gas temperature of the lower layer (see Figure 3-6). 

This configuration shows that a model that assumes well-ventilated conditions may not work 

well with under-ventilation conditions. In particular, the mass transfer between the lower and 

upper layers via the Heskestad correlation may lead to an over-estimate in the decrease in 

layer height 

3.2.2 Tests 3 and 9: door opened and ventilation off 

This scenario was designed to determine the predictive capability of models for wellventilated conditions. The nominal peak of HRR was 1 MW with a heptane fire located in the 

center of the compartment. The door was open during these tests and the mechanical ventilation was turned off with the supply and exhaust vents sealed. 

For this configuration, the calculated parameters are overall in good agreement with experimental results. 

The experimental heat release rate was used directly as input data of FLAMME_S (see 

Figure 3-10) so the fire did not extinguish through lack of oxygen but by the stopping of the 

fuel delivery system. 

The calculated height of the gas layer is in good agreement with the one estimated experimentally (see Figure 3-11). The calculated gas temperature of the upper layer is underestimated, but the relative error is less than 20 % (see Figure 3-12). The calculated gas 

temperature of the lower layer is also under-estimated by more than 20 %. 

The comparison of the molar fractions of oxygen and carbon dioxide shows that the hypothesis of a complete reaction of combustion is correct (see Figure 3-13 and Figure 3-14). 
3-4

The energy losses to side walls are in good agreement with experimental results (see Figure 

3-15). On the other hand, the energy loss to the ceiling is over-estimated and the energy 

loss to the floor is under-estimated (see Figure 3-16). The under-estimation of the loss to the 

floor may be due to the under-estimation of the gas temperature of the lower layer. The overestimation of the loss to the ceiling seems to be due to the heat transfer between the plume 

and the ceiling instead of the use of an option which prevent this heat exchange. 

In spite of these important differences on the losses to the ceiling and to the floor, the total 

energy loss calculated by the code is within 20 % of the measurements (see Figure 3-17). 

The prediction of the mass flow through the door is in good agreement with experimental 

results (see Figure 3-18). 

3.2.3 Tests 3 and 10: door closed and ventilation on 

This scenario was designed as a variation of test 2 for providing data to determine the predictive capability of models for closed door scenarios with the mechanical ventilation system 

on. The nominal peak of HRR was 1 MW with a heptane fire located in the center of the 

compartment. The door was closed during these tests and the mechanical ventilation was 

turned on. 

For this configuration, the heat release rate, specified as input data in the simulations, is the 

one mentioned in the report of experimental results 0, with a ramp up, a steady state and a 

ramp down (see Figure 3-19). 

The calculated layer height falls rapidly contrary to the layer height estimated experimentally 

which is stabilized around 1 m above the floor (see Figure 3-20). So, in the simulation, 6 min 

30 s after the fire ignition there is only one gas zone modeled. The average gas temperature, 

calculated by the code, is, in a first time, closed to the experimental temperature of the upper 

layer and then it is under-estimated (see Figure 3-21). The over-estimation of the gas temperature in the first minutes may be due to a bad estimation of the experimental heat release 

rate. 

The disappearance of the lower layer leads that the heat exchange between the gas and the 

floor are over-estimated (see Figure 3-22), contrary to the others heat exchanges which are 

in good agreement with experimental results (see Figure 3-23). 
3-5

The hypothesis of a complete reaction of combustion gives good results concerning the molar fractions (see Figure 3-24 and Figure 3-25). 

The pressure is in good agreement with experimental results except the over-pressure after 

fire ignition (see Figure 3-26). This result may be due to the over-estimation of the heat release rate in the first minutes (see Figure 3-19) and not to the mass flows through the exhaust and the supply vents which are well calculated (see Figure 3-27 and Figure 3-28). 

3.2.4 Test 5: door opened and ventilation on 

This scenario was designed as a variation of test 3 for fires in well ventilated conditions with 

natural and mechanical ventilation. The nominal peak of HRR was 1 MW with a heptane fire 

located in the center of the compartment. The door was opened during these tests and the 

mechanical ventilation was turned on. 

The heat release rate specified as input data in the simulations is the one mentioned in the 

report of experimental results 0, with a ramp up, a steady state and a ramp down (see Figure 

3-29). 

In this case, the layer height is in good agreement with the experimental estimation (see 

Figure 3-30). The gas temperature of the upper layer is well calculated and the one of the 

lower layer is colder than the experimental data (see Figure 3-31). 

The loss to the walls is over-estimated except the heat loss to the floor (see Figure 3-32 and 

Figure 3-33). 

The hypothesis of a complete reaction of combustion gives good results concerning the molar fractions (see Figure 3-34 and Figure 3-35). 

The pressure is weak because the fire is well-ventilated (see Figure 3-36). The order of 

magnitude of the mass flows through the door and through the vents is good (see Figure 

3-37 and Figure 3-38). 
3-6

3.3 Conclusions and Recommendations for FLAMME_S 

The two-zone fire model FLAMME_S has been applied to perform calculations for the 

benchmark exercise #3, to simulate heptane pool fires inside a compartment with different 

ventilation conditions. The calculated results are compared to experimental measurements 

of seven experiments. 

This exercise highlights that fires in a well-ventilated compartment are simulated adequately 

with the code and models used in a two-zone code are limited in the case of fires in underventilated conditions. 

The comparisons with experimental results show that the calculated height of the gas layer 

falls rapidly when the door is closed. These results may be due the plume model used which 

has been established under well ventilated conditions. 

The heat loss to the side wall is well predicted, but the heat exchange with the floor and with 

the ceiling is not. This problem is linked to the layer height: 

When the lower layer disappears, in under ventilated conditions, the loss to the floor is overestimated because the calculated gas temperature is higher than the experimental temperature; 

Under well ventilated condition, the loss to the floor is under estimated because the calculated temperature of the lower gas layer is always lower than the one which is estimated 

experimentally. 

Cases with door opened are those which are better simulated with the code and the calculated results are in good agreement with experimental results. 

In all cases, the calculated mass flows through the ventilation or through the door are in 

good agreement with experimental results. 
3-7

3.4 References 

Maranghides A., Hamins A., Bryant R., Johnson E., Mulholland G., Widdman J. (NIST), Test 

plan for International Fire Model Benchmarking and validation exercise #3, NIST, 

March 2003 

Hamins A., Maranghides A., Johnson R., Donnelly M., Yang J., Mulholland G., Anleitner R., 

Report of experimental results for the International Fire Model Benchmarking and 

validation exercise #3, NIST Special Publication 1013, January 2004 

The SFPE Handbook of Fire Protection Engineering, 1995 
3-8

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

0 300 600 900

Time (s)

Heat Release Rate (kW)

HRR (Tests 2 & 8)

Min. HRR (Tests 2 & 8)

Max. HRR (Tests 2 & 8)

Results of FLAMME_S

Input data of FLAMME_S

Figure 3-1: Heat release rate of the first configuration 

0.1

0.12

0.14

0.16

0.18

0.2

0.22

0 300 600 900 1200

Time (s)

XO2 (-)

O2-1 (Test 2)

O2-1 (Test 8)

O2-2 (Test 2)

O2-2 (Test 8)

FLAMME_S

Figure 3-2: Molar fraction of oxygen 
3-9

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0 300 600 900 1200

Temps (s)

XCO2 (-)

CO2-4 (Test 2)

CO2-4 (Test 8)

FLAMME_S

Figure 3-3: Molar fraction of carbon dioxide 

-500

-400

-300

-200

-100

0

100

200

300

400

500

-300 0 300 600 900 1200

Time (s)

Pressure (Pa)

Test 2

Test 8

FLAMME_S

Figure 3-4: Pressure of the compartment 
3-10

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 300 600 900 1200

Time (s)

Height (m)

Test 8

Test 2

FLAMME_S

Figure 3-5: Layer height 

0

50

100

150

200

250

0 300 600 900 1200

Time (s)

Temperature (°C)

Tlow (Test 2)

Tup (Test 2)

Tlow (Test 8)

Tup (Test 8)

TEMPERATURE_MOY (C)

TEMPERATURE 1 (C)

TEMPERATURE 2 (C)

Figure 3-6: Gas temperature in the compartment 
3-11

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

0 300 600 900 1200

Energy loss (kW)

Time (s)

Test 2

Figure 3-7: Total energy loss by all surfaces of the compartment 

0

50

100

150

200

250

0 300 600 900 1200

Time (s)

Energy loss (kW)

North Wall (Test 2)

South Wall (Test 2)

East Wall (Test 2)

West Wall (Test 2)

North Wall (FLAMME_S)

West Wall (FLAMME_S)

East Wall (FLAMME_S)

South Wall (FLAMME_S)

Figure 3-8: Energy loss to the side walls 
3-12

-100

0

100

200

300

400

500

0 300 600 900 1200

Time (s)

Energy loss (kW)

Floor (Test 2)

Floor (FLAMME_S)

Ceiling (Test 2)

Ceiling (FLAMME_S)

Figure 3-9: Energy loss to the ceiling and to the floor 
3-13

0

200

400

600

800

1000

1200

1400

1600

0 300 600 900 1200 1500 1800 2100

Time (s)

HRR (kW)

Test 3

Test 9

FLAMME_S

Figure 3-10: Heat release rate 

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 300 600 900 1200 1500 1800 2100

Time (s)

Height (m)

Test 3

Test 9

FLAMME_S

Figure 3-11: Layer height 
3-14

0

50

100

150

200

250

0 300 600 900 1200 1500 1800 2100

Time (s)

Temperature (°C)

Tup (Test 3)

Tup (Test 9)

Tup (FLAMME_S)

Tlow (Test 3)

Tlow (Test 9)

Tlow (FLAMME_S)

Average temperature (FLAMME_S)

Figure 3-12: Gas temperature of the compartment 

0.15

0.16

0.17

0.18

0.19

0.2

0.21

0.22

0 300 600 900 1200 1500 1800 2100

Time (s)

XO2 (-)

O2-1 (Test 3)

O2-2 (Test 3)

O2-lower layer (FLAMME_S)

O2-upper layer (FLAMME_S)

Figure 3-13: Molar fraction of oxygen 
3-15

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0 300 600 900 1200 1500 1800 2100

Time (s)

XCO2 (-)

CO2-4 (Test 3)

FLAMME_S

Figure 3-14: Molar fraction of carbon dioxide 

-50

0

50

100

150

200

0 300 600 900 1200 1500 1800 2100

Time (s)

Energy (kW)

North wall (Test 3)

South wall (Test 3)

South & North walls (FLAMME_S)

East wall (Test 3)

West wall (Test 3)

West & East wall (FLAMME_S)

Figure 3-15: Energy loss to the side walls 
3-16

-100

0

100

200

300

400

500

0 300 600 900 1200 1500 1800 2100

Time (s)

Energy (kW)

Floor (Test 3)

Floor (FLAMME_S)

Ceiling (Test 3)

Ceiling (FLAMME_S)

Figure 3-16: Energy loss to the ceiling and to the floor 

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

0 300 600 900 1200 1500 1800 2100

Time (s)

Energy (kW)

Test 3

FLAMME_S

Figure 3-17: Total energy loss 
3-17

-3

-2

-1

0

1

2

3

4

-300 0 300 600 900 1200 1500 1800 2100

Time (s)

Mass flow (kg/s)

Door flow in (Test 3)

Door flow in (FLAMME_S)

Door flow out (Test 3)

Door flow out (FLAMME_S)

Net door flow (Test 3)

Net door flow (FLAMME_S)

Figure 3-18: Mass flow through the door 
3-18

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 300 600 900 1200

Time (s)

Heat release rate (kW)

Test 4 - Experimental HRR

FLAMME_S 

Figure 3-19: Heat release rate of the third configuration 

0

0.5

1

1.5

2

2.5

3

3.5

4

0 300 600 900 120

Time (s)

Height (m)

Test 4

FLAMME_S

Figure 3-20: Layer height 
3-19

0

50

100

150

200

250

0 300 600 900 1200

Time (s)

Temperature (°C)

Tlow - Test 4

Tup - Test 4

Tav. - FLAMME_S 

Figure 3-21: Gas temperature 

-50

0

50

100

150

200

250

300

350

400

0 300 600 900 1200

Time (s)

Energy (kW)

Floor (Test 4)

Floor (FLAMME_S)

Ceiling (Test 4)

Ceiling (FLAMME_S)

Figure 3-22: Energy loss to the floor and to the ceiling 
3-20

0

20

40

60

80

100

120

140

160

180

200

0 300 600 900 1200

Time (s)

Energy (kW)

North wall (Test 4)

South wall (Test 4)

South & North walls (FLAMME_S)

East wall (Test 4)

West wall (Test 4)

East & West walls (FLAMME_S )

Figure 3-23: Energy loss to side walls 

0.1

0.12

0.14

0.16

0.18

0.2

0.22

0 300 600 900 1200

Time (s)

XO2 (-)

Test 4 - O2-1

Test 4 - O2-2

FLAMME_S 

Figure 3-24: Molar fraction of oxygen 
3-21

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 300 600 900 1200

Time (s)

XCO2 (-)

Test 4 (CO2-4)

FLAMME_S 

Figure 3-25: Fraction molar of carbon dioxide 

-150

-100

-50

0

50

100

0 300 600 900 1200

Time (s)

Pressure (Pa)

Test 4

FLAMME_S 

Figure 3-26: Pressure 
3-22

-0.5

0

0.5

1

1.5

2

2.5

0 300 600 900 1200

Time (s)

Mass flow (kg/s)

Exhaust - Test 4

Exhaust - FLAMME_S

Figure 3-27: Mass flow through the exhaust vent 

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 300 600 900 1200

Time (s)

Mass flow (kg/s)

Supply - Test 4

Supply - FLAMME_S 

Figure 3-28: Mass flow through the supply vent
3-23

-200

0

200

400

600

800

1000

1200

1400

1600

-300 0 300 600 900 1200 1500 1800 2100

Test 5

FLAMME_S

Figure 3-29: Heat release rate 

0

0.5

1

1.5

2

2.5

3

3.5

4

-300 0 300 600 900 1200 1500 1800 2100

Time (s)

Height (m)

Test 5

FLAMME_S

Figure 3-30: Layer height 
3-24

0

50

100

150

200

250

-300 0 300 600 900 1200 1500 1800 2100

Time (s)

Temperature (°C)

Tlow (Test 5)

Tup (Test 5)

Taverage (FLAMME_S)

Tlow (FLAMME_S)

Tup (FLAMME_S)

Figure 3-31: Gas temperature 

-50

0

50

100

150

200

-300 0 300 600 900 1200 1500 1800 2100

Time (s)

Energy (kW)

North wall (Test 5)

South wall (Test 5)

North & South walls (FLAMME_S)

East wall (Test 5)

West wall (Test 5)

East & West walls (FLAMME_S)

Figure 3-32: Energy loss to the side walls 
3-25

-100

-50

0

50

100

150

200

250

300

350

400

450

-300 0 300 600 900 1200 1500 1800 2100

Time (s)

Energy (kW)

Floor (Test 5)

FLOOR (FLAMME_S)

Ceiling (Test 5)

Ceiling (FLAMME_S)

Figure 3-33: Energy loss to the ceiling and to the floor 

0.175

0.18

0.185

0.19

0.195

0.2

0.205

0.21

0.215

-300 0 300 600 900 1200 1500 1800 2100

Time (s)

XO2 (-)

O2-1 (Test 5)

O2-2 (Test 5)

O2 Average (FLAMME_S)

O2 low (FLAMME_S)

O2 up (FLAMME_S)

Figure 3-34: Molar fraction of oxygen 
3-26

-0.005

0

0.005

0.01

0.015

0.02

0.025

-300 0 300 600 900 1200 1500 1800 2100

Time (s)

XCO2 (-)

Test 5

FLAMME_S

Figure 3-35: Molar fraction of carbon dioxide 

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

-300 0 300 600 900 1200 1500 1800 2100

Time (s)

Pressure (Pa)

Test 5

FLAMME_S

Figure 3-36: Pressure 
3-27

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 300 600 900 1200 1500 1800 2100

Time (s)

Mass flow (kg/s)

Supply (Test 5)

Supply (FLAMME_S)

Exhaust (Test 5)

Exhaust (FLAMME_S)

Figure 3-37: Mass flow through the supply vent and through the exhaust vent 

-3

-2

-1

0

1

2

3

4

-300 0 300 600 900 1200 1500 1800 2100

Time (s)

Mass flow (kg/s)

Door flow out (Test 5)

Door flow out (FLAMME_S)

Door flow in (Test 5)

Door flow in (FLAMME_S)

Net door flow (Test 5)

Net door flow (FLAMME_S)

Figure 3-38: Mass flow through the door 
4-1

4 Open Simulations using FATE (Fauske and Associates) 

The FATETM Computer Code is used for this analysis. FATE is the successor to HADCRT, 

which was used in previous ICFMP benchmarks. FATE version 2.11 contains upgrades to 

address fire modeling issues. FATE stands for Facility Flow, Aerosol, Thermal, and Explosion Model, for PCs and workstations [Plys and Lee, 2004]. FATE is used for design, offnormal, and accident analyses of nuclear and chemical facilities. 

General capabilities of FATE 2.11 include: 

• Fire model: Define burn rate and yields; Smoky layer model; Propagation of smoke in 

stratified layers throughout facility; Aerosol transport with smoky layers; Aerosol settling 

from smoky layer to lower layer and embedded surfaces. 

• Multiple-compartment thermodynamics and general species: Facility rooms have separate pressure, temperature, and composition; Compound property libraries are input; 

Tracking of condensed, gaseous, and aerosol species. 

• Facility nodalization and flow: Compartments are connected in arbitrary topology by flow 

paths; Flows are pressure-driven, density-driven counter-current, and diffusional. 

• Aerosol behavior: Aerosol coagulation, sedimentation, transport with flow; Deposition on 

bends and filters; Deposition by condensation; Aerosol formation by boiling and fog. 

• Heat transfer: Convection of liquids and gases to structures with internal temperature 

distributions; Linking for 2D and 3D heat transfer; Condensation. 

• Flammability and combustion of gases, vapors, and aerosols: Any input compound may 

participate; examples include solvent vapors, hydrogen, and U metal or hydride aerosols. 

• Entrainment of deposits to form aerosols: Powder, liquid, and sludge waste may be entrained by combustion or flow. 

• Thermal radiation networks: View factor models and automatic network balancing. 

• Event-oriented simulation: Intervention criteria and actions for scenario evolution. 

• Sources and time-dependent conditions. Prescribe liquid, gas, and aerosol source histories and environmental conditions with time. 
4-2

• Nuclear fuel and sludge models including chemical reactions. 

FATETM is owned and licensed by Fauske and Associates, LLC (FAI) and FATE is a registered trademark of FAI. FATE is created and maintained under the FAI Quality Assurance 

Program (10CFR50 App. B & ISO 9001 compliant). 

4.1 FATE Input Parameters and Assumptions 

4.1.1 Room Geometry and Ventilation 

The Benchmark Exercise 3 (BE-3) base model is based on a standardized room model successfully developed during Benchmark Exercise 1 (BE #1) (NISTIR-6986). The BE #1 effort 

demonstrated that the rectangular room geometry can be accurately modeled with a single 

region and 14 heat sinks to represent floor, ceiling, and walls, and a radiation network containing the heat sinks, fire source, and smoky layer. In addition the BE #1 effort provides an 

effective methodology for modeling forced ventilation, natural circulation through open doors, 

and intrinsic leakage through the use of five flow paths. Ventilation in the FATE standardized room model is refined in the current effort. 

Table 4-1 summarizes the heat sinks used to define the region boundaries, while Table 4-2 

summarizes the flow paths. The wall heat sinks are modeled as “strips” that circumscribe 

the room perimeter and extend vertically between the indicated elevations. The heat sinks 

are then subdivided in the FATE heat transfer model into 20 slabs for 1-dimensional conduction through the heat sink. The four side walls are modeled as a series of 12 stacked wall 

strips. The advantage to this approach is input and computational simplicity, while the limitation is that a single surface temperature is reported for the North, East, South, and West 

walls at each elevation. 

As will be discussed, calculation results proved to be sensitive to modeling of intrinsic leakage. The leak centerline elevation, leak area, and leak orientation are all shown to influence 

the smoky layer elevation and oxygen content of the room, even in the cases where the 

main door is open or the ventilation fan is on. Based on results from multiple sensitivity runs, 

a best match of the test data can be obtained by modeling intrinsic leakage only through 

assumed gaps in the closed door, and assumed gaps in the supply and exhaust duct louvers 

(for cases without forced ventilation). Table 4-2 shows an additional leak path (junction 5), 

but this is only used in sensitivity calculations. Junctions 2 and 3 are modified to model in-
4-3

trinsic leakage for cases without forced ventilation by assuming a 0.0054 m (0.21”) gap 

around the vent perimeter for a total leakage area of 0.015 m2

 for each junction. The door 

gap is assumed to be 0.0032 m (1/8”) around the perimeter of a set of double doors (2 doors 

2 m x 1 m, each), for a total leakage area of 0.032 m2

. Finally, for cases with forced ventilation, a constant fan volumetric flow of 1.06 m3

/s is imposed across junction 2. 

The leak path parameters and the open door loss coefficient were adjusted based on comparisons against BE-3 tests 1 (fans off, doors closed) and 3 (fans off, door open). The derived path parameters were then used for the remainder of the tests. The door loss coefficient was set at one-half of the recommended value, Kdoor = 0.54. 

Table 4-1 FATE BE-3 Base Model Heat Sink Summary Table 

Heat 

Sink 

# 

Label Type Bottom El. 

(m) 

Top El. 

(m) 

Material Thickness 

(m) 

1 FLOOR Upward facing 

rectangle -2.54E-02 0.00E+00

Gypsum 0.0254 

2 WALL-1 Rectangular 

enclosure strip 0.00E+00 3.18E-01 

Marinite 0.0254 

3 WALL-2 Rectangular 

enclosure strip 3.18E-01 6.37E-01 

Marinite 0.0254 

4 WALL-3 Rectangular 

enclosure strip 6.37E-01 9.55E-01 

Marinite 0.0254 

5 WALL-4 Rectangular 

enclosure strip 9.55E-01 1.27E+00

Marinite 0.0254 

6 WALL-5 Rectangular 

enclosure strip 1.27E+00 1.59E+00

Marinite 0.0254 

7 WALL-6 Rectangular 

enclosure strip 1.59E+00 1.91E+00

Marinite 0.0254 

8 WALL-7 Rectangular 

enclosure strip 1.91E+00 2.23E+00

Marinite 0.0254 

9 WALL-8 Rectangular 

enclosure strip 2.23E+00 2.55E+00

Marinite 0.0254 

10 WALL-9 Rectangular 

enclosure strip 2.55E+00 2.87E+00

Marinite 0.0254 

11 WALL-10 Rectangular 

enclosure strip 2.87E+00 3.18E+00

Marinite 0.0254 

12 WALL-11 Rectangular 

enclosure strip 3.18E+00 3.50E+00

Marinite 0.0254 

13 WALL-12 Rectangular 

enclosure strip 3.50E+00 3.82E+00

Marinite 0.0254 

14 CEILING Upward facing 

rectangle 3.82E+00 3.85E+00

Marinite 0.0254 
4-4

Table 4-2 FATE BE-3 Base Model Flow Path Summary 

Junction # Description Centerline el. 

(m) 

Area (m2

) 

1 DOOR 1 4, K = 0.54 

2 FAN (fan on) 

FAN (fan off) 

2.4 

2.4 

0.49 

0.015 (gap leak 0.0054 m) 

3 EXHAUST (fan on) 

EXHAUST (fan off) 

2.4 

2.4 

0.49, K = 1.08 

0.015 (gap leak 0.0054 m) 

4 HIGH LEAK 3.3 N/A 

5 

DOOR GAP LEAK 1.2 

Perimeter of double door (2 m x 

2 m) x assumed gap width of 

0.0032 m; total area = 0.032 m2

Note that junction 5, the door gap leak, uses the new door gap model added to FATE 

version 2.0.5. Also, for cases without forced ventilation, the gap leak model is also used 

to model leakage across junctions 2 and 3. 

4.1.2 Cable Targets 

A single cable target is included in the radiation network to model cable heating. A representative cable, based on the 3-conductor power cable with a hypalon jacket, is used as the 

basis for the target cable. The target is then modeled as a cylindrical composite heat sink 

with a 0.25 cm thick outer hypalon jacket (10 radial nodes) and a 0.13 cm layer of XLP insulation (5 radial nodes). The copper conductor and other complexities of the cable morphology are not considered. This simple cable target model allows prediction of the jacket outer 

surface and insulation inner surface temperatures, which is consistent with available experimental measurements. The cable target is then included in the radiation network. Axial 

conduction along the length of the cable is not considered, however the cable is divided azimuthally into three sections to consider variations in temperature around the cable surface. 

This approach allows the cable target to be placed at any arbitrary location within the room 

to represent a particular section of cable. 

Thermal properties of Hypalon are not provided as part of the standard test specification, 

therefore typical properties for high molecular weight polyethylene are used in the FATE 

model (www.er6s1.eng.ohio-state.edu; www.bpsolvaype.com ): 

 ρ = 930 kg/m3
4-5

 k = 0.50 W/m/C 

 cp = 1850 J/kg/C 

4.1.3 Test Matrix and Fire Source 

Tests 1 through 5, 14, 15, and 18 have been selected for simulation by FATE. Two sets of 

pilot fire inputs will vary from test case to test case. The first set of fire parameters is the 

definition of the fire surface for the radiation network. The fire is located in the room center 

for most cases (FATE input coordinates XRVF = 3.52, YRVF = 10.83). For tests 14, 15, and 

18 the fire location is as follows: 

Test XRVF YRVF 

14 5.24 10.83 

15 1.25 10.83 

18 1.55 10.83 

The second set of inputs is for the fire burn flux as a function of time. The test specification 

provides the peak fire heat rate (kW), linear ramp up and ramp down times, and time at peak 

heat rate, while FATE requires the fuel burn mass flux (kg/m2

/s) as a function of time. The 

fuel burn mass flux can be calculated as, G = Q/Hc/A, where Q is the heat rate, Hc is the 

heat of combustion (45 MJ/kg for heptanes and 40.3 MJ/kg for Toluene), and A is the fuel 

flow area. The fuel flow area is specified in input as A = 0.60 m2

. 

4.2 Comparison of FATE Predictions with Measurements 

FATE open calculations are presented below for BE-3 Tests 1, 2, 3, 4, 5, 14, 15, and 18. 

Calculations are performed on a personal computer with a 1.39 GHz AMD Athlon processor 

and a DOS/Windows XP operating environment. A typical run time for the model is 139 

seconds of CPU time for a 2500 second simulation, or 18 times faster than real time. 

4.2.1 BE-3 Case 1 FATE Open Benchmark Results 

Case 1 is characterized by a heptanes fuel fire with a peak power of 390 kW and no ventilation -- the main door is closed and ventilation system is off. Thus, this test case provides 

insights into the influence of normal room leakage on the room response and fire behavior. 

FATE calculations for BE-3 Case 1 are presented in Figure 4-1 through Figure 4-11. 
4-6

The FATE smoky layer height shows reasonable agreement with the test data with two notable exceptions. First, the FATE smoky layer minimum height is lower than the test data, 

and second, following fire termination, the FATE smoky layer recedes faster than indicated 

in the test data. These two results are typical of all the FATE calculations and indicate that 

either the leak path elevations or reverse flow characteristics may not be in perfect agreement with the test facility conditions. Furthermore, sensitivity cases indicate that the flow 

split of the air inflow between the smoky and lower layers influences both the smoky layer 

minimum elevation and the rat at which the smoky layer recedes one the fire is terminated. 

Base case results are obtained by assuming that all door leakage inflow is split such that half 

of the inflow goes to the smoky layer and half of the inflow goes to the lower layer. This flow 

split is non-mechanistic, however calculations for this case and the others to follow, suggest 

that there is a flow split that play a dominant role in the smoky layer behavior. 

Figure 4-2 shows the influence of door gap leakage on the calculated results. All FATE calculations presented in this figure place the air inflow into the lower layer, only. As shown in 

the figure, if all inflow goes to the lower layer, then the smoky layer recedes faster than if the 

inflow is split between the smoky and lower layers. Also, when leakage is increased, the 

smoky layer minimum elevation is consistent with the leak path centerline elevation (sensitivities a and b). If the door gap leakage is replaced with an equivalent leak area at a higher 

elevation (sensitivity c), the smoky layer descends to the floor elevation. If counter current 

flow is disabled through the door leak (sensitivity d), the smoke behavior is similar to case c 

where there is no door leak. These sensitivities in conjunction with the test data suggest that 

there is an influential leak path in the test near the 1 m elevation and that in general seemingly small leak paths can have a strong influence on smoky layer behavior. The sensitivity 

calculations also indicate that counter current flow is an important mechanism when considering small leaks through door gaps. 

Figure 4-4 compares average gas temperatures in the upper and lower layers. The average 

gas temperature is an indicator of the overall energy balance. The good agreement between 

the FATE calculations and the test data validates the FATE approach of modeling the room 

with one region specified through input and divided into two sub-regions by the fire submodels (a hot smoky layer and a relatively cool lower layer). This comparison also lends 

validation to the sub-models for plume behavior and radiant heat transfer (including automatic, continuous view factor calculation). 
4-7

Figure 4-5 through Figure 4-10 present comparisons of heat sink calculations. Points of interest from this set of figures are: 

• FATE represents the floor as s single heat sink with 20 slabs, or nodes, for onedimensional heat transfer through the floor thickness. Therefore, FATE presents an average heat sink surface temperature which is comparable to the reported temperatures 

taken at various locations across the test facility floor. The peak temperature in FATE is 

also consistent with the peak lower layer gas temperature. 

• The measured wall temperatures reflect a vertical temperature stratification within the 

smoky layer. Since FATE uses a single temperature to represent the smoky layer, FATE 

cannot distinguish this level of detail. However, the heat sink temperatures in the smoky 

and lower layers generally bound the test data temperature stratification. For example, 

in Figure 4-6, measurements are taken at an elevation of 1.49 m which is near the bottom of the smoky layer (1.2 m elevation). In FATE, the smoky layer descends to the 0.2 

m elevation, and as each wall strip becomes submerged in the smoky layer, its surface 

temperature increases due to convective heat transfer with the hot gas. These wall 

strips all exhibit temperatures in excess of the measured wall temperature. The single 

strip remaining in the FATE lower level (heat sink 2 at elevation 0.16 m) bounds the 

measured wall temperatures on the low side. Figure 4-8 compares wall temperatures 

above the 3.69 m elevation. As shown, the FATE calculation shows better agreement 

with the test data at this elevation because of the temperature stratification in the test. 

• As discussed above, even though FATE uses “strips” to represent all four sidewalls at a 

particular elevation, this representation provides reasonable agreement with the test 

data. The most influential factor in accurately determining wall temperatures is whether 

or not the wall section is submerged in the smoky layer. 

• Overall the good comparison of wall surface temperatures with test data validates the 

approach to modeling the side walls as a series of wall strips. Furthermore, the level of 

detail in the FATE standardized room model (12 wall strips to represent the entire wall 

height) is sufficiently detailed to accurately reflect the test conditions. 

One of the most important capabilities of a fire model is the ability to predict target response 

to a postulated fire. Figure 4-11 presents one such comparison of the FATE code against 

power cable F mid-plane temperatures for BE-3 Test 1. As shown, the peak cable temperature is accurately predicted. The time dependent behavior of the cable deviates slightly from 

the measured performance. This may be caused by the confluence of several factors includ-
4-8

ing, modeling of the fire power profile, smoky layer behavior, cable material properties, leak 

path behavior, and interaction between the fire, gas, and cable surface. 

Generally good agreement has been obtained between FATE and BE-3 Test 1 results, and it 

is noted that the FATE calculations are influenced by assumptions regarding the leakage 

flow paths. 
4-9

Figure 4-1 BE 3 CASE1 Smoky layer height. Air in leakage through the door is split equally 

between the smoky and lower layers. 
4-10

Figure 4-2 BE 3 CASE1 Smoky layer height sensitivity calculations. All air in leakage 

through the door goes into the lower layer. 
4-11

Figure 4-3 BE 3 CASE1 upper room gas concentrations 
4-12

Figure 4-4 BE 3 CASE1 upper and lower layer average gas temperatures 
4-13

Figure 4-5 BE 3 CASE1 floor surface temperatures 
4-14

Figure 4-6 BE 3 CASE1 North and South wall temperatures at the 1.49 m elevation 
4-15

Figure 4-7 BE 3 CASE1 North and South wall temperatures at the 1.86 m elevation 
4-16

Figure 4-8 BE 3 CASE1 North and South wall temperatures between the 3.69 and 3.82 m 

elevations 
4-17

Figure 4-9 BE 3 CASE1 East and West wall temperatures at the 1.12 m elevation 
4-18

Figure 4-10 BE 3 CASE1 East and West wall temperatures at the 2.42 m elevation 
4-19

Figure 4-11 BE 3 CASE1 Cable F midplane temperatures 
4-20

4.2.2 BE-3 Case 2 FATE Open Benchmark Results 

Case 2 is characterized by a heptanes fuel fire with a peak power of 1140 kW and no ventilation -- the main door is closed and ventilation system is off. This test case is similar to 

Case 1 except the fire power is significantly higher. Whereas case 1 calculations were used 

to set the leak path parameters, this test case will verify the applicability of these parameters 

when subjected to a stronger fire. Furthermore, data is available regarding heat sink heat 

losses for the current case, so the current case will provide additional insights into wall, floor, 

and ceiling modeling assumptions. FATE calculations for BE-3 Case 2 are presented in 

Figure 4-12 through Figure 4-26. 

Many of the results for the current case show the same trends observed in Case 1. For instance, FATE calculates a smoky layer in the unventilated room that is lower than observed 

experimentally. Also, as with Case 1, the FATE calculations of gas concentrations and gas 

layer temperatures show good agreement with the test data. The floor and wall surface 

temperatures also show similar trends. Namely, the controlling factor in surface temperature 

is the heat sink location relative to the smoky layer. The FATE calculations generally bound 

the test data. 

Figure 4-15 through Figure 4-25 compare measured heat losses to the FATE calculated heat 

losses. The calculated ceiling and wall heat losses are significantly higher than observed. 

The overestimate of the wall heat loss may be due to the additional coverage of the walls by 

the smoky layer in the FATE calculation. For example, when the heat loss to the walls below 1.0 m is not included in the FATE calculation significantly better agreement with the test 

data is obtained. Presumably since these wall elevations are submerged in the smoky layer 

in the FATE calculation but not in the test, the FATE heat transfer is overstated relative to 

the test. The over prediction of ceiling heat loss is a trend observed in other cases as well. 

Further investigation of code calculations and models is warranted. Overall, the predicted 

heat losses exceed the experimentally reported values, however general trends are predicted by the code. 

Finally, Figure 4-26 compares the cable F target temperatures. For the higher fire power, 

even though FATE shows good agreement with the test data for the smoky layer temperature, the target temperatures are under predicted. The FATE heating of the target lags behind the test data and the higher heating rate for a shorter duration seems to have exacerbated the target temperature differences. This may be due to FATE assumptions regarding 

radiation heat transfer from the fire to the target (i.e., cylindrical fire geometry with radiation 
4-21

from cylinder sides, only; no radiation heat transfer once the target is submerged in the 

smoky layer) or convective heat transfer coefficients (i.e., the higher fire power may have 

resulted in more turbulent mixing at the cable surface leading to higher heat transfer coefficients) and requires further investigation. 

Figure 4-12 BE 3 CASE2 Smoky layer height 
4-22

Figure 4-13 BE 3 CASE2 upper room gas concentrations 
4-23

Figure 4-14 BE 3 CASE2 upper and lower layer average gas temperatures 
4-24

Figure 4-15 BE 3 CASE2 floor surface temperatures 
4-25

Figure 4-16 BE 3 CASE2 North and South wall temperatures at the 1.49 m elevation 
4-26

Figure 4-17 BE 3 CASE2 North and South wall temperatures at the 1.86 m elevation 
4-27

Figure 4-18 BE 3 CASE2 North and South wall temperatures between the 3.69 and 3.82 m 

elevations 
4-28

Figure 4-19 BE 3 CASE2 East and West wall temperatures at the 1.12 m elevation 
4-29

Figure 4-20 BE 3 CASE2 East and West wall temperatures at the 2.42 m elevation 
4-30

Figure 4-21 BE 3 CASE2 ceiling heat loss (convective and radiative) 
4-31

Figure 4-22 BE 3 CASE2 floor heat loss (convective and radiative) 
4-32

Figure 4-23 BE 3 CASE2 side wall heat loss (convective and radiative) 
4-33

Figure 4-24 BE 3 CASE2 side wall heat loss not including convective heat loss in FATE for 

wall strips below 1.0 m (convective and radiative) 
4-34

Figure 4-25 BE 3 CASE2 total heat loss to ceiling, floor, and walls (convective and radiative) 
4-35

Figure 4-26 BE 3 CASE2 Cable F midplane temperatures 
4-36

4.2.3 BE-3 Case 3 FATE Open Benchmark Results 

Case 3 is characterized by a heptanes fuel fire with a peak power of 1150 kW and natural 

ventilation through the opened 2 m x 2 m doorway. However, there is no forced ventilation 

as the fan is off. FATE calculations for this case use the same vent supply and exhaust leak 

path assumptions as are used in Cases 1 and 2 and add the open doorway as an additional 

flow path. As with Cases 1 and 2, it is assumed that inflow through the doorway is split 

equally between the smoky and lower layers. As will be shown, the relatively low flow leak 

paths are influential in the smoky layer behavior and assumptions regarding flow split are 

also influential. In addition to providing heat transfer validation, this case also validates 

models and assumptions regarding counter-current flow through an open doorway when the 

doorway is partially submerged in the smoky layer. FATE calculations for BE-3 Case 3 are 

presented in Figure 4-27 through Figure 4-45. 

It is interesting to note that even with the door open, the smoky layer reported from the test 

data behaves similarly to Cases 1 and 2 where the door was closed. That is, the minimum 

elevation is about 1 m and following fire termination, the smoky layer does not recede or 

recedes only slightly and remains below the top of the door for the duration of the 2000 second comparison. FATE calculations show similar behavior if the door inflow is assumed to 

be split equally between the smoky and lower layers. In contrast, if the door inflow is assumed to go into the lower layer only, the FATE calculated smoky layer stops near the door 

mid-plane elevation and then recedes to the top of the ventilation ducts where the presumed 

leakage is modeled. Finally, if the door inflow is assumed to flow only into the smoky layer, 

then the FATE calculations closely follow the test data and the smoky layer recedes only 

slightly following fire termination. These sensitivity cases illustrate the importance crediting a 

flow split of all inflows between the smoky and lower layers and suggest that a mechanistic 

model for flow splitting is necessary. As a result of this benchmark exercise, a mechanistic 

model for flow splitting is now being developed for FATE. 

Additional FATE sensitivity calculations, presented in Figure 4-30, suggest that the smoky 

layer behavior is also influenced by counter current flow through the door and the leak path 

elevation. As shown, when doorway counter-current flow is stopped (artificially), the smoky 

layer descends to 0.5 m before receding to the vent elevation. If the leak top elevation is 

reduced to 1.5 m and counter-current flow is restored, then the smoky layer recedes to 2.1 

which is corresponds to the top of the doorway. This insight adds to that gained from the 

Case 1 comparison – counter-current flow and room leakage play a prominent role in the 

behavior of the smoky layer. 
4-37

The comparisons of layer temperatures and gas concentrations suggest that the fire power 

is higher in the FATE calculation than actually experienced in the test case. The presumably 

higher power level in the calculation contributes to higher floor and wall temperatures and 

higher heat transfer rates. Once again, the prediction of ceiling heat transfer is significantly 

higher than indicated by the test data. 

Finally, FATE provides a good prediction of the peak cable temperature. However the initial 

heat up rate lags behind the test data. 

Additional data is provided for this test to measure uni-directional and counter-current flow 

through the door. Generally good agreement is indicated between FATE and the test data. 

The door loss coefficient was reduced to 0.54 (one-half the recommended value) to obtain 

the agreement indicated in the figures. 
4-38

Figure 4-27 BE 3 CASE3 Smoky layer height. Door inflow is split equally between the 

smoky and lower layers. 
4-39

Figure 4-28 BE 3 CASE3 Smoky layer height. All door inflow goes to the lower layer. 
4-40

Figure 4-29 BE 3 CASE3 Smoky layer height. All door inflow goes to the smoky layer. 
4-41

Figure 4-30 BE 3 CASE3 Smoky layer height sensitivity calculations with all door inflow going to the lower layer. 
4-42

Figure 4-31 BE 3 CASE3 upper room gas concentrations 
4-43

Figure 4-32 BE 3 CASE3 upper and lower layer average gas temperatures 
4-44

Figure 4-33 BE 3 CASE3 floor surface temperatures 
4-45

Figure 4-34 BE 3 CASE3 North and South wall temperatures at the 1.49 m elevation 
4-46

Figure 4-35 BE 3 CASE3 North and South wall temperatures at the 1.86 m elevation 
4-47

Figure 4-36 BE 3 CASE3 North and South wall temperatures between the 3.69 and 3.82 m 

elevations 
4-48

Figure 4-37 BE 3 CASE3 East and West wall temperatures at the 1.12 m elevation 
4-49

Figure 4-38 BE 3 CASE3 East and West wall temperatures at the 2.42 m elevation 
4-50

Figure 4-39 BE 3 CASE3 ceiling heat loss (convective and radiative) 
4-51

Figure 4-40 BE 3 CASE3 floor heat loss (convective and radiative) 
4-52

Figure 4-41 BE 3 CASE3 side wall heat loss (convective and radiative) 
4-53

Figure 4-42 BE 3 CASE3 total heat loss to ceiling, floor, and walls (convective and radiative) 
4-54

Figure 4-43 BE 3 CASE3 Cable F midplane temperatures 
4-55

Figure 4-44 BE 3 CASE3 uni-direction flow through the doorway 
4-56

Figure 4-45 BE 3 CASE3 counter-current flow through the doorway 
4-57

4.2.4 BE-3 Case 4 FATE Open Benchmark Results 

Case 4 is characterized by a heptanes fuel fire with a peak power of 1150 kW and forced 

circulation due to operation of the fan supply and exhaust. A constant fan flow of 

1.06 m3

/sec (1.2 kg/s) is assumed for the duration of the run. The main doors are closed, 

however leakage around presumed door gaps is modeled. FATE calculations for BE-3 Case 

4 are presented in Figure 4-46 through Figure 4-60. 

As with all previous cases, test data indicates that the smoky layer descends to about 1.0 m. 

When the FATE calculation assumes a fan supply flow split equally between the smoky and 

lower regions, good agreement with the test data is obtained. If the fan flow is assumed to 

go to the smoky layer, only, then the smoky layer descends all the way to the floor and remains near the floor even after fire termination. Finally, if a best estimate fan flow during the 

fire period of 1 kg/s is assumed, then the calculated smoky layer elevation shows slightly 

better agreement with the data. 

The sensitivity to fan performance is also evident in the plot of gas concentration. When a 

best estimate fan flow of 1.0 kg/s in conjunction with a flow split equally between the smoky 

and lower regions is used, the FATE calculations closely follow the test data. 

The remaining calculations of gas and heat sink temperatures presented show similar levels 

of agreement as obtained in the preceding tests cases. 
4-58

Figure 4-46 BE 3 CASE4 Smoky layer height 
4-59

Figure 4-47 BE 3 CASE4 Smoky layer height sensitivity calculations 
4-60

Figure 4-48 BE 3 CASE4 upper room gas concentrations 
4-61

Figure 4-49 BE 3 CASE4 upper and lower layer average gas temperatures 
4-62

Figure 4-50 BE 3 CASE4 floor surface temperatures 
4-63

Figure 4-51 BE 3 CASE4 North and South wall temperatures at the 1.49 m elevation 
4-64

Figure 4-52 BE 3 CASE4 North and South wall temperatures at the 1.86 m elevation 
4-65

Figure 4-53 BE 3 CASE4 North and South wall temperatures between the 3.69 and 3.82 m 

elevations 
4-66

Figure 4-54 BE 3 CASE4 East and West wall temperatures at the 1.12 m elevation 
4-67

Figure 4-55 BE 3 CASE4 East and West wall temperatures at the 2.42 m elevation 
4-68

Figure 4-56 BE 3 CASE4 ceiling heat loss (convective and radiative) 
4-69

Figure 4-57 BE 3 CASE4 floor heat loss (convective and radiative) 
4-70

Figure 4-58 BE 3 CASE4 side wall heat loss (convective and radiative) 
4-71

Figure 4-59 BE 3 CASE4 total heat loss to ceiling, floor, and walls (convective and radiative) 
4-72

Figure 4-60 BE 3 CASE4 Cable F midplane temperatures 
4-73

4.2.5 BE-3 Case 5 FATE Open Benchmark Results 

Case 5 is a heptane fire with a peak power of 1150 kW and both forced circulation due to 

operation of the fan supply and exhaust and natural circulation through the open doors. A 

constant fan flow of 1.06 m3

/sec (1.2 kg/s) is assumed for the duration of the run. The fan 

inflow is assumed to go only into the smoky layer, while the door inflow is split equally between the lower and smoky layers. No new insights are obtained from this test case, however previous insights are confirmed. FATE calculations for BE-3 Case 4 are presented in 

Figure 4-61 through Figure 4-66. 

4.2.6 BE-3 Case 14, 15, and 18 FATE Open Benchmark Results 

Cases 14, ,15, and 18 are similar to previously analyzed Case 3, except the fire pan is 

moved to an off center location. In all cases the fire is nominally 1130 kW and the door is 

open but the fan is off. 

No new insights are obtained from these three test cases, however previous insights are 

confirmed. Comparisons of FATE calculations and test data for a subset of the measured 

quantities are presented in Figure 4-67 through Figure 4-82. 
4-74

Figure 4-61 BE 3 CASE5 Smoky layer height 
4-75

Figure 4-62 BE 3 CASE5 upper room gas concentrations 
4-76

Figure 4-63 BE 3 CASE5 upper and lower layer average gas temperatures 
4-77

Figure 4-64 BE 3 CASE5 Cable F midplane temperatures 
4-78

Figure 4-65 BE 3 CASE5 uni-direction flow through the doorway 
4-79

Figure 4-66 BE 3 CASE5 counter-current flow through the doorway 
4-80

Figure 4-67 BE 3 CASE14 Smoky layer height 
4-81

Figure 4-68 BE 3 CASE14 upper room gas concentrations 
4-82

Figure 4-69 BE 3 CASE14 upper and lower layer average gas temperatures 
4-83

Figure 4-70 BE 3 CASE14 Cable F midplane temperatures 
4-84

Figure 4-71 BE 3 CASE14 uni-direction flow through the doorway 
4-85

Figure 4-72 BE 3 CASE14 counter-current flow through the doorway 
4-86

Figure 4-73 BE 3 CASE15 Smoky layer height 
4-87

Figure 4-74 BE 3 CASE15 upper room gas concentrations 
4-88

Figure 4-75 BE 3 CASE15 upper and lower layer average gas temperatures 
4-89

Figure 4-76 BE 3 CASE15 uni-direction flow through the doorway 
4-90

Figure 4-77 BE 3 CASE15 counter-current flow through the doorway 
4-91

Figure 4-78 BE 3 CASE18 Smoky layer height 
4-92

Figure 4-79 BE 3 CASE18 upper room gas concentrations 
4-93

Figure 4-80 BE 3 CASE18 upper and lower layer average gas temperatures 
4-94

Figure 4-81 BE 3 CASE18 uni-direction flow through the doorway 
4-95

Figure 4-82 BE 3 CASE18 counter-current flow through the doorway 
4-96

4.3 Conclusions and Recommendations for FATE 

Open benchmark results based on the FATE computer program have been presented for 

Benchmark Exercise 3 Cases 1 through 5, 14, 15, and 18. Key conclusions from this 

benchmark effort are: 

1. Room leakage, even with doors open or fans on, plays an important role in smoky layer 

height and O2 concentration. Furthermore, counter current flow (through door for door 

open cases or through door gaps for door closed cases) is essential to obtaining reasonable estimates of smoke behavior. 

2. FATE calculations indicate that air inflow to the room, whether through open doorways, 

operating fans, or leak paths, mixes with both the smoky layer and lower layer. Proper 

behavior of the smoky layer was obtained when the inflow was split between the two 

layers. Development of a mechanistic flow split model is under consideration. 

3. The FATE standard room model consisting of a single region (subdivided into a smoky 

and lower region) with 14 heat sinks to represent floor, ceiling, and wall enclosure strips, 

and 5 junctions to represent door, fan supply and exhaust, miscellaneous leakage, and 

door gap leakage has proven to be effective in modeling prototypical cable room fires. 

4. The standard room model also relies on a radiation network containing all heat sinks, 

targets, the smoky layer, and fire, and automatically calculates view factors between the 

members of the radiation network. This benchmark exercise validated the radiation 

network approach used in the room model. 

5. In addition to the standard room model, a simplified cable model has also proven to be 

an effective means for evaluating target temperatures. The cable model simplifies the 

complex cable morphology into a 2 layer heat sink (outer jacket, inner cable insulation; 

typically the outer jacket encloses multiple cables with fill material in between the cables), neglects axial conduction along the cable, and divides the cable surface into 3 

components azimuthally. As shown in the benchmark, there is no azimuthal variation in 

temperature prediction by FATE, so future cable models can consider only 1 azimuthal 

component. 

Shortcomings in the FATE calculations are as follows: 

1. Heat loss to ceiling is consistently higher in FATE than indicated in test data.
4-97

2. Cable temperatures are often under-predicted. This is likely due to calculating too low of 

a value for the cable surface heat transfer coefficient. 

4.4 References 

Plys, Martin G., and Sung Jin Lee, 2004, FATETM 2.0: Facility Flow, Aerosol, Thermal, and 

Explosion Model (Improved and Combined HANSF and HADCRT Models), 

FAI/04-71, SNF-23281, Two Volumes, November. 

NIST, 2003, Special Publication, “Report of Experimental Results for the International Fire 

Model Benchmarking and Validation Exercise #3,”Anthony Hamins, Alexander 

Maranghides, Rik Johnsson, Michelle Donnelly, Jiann Yang, George Mulholland, 

Robert L. Anleitner, Building and Fire Research Laboratory (November, 2003).

NIST, 2004, “Test Plan For International Fire Model Benchmarking and Validation Exercise 

#3,” Alexander Maranghides, Anthony Hamins, Rodney Bryant, Erik Johnson, 

George Mulholland, John Widman (December 19, 2004).

NISTIR 6986, “International Collaborative Project to Evaluate Fire Models for Nuclear Power 

Plant Applications: Summary of 5th Meeting,“ Dey, M., Hamins, A., Miles, S. 

(September, 2003). 
4-98
5-1

5 Simulations using COCOSYS (Walter Klein-Hessling, GRS) 

COCOSYS is a so-called lumped-parameter code. To simulate the local conditions (natural 

convection, temperature stratification) the fire compartment has been divided into a relatively 

large number of control volumes. The idea is to have for each temperature measurement a 

separate control volume, and to have separate control volumes around the fire plume, the 

ventilation system, and the doors and openings. 

For the simulation a 3-D grid has been created using the grid generator GRIDGEN. With a 

specific interface routine a COCOSYS input file has been created. This interface routine calculates the view factors between different walls and from the control volumes to the walls 

using a Monte-Carlo simulation method. By this it is possible to simulate the radiation flux to 

the different targets in a realistic way. 

Blind calculations for tests 2, 3 and 4 were performed before the experiments were conducted. After the release of the experimental data for tests 2, 3 and 4, the calculations were 

improved and presented as open calculations. Finally, using the specified input parameters 

from the test documents (like the fire’s radiative fraction), the remainder of the tests were 

calculated without knowledge of the experimental results. 

5.1 COCOSYS Input Parameters and Assumptions 

COCOSYS is a so-called lumped-parameter code, dividing the compartments into several 

control volumes, where the mass and energy balance is solved. The main difference to usual 

CFD codes (like CFX or FDS) is that the momentum balance is not considered. The nodalization is presented in Fig. 5-1 and Fig. 5-2. So far as possible each measurement point has 

its own control volume. The nodalization has been created with the commercial tool 

GRIDGEN, and with an interface program the COCOSYS input was created. The door was 

sub-divided into four levels to allow counter-current flow. The cable targets were represented 

as structures. Therefore they were placed between the zone levels. As seen in Fig. 5-2 the 

nodalization is more detailed near the fire and the cable targets. In total, 274 zones (control 

volumes) were created (Fig. 5-3). 
5-2

Fig. 5-1 Side view of COCOSYS model 

Fig. 5-2 Top view of COCOSYS model 
5-3

Fig. 5-3 3-D view of COCOSYS model 

1-D heat conduction through the 2.54 cm thick outside walls was performed. The leak area 

was assumed to be 0.0289 m2

 in the first blind calculation (test 2, 3 and 4) as given in the 

specification. According to the experimental results this value was increased to 0.058 m2

(value for test 2) for the open calculations and further blind calculations. Although specific 

leakage areas were given for each experiment, this value was not changed in the 

COCOSYS input. 

For the simulation of the heptane fire, injection tables were used. The flow rate was estimated using the specified heat of combustion of 45 MJ/kg. In the first blind calculations (test 

2, 3 and 4) the fuel flow rates were based on the specified heat release rate of 1 MW. In the 

following open and blind calculations, the measured values were used. For the first blind 

calculations a radiative fraction of 35 % was assumed. In the following calculations this value 

was increased to 44 % according to the documented value. In Tab. 5-1 the parameters for 

combustion in the first blind and the following open/blind tests are presented. In the open 

and further blind calculations the heat release rate was increased. In the first blind calculations the CO reaction was under-estimated, so the CO reaction rate was increased. In the 

same way the combustion stoichiometry was adjusted (Tab. 5-2). 
5-4

In COCOSYS it is possible to stop the calculation if the oxygen concentration in a certain 

control volume falls below a given value. This option was used in the blind calculations. After 

the stop, the calculation was restarted without a fire. In the open calculations the times of 

fuel supply were used directly. 

In the calculations for tests 4, 5, 10 and 16, an air supply and exhaust system was used. 

This was modeled with the fan system model in COCOSYS. The fan characteristics are 

shown in Tab. 5-3. These characteristics were used for all calculations. Only the flow rate 

was increased from 0.75 m3

/s to 1.1 m3/s in the open and further blind calculations. 

The cable targets are simulated by plate-type wall structures (Fig. 5-4). These structures are 

composed of the outside insulation material with an inner metal core. The area of the plate 

corresponds to the projection of the cable or cable tray. The thickness is estimated to the 

existing cross sections of wires and insulation material. It has to kept in mind, that the interaction with the environment is only via the plate surface. Especially for small cable objects 

some differences may be expected. 

The junction box was simulated by an additional control volume BOX connected via a feraloy 

structure to the fire compartment and to the ceiling via a combined feraloy-marinite structure. 

Because this additional volume was not created by GRIDGEN, the junction box structure 

was not considered in the view factor calculation and no wall-to-wall radiation was considered. That means only convective and radiative heat transfer from the connected control 

volume of the fire compartment. 
5-5

Tab. 5-1 Combustion Parameters 

Parameter Comment First blind Open/blind 

PYRMIX Mixing velocity [m/s] 2.0 0.5 

TIGNMX Ignition temperature [°C] 280. 300. 

TIGNMN Min. burning temperature [°C] 70. 70. 

RLIM_CHX CHX ignition conc. [Vol-%] 0.05 0.24 

RIGN_CO CO ignition conc. [Vol-%] 0.5 0.1 

DLIM_O2 Lower oxygen limit [Vol-%] 0.0+2.0 0.0+2.0 

FEFF Burning efficiency [-] 0.99 0.99 

Tab. 5-2 Combustion Stoichiometry 

 First blind Open/blind 

O2 conc. [VOL-%] FCHX FCO FCHX FCO 

0. 0. 0. 0. 0. 

4. 0.1 0.1 

4.84 0.07 0.85 

11.15 0.39 0.97 

12. 0.1 0.3 

15. 0.8 0.8 0.78 1.0 

17. 0.9 1.0 

21. 1.0 1.0 1.0 1.0 

25. 1.0 1.0 1.0 1.0 
5-6

Tab. 5-3 Fan characteristics 

Fig. 5-4 Simulation of cable targets with plate-type wall structures 
5-7

5.2 Comparison of COCOSYS Predictions with Measurements 

In the following the results of all performed calculations will be presented. Due to the high 

number of calculations it is somewhat difficult to discuss each point in detail. On the other 

hand it is important to present all results at least as figures. Therefore not all figures may be 

commented. 

Fig. 5-1 presents the list of calculations performed (green shaded). The blind calculations of 

tests 2, 3 and 4 are indicated by blue text. Tests 1, 5, 7, 10, 13, 16, 17 and 18 were calculated blind using the measured HRR. Tests 8 and 9 were identical to 2 and 3, respectively, 

and were not calculated. In tests 14 and 15 the fire location was changed. But this change 

did not conform to the nodalization used and were therefore not calculated. 

Fig. 5-5 Calculation Matrix 
5-8

5.2.1 First set of blind calculations for tests 2, 3 and 4 

Inside this section the results of first blind calculations of test 2, 3 and 4 will be presented. 

• Gas temperatures at Tree 1 

Fig. 5-6 to Fig. 5-8 shows the comparison for the temperature Tree 1. The temperature 

spreading between the lowest and highest position is simulated quite well for test 1 (closed 

conditions). Only in the inner positions the maximum deviations are larger and about 50 K. 

The time behavior shows that the fuel supply has been stopped about 100 s too early. The 

deviations in test 3 are somewhat larger. The maximum temperature below the ceiling is 

calculated about 20 K too low. Also the temperatures at the lowest position 2 and 3 are under-estimated by about 25 K. The temperatures at position 3 (1.05 m) and 4 (1.40 m) are 

quite different. In the COCOSYS simulation these positions belong to the same control volume (level between 1.0 and 1.5 m). Therefore the separation between hot and cold gas layer 

is sometimes not well-resolved in the COCOSYS simulation. For test 4 the temperatures 

below the ceiling are over-estimated by about 50 K. The main reason seems to be the under-estimate of air flow from the ventilation system. 

• Temperature profiles

Fig. 5-9 to Fig. 5-11 show the temperature profiles at all trees at certain times close to the 

maximum temperatures of the corresponding test. For test 2 the deviations are about 50 K 

and somewhat larger as in the lower part. One has to keep in mind that this kind of deviation 

includes deviations in time and in values. For test 3 the temperature of tree 3 is underestimated for all positions. The experimental measurement at tree 6 is possibly flawed. All 

other values are quite good. In test 4 the deviations in the upper part are larger also. This is 

valid especially for trees 3 to 5 close to the ventilation supply. Due to the missing momentum 

balance the simulation is limited close to such systems. But on the other side the ventilation 

flow rate is too small here, leading to higher gas temperatures. 

• Wall temperatures

The temperatures on the floor are shown in Fig. 5-12 to Fig. 5-14. In the tests 2 and 3 the 

calculated values are somewhat lower than in the experiment. Only for test 4 do the calculated temperatures reach the right level. The measured value at position U4 seems to be too 

high. The corresponding symmetric value at position U5 is much lower. The radiation to the 

floor seems to be under-estimated in the COCOSYS calculation. It has to be kept in mind 
5-9

that the fuel spray is not simulated. The flame height in COCOSYS (control volumes with 

energy release) may be too low. 

Fig. 5-15 to Fig. 5-17 shows the wall temperatures at the west side. The deviations are about 

20 K in test 2 and 3 and about 50 K for test 4. The direction of deviation corresponds to the 

calculated atmospheric temperatures. The deviations are somewhat higher for the south wall 

(Fig. 5-18 to Fig. 5-20) in test 2. These are for the upper positions about 40 K. In test 3 the 

correspondence is much better, whereas in test 4 the calculated values are too high. 

The ceiling temperatures (Fig. 5-21 to Fig. 5-23) are not so strongly influenced by a possible 

wrong calculation of stratification. Therefore the temperatures are calculated quite well for 

test 2. For test 3 the deviations are somewhat larger (50 K) and the temperatures are overestimated for test 4. The difference between position U4 and U5 show the influence of the 

ventilation system. This could not be simulated in COCOSYS. 

• Concentrations

Fig. 5-24 to Fig. 5-26 shows the comparison for the gas concentrations. The lower oxygen 

concentration in tests 2 and 4 decreases rapidly when the hot gas layer reaches the measurement position. Due to the fixed grid and the resulting numerical diffusion, the calculated 

decrease is less rapid. Regardless, the time to fuel stop is calculated quite well. After the fuel 

stop the concentrations became more or less equal in the experiment. This is somewhat 

underestimated in the COCOSYS calculation. Further, the CO2 concentration is underestimated as well in tests 2 and 3. Due to the low air supply in test 4 the CO2 concentration 

is much better here. But this is a compensating effect. 

• Tray temperatures

One main objective of these experiments was the evaluation of temperature loads on cable 

trays of different size and distance to the fire source. Due to the high number of temperature 

measurements not all results could be discussed, but all comparisons are shown in the Fig. 

5-27 to Fig. 5-50. Mostly the temperature inside and on the cable surface are somewhat under-estimated in COCOSYS (partly up to 50 K). It has to be kept in mind, that in the blind 

calculations a radiation fraction of 35 % is used, which is lower as observed in other experiments. The differences between experiment and calculation is much less for control cable A 

compared to the power cable F (see Fig. 5-31, Fig. 5-39 and Fig. 5-47) In test 4 the cable 

temperatures close to the ventilation system may be cooled by the air flow. Therefore the 

deviation between calculation and experiment is much larger (Fig. 5-46). The deviations at 
5-10

position 22 and 23 are much larger compared to the positions 8 and 9. The main reason is 

the COCOSYS results, which is about 50 K higher. The reason for this asymmetric behavior 

is not clear. 

• Junction box

The results for the junction box are unlike the other temperature results (Fig. 5-51 to Fig. 

5-53). The reason is not clear, because due to the missing radiation term between fire 

source and box in the heat transfer correlation the temperatures should be lower compared 

to the experiment. Also the trend in test 3 and 4 is not consistent with the experimental results. Further investigations are necessary. 

• Temperatures and velocity at door in test 3

In test 3 the door to the environment was open. The temperature results are presented in 

Fig. 5-54 to Fig. 5-57 and the velocity in Fig. 5-58 to Fig. 5-61. The use of four levels of control volumes allows the simulation of counter-current flow structures, but the resolution is 

somewhat limited. The calculated results are taken from control volumes close to the door 

but inside the fire compartment. Therefore the temperatures in the lower part are too high. 

Overall the quality of the results is quite good. The experiment shows that the flow direction 

changes in level 2 (Fig. 5-59). Therefore, the COCOSYS results are qualitatively correct, but 

it is not possible to provide a more quantitative result. 

• Ventilation in test 4

Fig. 5-62 shows the comparison of ventilation flow rate. The calculated supply flow rate is by 

a factor of two too low compared to the experiment. This could explain the high gas temperatures in test 4. The difference at t = 0 s between the measured inlet and outlet flow should be 

explained in more detail. The time history looks quite similar between experiment and calculation. 
5-11

Test 2 (blind) :Temperature Tree 1

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-6 Test 2: Temperatures at Tree 1 

Test 3 (blind) :Temperature Tree 1

0

50

100

150

200

250

300

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-7 Test 3: Temperatures at Tree 1 
5-12

Test 4 (blind) :Temperature Tree 1

0

50

100

150

200

250

300

350

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-8 Test 4: Temperatures at Tree 1 

Test 2 (blind) : Tree temperature profiles 

0

50

100

150

200

250

300

350

400

0 0.5 1 1.5 2 2.5 3 3.5 4

Heigt h [m]

Temperature T [°C] at t = 400s

T1-Tree1 (exp)

T1-Tree1 (coc)

T1-Tree2 (exp)

T1-Tree2 (coc)

T1-Tree3 (exp)

T1-Tree3 (coc)

T1-Tree4 (exp)

T1-Tree4 (coc)

T1-Tree5 (exp)

T1-Tree5 (coc)

T1-Tree6 (exp)

T1-Tree6 (coc)

T1-Tree7 (exp)

T1-Tree7 (coc)

Fig. 5-9 Test 2: Temperature profiles at 400 s 
5-13

Test 3 (blind) : Tree temperature profiles 

0

50

100

150

200

250

300

350

400

450

0 0.5 1 1.5 2 2.5 3 3.5 4

Heigt h [m]

Temperature T [°C] at t = 400s

T1-Tree1 (exp)

T1-Tree1 (coc)

T1-Tree2 (exp)

T1-Tree2 (coc)

T1-Tree3 (exp)

T1-Tree3 (coc)

T1-Tree4 (exp)

T1-Tree4 (coc)

T1-Tree5 (exp)

T1-Tree5 (coc)

T1-Tree6 (exp)

T1-Tree6 (coc)

T1-Tree7 (exp)

T1-Tree7 (coc)

Fig. 5-10 Test 3: Temperature profiles 

Test 4 (blind) : Tree temperature profiles 

0

50

100

150

200

250

300

350

400

450

0 0.5 1 1.5 2 2.5 3 3.5 4

Heigt h [m]

Temperature T [°C] at t = 800s

T1-Tree1 (exp)

T1-Tree1 (coc)

T1-Tree2 (exp)

T1-Tree2 (coc)

T1-Tree3 (exp)

T1-Tree3 (coc)

T1-Tree4 (exp)

T1-Tree4 (coc)

T1-Tree5 (exp)

T1-Tree5 (coc)

T1-Tree6 (exp)

T1-Tree6 (coc)

T1-Tree7 (exp)

T1-Tree7 (coc)

Fig. 5-11 Test 4 : Temperature profiles 
5-14

Test 2 (blind) : Inner Floor temperatures

0

20

40

60

80

100

120

140

160

180

200

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

Floor U1 exp

Floor U2 exp

Floor U3 exp

Floor U4 exp

Floor U5 exp

Floor U6 exp

Floor U7 exp

Floor U8 exp

Floor U1 coc

Floor U2 coc

Floor U3 coc

Floor U4 coc

Floor U5 coc

Floor U6 coc

Floor U7 coc

Floor U8 coc

Fig. 5-12 Test 2: Floor wall temperatures 

Test 3 (blind) : Inner Floor temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Floor U1 exp

Floor U2 exp

Floor U3 exp

Floor U4 exp

Floor U5 exp

Floor U6 exp

Floor U7 exp

Floor U8 exp

Floor U1 coc

Floor U2 coc

Floor U3 coc

Floor U4 coc

Floor U5 coc

Floor U6 coc

Floor U7 coc

Floor U8 coc

Fig. 5-13 Test 3: Floor wall temperatures 
5-15

Test 4 (blind) : Inner Floor temperatures

0

20

40

60

80

100

120

140

160

180

200

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Floor U1 exp

Floor U2 exp

Floor U3 exp

Floor U4 exp

Floor U5 exp

Floor U6 exp

Floor U7 exp

Floor U8 exp

Floor U1 coc

Floor U2 coc

Floor U3 coc

Floor U4 coc

Floor U5 coc

Floor U6 coc

Floor U7 coc

Floor U8 coc

Fig. 5-14 Test 4: Floor wall temperatures 

Test 2 (blind) : Inner west wall temperatures

0

20

40

60

80

100

120

140

160

180

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

West-U1 exp

West U2 exp

West U3 exp

West U4 exp

West U1 coc

West U2 coc

West U3 coc

West U4 coc

Fig. 5-15 Test 2: West wall temperatures 
5-16

Test 3 (blind) : Inner west wall temperatures

0

20

40

60

80

100

120

140

160

180

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

West-U1 exp

West U2 exp

West U3 exp

West U4 exp

West U1 coc

West U2 coc

West U3 coc

West U4 coc

Fig. 5-16 Test 3: West wall temperatures 

Test 4 (blind) : Inner west wall temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

West-U1 exp

West U2 exp

West U3 exp

West U4 exp

West U1 coc

West U2 coc

West U3 coc

West U4 coc

Fig. 5-17 Test 4: West wall temperatures 
5-17

Test 2 (blind) : Inner south wall temperatures

0

20

40

60

80

100

120

140

160

180

200

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

South-U1 exp

South U2 exp

South U4 exp

South U5 exp

South U6 exp

South U1 coc

South U2 coc

South U3 coc

South U4 coc

South U5 coc

South U6 coc

Fig. 5-18 Test 2: South wall temperatures 

Test 3 (blind) : Inner south wall temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

South-U1 exp

South U2 exp

South U4 exp

South U5 exp

South U6 exp

South U1 coc

South U2 coc

South U3 coc

South U4 coc

South U5 coc

South U6 coc

Fig. 5-19 Test 3: South wall temperatures 
5-18

Test 4 (blind) : Inner south wall temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

South-U1 exp

South U2 exp

South U4 exp

South U5 exp

South U6 exp

South U1 coc

South U2 coc

South U3 coc

South U4 coc

South U5 coc

South U6 coc

Fig. 5-20 Test 4: South wall temperatures 

Test 2 (blind) : Inner ceiling temperatures

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

Ceiling U1 exp

Ceiling U2 exp

Ceiling U3 exp

Ceiling U4 exp

Ceiling U5 exp

Ceiling U6 exp

Ceiling U7 exp

Ceiling U8 exp

Ceiling U1 coc

Ceiling U2 coc

Ceiling U3 coc

Ceiling U4 coc

Ceiling U5 coc

Ceiling U6 coc

Ceiling U7 coc

Ceiling U8 coc

Fig. 5-21 Test 2: Ceiling temperatures 
5-19

Test 3 (blind) : Inner ceiling temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Ceiling U1 exp

Ceiling U2 exp

Ceiling U3 exp

Ceiling U4 exp

Ceiling U5 exp

Ceiling U6 exp

Ceiling U7 exp

Ceiling U8 exp

Ceiling U1 coc

Ceiling U2 coc

Ceiling U3 coc

Ceiling U4 coc

Ceiling U5 coc

Ceiling U6 coc

Ceiling U7 coc

Ceiling U8 coc

Fig. 5-22 Test 3: Ceiling temperatures 

Test 4 (blind) : Inner ceiling temperatures

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Ceiling U1 exp

Ceiling U2 exp

Ceiling U3 exp

Ceiling U4 exp

Ceiling U5 exp

Ceiling U6 exp

Ceiling U7 exp

Ceiling U8 exp

Ceiling U1 coc

Ceiling U2 coc

Ceiling U3 coc

Ceiling U4 coc

Ceiling U5 coc

Ceiling U6 coc

Ceiling U7 coc

Ceiling U8 coc

Fig. 5-23 Test 4: Ceiling temperatures 
5-20

Test 2 (blind) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-24 Test 2: Concentrations 

Test 3 (blind) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-25 Test 3: Concentrations 
5-21

Test 4 (blind) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-26 Test 4: Concentrations 

Test 2 (blind) : Tray temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-27 Test 2: tray temperatures 1 to 7 
5-22

Test 2 (blind) : Tray temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

C-Ts-8 exp

C-Tc-9 exp

C-Ts-8 coc

C-Tc-9 coc

Fig. 5-28 Test 2: tray temperatures 8 to 9 

Test 2 (blind) : Tray temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

C-Ts-10 exp

C-Tc-11 exp

D-Ts-13 exp

C-Ts-10 coc

C-Tc-11 coc

D-Ts-13 coc

Fig. 5-29 Test 2: tray temperatures 10 to 13 
5-23

Test 2 (blind) : Tray temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

B-Ts-14 exp

B-Tc-15 exp

E-Ts-16b exp

E-Tc-17 exp

B-Ts-14 coc

B-Tc-15 coc

E-Ts-16b coc

E-Tc-17 coc

Fig. 5-30 Test 2: tray temperatures 14 to 17 

Test 2 (blind) : Tray temperatures

0

20

40

60

80

100

120

140

160

180

200

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

A-Ts-18 exp

A-Tc-19 exp

F-Ts-20 exp

F-Tc-21 exp

A-Ts-18 coc

A-Tc-19 coc

F-Ts-20 coc

F-Tc-21 coc

Fig. 5-31 Test 2: tray temperatures 18 to 21 
5-24

Test 2 (blind) : Tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

C-Ts-22 exp

C-Tc-23 exp

C-Ts-22 coc

C-Tc-23 coc

Fig. 5-32 Test 2: tray temperatures 22 to 23 

Test 2 (blind) : Tray temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

C-Ts-24 exp

C-Tc-25 exp

D-Ts-26 exp

B-Ts-27 exp

A-Ts-29 exp

F-Ts-30 exp

C-Ts-24 coc

C-Tc-25 coc

D-Ts-26 coc

B-Ts-27 coc

A-Ts-29 coc

F-Ts-30 coc

Fig. 5-33 Test 2: tray temperatures 24 to 30 
5-25

Test 2 (blind) : Vertical tray temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

Ts-31 exp

Ts-32 exp

Ts-33 exp

Tc-34 exp

Ts-35 exp

Ts-36 exp

Ts-31 coc

Ts-32 coc

Ts-33 coc

Tc-34 coc

Ts-3 coc

Ts-36 coc

Fig. 5-34 Test 2: tray temperatures 31 to 36 

Test 3 (blind) : Tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-35 Test 3: tray temperatures 1 to 7 
5-26

Test 3 (blind) : Tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-8 exp

C-Tc-9 exp

C-Ts-8 coc

C-Tc-9 coc

Fig. 5-36 Test 3: tray temperatures 8 to 9 

Test 3 (blind) : Tray temperatures

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-10 exp

C-Tc-11 exp

D-Ts-13 exp

C-Ts-10 coc

C-Tc-11 coc

D-Ts-13 coc

Fig. 5-37 Test 3: tray temperatures 10 to 13 
5-27

Test 3 (blind) : Tray temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

B-Ts-14 exp

B-Tc-15 exp

E-Ts-16b exp

E-Tc-17 exp

B-Ts-14 coc

B-Tc-15 coc

E-Ts-16b coc

E-Tc-17 coc

Fig. 5-38 Test 3: tray temperatures 14 to 17 

Test 3 (blind) : Tray temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

A-Ts-18 exp

A-Tc-19 exp

F-Ts-20 exp

F-Tc-21 exp

A-Ts-18 coc

A-Tc-19 coc

F-Ts-20 coc

F-Tc-21 coc

Fig. 5-39 Test 3: tray temperatures 18 to 21 
5-28

Test 3 (blind) : Tray temperatures

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-22 exp

C-Tc-23 exp

C-Ts-22 coc

C-Tc-23 coc

Fig. 5-40 Test 3: tray temperatures 22 to 23 

Test 3 (blind) : Tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-24 exp

C-Tc-25 exp

D-Ts-26 exp

B-Ts-27 exp

A-Ts-29 exp

F-Ts-30 exp

C-Ts-24 coc

C-Tc-25 coc

D-Ts-26 coc

B-Ts-27 coc

A-Ts-29 coc

F-Ts-30 coc

Fig. 5-41 Test 3: tray temperatures 24 to 30 
5-29

Test 3 (blind) : Vertical tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Ts-31 exp

Ts-32 exp

Ts-33 exp

Tc-34 exp

Ts-35 exp

Ts-36 exp

Ts-31 coc

Ts-32 coc

Ts-33 coc

Tc-34 coc

Ts-3 coc

Ts-36 coc

Fig. 5-42 Test 3: tray temperatures 31 to 36 

Test 4 (blind) : Tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-43 Test 4: tray temperatures 1 to 7 
5-30

Test 4 (blind) : Tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-8 exp

C-Tc-9 exp

C-Ts-8 coc

C-Tc-9 coc

Fig. 5-44 Test 4: tray temperatures 8 to 9 

Test 4 (blind) : Tray temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-10 exp

C-Tc-11 exp

D-Ts-13 exp

C-Ts-10 coc

C-Tc-11 coc

D-Ts-13 coc

Fig. 5-45 Test 4: tray temperatures 10 to 13 
5-31

Test 4 (blind) : Tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

B-Ts-14 exp

B-Tc-15 exp

E-Ts-16b exp

E-Tc-17 exp

B-Ts-14 coc

B-Tc-15 coc

E-Ts-16b coc

E-Tc-17 coc

Fig. 5-46 Test 4: tray temperatures 14 to 17 

Test 4 (blind) : Tray temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

A-Ts-18 exp

A-Tc-19 exp

F-Ts-20 exp

F-Tc-21 exp

A-Ts-18 coc

A-Tc-19 coc

F-Ts-20 coc

F-Tc-21 coc

Fig. 5-47 Test 4: tray temperatures 18 to 21 
5-32

Test 4 (blind) : Tray temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-22 exp

C-Tc-23 exp

C-Ts-22 coc

C-Tc-23 coc

Fig. 5-48 Test 4: tray temperatures 22 to 23 

Test 4 (blind) : Tray temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-24 exp

C-Tc-25 exp

D-Ts-26 exp

B-Ts-27 exp

A-Ts-29 exp

F-Ts-30 exp

C-Ts-24 coc

C-Tc-25 coc

D-Ts-26 coc

B-Ts-27 coc

A-Ts-29 coc

F-Ts-30 coc

Fig. 5-49 Test 4: tray temperatures 24 to 30 
5-33

Test 4 (blind) : Vertical tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Ts-31 exp

Ts-32 exp

Ts-33 exp

Tc-34 exp

Ts-35 exp

Ts-36 exp

Ts-31 coc

Ts-32 coc

Ts-33 coc

Tc-34 coc

Ts-3 coc

Ts-36 coc

Fig. 5-50 Test 4: tray temperatures 31 to 36 

Test 2 (blind) : Junction box temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

JB-Tc-37 exp

JB-Ts-38 exp

JB-Tc-37 coc

JB-Ts-38 coc

Fig. 5-51 Test 2: Temperatures at junction box 
5-34

Test 3 (blind) : Junction box temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

JB-Tc-37 exp

JB-Ts-38 exp

JB-Tc-37 coc

JB-Ts-38 coc

Fig. 5-52 Test 3: Temperatures at junction box 

Test 4 (blind) : Junction box temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

JB-Tc-37 exp

JB-Ts-38 exp

JB-Tc-37 coc

JB-Ts-38 coc

Fig. 5-53 Test 4: Temperatures at junction box 
5-35

Test 3 (blind) : Temperatures at door

0

5

10

15

20

25

30

35

40

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

TC Door-1 exp

TC Door-9 exp

TC Door-17 exp

TC Door-1 coc

Fig. 5-54 Test 3: Temperature at door (level 1) 

Test 3 (blind) : Temperatures at door

0

20

40

60

80

100

120

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

TC-Door-2 exp

TC Door-3 exp

TC Door 10 exp

TC Door-11 exp

TC Door-18 exp

TC Door-19 exp

TC Door-2 coc

Fig. 5-55 Test 3: Temperature at door (level 2) 
5-36

Test 3 (blind) : Temperatures at door

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

TC-Door-4 exp

TC Door-5 exp

TC Door-12 exp

TC Door-13 exp

TC Door-20 exp

TC Door-21 exp

TC Door-4 coc

Fig. 5-56 Test 3: Temperature at door (level 3) 

Test 3 (blind) : Temperatures at door

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

TC-Door-6 exp

TC Door-7 exp

TC Door-8 exp

TC Door-14 exp

TC Door-15 exp

TC Door-16 exp

TC Door-6 coc

Fig. 5-57 Test 3: Temperature at door (level 4) 
5-37

Test 3 (blind) : Velocity at door

-1

-0.5

0

0.5

1

1.5

2

2.5

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

velocity v [m/s]

BP Door-1 exp

BP Door-6 exp

BP Door-11 exp

BP Door-1 coc

Fig. 5-58 Test 3: Velocity at door (level 1) 

Test 3 (blind) : Velocity at door

-1.5

-1

-0.5

0

0.5

1

1.5

2

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

velocity v [m/s]

BP Door-2 exp

BP Door-3 exp

BP Door-7 exp

BP Door-8 exp

TC Door-12 exp

BP Door-13 exp

BP Door-2 coc

Fig. 5-59 Test 3: Velocity at door (level 2) 
5-38

Test 3 (blind) : Velocity at door

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

velocity v [m/s]

BP Door-4 exp

BP Door-9 exp

BP Door-14 exp

BP Door-4 coc

Fig. 5-60 Test 3: Velocity at door (level 3) 

Test 3 (blind) : Velocity at door

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

velocity v [m/s]

BP Door-5 exp

BP Door-10 exp

BP Door-14 exp

BP Door-5 coc

Fig. 5-61 Test 3: Velocity at door (level 4) 
5-39

Test 4 (blind) : Ventilation

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

velocity v [m/s]

BP supply exp

BP exhaust exp

BP supply coc

BP exhaust coc

Fig. 5-62 Test 4: Velocity at ventilation 
5-40

5.2.2 Open calculation of test 2, 3 and 4 

The calculations of tests 2, 3 and 4 were repeated after the release of the experimental data. 

As far as possible, the given experimental boundary conditions were used. In the following 

only some part of the results are discussed, especially the differences from the blind calculations. 

Fig. 5-63 to Fig. 5-65 show the temperature results at tree 1 for the three tests. Compared to 

the blind calculation the results are now better. This is valid especially for the test 3 and for 

test 4 with the improved ventilation flow rate. Only in the lower positions the deviations are 

somewhat larger. 

The quality of the results is very similar to that of the blind calculations. Larger changes 

could be observed for test 4. For example the calculated temperatures on the floor area is 

now too low (Fig. 5-66). The increase of the radiation fraction could not compensate the increased volume exchange via the ventilation. Additionally the calculated oxygen concentrations are now too high in this case. In case of an automatic simulation of the stop of fuel 

supply, the fuel supply wouldn’t have stopped. The calculated CO2 concentration has been 

underestimated. These results show that the heat release and oxygen consumption are 

somewhat inconsistent in this calculation. Further tests are needed for the estimation of volume flow through the ventilation. 

Fig. 5-68 to Fig. 5-72 show some results for the tray temperatures. Due to the higher radiation fraction the calculated values are somewhat higher. This effect is stronger for temperature positions close to the fire. The deviations in test 4 close to the ventilation are still rather 

high (Fig. 5-72). This problem results from the missing momentum balance in the COCOSYS 

simulation, so that cold jets close to the ventilation could not directly be simulated. One possible solution is the distribution of the air supply volume flow into several control volumes 

around the system. 

Fig. 5-73 shows the comparison of the improved ventilation flow in test 4. The exhaust velocity follows now more or less the experimental data. Larger deviations exist still for the supply 

velocity. But the difference in the velocity at the beginning should be clarified first. 
5-41

Test 2 (open) :Temperature Tree 1

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-63 Test 2 (open) : Temperatures at tree 1 

Test 3 (open) :Temperature Tree 1

0

50

100

150

200

250

300

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-64 Test 3 (open) : Temperatures at tree 1 
5-42

Test 4 (open) :Temperature Tree 1

0

50

100

150

200

250

300

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-65 Test 4 (open) : Temperatures at tree 1 

Test 4 (open) : Inner Floor temperatures

0

20

40

60

80

100

120

140

160

180

200

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Floor U1 exp

Floor U2 exp

Floor U3 exp

Floor U4 exp

Floor U5 exp

Floor U6 exp

Floor U7 exp

Floor U8 exp

Floor U1 coc

Floor U2 coc

Floor U3 coc

Floor U4 coc

Floor U5 coc

Floor U6 coc

Floor U7 coc

Floor U8 coc

Fig. 5-66 Test 4 (open) : Temperatures at floor 
5-43

Test 4 (open) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-67 Test 4 (open) : Gas concentrations 

Test 2 (open) : Tray temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-68 Test 2 (open) : Tray temperatures at 1 to 7 
5-44

Test 2 (open) : Tray temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600

time t [s]

temperature T [°C]

C-Ts-10 exp

C-Tc-11 exp

D-Ts-13 exp

C-Ts-10 coc

C-Tc-11 coc

D-Ts-13 coc

Fig. 5-69 Test 2 (open) : Tray temperatures at 10 to 13 

Test 3 (open) : Tray temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-70 Test 3 (open) : Tray temperatures at 1 to 7 
5-45

Test 4 (open) : Tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-71 Test 4 (open) : Tray temperatures at 1 to 7 

Test 4 (open) : Tray temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-10 exp

C-Tc-11 exp

D-Ts-13 exp

C-Ts-10 coc

C-Tc-11 coc

D-Ts-13 coc

Fig. 5-72 Test 4 (open) : Tray temperatures 10 to 13 (close to ventilation) 
5-46

Test 4 (blind) : Ventilation

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

velocity v [m/s]

BP supply exp

BP exhaust exp

BP supply coc

BP exhaust coc

Fig. 5-73 Test 4 (open) : Velocity at ventilation openings 
5-47

5.2.3 Further blind calculations 

In this section, the blind calculations of the remaining tests are discussed. 

Test 1 

The test 1 is similar to test 2 with a reduced heat release of about 0.35 MW. The calculated 

temperatures at tree 1 are quite similar to the experimental values (Fig. 5-74). Only in the 

lower regions the calculated temperatures are overestimated by about 40 K (position 2), 

which may be caused by numerical diffusion. The picture concerning to the temperature 

loads on the cable is quite similar to other tests (Fig. 5-75). The temperature load on control 

cables are overestimated by 20 K. The calculated temperature on the power cable is quite 

good. But is has to be considered that the atmospheric temperature is about 20 K too high at 

this location. The simulation of oxygen and carbondioxid concentration is quite good. Only 

the lower oxygen concentration is underestimated by a few percent. This corresponds to the 

too high temperatures at lower positions (numerical diffusion). 

Test 5 

In test 5 a 1 MW fire was used with open doors and running ventilation system. In this simulation the upper temperatures at tree 1 are overestimated by about 30 K. The lower temperatures are calculated quite well (Fig. 5-77). Due to the open door these temperatures are 

lower than the temperatures far inside the fire compartment. Therefore the maximum calculated temperature load on the cables (like position 1 to 7) is larger and reaches values up to 

350 °C (at position 10). Concerning the temperature load especially close the ventilation 

system the deviations to the experiment are rather large and reaches about 150 K for the 

single control cable (position 10) and about 100 K for the cable tray D (position 13). These 

deviations close to the ventilation system could be observed in the comparison of the temperature profile also (Fig. 5-78). Especially the temperatures at the upper positions of tree 3, 

4 and 5 are overestimated by COCOSYS. The experimental values at tree 6 are rather high, 

especially at about 1 m. This indicates a defection of the flame to the east side. In 

COCOSYS the plume is not really modeled. Due to the missing momentum balance a possible deflection could not be calculated also. The gas concentrations are simulated quite well 

(Fig. 5-81). Some results concerning velocity at door are shown in Fig. 5-82 and Fig. 5-83. 

In the lowest level the calculated results are quite similar to the experiment. One level higher 
5-48

the counter current effects occur in the range of 50 cm. This indicates a sharp layer separation in the atmospheric flow. 

Test 7 

Test 7 is a replicate test to test 1. Only the cable material has been changed from XPE to 

PVC. Therefore the calculated results are similar to test 1. This is valid for the experimental 

data too, show the reproducibility of the tests. In the experiment the target temperatures are 

slightly higher for PVC material (Fig. 5-85). This could not be reproduced in the COCOSYS 

calculation. Here the results for XPE are higher compared to PVC. The reason may be the 

used thickness of the material layers, because all other input parameters are exactly the 

same. Here further clarification is necessary. Further the difference between calculated surface and center temperature is much larger compared to the experiment. The delivered results for the center temperature belongs to the real center of the cable. But the measured 

location is below the insulation jacket. 

Test 10

Test 10 is a replicate test to test 4. In this blind calculation the fuel stop is estimated by the 

calculated oxygen concentration. Unfortunately the calculated values are somewhat to high, 

so that the fuel stop is calculated about 600 s too late. Therefore the temperature at tree 1 

and gas concentrations are presented only. 

Test 13

Test 13 has been performed with closed fire compartment and a heat release rate of about 2 

MW. Fig. 5-88 shows the comparison of temperatures at tree 1. The deviations are about 50 

K with a slight over-estimation in the upper part and an under-estimation in the lower part. 

The temperature decrease after the fuel stop is simulated too slowly. This indicates that the 

heat loss is higher than assumed in the COCOSYS calculation. Fig. 5-89 presents the temperature profile at 300 s. As before the measured temperatures at tree 6 are much higher 

than those calculated by COCOSYS. These temperatures may be influenced by the spray 

fire directly. Otherwise the temperature profile is calculated quite well, with some larger deviations for tree 3 (also relatively close to the fire) and some larger deviations in the upper 

part. The temperature load is simulated quite well, with some underestimation of the maximum temperatures. Fig. 5-90 presents the tray temperatures at position 1 to 7. The temperature increase of the surface temperature of the control cable C (highest position) is 

simulated quite well. Corresponding to the atmospheric temperatures the temperature de-
5-49

crease is underestimated. The temperature increase of the control cable A and B is underestimated, although the atmospheric temperature is simulated quite well at these locations. As 

in other cases the surface temperature of the power cable is underestimated. Fig. 5-91 and 

Fig. 5-92 present the comparison for the west wall and the ceiling temperatures. The deviations for the west wall are rather high, especially for the upper positions U2 and U4. Here the 

experimental values are not correct, because these have lower temperatures compared to 

the lower measurement positions. The ceiling temperatures are underestimated by about 

100 K for the locations close to the fire plume. Here the measured values at position U1 and 

U8 are about 60 °C and much lower compared to test 2 with a lower heat release rate. The 

gas concentrations are simulated quite well (Fig. 5-93). 

Test 16

The test 16 can be compared to test 13 with an additional active ventilation. The volume flow 

rate is quite important. This may be the explanation for the deviations in the gas concentrations (Fig. 5-95) which are higher compared to test 13. The deviations lead to a delay in the 

fuel supply stop. Up to the time point of the fuel stop in the experiment the temperature results are quite well (e. g. tree 1 in Fig. 5-94). The velocities at the air supply and exhaust 

system show a similar behavior as in the other tests. Here some additional clarification is 

needed, especially again for the initial values at t = 0 s. The results for the junction box are 

bad as in all cases. Fig. 5-99 shows the comparison for the vertical tray temperatures. These 

are somewhat underestimated in the COCOSYS calculation, although the south wall temperatures are quite similar to the experiment. Therefore it may be necessary to improve the 

set up of cable tray materials (size and thickness) in the COCOSYS input data. 

Test 17

Test 17 is the only test using toluene instead of heptane. Due to the high soot production the 

fuel supply was stopped earlier, before the threshold value of 15 % oxygen was reached. 

This explains the large deviations between experiment and calculation. Up to the time point 

of fuel supply stop the increase of atmospheric temperature is simulated quite well. Only the 

ceiling temperatures are underestimated. 

Test 18

In this test a 1 MW was used at a different location and with open door. The measured atmospheric temperature increase is quite similar to test 3. In COCOSYS the results are 

somewhat lower (Fig. 5-103). It seems that the nodalization around the fire plume is not 
5-50

good enough in this case. This shows that the nodalization may have an influence on the 

temperature development in the fire compartment. This effect has to be considered in the 

evaluation of the calculated results. For the results of ceiling temperatures it is interesting to 

compare the positions of U4 (close to fire) and U5. In COCOSYS the value at U4 is quite 

good, but the value at U5 is underestimated by about 50 K. Larger deviations (also compared to test 3) could be observed for position U6. The higher value could be explained by 

the ‘long’ control volumes leading to a stronger heat distribution to the side. Surprisingly the 

experimental values for U2 and U6 are quite different. It looks that the experimental value at 

U6 is too low. The fire source is now much closer to the south wall leading to an increased 

wall temperature there (position U4). This has not been reproduced in the COCOSYS calculation so far. Here the differences are about 110 K. This seems to be the results of the missing plume model in COCOSYS. The vertical tray temperatures and the gas concentration is 

simulated quite good and the quality is similar to that of test 3 calculation. 
5-51

Test 1 - Temperature Tree 1

0

20

40

60

80

100

120

140

160

180

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-74 Test 1 : Temperatures at tree 1 

Test 1 (blind) : Tray temperatures

0

20

40

60

80

100

120

140

160

180

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-75 Test 1: Tray temperatures at 1 to 7 
5-52

Test 1 (blind): Concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-76 Test 1: Gas concentrations 

Test 5 (blind) :Temperature Tree 1

0

50

100

150

200

250

300

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-77 Test 5: Temperatures at tree 1 
5-53

Test 5 (blind) : Tree temperature profiles 

0

50

100

150

200

250

300

350

400

450

0 0.5 1 1.5 2 2.5 3 3.5 4

Heigt h [m]

Temperature T [°C] at t = 1200s

T1-Tree1 (exp)

T1-Tree1 (coc)

T1-Tree2 (exp)

T1-Tree2 (coc)

T1-Tree3 (exp)

T1-Tree3 (coc)

T1-Tree4 (exp)

T1-Tree4 (coc)

T1-Tree5 (exp)

T1-Tree5 (coc)

T1-Tree6 (exp)

T1-Tree6 (coc)

T1-Tree7 (exp)

T1-Tree7 (coc)

Fig. 5-78 Test 5: Temperature profile at 1200 s 

Test 5 (blind) : Tray temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-79 Test 5: Tray temperatures at position 1 to 7 
5-54

Test 5 (blind) : Tray temperatures

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-10 exp

C-Tc-11 exp

D-Ts-13 exp

C-Ts-10 coc

C-Tc-11 coc

D-Ts-13 coc

Fig. 5-80 Tray temperatures at position 10 to 13 

Test 5 (blind) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-81 Test 5: Gas concentrations 
5-55

Test 5 (blind) : Velocity at door

-1

-0.5

0

0.5

1

1.5

2

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

velocity v [m/s]

BP Door-1 exp

BP Door-6 exp

BP Door-11 exp

BP Door-1 coc

Fig. 5-82 Test 5: Velocity at door (level 1) 

Test 5 (blind) : Velocity at door

-1.5

-1

-0.5

0

0.5

1

1.5

2

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

velocity v [m/s]

BP Door-2 exp

BP Door-3 exp

BP Door-7 exp

BP Door-8 exp

TC Door-12 exp

BP Door-13 exp

BP Door-2 coc

Fig. 5-83 Test 5: Velocity at door (level 2) 
5-56

Test 7 (blind) :Temperature Tree 1

0

20

40

60

80

100

120

140

160

180

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-84 Test 7: Temperature at tree 1 

Test 7 (blind) : Tray temperatures

0

20

40

60

80

100

120

140

160

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-85 Test 7: Tray temperatures at position 1 to 7 
5-57

Test 10 (blind) :Temperature Tree 1

0

50

100

150

200

250

300

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-86 Test 10: Temperatures at tree 1 

Test 10 (blind) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-87 Test 10: Gas concentrations 
5-58

Test 13 (blind) :Temperature Tree 1

0

50

100

150

200

250

300

350

400

450

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-88 Test 13: Temperatures at tree 1 

Test 13 (blind) : Tree temperature profiles 

0

100

200

300

400

500

600

0 0.5 1 1.5 2 2.5 3 3.5 4

Heigt h [m]

Temperature T [°C] at t = 300s

T1-Tree1 (exp)

T1-Tree1 (coc)

T1-Tree2 (exp)

T1-Tree2 (coc)

T1-Tree3 (exp)

T1-Tree3 (coc)

T1-Tree4 (exp)

T1-Tree4 (coc)

T1-Tree5 (exp)

T1-Tree5 (coc)

T1-Tree6 (exp)

T1-Tree6 (coc)

T1-Tree7 (exp)

T1-Tree7 (coc)

Fig. 5-89 Test 13: Temperature profile at 300 s 
5-59

Test 13 (blind) : Tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

C-Ts-1 exp

C-Tc-2 exp

D-Ts-3 exp

B-Ts-4 exp

A-Ts-6 exp

F-Ts-7 exp

C-Ts-1 coc

C-Tc-2 coc

D-Ts-3 coc

B-Ts-4 coc

A-Ts-6 coc

F-Ts-7 coc

Fig. 5-90 Test 13: Tray temperatures at position 1 to 7 

Test 13 (blind) : Inner west wall temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

West-U1 exp

West U2 exp

West U3 exp

West U4 exp

West U1 coc

West U2 coc

West U3 coc

West U4 coc

Fig. 5-91 Test 13: West wall temperatures 
5-60

Test 13 (blind) : Inner ceiling temperatures

0

100

200

300

400

500

600

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Ceiling U1 exp

Ceiling U2 exp

Ceiling U3 exp

Ceiling U4 exp

Ceiling U5 exp

Ceiling U6 exp

Ceiling U7 exp

Ceiling U8 exp

Ceiling U1 coc

Ceiling U2 coc

Ceiling U3 coc

Ceiling U4 coc

Ceiling U5 coc

Ceiling U6 coc

Ceiling U7 coc

Ceiling U8 coc

Fig. 5-92 Test 13: Ceiling temperatures 

Test 13 (blind) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-93 Test 13: Gas concentrations 
5-61

Test 16 (blind) :Temperature Tree 1

0

50

100

150

200

250

300

350

400

450

500

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-94 Test 16: Temperatures at tree 1 

Test 16 (blind) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-95 Test 16: Gas concentrations 
5-62

Test 16 (blind) : Ventilation

0

2

4

6

8

10

12

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

velocity v [m/s]

BP supply exp

BP exhaust exp

BP supply coc

BP exhaust coc

Fig. 5-96 Test 16: Velocities at ventilation systems 

Test 16 (blind) : Junction Box

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

JB-Tc-37 exp

JB-Ts-38 exp

JB-Tc-37 coc

JB-Ts-38 coc

Fig. 5-97 Test 16: Temperatures at junction box 
5-63

Test 16 (blind) : Inner south wall temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

South-U1 exp

South U2 exp

South U4 exp

South U5 exp

South U6 exp

South U1 coc

South U2 coc

South U3 coc

South U4 coc

South U5 coc

South U6 coc

Fig. 5-98 Test 16: South wall temperatures 

Test 16 (blind) : Vertical tray temperatures

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Ts-31 exp

Ts-32 exp

Ts-33 exp

Tc-34 exp

Ts-35 exp

Ts-36 exp

Ts-31 coc

Ts-32 coc

Ts-33 coc

Tc-34 coc

Ts-3 coc

Ts-36 coc

Fig. 5-99 Test 16: Vertical tray temperatures 
5-64

Test 17 (blind) :Temperature Tree 1

0

50

100

150

200

250

300

350

400

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-100 Test 17: Temperatures at tree 1 

Test 17 (blind) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-101 Test 17: Gas concentration 
5-65

Test 17 (blind) : Inner ceiling temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Ceiling U1 exp

Ceiling U2 exp

Ceiling U3 exp

Ceiling U4 exp

Ceiling U5 exp

Ceiling U6 exp

Ceiling U7 exp

Ceiling U8 exp

Ceiling U1 coc

Ceiling U2 coc

Ceiling U3 coc

Ceiling U4 coc

Ceiling U5 coc

Ceiling U6 coc

Ceiling U7 coc

Ceiling U8 coc

Fig. 5-102 Test 17: Ceiling temperatures 

Test 18 (blind) :Temperature Tree 1

0

50

100

150

200

250

300

0 500 1000 1500 2000

time t [s]

temperature T [°C]

Tree1-1 exp

Tree1-1 coc

Tree1-2 exp

Tree1-2 coc

Tree1-3 exp

Tree1-3 coc

Tree1-4 exp

Tree1-4 coc

Tree1-5 exp

Tree1-5 coc

Tree1-6 exp

Tree1-6 coc

Tree1-7 exp

Tree1-7 coc

Tree1-8 exp

Tree1-8 coc

Tree1-9 exp

Tree1-9 coc

Tree1-10 exp

Tree1-10 coc

Fig. 5-103 Test 18: Temperatures at tree 1 
5-66

Test 18 (blind) : Inner ceiling temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Ceiling U1 exp

Ceiling U2 exp

Ceiling U3 exp

Ceiling U4 exp

Ceiling U5 exp

Ceiling U6 exp

Ceiling U7 exp

Ceiling U8 exp

Ceiling U1 coc

Ceiling U2 coc

Ceiling U3 coc

Ceiling U4 coc

Ceiling U5 coc

Ceiling U6 coc

Ceiling U7 coc

Ceiling U8 coc

Fig. 5-104 Test 18: Ceiling temperatures 

Test 18 (blind) : Inner south wall temperatures

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

South-U1 exp

South U2 exp

South U4 exp

South U5 exp

South U6 exp

South U1 coc

South U2 coc

South U3 coc

South U4 coc

South U5 coc

South U6 coc

Fig. 5-105 Test 18: South wall temperatures 
5-67

Test 18 (blind) : Vertical tray temperatures

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

temperature T [°C]

Ts-31 exp

Ts-32 exp

Ts-33 exp

Tc-34 exp

Ts-35 exp

Ts-36 exp

Ts-31 coc

Ts-32 coc

Ts-33 coc

Tc-34 coc

Ts-3 coc

Ts-36 coc

Fig. 5-106 Test 18: Temperatures at vertical tray 

Test 18 (blind) : Gas concentrations

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

time t [s]

concentration c [-]

O2-1 exp

O2-2 exp

CO2-4 exp

O2-1 coc

O2-2 coc

CO2-4 coc

Fig. 5-107 Test 18: Gas concentration 
5-68

5.3 Conclusions and Recommendations for COCOSYS 

Within the framework of ICFMP benchmark #3 several blind and open calculations have 

been performed using COCOSYS. The pyrolysis model in COCOSYS is quite new. Therefore the possibility to perform a set of blind calculations was a good opportunity to check the 

quality of the models inside COCOSYS. The calculations have been performed in three 

steps: first blind calculations of test 2, 3 and 4 followed by corresponding open calculations. 

For these open calculations additional information (like fuel flow rate, heat release) was 

given. Further the radiation fraction has been specified in more detail. As far as possible 

COCOSYS has used all these specified material properties. The overall quality of the results 

is quite good, although due to some restriction inside the lumped-parameter concept of 

COCOSYS and missing models some deviations could be observed. In the following these 

are discussed in more detail: 

• In the lumped-parameter concept it is possible to get more local information compared to 

zone models, but on the other side the momentum balance is not solved. This leads to 

some deviations mostly closed to the fire plume and close to possible ventilation jets. 

This could be observed especially for tests with running ventilation, although the volume 

flow rate should be clarified in more detail. 

• Up to now COCOSYS did not have a fire plume model. Therefore test 18 shows some 

effects due to the less appropriate nodalization around the fire source. The fire source 

has been simulated by an injection on a ‘pan’ (structure surface). No spraying a somewhat higher location has been used. This may explain the deviations of the floor temperatures close to the fire. 

• The targets were simulated by plate-type wall structures. The surface corresponds to the 

vertical projection of the tray or cable. The thickness to the material density. Some consistent deviation could be observed between control (mostly over-estimated temperatures) and power cable (mostly under-estimated temperatures). Here some rules are 

needed for the future, how to set up these kinds of targets. 

• The velocity and temperature close to the door show the strong separation between the 

hot and cold gas layer. In COCOSYS eight layers of control volumes have been used. 

Using a ‘fixed grid’ some numerical diffusion will occur. Therefore the temperature profile 

is usually smoother in COCOSYS compared to the experiment. 
5-69

• The results for the junction box are completely wrong. Here some additional clarification 

is necessary. 

In the future further model improvements are planned. This test series has provided information on what has to be improved. Further, the knowledge concerning interpretations of results has been increased. 
6-1

6 Open Simulations using CFX (Matthias Heitsch, GRS) 

For the simulation of selected tests from Benchmark #3, the code CFX 5.7 was used. CFX is 

a general purpose CFD code, which is not specially developed for fire simulation, offers 

however most of the features and models needed. Only for special results like sub-layer 

height is additional coding necessary. For this purpose a Fortran interface is provided to add 

or modify code models. 

Between Benchmark #2 and #3 the code was completely rewritten and changed to a different internal structure. In this light the application to Benchmark #3 experiments involves 

something like a test phase for CFX 5. Taking into account the higher computational effort 

compared with other codes, it was not possible to carry out parametric studies to improve 

results if necessary. The results presented in the following chapters were calculated with the 

code options valid also for other benchmarks. A number of results do not exhibit a satisfactory agreement with data. Work on improvement of results is continuing. 

From the available test matrix the tests 2, 3 and 4 were simulated. These tests represent 

basic situations and are therefore of general interest. 

6.1 CFX Input Parameters and Assumptions 

The basic model developed for CFX is shown in Fig. 6-1. The model varies slightly for tests 

2, 3 and 4. 

For all cases simulated some assumptions were made. In view of large compartments or 

arrangements of compartments to model, the surrounding walls were not included in the 

mesh explicitly. Instead, an extra model to simulate one-dimensional heat conduction was 

used as a boundary condition for CFX. With the intention to really save computing effort, the 

ceiling, the side walls and the floor are represented by a single solid temperature each. This 

may include some deficiencies in the representation of wall temperatures in the simulations. 

A problem was detected concerning the location of the vertical ladder tray relative to the exhaust vent. In the specification report, the location of the ladder tray G is indicated to be in 

the center of the north wall and is 0.3 m wide. This means, it extends from 10.68 m to 
6-2

10.98 m. The exhaust vent however, was specified to be located between 10.87 m and 

11.57 m. This would imply that tray and vent overlap. But this was not intended. The tray 

was consequently moved to a position close to the exhaust opening. As a result, the specified monitor locations for tray G do no longer match. This involves some uncertainties for 

simulated temperatures. 

In Fig. 6-1 the leakage area of the test room in the west wall is shown in green. 

Not all targets specified were included in the mesh. Only the targets A, D and G are represented. The junction box was not included in the mesh. 

The mesh is almost identical for all three simulated tests. Two cuts through the mesh are 

shown in Fig. 6-2. There are a total of 163411 cells. The mesh was developed as a mixture 

of structured and unstructured cells. Unstructured cells were grouped around the tiny cable 

targets and at some distance transferred into structured cells. This hybrid approach offers 

more flexibility in combining different length scales. However, the number of cells increases 

rapidly if unstructured cells are used. Although these cells represent only a small portion of 

the total volume, the ratio of structured to unstructured cells is 50649 to 112762. 

The mixture of air and fuel is modeled by the individual species, which are heptane (tests 2 

to 4), oxygen, nitrogen, carbon dioxide and water vapor. Soot is also created according to 

the Magnussen soot model implemented in CFX. In this model a number of constants are 

used, which were not further investigated in the given context. Nitrogen represents a background gas, not participating in any reaction. The chemical reaction of heptane and oxygen 

(C7H16 + 11O2 -> 7CO2 + 8H2O) is represented by a single-step mixing controlled reaction 

within the Eddy Dissipation model. A predefined share of the reaction heat (44%) is emitted 

from the fire tray as radiation flux and distributed by the P1 radiation model in CFX. This radiation model solves an extra transport equation and assumes direction independent radiation transport. It allows heating of the fluid due to radiation from a boundary (here the fuel 

pan). The fuel flow from the fire pan is prescribed according to the measured fuel consumption. The uncertainty in the measured heat release rate and the radiative fraction were not 

considered; instead the nominal values were used. The chemical reaction happens according to the mixing intensity in the fluid domain and the local availability of oxygen. For test 4 

the flow through the supply opening was set according to the recorded test results. 
6-3

Instead of using the 15% oxygen fire termination threshold as for the tests, it was decided to 

use the recorded heptane consumption curves. This was done to avoid uncertainties in the 

heat release release. 

6.2 Comparison of CFX Predictions with Measurements 

6.2.1 Test 2 

In Fig. 6-3 the heptane mass flow entered to the code is displayed. It follows the specification in the beginning section of the experiment and decreases to zero when the test is terminated because of oxygen decrease. Fig. 6-4 through Fig. 6-6 shows gas temperatures for 

trees 1, 5 and 7. There is a general under-estimation for all values. The calculated values do 

not include any radiative influence; the measured temperatures, however, are subject to this. 

Another influence on the calculation of gas temperatures may be the approximated temperature of the surrounding walls. The calculated total heat flow (convection and radiation) to the 

ceiling corresponds well with measured data, as Fig. 6-7 shows. A similar comparison for the 

floor heat flow in Fig. 6-8 reveals much less correspondence to the data. In the calculation 

considerably less energy flows to the floor. The radiative fraction of the heat release rate is 

emitted from the tray surface in the CFX model. In reality radiation is released from the flame 

above the fire tray, and more radiation is emitted towards the ground. In the model this is not 

possible as the tray surface has no direct view path to the floor. 

Fig. 6-9 shows the CO2 history in the test compartment. For a specific time 600 s after initiation of the fire the distribution of CO2 in the test facility is depicted in Fig. 6-10. All along the 

floor there is a layer with very low CO2. The oxygen history in Fig. 6-11 reveals that this species decreases too fast. The spatial distribution at 600 s is shown in Fig. 6-12. Lowest values 

are found directly below the ceiling and highest close to the floor. It may be that the boundary between high and low oxygen in the simulation is slightly displaced compared with the 

measurement, resulting in a lower calculated values. The time 600 s belongs to the period 

when the fire is still at full power. Shortly after at 700 s the fire is extinguished because of 

low oxygen. Then the leak flow reverses and through the leakage opening fresh air enters 

the compartment. This is displayed in Fig. 6-13. The leakage mass flow over time (Fig. 6-14) 

exhibits the same tendency. With the extinction of the fire the heat source collapses, the 

pressure decreases and sucks fresh air from outside into the fire lab. 
6-4

Fig. 6-15 depicts the flow distribution in the facility short before termination of the experiment. Close to the ceiling there is an expansion flow away from the fire pan, in the lower 

section it is directed towards the fire. Underneath the expansion flow from the fire along the 

ceiling there is a layer of gas flowing backwards to the fire. 

6.2.2 Test 3 

Calculation results for test 3 show more severe disagreements with measurement but they 

presented for completeness. Work for improvement is continuing concerning radiation modelling and wall representation. 

Test 3 uses ventilation through an open door. In order to realistically calculate the flow 

across this opening, an extra block was added to the model of the fire lab. The connection to 

environment by means of a pressure boundary is thereby moved away from the door, where 

uniform pressure is more realistic. The model together with cuts through the mesh is shown 

in Fig. 6-17 and Fig. 6-18. The leakage opening right from the door in the same wall is kept 

open as for the other tests. If this affects the flow in and out of the door was not investigated. 

The heptane release and consumption which was input to the code is shown in Fig. 6-19. 

This curve corresponds to a nominal fire power of 1150 kW. 

A temperature distribution in the fire lab at 1000 s is displayed in Fig. 6-20. The simulation 

time at 1000 s has been selected because it is well placed in the long steady state period 

developed for this experiment and will also be used for other 2D distributions. Temperatures 

along trees 1, 5 and 7 are shown in Fig. 6-21 through Fig. 6-23. Unlike simulations for tests 2 

and 4 temperatures are over-predicted by CFX. This behavior is still under investigation. It is 

possible that under fully ventilated conditions (with enough oxygen in all locations) the simulated reaction rate is higher than measured and under locally reduced oxygen availability it is 

too low. The oxygen history at probe location O2-2 is depicted in Fig. 6-24. The simulation 

predicts a slight decrease which was not measured. The 2D distribution for oxygen in Fig. 

6-25 indicates quite uniform availability. A slight enrichment is found close to the floor due to 

inflow from the door. The opposite behavior as for oxygen is found for the CO2 production at 

the available probe location CO2-4 (Fig. 6-26). Here the simulation calculates, at least at the 

given probe location, a lower molar fraction. 
6-5

The door flow can be characterized by the flow velocity size and orientation. Selected velocity probes in the middle plane of the door are displayed and compared with CFX predictions 

in Fig. 6-27. In the simulation the inwards directed flow (low elevation, blue) is calculated at a 

higher speed than measured. In the middle location (z=1m) CFX calculates a weak outflow 

whereas from the measurement inflow can be seen. There may be some uncertainty in the 

location of the boundary between positive and negative velocities, which is quite sensitive to 

predict. The outflow velocity at 1.79 m is well predicted. A qualitative velocity distribution of 

flow velocities can be seen in Fig. 6-28. The net mass flow through the door is close to zero 

for most of the time. This is also predicted by CFX (Fig. 6-29), although the initial outflow 

peak is almost completely missing. It should be mentioned, that flow through the neighboring 

leak opening is also enabled for this experiment. It may have some effect on the door flow. 

6.2.3 Test 4 

The test 4 model is shown in Fig. 6-30. The supply and exhaust openings in the model were 

extruded outwards. This eases the formation of a stable flow profile in the supply opening 

and results in a more uniform pressure distribution in the exhaust opening. This corresponds 

better to the pressure condition available in CFX for openings. Two cuts through the computational mesh are shown in Fig. 6-31. Some sections around the horizontal trays are meshed 

with unstructured cells, most parts of the test facility contain structured cells. 

The heptane flow released for reaction in the gas space is shown in Fig. 6-32. After about 

814 s the fire is stopped because of oxygen consumption below 15 % at location O2-2. Fig. 

6-33 through Fig. 6-37 display gas temperatures at three trees. Similar to the simulations of 

tests 2 and 3 gas temperatures are under-predicted. This may be due to the fact that in the 

simulation only convection contributes to the gas heat up. Thermocouples instead are affected by radiation. In Fig. 6-34 temperatures from tree 5 are depicted. The temperature in 

position 5 (red) is very low. This is due to cold air coming through the supply opening. The 

corresponding flow pattern and temperature distribution in the whole test facility is shown in 

Fig. 6-35 at time 700 s. A vertical temperature profile along tree 5 is also added to this figure. 

The measurement however shows the characteristic decrease due to cold air inflow at a 

more elevated location. Fig. 6-36 compares calculated and measured temperature profiles. 

The experimental profile has the cold air temperature minimum above 2.5 m whereas the 

calculation predicts it at about 2 m. This difference may be related to the lower calculated 

gas temperatures in general. A smaller difference to the environmental temperature means 

less buoyancy and consequently a stronger fall-down of the incoming air flow. 
6-6

The calculated oxygen decrease in the test lab is compared to available test data in Fig. 

6-38. Fig. 6-39 was added to illustrate the oxygen distribution at different 2D planes. The 

selected time (700 s) is representative for most of the experiment and shows a continuous 

increase towards the floor. In some sections of the test facility more oxygen is found on the 

side of the supply opening. A comparison of the CO2 formation at location CO2-4 can be 

found in Fig. 6-40. Oxygen and CO2 behave in a consistent way: Slightly less oxygen is consumed and less CO2 is built up. 

Fig. 6-41 and Fig. 6-42 summarize the total energy flows to ceiling and floor. Radiation plays 

with 44 % of the total energy release an important role. Radiation is emitted from the plane 

fire tray surface and behaves therefore different from reality. The ceiling receives the correct 

energy flow (Fig. 6-41). Side walls and in particular the floor, however, do not receive 

enough radiation. This is reflected in Fig. 6-42. 

The mass flow into the test lab through the supply opening was specified according to the 

recorded data from the test. The exhaust flow was calculated. Fig. 6-43 compares both 

flows. The exhaust flow compares qualitatively well with the data but under-estimates the 

values slightly. An illustration of the flow distribution at selected planes is shown in Fig. 6-44. 

Highest speeds can be found along the ceiling. There is also a layer of higher flow speed in 

the middle of the test lab. 
6-7

6.3 Conclusions and Recommendations for CFX 

For the simulated test cases (2, 3 and 4) the agreement with measured data is worse compared with other benchmark exercises of the ICFMP. A main reason is seen in the way the 

radiative fraction of the reaction heat is released. For simplicity this was done from the surface of the fire tray. This location involves incorrect radiative fluxes to side walls and floor. 

Lower wall temperatures are the result. In turn this involves higher convective heat fluxes 

from the gas and lower gas temperatures. Also, the surrounding walls were not included in 

the mesh in order to limit the computing effort. Instead, a one-dimensional algebraic heat 

conduction model was applied but only to larger patches. An improvement can be achieved 

by calculating extra wall (surface and inner sections) temperatures for each individual fluid 

cell. 

In a further step, the data obtained from the experiments can be used to validate constants 

to be set in the Magnussen soot model available in CFX. 

Acknowledgement 

The presented work was funded by the German Ministry of Environmental Protection and 

Radiological Protection (BMU), which is gratefully acknowledged. 
6-8

Fig. 6-1 CFX model for test 2 
6-9

Fig. 6-2 Distribution of cells within the test facility 
6-10

0 200 400 600 800 1000

Time [s]

0

0.01

0.02

0.03

Mass Flow [kg/s]

CFX

BenchMark #3

Test T2

Heptane Mass Consumption

Fig. 6-3 Heptane mass release (test 2) 
6-11

0 400 800 1200 1600

Time [s]

0

100

200

300

Temperature [Deg C]

Tree 1:

Pos. 10 (3.5m)

CFX Pos.10

Pos. 7 (2.45m)

Pos. 5 (1.75m)

CFX Pos.5

Pos. 3 (1.05m)

Pos. 1 (0.35m)

CFX Pos.1

BenchMark #3

Test T2

Fig. 6-4 Selected temperatures in tree 1 (test 2) 
6-12

0 400 800 1200 1600

Time [s]

0

100

200

300

400

Temperature [Deg C]

Tree 5:

Pos. 10 (3.5m)

CFX Pos.10

Pos. 7 (2.45m)

Pos. 5 (1.75m)

CFX Pos.5

Pos. 3 (1.05m)

Pos. 1 (0.35m)

CFX Pos.1

BenchMark #3

Test T2

Fig. 6-5 Selected temperatures in tree 5 (test 2) 
6-13

0 400 800 1200 1600

Time [s]

0

100

200

300

400

Temperature [Deg C]

Tree 7:

Pos. 10 (3.5m)

CFX Pos.10

Pos. 5 (1.75m)

CFX Pos.5

Pos. 1 (0.35m)

CFX Pos.1

BenchMark #3

Test T2

Fig. 6-6 Selected temperatures in tree 7 (test 2) 
6-14

0 200 400 600 800 1000

Time [s]

-100

0

100

200

300

400

500

Energy Flow [kW]

Experiment

CFX

BenchMark #3

Test T2

Total Energy Flow at Ceiling

Fig. 6-7 Total energy flow to ceiling (test 2) 
6-15

0 200 400 600 800 1000

Time [s]

0

100

200

300

Energy Flow [kW]

Experiment

CFX

BenchMark #3

Test T2

Total Energy Flow at Floor

Fig. 6-8 Total energy flow to floor (test 2) 
6-16

0 200 400 600 800 1000

Time [s]

0

0.02

0.04

0.06

0.08

CO2 Molar Fraction [-]

Location:

CO2-4 (6.85, 3.52, 3.2m)

CFX

BenchMark #3

Test T2

Fig. 6-9 CO2 history at probe location 4 (test 2) 
6-17

Fig. 6-10 CO2 distribution at different locations after 600 s (test 2) 
6-18

0 200 400 600 800 1000

Time [s]

0.12

0.14

0.16

0.18

0.2

0.22

Oxygen Molar Fraction [-]

Location:

O2-2 (6.85, 3.52, 0.5m)

CFX

BenchMark #3

Test T2

Fig. 6-11 Oxygen history at lower probe location (test 2) 
6-19

Fig. 6-12 Oxygen distribution at different locations after 600 s (test 2) 
6-20

Fig. 6-13 Oxygen distribution at different locations after 700 s (test 2) 
6-21

0 200 400 600 800 1000

Time [s]

-1

-0.5

0

0.5

1

1.5

Mass Flow [kg/s]

CFX

BenchMark #3

Test T2

Leakage Flow

Fig. 6-14 Mass flow through leakage opening (test 2) 
6-22

Fig. 6-15 Flow speed distribution in the test facility after 600 s (test 2) 
6-23

Fig. 6-16 Temperature distribution along trays D, F and G (test 2) 
6-24

Fig. 6-17 CFX model for test 3 
6-25

Fig. 6-18 Cuts showing the mesh for test 3 
6-26

0 400 800 1200 1600

Time [s]

0

0.01

0.02

0.03

Mass Flow [kg/s]

CFX

BenchMark #3

Test 3

Heptane Mass Consumption

Fig. 6-19 Heptane release during test 3 
6-27

Fig. 6-20 Temperature distribution at 1000 s (test 3) 
6-28

0 500 1000 1500 2000 2500

Time [s]

300

400

500

600

Temperature [K]

Tree 1:

Pos. 10 (3.5m)

CFX Pos.10

Pos. 5 (1.75m)

CFX Pos.5

Pos. 1 (0.35m)

CFX Pos.1

Benchmark #3

Test 3

Fig. 6-21 Tree 1 temperatures (test 3) 
6-29

0 500 1000 1500 2000 2500

Time [s]

200

300

400

500

600

700

Temperature [K]

Tree 5:

Pos. 10 (3.5m)

CFX Pos.10

Pos. 5 (1.75m)

CFX Pos.5

Pos. 1 (0.35m)

CFX Pos.1

BenchMark #3

Test 3

Fig. 6-22 Tree 5 temperatures (test 3) 
6-30

0 500 1000 1500 2000 2500

Time [s]

200

300

400

500

600

700

Temperature [K]

Tree 7:

Pos. 10 (3.5m)

CFX Pos.10

Pos. 5 (1.75m)

CFX Pos.5

Pos. 1 (0.35m)

CFX Pos.1

BenchMark #3

Test 3

Fig. 6-23 Tree 7 temperatures (test 3) 
6-31

0 400 800 1200 1600 2000

Time [s]

0.16

0.18

0.2

0.22

Oxygen Molar Fraction [-]

Location O2-2 (6.85, 3.52, 0.5m):

Experiment

CFX

BenchMark #3

Test T3

Fig. 6-24 Oxygen behaviour at location O2-2 (test 3) 
6-32

Fig. 6-25 Oxygen distribution at 1000 s (test 3) 
6-33

0 400 800 1200 1600 2000

Time [s]

0

0.01

0.02

0.03

0.04

CO2 Molar Fraction [-]

Location:

CO2-4 (6.85, 3.52, 3.2m)

CFX

BenchMark #3

Test 3

Fig. 6-26 CO2 concentration at location CO2-4 (test 3) 
6-34

0 500 1000 1500 2000 2500

Time [s]

-3

-2

-1

0

1

2

Mass Flow [kg/s]

Location (0.1, 3.52, zm):

BP Door-6 (z=0.19m)

CFX (z=0.19m)

BP Door-8 (z=1.00m)

CFX (z=1.00m)

BP Door-10 (z=1.79m)

CFX (z=1.79m)

BenchMark #3

Test 3

Door Flow Velocity

Fig. 6-27 Selected flow velocities in the door opening (test 3) 
6-35

Fig. 6-28 Flow speed distribution at door and in the fire compartment at 1000 s (Test 3) 
6-36

0 200 400 600 800 1000

Time [s]

-3

-2

-1

0

1

Mass Flow [kg/s]

Supply Flow Experiment

Supply Flow CFX

BenchMark #3

Test 3

Net Door Flow

Fig. 6-29 Net mass flow through door (test 3) 
6-37

 Fig. 6-30 Configuration of the test facility for test 4 
6-38

Fig. 6-31 Mesh and main components of test configuration 4 
6-39

0 200 400 600 800 1000

Time [s]

0

0.01

0.02

0.03

Mass Flow [kg/s]

CFX

BenchMark #3

Test 4

Heptane Mass Consumption

Fig. 6-32 Heptane mass consumption (test 4) 
6-40

0 400 800 1200 1600

Time [s]

0

50

100

150

200

250

300

Temperature [Deg C]

Tree 1:

Pos. 10 (3.5m)

CFX Pos.10

Pos. 5 (1.75m)

CFX Pos.5

Pos. 1 (0.35m)

CFX Pos.1

BenchMark #3

Test 4

Fig. 6-33 Selected temperatures on tree 1 (test 4) 
6-41

0 400 800 1200 1600

Time [s]

0

50

100

150

200

250

300

Temperature [Deg C]

Tree 5:

Pos. 10 (3.5m)

CFX Pos.10

Pos. 5 (1.75m)

CFX Pos.5

Pos. 1 (0.35m)

CFX Pos.1

BenchMark #3

Test 4

Fig. 6-34 Selected temperatures on tree 5 (test 4) 
6-42

Fig. 6-35 Temperature distribution and tree 5 profile at 700 s (test 4) 
6-43

0 50 100 150 200 250 300

Temperature [Deg C]

0

1

2

3

4

Elevation [m]

Vertical Profile at 700s:

Experiment

CFX

Benchmark #3

Tree 5 at 700 s

Fig. 6-36 Vertical temperature profile at 700 s (test 4) 
6-44

0 400 800 1200 1600

Time [s]

0

50

100

150

200

250

300

Temperature [Deg C]

Tree 7:

Pos. 10 (3.5m)

CFX Pos.10

Pos. 5 (1.75m)

CFX Pos.5

Pos. 1 (0.35m)

CFX Pos.1

BenchMark #3

Test 4

Fig. 6-37 Selected temperatures on tree 7 (test 4) 
6-45

0 400 800 1200

Time [s]

0.14

0.16

0.18

0.2

0.22

Oxygen Molar Fraction [-]

Location:

O2-2 (6.85, 3.52, 0.5m)

CFX

BenchMark #3

Test 4

Fig. 6-38 Oxygen behaviour at position O2-2 (test 4) 
6-46

Fig. 6-39 Oxygen in the fire lab after 700 s (test 4) 
6-47

0 400 800 1200

Time [s]

0

0.02

0.04

0.06

0.08

CO2 Molar Fraction [-]

Location:

CO2-4 (6.85, 3.52, 3.2m)

CFX

BenchMark #3

Test 4

Fig. 6-40 CO2 behaviour at position CO2-4 (test 4) 
6-48

0 200 400 600 800 1000

Time [s]

-100

0

100

200

300

400

Energy Flow [kW]

Experiment

CFX

BenchMark #3

Test 4

Total Energy Flow at Ceiling

Fig. 6-41 Total energy flow to the ceiling (test 4) 
6-49

0 200 400 600 800 1000

Time [s]

0

100

200

300

Energy Flow [kW]

Experiment

CFX

BenchMark #3

Test 4

Total Energy Flow at Floor

Fig. 6-42 Total energy flow to the floor (test 4) 
6-50

0 200 400 600 800 1000

Time [s]

-3

-2

-1

0

1

2

Mass Flow [kg/s]

Supply Flow Experiment

Supply Flow CFX

Exhaust Flow Experiment

Exhaust Flow CFX

BenchMark #3

Test 4

Supply and Vent Flow

Fig. 6-43 Mass flows through supply and exhaust (test 4) 
6-51

Fig. 6-44 Flow speed distribution after 700 s (test 4) 
6-52
7-1

7 Open Simulations using FDS (Kevin McGrattan, NIST) 

Benchmark Exercise 3 was used to assess the accuracy of the Fire Dynamics Simulator 

(FDS) in calculating the transport of energy and combustion products from a fire of known 

heat release rate. The intent of the exercise was not to predict the heat release rate, but 

rather the transport of the fire’s exhaust products throughout a fairly large compartment. The 

compartment was heavily instrumented so that all of the energy from the fire could be accounted for and reported in terms of conductive losses to walls, convective flux through 

openings, etc. With the large number of measurements, it was possible to go beyond the 

traditional point by point comparison and discover why the model either over-predicted or 

under-predicted a given measurement. It was also possible to compare the transport of energy, starting with the combustion of fuel, and ending with effluent exiting into a large hood. 

Based on these integrated quantities, discrepancies in heat flux and gas concentration predictions could be tied to errors in the overall energy budget allowing us to assess the accuracy of various components within the model. 

7.1 FDS Input Parameters and Assumptions 

In cooperation with the fire protection engineering community, a computational fire model, 

Fire Dynamics Simulator (FDS), has been developed at the National Institute of Standards 

and Technology (NIST) in the USA to study fire behavior and to evaluate the performance of 

fire protection systems in buildings. The software was released into the public domain in 

2000, and since then has been used for a wide variety of analyses by fire protection engineers. A complete description of the model can be found in McGrattan (2004). Briefly, FDS 

is a computational fluid dynamics code that solves the Navier-Stokes equations in low Mach 

number, or thermally-expandable, form. The transport algorithm is based on large eddy 

simulation techniques, radiation is modeled using a gray-gas approximation and a finitevolume method is used to solve the radiation transport equation. Combustion is modeled 

using a mixture fraction approach, in which a single transport equation is solved for a scalar 

variable representing the fraction of gas originating in the fuel stream. 

In this section, the most important features of the simulations are described, with emphasis 

placed on those features that were most important for this particular application. 
7-2

7.1.1 Compartment Geometry 

The geometry of the compartment was relatively simple. The overall enclosure was rectangular, as were the vents and most of the obstructions. A single, rectilinear grid spanned the 

interior of the compartment. The dimensions of the grid were 100 × 36 × 32, and the cells 

were shrunk in the horizontal directions to create cells nominally 10 cm in size in the vicinity 

of the fire pan. The decision to use a 10 cm grid was based on the observation that the ratio 

of the fire’s characteristic diameter, D*, to the size of the grid cell, dx, is an indicator of the 

degree of resolution achieved by the simulation. D* is given by the expression 

2 / 5 (Q/ c T g ) ∞ p ∞

•

ρ , and was about 1 m for this series of fires. In short, the greater the ratio 

D*/dx, the more the fire dynamics are resolved directly, and the more accurate the simulation. Past experience has shown that a ratio of 10 produces favorable results at a moderate 

computational cost (McGrattan et al. 2003). 

The vent and door of the compartment conformed to the local gas phase grid. Both were 

rectangular. The vent was given a prescribed volume flow rate, and the door (when open) 

was taken as a constant-pressure boundary. In the closed door tests, the compartment was 

assumed to leak via a small uniform flow spread over the walls and ceiling. The leakage rate 

was determined from the prescribed leak area and the computed compartment overpressure. 

FDS performs a one-dimensional heat transfer calculation into an assumed homogenous 

material of given thickness and (temperature-dependent) thermal properties. Solid obstructions within the computational domain must conform to the underlying gas phase grid, but 

the assumed thickness of the solid is not tied to the gas phase grid. Thus, the solid phase 

heat transfer calculation is entirely decoupled from the gas phase except for the transfer of 

mass and heat at the gas-solid interface. The compartment walls and ceiling were made of 

2.54 cm thick Marinite I, a product of BNZ Materials, Inc. The manufacturer provided the 

thermal properties of the material used in the calculation: density 737 kg/m3

, conductivity 

0.12 W/m/K, specific heat 1.17 kJ/kg/K at 93 °C ramping linearly to 1.42 kJ/kg/K at 425 °C. A 

testing laboratory also provided thermal properties, but the results were relatively insensitive 

to the differences, as will be shown below. 

The cable trays were modeled as rectangular solids with cross sectional areas conforming to 

the local computational grid. The sides of the solids were assumed to be made of thin steel, 

the top and bottom slabs of plastic (PVC or XLP) whose properties were provided. No at-
7-3

tempt was made to model the individual cables. Rather, the collections of cables were taken 

as solid slabs with a thickness equal to their actual diameter. Lateral heat conduction along 

the metal conductors within the cables was not modeled. There are no specific sub-models 

in FDS to address the thermal response of bundled power cables other than the assumptions just discussed. Thus, for this type of fire scenario, the physical description of the heat 

transfer and ultimately the burning of the cables is the most likely cause of “user effects”. 

FDS is designed to produce an accurate prediction of the gas temperature and heat flux to 

objects in the compartment. It does not have detailed algorithms to model the thermal response of a complicated object, but rather that of a simplified object of equivalent thermal 

behavior. The user must describe using a limited set of parameters how this simpler object is 

to be represented in the model, and little guidance is provided in the model documentation 

as there are simply too many objects to consider. 

Figure 7-1. View of Test 3 simulation from the rear of the compartment. 

7.1.2 Fire 

The properties of the liquid fuels used in the tests were provided from measurements made 

on a series of unconfined burns (Hamins 2003). Most of the tests were run with a blend of 

heptane isomers, primarily C7H16. Its soot yield was prescribed a constant value of 1.5 %.; 

the CO yield a constant value of 0.6 %. The present version of FDS does not adjust the soot 
7-4

or CO yield as a consequence of reduced compartment ventilation or combustion efficiency. 

In one test (Test 17) the fuel used was toluene, C7H8, with a soot yield of 16 % and a CO 

yield of 7 %2

. The reported radiative fractions of the test fires was not used directly in the 

calculations. Rather, FDS assumed that the radiative fraction from the fire was the larger of 

two values: 35 % or that which was calculated directly by the radiation solver. Details can by 

found in McGrattan (2004). 

The heat release rate of the simulated burner was set to that which was measured in the 

experiments. No attempt was made to model the spray burner. The pan was simply prescribed as a solid object out of which the given fuel flowed uniformly at a rate necessary to 

achieve the specified heat release rate. The only change made was to make the pan 1 m by 

1 m in the model, to account for the fact that the fire did not engulf the entire pan area, but 

roughly half. This change was made after the series of blind calculations. It was an easy 

change to make, and produced only a slight improvement in results. 

In almost all fire simulations, the heat release rate (HRR) is the most important parameter. 

The mass and energy introduced into the compartment are proportional to the HRR, and the 

measured quantities are all nearly linear functions of the HRR. While the simulations of the 

fire tests involved dozens of user-prescribed parameters, none was more important than the 

HRR. The specified HRR was not achieved in the experiments, and as a result the calculations that were re-done after the blind series were modified with a roughly 15% increase in 

the HRR. 

7.1.3 Radiation 

FDS uses a finite volume method to solve the radiation transport equation in the gray gas 

limit. By default, the radiation from the fire and hot gases is tracked in 100 directions. While 

this is adequate to predict the radiation heat flux to nearby targets (a few fire diameters 

away), it is not always adequate to predict the flux to distant targets (greater than three diameters, roughly). Because part of the exercise was to predict the heat flux to targets 

greater than 3 m from the fire, the number of radiation angles used by the solver in FDS was 

increased to 200. To compensate for the increased computational cost of doubling the num-

 

2

 The test specification listed the soot yield of the toluene as 19.5 % ± 5.2 %. In the simulations, 16 % 

was used simply because it was left over from another study. 
7-5

ber of angles, the frequency at which the radiation field was updated was roughly halved. 

The loss in temporal fidelity was not considered a problem because the fire was not spreading or changing rapidly in size. Given the time step used in the simulations, the radiation field 

was fully updated about every 0.2 s. 

Figure 7-2 demonstrates the “spotting” by the radiation solver early in the simulation of Test 

3 (40 s). Note that the east wall (left side of figure) shows evidence of the finite number of 

angles with which the radiation solver uses to calculate the transport of radiation from the 

fire. Slightly later, at 90 s, the spotting is less pronounced because the source of the thermal 

radiation is no longer the fire alone, but rather the hot upper layer forming over the entire 

length and width of the compartment. The sensitivity of the results to the choice of radiation 

angles is discussed below. 
7-6

Figure 7-2. Heat flux to compartment surfaces, highlighting numerical effects. 
7-7

7.1.4 Output 

During the simulation, values of temperature, heat flux and gas species concentrations, etc., 

were reported as 5 s averages. Linear interpolation was used to approximate values between the 10 cm grid cells. The results were saved in a text file and compared with the 

measurements. 

Note that the measured and predicted gas temperatures that are reported here are the barebead thermocouple temperatures. FDS has an option of estimating the temperature of the 

thermocouple bead itself, rather than the true gas temperature (Welsh and Rubini 1997; 

McGrattan and Forney 2004). Often the reported gas temperature is actually the temperature of the thermocouple bead itself. The distinction usually only matters for the lower layer 

bare-bead thermocouples that are subjected to significant heat fluxes from the nearby fire 

and/or hot smoke layer. The original predictions of gas temperature under-predicted the lowest thermocouple temperatures by 20 % to 30 %. When recomputed as thermocouple temperatures, the agreement was significantly improved3

. 

Also, note that the heat flux to the compartment walls was reported by the experimentalists 

as a net flux. The uncooled wall flux gauges consisted of essentially a thermocouple 

preened to the back side of a small steel plate. On the other hand, the heat flux gauges 

mounted near the cable trays were cooled and measured the total heat flux. To make both 

sets of heat flux measurements/predictions consistent, the measured net heat flux to the 

compartment walls, ceiling and floor were corrected (by the analyst, not the experimentalists) 

using the formula: 

( ) ( ) '' '' 4 4qtotal = qnet + σ Ts − T∞ + h Ts − T∞ &

where Ts is the surface temperature, T∞ is the ambient temperature, and h is the heat transfer coefficient between the gas and the wall. The total heat flux was predicted directly by 

FDS. The heat transfer coefficient used in the conversion of the measured fluxes was the 

same correlation that was used by FDS (McGrattan 2004). 

 

3

 When correcting the predicted gas temperatures, it was assumed that the bead diameter was 1 mm 

and the emissivity of the bead was 0.85, the default settings in FDS. 
7-8

Whether one compares the total or net heat flux, there are problems of interpretation. The 

net heat flux is dependent on the surface temperature of the target, which is another quantity 

that the model is attempting to predict. The total heat flux is the heat flux to a “virtual” target 

whose temperature remains at ambient. This is a preferable quantity to use for comparison, 

but it is a more expensive measurement. Converting net to total or vis verse also introduces 

additional uncertainty. Thus, for the purpose of evaluating the heat flux predictions to the 

walls, the better comparison is that of wall surface temperature itself. No corrections were 

made to either measurement or prediction of wall surface temperature. In some sense, the 

wall itself acted as a type of flux gauge since its thermal properties were known to a fairly 

high degree of certainty. The heat flux measurements merely served as a “second opinion,” 

suggesting why a particular wall temperature might have been over or under-predicted. 

7.1.5 Summary 

For Benchmark Exercise 3, the principal developer of FDS (McGrattan) observed the experiments and performed simulations before and after they were conducted. There is a tremendous advantage in understanding the subtleties of both. Thus, for the final calculations 

that are presented in the next section, care was taken to set up the input files in a way that 

could be expected of most engineers using the model. Nevertheless, some features were 

used that are often overlooked or not understood by the practicing engineer, even though 

they are documented in the User’s Guide. Following is a list of those features: 

• Outputting the thermocouple, as opposed to the gas, temperature. 

• Increasing the number of angles in the radiation calculation. 

• Stretching and shrinking the grid to increase spatial resolution near the fire. 

• Choosing the geometric parameters for the modeled cable trays. 

• Adjusting the burn area of the fire to conform to observation. 
7-9

7.2 Comparison of FDS Open Predictions with Measurements 

Fifteen fire experiments were conducted as part of Benchmark Exercise 3. Of these, four 

were considered replicates. Thus, in this section, only the results of the 11 non-replicates are 

presented (Tests 1-5 and 13-18). 

Wherever possible, multiple measurements at a given location in the compartment are presented on the same page to enable easier comparison. Experimental results are always plotted with solid lines, simulation with dotted lines. The labels included in the legends for each 

figure are the original labels found in the experimental data files and the simulation input 

files. 

7.2.1 Gas Temperatures 

Gas temperatures were measured in the experiments using seven floor-to-ceiling thermocouple arrays (or “trees”) distributed throughout the compartment. Figure 7-3 through Figure 

7-13 display the time histories of both measured and predicted compartment gas temperatures. Three measurement points were chosen from each tree: #10 (green) which was 30 cm 

below the ceiling, #5 (red) which was about halfway between floor and ceiling; and #1 (black) 

which was 35 cm above the floor. In addition, several measurement locations were chosen 

in the doorway of the open-door tests: #16 (black) which was 10 cm below the top of the 

door; #11 (red) which was halfway between door top and bottom; and #9 (green) which was 

20 cm above the floor. 

A means of assessing the accuracy of the predicted temperatures is to first consider the accuracy of the prescribed heat release rate. According to an empirical correlation by 

McCaffrey, Quintiere and Harkleroad (Walton and Thomas 2003), the increase above ambient in the upper layer gas temperature is proportional to the HRR raised to the 2/3 power. 

The reported uncertainty in the HRR measurement was 15 % (two standard deviations). This 

uncertainty led to a 2/3 × 15 % = 10 % uncertainty in the temperature rise. The difference 

between measured and predicted compartment temperature for most of the measurement 

locations was less than 10 %, i.e. within experimental uncertainty, with some notable exceptions that are discussed below. Errors due to the FDS computation of the thermocouple, as 

opposed to the gas, temperatures, plus errors in the thermocouple measurements themselves, were far less than the uncertainty associated with the measured HRR. 
7-10

Notable disagreement with experimental measurement of compartment temperatures occurred for two reasons. First, in Tests 4, 5 and 16, a fan blew air into the compartment 

through a vent in the south wall. The measured velocity profiles were input into FDS, but in 

Tests 4 and 5, the observed cooling of the upper layer temperatures at Tree 3, 4 and 5 was 

not replicated in the model (In the figures, this discrepancy is denoted by the phrase “Ventilation Effects”). In Test 16, the cooling effect was not observed in either the experiments or 

the predictions. A possible reason for the discrepancy in Tests 4 and 5 may have been that 

the grid resolution at the fan was fairly coarse. The grid was shrunk near the burner, but 

stretched elsewhere. Also, the velocity profile at the supply duct was not uniform, with the 

bulk of the air blowing from the lower third of the duct, and some recirculation occurring 

above. 

The second notable source of disagreement between measured and predicted temperatures 

was the near-field behavior of the fire. The lower thermocouple predictions for Tree 6 were 

often in poor agreement with measurement (In the figures, this discrepancy is denoted by 

the phrase “Near-Field Effects”). Tree 6 was 10 cm east of the fuel pan, but in the simulations, the pan was shortened because the burning fuel was observed to have been restricted 

mainly to the center of the pan. Nevertheless, the shifting of the fire’s “footprint” in the model 

effectively moved the lower thermocouples on Tree 6 further from the fire, leading to lower 

predictions of their temperature. The situation could have been improved somewhat by experimenting with different “footprints”, but such “tweaking” would have given the impression 

that the model was more accurate in the near-field than it actually was. Remember that the 

grid cells were 10 cm, and moving the fire by increments of 10 cm would have led to noticeable variations in the near-field predictions. 
7-11

Test 1, Tree 1 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Test 1, Tree 2 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Test 1, Tree 3 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Test 1, Tree 4 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Test 1, Tree 5 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Test 1, Tree 6 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Test 1, Tree 7 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Closed Door Test; 

No Doorway Temperatures 

Figure 7-3. Gas temperature comparison for Test 1. 
7-12

Test 2, Tree 1 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

350

400

Test 2, Tree 2 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

350

400

Test 2, Tree 3 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

350

400

Test 2, Tree 4 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

350

400

Test 2, Tree 5 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

350

400

Test 2, Tree 6 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

350

400

Test 2, Tree 7 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

350

400

Closed Door Test; 

No Doorway Temperatures 

Figure 7-4. Gas temperature comparison for Test 2. 
7-13

Test 3, Tree 1 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 3, Tree 2 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 3, Tree 3 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 3, Tree 4 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 3, Tree 5 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 3, Tree 6 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

500

Near-Field Effects

Near-Field Effects

Test 3, Tree 7 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 3, Door Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

FDS Time vs TC Door 16 

FDS Time vs TC Door 11 

FDS Time vs TC Door 9 

Exp Time vs 222 TD16 

Exp Time vs 217 TD11 

Exp Time vs 215 TD9 

Figure 7-5. Gas temperature comparison for Test 3. 
7-14

Test 4, Tree 1 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

Test 4, Tree 2 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

300

350

400

Test 4, Tree 3 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

Ventilation Effects

Test 4, Tree 4 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

Ventilation Effects

Test 4, Tree 5 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

Test 4, Tree 6 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

Test 4, Tree 7 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

Closed Door Test; 

No Doorway Temperatures 

Figure 7-6. Gas temperature comparison for Test 4. 
7-15

Test 5, Tree 1 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 5, Tree 2 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 5, Tree 3 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Ventilation Effects

Test 5, Tree 4 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Ventilation Effects

Test 5, Tree 5 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Ventilation Effects

Test 5, Tree 6 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Near-Field Effects

Near-Field Effects

Test 5, Tree 7 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 5, Door Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

FDS Time vs TC Door 16 

FDS Time vs TC Door 11 

FDS Time vs TC Door 9 

Exp Time vs 222 TD16 

Exp Time vs 217 TD11 

Exp Time vs 215 TD9 

Figure 7-7. Gas temperature comparison for Test 5. 
7-16

Test 13, Tree 1 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

500

Test 13, Tree 2 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

500

Test 13, Tree 3 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

500

Test 13, Tree 4 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

500

Test 13, Tree 5 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

500

Test 13, Tree 6 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

500

600

700

Near-Field Effects

Test 13, Tree 7 Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

500

Closed Door Test; 

No Doorway Temperatures 

Figure 7-8. Gas temperature comparison for Test 13. 
7-17

Test 14, Tree 1 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 14, Tree 2 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 14, Tree 3 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 14, Tree 4 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 14, Tree 5 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 14, Tree 6 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 14, Tree 7 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Test 14, Door Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

FDS Time vs TC Door 16 

FDS Time vs TC Door 11 

FDS Time vs TC Door 9 

Exp Time vs 222 TD16 

Exp Time vs 217 TD11 

Exp Time vs 215 TD9 

Figure 7-9. Gas temperature comparison for Test 14. 
7-18

Test 15, Tree 1 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 15, Tree 2 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 15, Tree 3 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 15, Tree 4 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 15, Tree 5 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 15, Tree 6 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 15, Tree 7 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 15, Door Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

FDS Time vs TC Door 16 

FDS Time vs TC Door 11 

FDS Time vs TC Door 9 

Exp Time vs 222 TD16 

Exp Time vs 217 TD11 

Exp Time vs 215 TD9 

Figure 7-10. Gas temperature comparison for Test 15. 
7-19

Test 16, Tree 1 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

100

200

300

400

500

Test 16, Tree 2 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

100

200

300

400

500

Test 16, Tree 3 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

100

200

300

400

500

Test 16, Tree 4 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

100

200

300

400

500

Test 16, Tree 5 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

100

200

300

400

500

Test 16, Tree 6 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

100

200

300

400

500

These spikes in near-field 

temperature were observed in

the experiment as the fire became

under-ventilated. These spikes 

were not observed in the

simulation. 

Test 16, Tree 7 Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

100

200

300

400

500

Closed Door Test; 

No Doorway Temperatures 

Figure 7-11. Gas temperature comparison for Test 16. 
7-20

Test 17, Tree 1 Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

50

100

150

200

250

300

Test 17, Tree 2 Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

50

100

150

200

250

300

Test 17, Tree 3 Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

50

100

150

200

250

300

Test 17, Tree 4 Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

50

100

150

200

250

300

Predictions Only;

Instrumentation Failed

Test 17, Tree 5 Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

50

100

150

200

250

300

Test 17, Tree 6 Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

50

100

150

200

250

300

Near-Field Effects

Test 17, Tree 7 Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

50

100

150

200

250

300

Closed Door Test; 

No Doorway Temperatures 

Figure 7-12. Gas temperature comparison for Test 17. 
7-21

Test 18, Tree 1 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Test 18, Tree 2 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Test 18, Tree 3 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 18, Tree 4 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

200

400

600

800

1000

1200

Exp Time vs 94 T4-1 

Exp Time vs 98 T4-5 

Exp Time vs 103 T4-10 

FDS Time vs Tree 4-1 

FDS Time vs Tree 4-5 

FDS Time vs Tree 4-10 

Near-Field Effects;

Thermocouple tree

directly above fire pan

Test 18, Tree 5 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

500

Near-Field Effects

Near-Field Effects

Test 18, Tree 6 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Test 18, Tree 7 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Test 18, Door Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

FDS Time vs TC Door 16 

FDS Time vs TC Door 11 

FDS Time vs TC Door 9 

Exp Time vs 222 TD16 

Exp Time vs 217 TD11 

Exp Time vs 215 TD9 

Figure 7-13. Gas temperature comparison for Test 18. 
7-22

7.2.2 Heat Flux and Surface Temperature at the Walls, Ceiling and Floor 

Heat flux gauges were positioned at various locations on all four walls of the compartment, 

plus the ceiling and floor. Comparisons between measured and predicted heat fluxes and 

surface temperatures are shown in Figure 7-14 through Figure 7-24. Only half of the measurement points are shown because the points not shown were in roughly the same relative 

location to the fire and hence the measurements and predictions were similar. For example, 

only data for the east and north walls are shown because the data from the south and west 

walls are comparable. 

Overall, the compartment surface temperature predictions were very accurate because away 

from the immediate vicinity of the fire, these surfaces were heated primarily by the hot 

smoke layer whose temperature was also accurately predicted. The compartment was lined 

with a material (Marinite) whose thermal properties were well-characterized, there were no 

steep gradients in the gas temperature field, the convective heat transfer to the wall was 

based on a fairly reliable experimental correlation, and the radiative flux was easy to calculate as the upper layer gases were of fairly uniform composition and temperature. 

Overall, the compartment surface temperature predictions were within 10 % of the measurements, except at locations near the fire where deviations were sometimes larger. Some 

discrepancies could not be explained, which is why there are many measurement points 

included in the figures to provide a reasonable sampling of the results. 
7-23

Test 1, East Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0.0

0.5

1.0

1.5

2.0

Exp Time vs 337 E1 

Exp Time vs 338 E2 

FDS Time vs East U-1 

FDS Time vs East U-2 

Test 1, East Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

Exp Time vs 159 TE1-1 

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Test 1, North Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0.0

0.5

1.0

1.5

2.0

2.5

Exp Time vs 32 N1 

Exp Time vs 34 N3 

Exp Time vs 37 N6 

FDS Time vs North U-1 

FDS Time vs North U-3 

FDS Time vs North U-6 

Test 1, North Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

Exp Time vs 134 TN1-1 

Exp Time vs 138 TN3-1 

Exp Time vs 144 TN6-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-3 

FDS Time vs TC North U-6 

Test 1, Ceiling Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

5 Exp Time vs 56 C1 

Exp Time vs 57 C2 

Exp Time vs 59 C4 

FDS Time vs Ceiling U-1 

FDS Time vs Ceiling C-2 

FDS Time vs Ceiling C-4 

Test 1, Ceiling Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 191 TC1-1 

Exp Time vs 193 TC2-1 

Exp Time vs 197 TC4-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-2 

FDS Time vs TC Ceiling C-4 

Test 1, Floor Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0.0

0.5

1.0

1.5

2.0

2.5

3.0 Exp Time vs 48 F1 

Exp Time vs 49 F2 

Exp Time vs 51 F4 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

FDS Time vs Floor U-4 

Test 1, Floor Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

Exp Time vs 175 TF1-1 

Exp Time vs 177 TF2-1 

Exp Time vs 181 TF4-1 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

FDS Time vs TC Floor U-4 

Figure 7-14. Heat flux and temperature at select points on the walls, Test 1. 
7-24

Test 2, East Wall Heat Flux

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2

) 0

1

2

3

4

5

Exp Time vs 337 E1 

Exp Time vs 338 E2 

FDS Time vs East U-1 

FDS Time vs East U-2 

Test 2, East Wall Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 159 TE1-1 

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Test 2, North Wall Heat Flux

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2

) 0

1

2

3

4

5

6

Exp Time vs 32 N1 

Exp Time vs 35 N4 

Exp Time vs 37 N6 

FDS Time vs North U-1 

FDS Time vs North U-4 

FDS Time vs North U-6 

Test 2, North Wall Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

Exp Time vs 134 TN1-1 

Exp Time vs 140 TN4-1 

Exp Time vs 144 TN6-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-4 

FDS Time vs TC North U-6 

Test 2, Ceiling Heat Flux

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2

)

0

2

4

6

8

10

12

14

16

18

Exp Time vs 56 C1 

Exp Time vs 57 C2 

Exp Time vs 59 C4 

FDS Time vs Ceiling U-1 

FDS Time vs Ceiling C-2 

FDS Time vs Ceiling C-4 

Flux Gauge

malfunction

Test 2, Ceiling Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

350

400

Exp Time vs 191 TC1-1 

Exp Time vs 193 TC2-1 

Exp Time vs 197 TC4-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-2 

FDS Time vs TC Ceiling C-4 

Instrument

malfunction

Test 2, Floor Heat Flux

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2

)

0

2

4

6

8

10 Exp Time vs 48 F1 

Exp Time vs 49 F2 

Exp Time vs 51 F4 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

FDS Time vs Floor U-4 

Test 2, Floor Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 175 TF1-1 

Exp Time vs 177 TF2-1 

Exp Time vs 181 TF4-1 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

FDS Time vs TC Floor U-4 

Figure 7-15. Heat flux and temperature at select points on the walls, Test 2. 
7-25

Test 3, East Wall Flux Gauges

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

5

Exp Time vs 337 E1 

Exp Time vs 338 E2 

FDS Time vs East U-1 

FDS Time vs East U-2 

Test 3, East Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 159 TE1-1 

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Malfunction

Test 3, North Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

5

6

Exp Time vs 32 N1 

Exp Time vs 34 N3 

Exp Time vs 37 N6 

FDS Time vs North U-1 

FDS Time vs North U-3 

FDS Time vs North U-6 

Malfunction

Test 3, North Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 134 TN1-1 

Exp Time vs 138 TN3-1 

Exp Time vs 144 TN6-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-3 

FDS Time vs TC North U-6 

Malfunction

Test 3, Ceiling Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

12 Exp Time vs 56 C1 

Exp Time vs 58 C3 

Exp Time vs 59 C4 

FDS Time vs Ceiling U-1 

FDS Time vs Ceiling C-3 

FDS Time vs Ceiling C-4 

Test 3, Ceiling Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Exp Time vs 191 TC1-1 

Exp Time vs 195 TC3-1 

Exp Time vs 197 TC4-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-3 

FDS Time vs TC Ceiling C-4 

Test 3, Floor Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

12 Exp Time vs 48 F1 

Exp Time vs 49 F2 

Exp Time vs 51 F4 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

FDS Time vs Floor U-4 

Test 3, Floor Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 175 TF1-1 

Exp Time vs 177 TF2-1 

Exp Time vs 181 TF4-1 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

FDS Time vs TC Floor U-4 

Figure 7-16. Heat flux and temperature at select points on the walls, Test 3. 
7-26

Test 4, East Wall Heat Flux

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2

) 0

1

2

3

4

5

Exp Time vs 337 E1 

Exp Time vs 338 E2 

FDS Time vs East U-1 

FDS Time vs East U-2 

Test 4, East Wall Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

20

40

60

80

100

120

140

160

Exp Time vs 159 TE1-1 

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Test 4, North Wall Heat Flux

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2

) 0

1

2

3

4

5

6

Exp Time vs 32 N1 

Exp Time vs 34 N3 

Exp Time vs 37 N6 

FDS Time vs North U-1 

FDS Time vs North U-3 

FDS Time vs North U-6 

Test 4, North Wall Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 134 TN1-1 

Exp Time vs 138 TN3-1 

Exp Time vs 144 TN6-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-3 

FDS Time vs TC North U-6 

Test 4, Ceiling Heat Flux

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2

)

0

2

4

6

8

10

12

14

Exp Time vs 56 C1 

Exp Time vs 58 C3 

Exp Time vs 60 C5 

FDS Time vs Ceiling U-1 

FDS Time vs Ceiling C-3 

FDS Time vs Ceiling C-5 

Test 4, Ceiling Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

300

350

400

Exp Time vs 191 TC1-1 

Exp Time vs 195 TC3-1 

Exp Time vs 199 TC5-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-3 

FDS Time vs TC Ceiling C-5 

Test 4, Floor Heat Flux

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2

)

0

2

4

6

8

10 Exp Time vs 48 F1 

Exp Time vs 49 F2 

Exp Time vs 51 F4 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

FDS Time vs Floor U-4 

Test 4, Floor Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 175 TF1-1 

Exp Time vs 177 TF2-1 

Exp Time vs 181 TF4-1 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

FDS Time vs TC Floor U-4 

Figure 7-17. Heat flux and temperature at select points on the walls, Test 4. 
7-27

Test 5, East Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

Exp Time vs 337 E1 

Exp Time vs 338 E2 

FDS Time vs East U-1 

FDS Time vs East U-2 

Test 5, East Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

Exp Time vs 159 TE1-1 

Exp Time vs 162 TE2-2 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Test 5, North Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

5

Exp Time vs 32 N1 

Exp Time vs 34 N3 

Exp Time vs 37 N6 

FDS Time vs North U-1 

FDS Time vs North U-3 

FDS Time vs North U-6 

Test 5, North Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 134 TN1-1 

Exp Time vs 138 TN3-1 

Exp Time vs 144 TN6-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-3 

FDS Time vs TC North U-6 

Test 5, Ceiling Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

Test 5, Ceiling Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 191 TC1-1 

Exp Time vs 193 TC2-1 

Exp Time vs 199 TC5-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-2 

FDS Time vs TC Ceiling C-5 

Test 5, Floor Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10 Exp Time vs 48 F1 

Exp Time vs 49 F2 

Exp Time vs 51 F4 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

FDS Time vs Floor U-4 

Test 5, Floor Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 175 TF1-1 

Exp Time vs 177 TF2-1 

Exp Time vs 181 TF4-1 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

FDS Time vs TC Floor U-4 

Figure 7-18. Heat flux and temperature at select points on the walls, Test 5. 
7-28

Test 13, East Wall Heat Flux

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2

) 0

1

2

3

4

5

FDS Time vs East U-1 

Exp Time vs 337 E1 

Test 13, East Wall Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

Exp Time vs 160 TE1-2 

FDS Time vs TC East U-1 

Test 13, North Wall Heat Flux

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2

) 0

2

4

6

8

Exp Time vs 32 N1 

Exp Time vs 35 N4 

FDS Time vs North U-1 

FDS Time vs North U-4 

Test 13, North Wall Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

220

Exp Time vs 134 TN1-1 

Exp Time vs 140 TN4-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-4 

Test 13, Ceiling Heat Flux

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2

)

0

5

10

15

20

25

30

Exp Time vs 62 C7 

Exp Time vs 57 C2 

Exp Time vs 60 C5 

FDS Time vs Ceiling C-7 

FDS Time vs Ceiling C-2 

FDS Time vs Ceiling C-5 

Test 13, Ceiling Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

500

600

Exp Time vs 203 TC7-1 

Exp Time vs 193 TC2-1 

Exp Time vs 199 TC5-1 

FDS Time vs TC Ceiling C-7 

FDS Time vs TC Ceiling C-2 

FDS Time vs TC Ceiling C-5 

Test 13, Floor Heat Flux

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2

)

0

2

4

6

8

10

Exp Time vs 48 F1 

Exp Time vs 49 F2 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

Test 13, Floor Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 175 TF1-1 

Exp Time vs 177 TF2-1 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

Figure 7-19. Heat flux and temperature at select points on the walls, Test 13. 
7-29

Test 14, East Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

5

Exp Time vs 337 E1 

Exp Time vs 338 E2 

FDS Time vs East U-1 

FDS Time vs East U-2 

Test 14, East Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

Exp Time vs 160 TE1-2 

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Test 14, North Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

Exp Time vs 32 N1 

Exp Time vs 35 N4 

Exp Time vs 37 N6 

FDS Time vs North U-1 

FDS Time vs North U-4 

FDS Time vs North U-6 

Malfunction

Test 14, North Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 134 TN1-1 

Exp Time vs 140 TN4-1 

Exp Time vs 144 TN6-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-4 

FDS Time vs TC North U-6 

Malfunction

Test 14, Ceiling Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

Exp Time vs 56 C1 

Exp Time vs 57 C2 

Exp Time vs 58 C3 

FDS Time vs Ceiling U-1 

FDS Time vs Ceiling C-2 

FDS Time vs Ceiling C-3 

Test 14, Ceiling Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 191 TC1-1 

Exp Time vs 193 TC2-1 

Exp Time vs 195 TC3-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-2 

FDS Time vs TC Ceiling C-3 

Test 14, Floor Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Exp Time vs 48 F1 

Exp Time vs 49 F2 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

Test 14, Floor Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

Exp Time vs 176 TF1-2 

Exp Time vs 178 TF2-2 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

Figure 7-20. Heat flux and temperature at select points on the walls, Test 14. 
7-30

Test 15, East Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

5

Exp Time vs 337 E1 

Exp Time vs 338 E2 

FDS Time vs East U-1 

FDS Time vs East U-2 

Test 15, East Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 160 TE1-2 

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Test 15, North Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

Exp Time vs 32 N1 

Exp Time vs 35 N4 

FDS Time vs North U-1 

FDS Time vs North U-4 

Test 15, North Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 134 TN1-1 

Exp Time vs 140 TN4-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-4 

Test 15, Ceiling Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

Exp Time vs 56 C1 

Exp Time vs 57 C2 

Exp Time vs 59 C4 

FDS Time vs Ceiling U-1 

FDS Time vs Ceiling C-2 

FDS Time vs Ceiling C-4 

Flux Gauge

not trusted

Test 15, Ceiling Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 191 TC1-1 

Exp Time vs 193 TC2-1 

Exp Time vs 197 TC4-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-2 

FDS Time vs TC Ceiling C-4 

Test 15, Floor Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0.0

0.5

1.0

1.5

2.0

2.5

3.0

Exp Time vs 48 F1 

Exp Time vs 50 F3 

FDS Time vs Floor U-1 

FDS Time vs Floor U-3 

Test 15, Floor Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

Exp Time vs 175 TF1-1 

Exp Time vs 179 TF3-1 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-3 

Figure 7-21. Heat flux and temperature at select points on the walls, Test 15. 
7-31

Test 16, East Wall Heat Flux

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2

) 0

2

4

6

8

Exp Time vs 339 E3 

Exp Time vs 340 E4 

FDS Time vs East U-3 

FDS Time vs East U-4 

Test 16, East Wall Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 163 TE3-1 

Exp Time vs 165 TE4-1 

FDS Time vs TC East U-3 

FDS Time vs TC East U-4 

Test 16, North Wall Heat Flux

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2

)

0

2

4

6

8

10

Exp Time vs 32 N1 

Exp Time vs 33 N2 

FDS Time vs North U-1 

FDS Time vs North U-2 

Test 16, North Wall Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 134 TN1-1 

Exp Time vs 136 TN2-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-2 

Test 16, Ceiling Heat Flux

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2

)

0

5

10

15

20

Exp Time vs 56 C1 

Exp Time vs 57 C2 

FDS Time vs Ceiling U-1 

FDS Time vs Ceiling C-2 

Flux Gauge Malfunction

Test 16, Ceiling Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

350

400

Exp Time vs 191 TC1-1 

Exp Time vs 193 TC2-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-2 

Test 16, Floor Heat Flux

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2

)

0

2

4

6

8

10

12

14

16

Exp Time vs 48 F1 

Exp Time vs 49 F2 

Exp Time vs 51 F4 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

FDS Time vs Floor U-4 

Test 16, Floor Temperatures

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 176 TF1-2 

Exp Time vs 178 TF2-2 

Exp Time vs 181 TF4-1 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

FDS Time vs TC Floor U-4 

Figure 7-22. Heat flux and temperature at select points on the walls, Test 16. 
7-32

Test 17, East Wall Heat Flux

Time (s)

0 100 200 300 400 500 600

Heat Flux (kW/m2

) 0.0

0.5

1.0

1.5

2.0

2.5

3.0

Exp Time vs 337 E1 

Exp Time vs 338 E2 

FDS Time vs East U-1 

FDS Time vs East U-2 

Test 17, East Wall Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Prediction Only;

Thermocouple Inoperative

Test 17, North Wall Heat Flux

Time (s)

0 100 200 300 400 500 600

Heat Flux (kW/m2

) 0

1

2

3

4

Exp Time vs 32 N1 

Exp Time vs 33 N2 

FDS Time vs North U-1 

FDS Time vs North U-2 

Test 17, North Wall Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

Exp Time vs 134 TN1-1 

Exp Time vs 136 TN2-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-2 

Test 17, Ceiling Heat Flux

Time (s)

0 100 200 300 400 500 600

Heat Flux (kW/m2

)

0

2

4

6

8

10

Exp Time vs 57 C2 

FDS Time vs Ceiling U-1 

FDS Time vs Ceiling C-2 

FDS Time vs Ceiling C-4 

Corresponding

measurements failed

Test 17, Ceiling Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

50

100

150

200

250

Exp Time vs 191 TC1-1 

Exp Time vs 193 TC2-1 

Exp Time vs 197 TC4-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-2 

FDS Time vs TC Ceiling C-4 

Test 17, Floor Heat Flux

Time (s)

0 100 200 300 400 500 600

Heat Flux (kW/m2

) 0.0

0.5

1.0

1.5

2.0

2.5

Exp Time vs 48 F1 

Exp Time vs 49 F2 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

Test 17, Floor Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

Exp Time vs 175 TF1-1 

Exp Time vs 178 TF2-2 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

Figure 7-23. Heat flux and temperature at select points on the walls, Test 17. 
7-33

Test 18, East Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

5

6

Exp Time vs 337 E1 

Exp Time vs 338 E2 

FDS Time vs East U-1 

FDS Time vs East U-2 

Test 18, East Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 160 TE1-2 

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Test 18, North Wall Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

) 0

1

2

3

4

5

6

Exp Time vs 32 N1 

Exp Time vs 33 N2 

Exp Time vs 35 N4 

FDS Time vs North U-1 

FDS Time vs North U-2 

FDS Time vs North U-4 

Test 18, North Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 134 TN1-1 

Exp Time vs 136 TN2-1 

Exp Time vs 140 TN4-1 

FDS Time vs TC North U-1 

FDS Time vs TC North U-2 

FDS Time vs TC North U-4 

Test 18, Ceiling Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

12

Exp Time vs 57 C2 

Exp Time vs 59 C4 

FDS Time vs Ceiling U-1 

FDS Time vs Ceiling C-2 

FDS Time vs Ceiling C-4 

Prediction Only;

Flux Gauge Inoperable

Test 18, Ceiling Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Exp Time vs 191 TC1-1 

Exp Time vs 193 TC2-1 

Exp Time vs 197 TC4-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-2 

FDS Time vs TC Ceiling C-4 

Test 18, Floor Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

12

Exp Time vs 48 F1 

Exp Time vs 49 F2 

Exp Time vs 51 F4 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

FDS Time vs Floor U-4 

Gauge Malfunction

Test 18, Floor Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 175 TF1-1 

Exp Time vs 178 TF2-2 

Exp Time vs 181 TF4-1 

FDS Time vs TC Floor U-1 

FDS Time vs TC Floor U-2 

FDS Time vs TC Floor U-4 

Figure 7-24. Heat flux and temperature at select points on the walls, Test 18. 
7-34

7.2.3 Heat Flux and Surface Temperature at Cable Targets 

Each of the cable trays were instrumented with thermocouples and heat flux gauges, plus a 

thermocouple tree was positioned near to each one. For the purpose of model validation, the 

central measurement location for each tray was the most valuable because at this point, the 

gas temperature, heat flux and surface temperature could be analyzed together. Shown in 

Figure 7-25 through Figure 7-46 are the gas temperatures, heat flux and cable surface temperatures for Trays/Targets D, E, F and G. The individual cables A, B and C could not be 

included in the simulation because of their small size relative to the numerical grid. Nevertheless, the data for Trays/Targets D, E, F and G demonstrate the model’s ability to characterize the thermal environment in the vicinity of relatively small objects. 

Note that only the inner temperature of “slab” E is reported. FDS does not have a detailed 

solid phase model that can account for the heat transfer within the bundled, cylindrical, nonhomogenous cables. At best, it calculates the surface temperature of the outermost cable in 

the bundle assuming that it is a solid, homogenous mass of similar thickness to the width of 

the bundle. Only the solid rectangular stick of plastic (Target E) could be modeled both inside and out even though the predicted surface and inner temperature of this 1 cm × 1 cm 

stick were in greatest disagreement with measurement. The reason is that FDS only performs a one-dimensional heat transfer calculation normal to the surface, assuming that the 

surface area greatly exceeds the depth. In reality, the heat penetrated the plastic stick in all 

directions, leading to a consistently higher measured surface and inner temperature than the 

corresponding predictions. 

The superposition of gas temperature, heat flux and surface temperature in the figures on 

the following pages was a very valuable exercise. Favorable or unfavorable predictions of 

cable surface temperatures could usually be explained in terms of comparable errors in the 

prediction of the thermal environment in the vicinity of the cable tray. Regardless of the complexity of the target, the model must be able to predict the thermal insult to it. In most cases, 

the cable surface temperatures in trays D, F and G were predicted to within 10 % of the 

measurements, with deviations due to a number of near-field effects, plus errors related to 

the simplification of the cable bundles as solid slabs of plastic. 
7-35

Test 1, Gas Temperature near Cable Tray D

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 1, Gas Temperature near Target E

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Test 1, Heat Flux to Cable Tray D

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2) 0.0

0.5

1.0

1.5

2.0

2.5

3.0

FDS Time vs Flux Gauge 8 

Prediction Only;

Flux Gauge Inoperative

Test 1, Heat Flux to Target E

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2) 0.0

0.5

1.0

1.5

2.0

2.5

3.0

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 1, Cable D Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

FDS Time vs D Ts-12 

Prediction Only;

Thermocouple Inoperative

Test 1, Target E Surface/Inner Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

Exp Time vs 248 TCEs16 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Figure 7-25. Thermal environment near Tray D and Target E, Test 1. 
7-36

Test 1, Gas Temperature near Cable Tray F

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 1, Gas Temperature near Cable Tray G

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 1, Heat Flux to Cable Tray F

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2) 0.0

0.5

1.0

1.5

2.0

2.5

3.0

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 1, Heat Flux to Cable Tray G

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2) 0.0

0.5

1.0

1.5

2.0

2.5

3.0

Exp Time vs 350 RG10 

FDS Time vs Flux Gauge 9 

Radiation Only

Test 1, Cable F Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 1, Cable G Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-26. Thermal environment near Cable Trays F and G, Test 1. 
7-37

Test 2, Gas Temperature near Cable Tray D

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 2, Gas Temperature near Target E

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Test 2, Heat Flux to Cable Tray D

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2)

0

2

4

6

8

10

FDS Time vs Flux Gauge 8 

Exp Time vs 347 RG7 

Radiation Only

Test 2, Heat Flux to Target E

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 2, Cable D Surface Temperature

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Test 2, Target E Surface/Inner Temperature

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 248 TCEs16 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Figure 7-27. Thermal environment near Tray D and Target E, Test 2. 
7-38

Test 2, Gas Temperature near Cable Tray F

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 2, Gas Temperature near Cable Tray G

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 2, Heat Flux to Cable Tray F

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 2, Heat Flux to Cable Tray G

Time (s)

0 200 400 600 800 1000

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 350 RG10 

FDS Time vs Flux Gauge 9 

Test 2, Cable F Surface Temperature

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 2, Cable G Surface Temperature

Time (s)

0 200 400 600 800 1000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-28. Thermal environment near Cable Trays F and G, Test 2. 
7-39

Test 3, Gas Temperature near Cable Tray D

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 3, Gas Temperature near Target E

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Test 3, Heat Flux to Cable Tray D

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

12

FDS Time vs Flux Gauge 8 

Exp Time vs 347 RG7 

Malfunction

Test 3, Heat Flux to Target E

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

12

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 3, Cable D Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Test 3, Target E Surface/Inner Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Prediction Only;

Surface thermocouple

malfunctioned

Inner Temperatures

Figure 7-29. Thermal environment near Tray D and Target E, Test 3. 
7-40

Test 3, Gas Temperature near Cable Tray F

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 3, Gas Temperature near Cable Tray G

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 3, Heat Flux to Cable Tray F

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

12

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 3, Heat Flux to Cable Tray G

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

12

Exp Time vs 350 RG10 

FDS Time vs Flux Gauge 9 

Test 3, Cable F Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 3, Cable G Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-30. Thermal environment near Cable Trays F and G, Test 3. 
7-41

Test 4, Gas Temperature near Cable Tray D

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 4, Gas Temperature near Target E

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Test 4, Heat Flux to Cable Tray D

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2)

0

2

4

6

8

10

FDS Time vs Flux Gauge 8 

Exp Time vs 347 RG7 

Radiative Heat Flux Only

Test 4, Heat Flux to Target E

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 4, Cable D Surface Temperature

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Test 4, Target E Surface/Inner Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

Exp Time vs 248 TCEs16 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Target Melted

Figure 7-31. Thermal environment near Tray D and Target E, Test 4. 
7-42

Test 4, Gas Temperature near Cable Tray F

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 4, Gas Temperature near Cable Tray G

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 4, Heat Flux to Cable Tray F

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2) 0

2

4

6

8

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 4, Heat Flux to Cable Tray G

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2) 0

2

4

6

8

Exp Time vs 349 FG9 

FDS Time vs Flux Gauge 9 

Test 4, Cable F Surface Temperature

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 4, Cable G Surface Temperature

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-32. Thermal environment near Cable Trays F and G, Test 4. 
7-43

Test 5, Gas Temperature near Cable Tray D

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 5, Gas Temperature near Target E

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Test 5, Heat Flux to Cable Tray D

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

FDS Time vs Flux Gauge 8 

Exp Time vs 347 RG7 

Radiation Only

Test 5, Heat Flux to Target E

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 5, Cable D Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Test 5, Target E Surface/Inner Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 248 TCEs16 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Target Melted

Figure 7-33. Thermal environment near Tray D and Target E, Test 5. 
7-44

Test 5, Gas Temperature near Cable Tray F

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 5, Gas Temperature near Cable Tray G

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 5, Heat Flux to Cable Tray F

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 5, Heat Flux to Cable Tray G

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 350 RG10 

FDS Time vs Flux Gauge 9 

Test 5, Cable F Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 5, Cable G Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-34. Thermal environment near Cable Trays F and G, Test 5. 
7-45

Test 13, Gas Temperature near Cable Tray D

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

300

350

400

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 13, Gas Temperature near Target E

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Test 13, Heat Flux to Cable Tray D

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2)

0

5

10

15

20

FDS Time vs Flux Gauge 8 

Exp Time vs 347 RG7 

Radiation Only

Test 13, Heat Flux to Target E

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2)

0

5

10

15

20

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 13, Cable D Surface Temperature

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Test 13, Target E Surface/Inner Temperatures

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

Exp Time vs 248 TCEs16 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Target Melted

Figure 7-35. Thermal environment near Tray D and Target E, Test 13. 
7-46

Test 13, Gas Temperature near Cable Tray F

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 13, Gas Temperature near Cable Tray G

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

100

200

300

400

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 13, Heat Flux to Cable Tray F

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2)

0

5

10

15

20

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 13, Heat Flux to Cable Tray G

Time (s)

0 200 400 600 800 1000 1200

Heat Flux (kW/m2)

0

5

10

15

20

Exp Time vs 349 FG9 

FDS Time vs Flux Gauge 9 

Test 13, Cable F Surface Temperature

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 13, Cable G Surface Temperature

Time (s)

0 200 400 600 800 1000 1200

Temperature (C)

0

50

100

150

200

250

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-36. Thermal environment near Cable Trays F and G, Test 13. 
7-47

Test 14, Gas Temperature near Cable Tray D

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 14, Gas Temperature near Target E

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Test 14, Heat Flux to Cable Tray D

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

12

FDS Time vs Flux Gauge 8 

Exp Time vs 347 RG7 Radiation Only

Test 14, Heat Flux to Target E

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

12

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 14, Cable D Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Test 14, Target E Surface/Inner Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

Exp Time vs 248 TCEs16 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Target Melted

Figure 7-37. Thermal environment near Tray D and Target E, Test 14. 
7-48

Test 14, Gas Temperature near Cable Tray F

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 14, Gas Temperature near Cable Tray G

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 14, Heat Flux to Cable Tray F

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

12

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 14, Heat Flux to Cable Tray G

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

12

Exp Time vs 350 RG10 

FDS Time vs Flux Gauge 9 

Radiation Only

Test 14, Cable F Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 14, Cable G Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-38. Thermal environment near Cable Trays F and G, Test 14. 
7-49

Test 15, Gas Temperature near Cable Tray D

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 15, Gas Temperature near Target E

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Test 15, Heat Flux to Cable Tray D

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

FDS Time vs Flux Gauge 8 

Prediction Only;

Flux Gauge Inoperative

Test 15, Heat Flux to Target E

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 15, Cable D Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Test 15, Target E Surface/Inner Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 248 TCEs16 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Target Melted;

Faulty Measurement

Figure 7-39. Thermal environment near Tray D and Target E, Test 15. 
7-50

Test 15, Gas Temperature near Cable Tray F

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 15, Gas Temperature near Cable Tray G

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 15, Heat Flux to Cable Tray F

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 15, Heat Flux to Cable Tray G

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

2

4

6

8

10

Exp Time vs 350 RG10 

FDS Time vs Flux Gauge 9 

Radiation Only

Test 15, Cable F Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 15, Cable G Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-40. Thermal environment near Cable Trays F and G, Test 15. 
7-51

Test 16, Gas Temperature near Cable Tray D

Time (s)

0 200 400 600 800

Temperature (C)

0

100

200

300

400

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 16, Gas Temperature near Target E

Time (s)

0 200 400 600 800

Temperature (C)

0

100

200

300

400

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Test 16, Heat Flux to Cable Tray D

Time (s)

0 200 400 600 800

Heat Flux (kW/m2)

0

2

4

6

8

10

12

14

FDS Time vs Flux Gauge 8 

Exp Time vs 347 RG7 

Radiation only

Test 16, Heat Flux to Target E

Time (s)

0 200 400 600 800

Heat Flux (kW/m2)

0

2

4

6

8

10

12

14

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 16, Cable D Surface Temperature

Time (s)

0 200 400 600 800

Temperature (C)

0

50

100

150

200

250

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Test 16, Target E Surface/Inner Temperatures

Time (s)

0 200 400 600 800

Temperature (C)

0

50

100

150

200

250

Exp Time vs 248 TCEs16bottom 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Figure 7-41. Thermal environment near Tray D and Target E, Test 16. 
7-52

Test 16, Gas Temperature near Cable Tray F

Time (s)

0 200 400 600 800

Temperature (C)

0

100

200

300

400

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 16, Gas Temperature near Cable Tray G

Time (s)

0 200 400 600 800

Temperature (C)

0

100

200

300

400

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 16, Heat Flux to Cable Tray F

Time (s)

0 200 400 600 800

Heat Flux (kW/m2)

0

2

4

6

8

10

12

14

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 16, Heat Flux to Cable Tray G

Time (s)

0 200 400 600 800

Heat Flux (kW/m2)

0

2

4

6

8

10

12

14

Exp Time vs 349 FG9 

FDS Time vs Flux Gauge 9 

Test 16, Cable F Surface Temperature

Time (s)

0 200 400 600 800

Temperature (C)

0

50

100

150

200

250

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 16, Cable G Surface Temperature

Time (s)

0 200 400 600 800

Temperature (C)

0

50

100

150

200

250

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-42. Thermal environment near Cable Trays F and G, Test 16. 
7-53

Test 17, Gas Temperature near Cable Tray D

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 17, Gas Temperature near Target E

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

FDS Time vs Tree 4-8 

Prediction Only;

Thermocouple did not operate

Test 17, Heat Flux to Cable Tray D

Time (s)

0 100 200 300 400 500 600

Heat Flux (kW/m2) 0

1

2

3

4

5

FDS Time vs Flux Gauge 8 

Exp Time vs 347 RG7 

Radiation Only

Test 17, Heat Flux to Target E

Time (s)

0 100 200 300 400 500 600

Heat Flux (kW/m2) 0

1

2

3

4

5

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 17, Cable D Surface Temperature

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

120

140

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Measurement not trusted

Test 17, Target E Surface/Inner Temperatures

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

120

140

Exp Time vs 248 TCEs16bottom 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Figure 7-43. Thermal environment near Tray D and Target E, Test 17. 
7-54

Test 17, Gas Temperature near Cable Tray F

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 17, Gas Temperature near Cable Tray G

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 17, Heat Flux to Cable Tray F

Time (s)

0 100 200 300 400 500 600

Heat Flux (kW/m2) 0

1

2

3

4

5

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 17, Heat Flux to Cable Tray G

Time (s)

0 100 200 300 400 500 600

Heat Flux (kW/m2) 0

1

2

3

4

5

Exp Time vs 349 FG9 

FDS Time vs Flux Gauge 9 

Test 17, Cable F Surface Temperature

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

120

140

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Measurement not trusted

Test 17, Cable G Surface Temperature

Time (s)

0 100 200 300 400 500 600

Temperature (C)

0

20

40

60

80

100

120

140

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-44. Thermal environment near Cable Trays F and G, Test 17. 
7-55

Test 18, Gas Temperature near Cable Tray D

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

500

600

Exp Time vs 92 T3-9 

FDS Time vs Tree 3-9 

Test 18, Gas Temperature near Target E

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

200

400

600

800

1000

Exp Time vs 101 T4-8 

FDS Time vs Tree 4-8 

Actual fire 

engulfed target

Test 18, Heat Flux to Cable Tray D

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

5

10

15

20

FDS Time vs Flux Gauge 8 

Exp Time vs 347 RG7 

Radiation Only

Test 18, Heat Flux to Target E

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

20

40

60

80

Exp Time vs 344 FG4 

Exp Time vs 346 FG6 

FDS Time vs Flux Gauge 4 

FDS Time vs Flux Gauge 6 

Test 18, Cable D Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

Exp Time vs 244 TCDs12 

FDS Time vs D Ts-12 

Test 18, Target E Surface/Inner Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

200

400

600

800

Exp Time vs 248 TCEs16bottom 

Exp Time vs 249 TCEc17 

FDS Time vs E Ts-16 

FDS Time vs E Tc-17 

Target E melted;

Temperatures not trusted

Figure 7-45. Thermal environment near Tray D and Target E, Test 18. 
7-56

Test 18, Gas Temperature near Cable Tray F

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

100

200

300

400

500

600

Exp Time vs 109 T5-6 

FDS Time vs Tree 5-6 

Test 18, Gas Temperature near Cable Tray G

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

Exp Time vs 78 T2-5 

FDS Time vs Tree 2-5 

Test 18, Heat Flux to Cable Tray F

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2)

0

10

20

30

40

50

Exp Time vs 342 FG2 

FDS Time vs Flux Gauge 2 

Test 18, Heat Flux to Cable Tray G

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2) 0

1

2

3

4

5

Exp Time vs 350 RG10 

FDS Time vs Flux Gauge 9 

Radiation Only

Test 18, Cable F Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

200

400

600

800

Exp Time vs 252 TCFs20 

FDS Time vs F Ts-20 

Test 18, Cable G Surface Temperature

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 265 TCVs33 

FDS Time vs Vertical Cable Ts-33 

Figure 7-46. Thermal environment near Cable Trays F and G, Test 18. 
7-57

7.2.4 Gas Species Concentrations 

FDS uses a mixture fraction combustion model, meaning that all gas species within the 

compartment are assumed to be functions of a single scalar variable. FDS solves only one 

transport equation for this variable, and reports gas concentrations at any given point at any 

given time by extracting its value from a pre-computed “look-up table.” For the major species, like carbon dioxide and oxygen, the predictions are essentially an indicator of how well 

FDS is predicting the bulk transport of combustion products throughout the space. For minor 

species, like carbon monoxide, FDS at the present time does not account for changes in 

combustion efficiency, relying only on a fixed yield of CO from the combustion process. In 

reality, the generation rate of CO changes depending on the ventilation conditions in the 

compartment. 

Figure 7-47 through Figure 7-49 present comparisons of oxygen and carbon dioxide concentration predictions with experiment. There were two oxygen measurements, one in the upper 

layer, one in the lower layer. There was only one carbon dioxide measurement in the upper 

layer. The agreement between measurement and prediction was about 10 %, consistent with 

the accuracy of the temperature predictions and confirming that FDS is handling the bulk 

transport of gases well. 

The CO predictions are not shown because the measurements appeared flawed. Instead, 

the smoke, another combustion product with a fixed yield, is described in the next section. 
7-58

Test 1, Oxygen Concentration

Time (s)

0 500 1000 1500 2000

Volume Fraction

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 1, CO2 Concentration

Time

0 500 1000 1500 2000

Volume Fraction

0.00

0.01

0.02

0.03

0.04

0.05

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Malfunction

Test 2, Oxygen Concentration

Time (s)

0 200 400 600 800 1000

Volume Fraction

0.10

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 2, CO2 Concentration

Time

0 200 400 600 800 1000

Volume Fraction

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Malfunction

Test 3, Oxygen Concentration

Time (s)

0 500 1000 1500 2000

Volume Fraction

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 3, CO2 Concentration

Time

0 500 1000 1500 2000

Volume Fraction

0.00

0.01

0.02

0.03

0.04

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Test 4, Oxygen Concentration

Time (s)

0 200 400 600 800 1000 1200

Volume Fraction

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 4, CO2 Concentration

Time

0 200 400 600 800 1000 1200

Volume Fraction

0.00

0.01

0.02

0.03

0.04

0.05

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Malfunction

Figure 7-47. Oxygen and carbon dioxide concentration, Tests 1-4. 
7-59

Test 5, Oxygen Concentration

Time (s)

0 500 1000 1500 2000

Volume Fraction

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 5, CO2 Concentration

Time

0 500 1000 1500 2000

Volume Fraction

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Test 13, Oxygen Concentration

Time (s)

0 200 400 600 800 1000 1200

Volume Fraction

0.10

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 13, CO2 Concentration

Time

0 200 400 600 800 1000 1200

Volume Fraction

0.00

0.02

0.04

0.06

0.08

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Malfunction

Test 14, Oxygen Concentration

Time (s)

0 500 1000 1500 2000

Volume Fraction

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 14, CO2 Concentration

Time

0 500 1000 1500 2000

Volume Fraction

0.00

0.01

0.02

0.03

0.04

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Test 15, Oxygen Concentration

Time (s)

0 500 1000 1500 2000

Volume Fraction

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 15, CO2 Concentration

Time

0 500 1000 1500 2000

Volume Fraction

0.00

0.01

0.02

0.03

0.04

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Figure 7-48. Oxygen and carbon dioxide concentration, Tests 5, 13-15. 
7-60

Test 16, Oxygen Concentration

Time (s)

0 200 400 600 800 1000

Volume Fraction

0.10

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 16, CO2 Concentration

Time

0 200 400 600 800 1000

Volume Fraction

0.00

0.01

0.02

0.03

0.04

0.05

0.06

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Faulty Measurement

Test 17, Oxygen Concentration

Time (s)

0 100 200 300 400 500 600

Volume Fraction

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 17, CO2 Concentration

Time

0 100 200 300 400 500 600

Volume Fraction

0.000

0.005

0.010

0.015

0.020

0.025

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Test 18, Oxygen Concentration

Time (s)

0 500 1000 1500 2000

Volume Fraction

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 18, CO2 Concentration

Time

0 500 1000 1500 2000

Volume Fraction

0.00

0.01

0.02

0.03

0.04

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Figure 7-49. Oxygen and carbon dioxide concentration, Tests 16-18. 
7-61

7.2.5 Smoke Concentration 

FDS treats smoke like all other combustion products, basically a tracer gas whose mass 

fraction is a function of the mixture fraction. To model smoke movement, the user need only 

prescribe the smoke yield, that is, the fraction of the fuel mass that is converted to smoke 

particulate. For BE #3, the smoke yield was specified as one of the test parameters. 

Figure 7-50 and Figure 7-51 contain comparisons of measured and predicted smoke concentration at one measuring station in the upper layer. There are two obvious trends in the 

figures: first, the predicted concentrations were about 50 % higher than the measured. Second, the predicted concentrations increased at the end of the closed door tests. 

Consider the first issue. The reported mass concentration of smoke was computed using the 

following expression 

L

I I M

s

s φ

ln( / ) 0 =

Errors in the measurement were due to errors in the path length L , the light attenuation 

I / I 0 , and the assumed specific extinction coefficient φs . Hamins reported the expanded 

uncertainty of the measurement to be 18 %. In addition, the simulation was subject to error 

mainly from the prescribed soot yield. The soot yields were given as 1.5 % ± 0.3 % (heptane) and 20 % ± 5 % (toluene, Test 17). The combination of numerical and measurement 

error for the heptane tests was therefore 18 % + 20 % = 40 %, and for the toluene test 18 % 

+ 25 % = 45 %. 

Assuming that the mixture fraction model is valid, at least for the open door tests, it can be 

assumed that virtually all of the carbon atoms in the fuel either ended up in the CO2 or the 

soot (with relatively small amounts going to CO, unburned hydrocarbons, etc.). It can also be 

assumed that the soot (smoke) and CO2 were transported together with no significant separation or reaction. If these assumptions are true, there is no reason to expect the predicted 

smoke concentration shown in Figure 7-52 to be roughly 50 % higher than the measured 

value unless the soot yield uncertainty and the measurement error combined to cause it. 
7-62

Test 1, Smoke Concentration

Time (s)

0 500 1000 1500 2000

Smoke Density (mg/m3

)

0

100

200

300

400

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Test 2, Smoke Concentration

Time (s)

0 200 400 600 800 1000

Smoke Density (mg/m3

)

0

100

200

300

400

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Test 3, Smoke Concentration

Time (s)

0 500 1000 1500 2000

Smoke Density (mg/m3

)

0

50

100

150

200

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Test 4, Smoke Concentration

Time (s)

0 200 400 600 800 1000 1200

Smoke Density (mg/m3

)

0

50

100

150

200

250

300

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Test 5, Smoke Concentration

Time (s)

0 500 1000 1500 2000

Smoke Density (mg/m3

)

0

50

100

150

200

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Test 13, Smoke Concentration

Time (s)

0 200 400 600 800 1000 1200

Smoke Density (mg/m3

)

0

100

200

300

400

500

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Figure 7-50. Smoke Concentration, Tests 1-5 and 13. 
7-63

Test 14, Smoke Concentration

Time (s)

0 500 1000 1500 2000

Smoke Density (mg/m3

)

0

50

100

150

200

250

300

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Test 15, Smoke Concentration

Time (s)

0 500 1000 1500 2000

Smoke Density (mg/m3

)

0

50

100

150

200

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Test 16, Smoke Concentration

Time (s)

0 200 400 600 800 1000

Smoke Density (mg/m3

)

0

100

200

300

400

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Test 17, Smoke Concentration

Time (s)

0 100 200 300 400 500 600

Smoke Density (mg/m3

)

0

500

1000

1500

2000

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Note: This test conducted with

toluene, rather than heptane.

Test 18, Smoke Concentration

Time (s)

0 500 1000 1500 2000

Smoke Density (mg/m3

)

0

50

100

150

200

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Figure 7-51. Smoke Concentration, Tests 14-18. 
7-64

Test 3, CO2 Concentration

Time

0 500 1000 1500 2000

Volume Fraction

0.00

0.01

0.02

0.03

0.04

Exp Time vs 335 CO2-4raw 

FDS Time vs CO2 4 

Test 3, Smoke Concentration

Time (s)

0 500 1000 1500 2000

Smoke Density (mg/m3

)

0

50

100

150

200

Exp Time vs 354 SM 

FDS Time vs Smoke Concentration 

Figure 7-52. Tracking the carbon in Test 3. 

The other notable difference between measured and predicted smoke concentration was the 

increase in predicted concentration after the closed door test fires were extinguished. In the 

model, the smoke concentration is the product of the mixture fraction × soot yield × gas density. As no doors were opened after the fires were extinguished, the mixture fraction at any 

given location did not change appreciably, but the density increased as the temperature decreased. Thus the predicted smoke concentration increased as the smoke layer shrank in 

volume. This effect was not observed in the measured smoke concentration histories. 

7.2.6 Compartment Pressure 

The pressure within the compartment was measured at a single point. Comparisons between measurement and prediction are shown in Figure 7-53 and Figure 7-54. For those 

tests in which the door to the compartment was open, the over-pressures were only a few 

Pascals, whereas when the door was closed, the over-pressures were several hundred Pascals. 

In general, the predicted pressures were of comparable magnitude to the measured pressures, and in most cases differences could be explained using the reported uncertainties in 

the leakage area and the fact that the leakage area changed from test to test because of the 

thermal stress put on the compartment walls. The two notable exceptions were Tests 4 and 

16. These were the only two experiments performed with the door closed and ventilation on. 

The measured mass flow through the exhaust duct exceeded the mass flow through the 

supply duct by roughly 40 %. The FDS simulations were performed with a fixed and equal 
7-65

volume (not mass) flow rate at the supply and exhaust ducts, which is why the FDS simulations over-predicted the peak compartment pressures in Tests 4 and 16. 
7-66

Test 1, Compartment Pressure

Time (s)

0 500 1000 1500 2000

Pressure (Pa)

-80

-60

-40

-20

0

20

40

60

80

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Test 2, Compartment Pressure

Time (s)

0 200 400 600 800 1000

Pressure (Pa)

-400

-200

0

200

400

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Test 3, Compartment Pressure

Time (s)

0 500 1000 1500 2000

Pressure (Pa)

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Test 4, Compartment Pressure

Time (s)

0 200 400 600 800 1000 1200

Pressure (Pa)

-200

-100

0

100

200

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Ventilation Effect

Test 5, Compartment Pressure

Time (s)

0 500 1000 1500 2000

Pressure (Pa)

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Test 13, Compartment Pressure

Time (s)

0 200 400 600 800 1000 1200

Pressure (Pa)

-400

-200

0

200

400

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Figure 7-53. Compartment pressure, Tests 1-5 and 13. 
7-67

Test 14, Compartment Pressure

Time (s)

0 500 1000 1500 2000

Pressure (Pa)

-3

-2

-1

0

1

2

3

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Test 15, Compartment Pressure

Time (s)

0 500 1000 1500 2000

Pressure (Pa)

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Test 16, Compartment Pressure

Time (s)

0 200 400 600 800 1000

Pressure (Pa)

-200

0

200

400

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Ventilation Effect

Test 17, Compartment Pressure

Time (s)

0 100 200 300 400 500 600

Pressure (Pa)

-300

-200

-100

0

100

200

300

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Test 18, Compartment Pressure

Time (s)

0 500 1000 1500 2000

Pressure (Pa)

-2

-1

0

1

2

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Figure 7-54. Compartment pressure, Tests 14-18. 
7-68

7.2.7 Velocity 

Three vertical arrays of velocity (bi-directional) probes were placed in the 2 m × 2 m doorway. Comparisons of experimental measurement and model prediction for the open-door 

tests (3, 5, 14, 15 and 18) are shown in Figure 7-56. The data shown was taken from the 

array that was located nominally 50 cm south of the north edge of the doorway. Probe 15 

(black) was located 20 cm below the top of the doorway. Probe 13 (red) was 1 m below, and 

Probe 11 (green) was 20 m above the floor. The results from the other two arrays of probes 

were similar to this one and are not included. 

The comparison of inlet and outlet velocities reveals that the model is over-predicting the 

velocity near the top of the doorway. This is most likely a grid resolution effect. Near the top 

of the doorway, the jet of hot gases exiting the compartment could not be resolved adequately with a 10 cm grid (see Figure 7-55). This is not to say that the model inaccurately 

predicted the integrated mass or volume flux, but rather that it had difficulty predicting accurately the velocity at any given point in the doorway. Overall mass conservation was validated by the compartment pressure comparisons for open-door Tests 3, 5, 14, 15, and 18. 

Also, the integrations associated with the global energy budget discussed below are a further check that the model is handling well the bulk transport of mass through the doorway. 

Figure 7-55. Flow vectors near the compartment doorway. 
7-69

Test 3, Door Velocities

Time (s)

0 500 1000 1500 2000

Velocity (m/s)

-2

-1

0

1

2

Exp Time vs 320 PD15 

Exp Time vs 318 PD13 

Exp Time vs 316 PD11 

FDS Time vs BP Door 15 

FDS Time vs BP Door 13 

FDS Time vs BP Door 11 

Test 5, Door Velocities

Time (s)

0 500 1000 1500 2000

Velocity (m/s)

-2

-1

0

1

2

Exp Time vs 320 PD15 

Exp Time vs 318 PD13 

Exp Time vs 316 PD11 

FDS Time vs BP Door 15 

FDS Time vs BP Door 13 

FDS Time vs BP Door 11 

Test 14, Door Velocities

Time (s)

0 500 1000 1500 2000

Velocity (m/s)

-2

-1

0

1

2

Exp Time vs 320 PD15 

Exp Time vs 318 PD13 

Exp Time vs 316 PD11 

FDS Time vs BP Door 15 

FDS Time vs BP Door 13 

FDS Time vs BP Door 11 

Test 15, Door Velocities

Time (s)

0 500 1000 1500 2000

Velocity (m/s)

-2

-1

0

1

2

Exp Time vs 320 PD15 

Exp Time vs 318 PD13 

Exp Time vs 316 PD11 

FDS Time vs BP Door 15 

FDS Time vs BP Door 13 

FDS Time vs BP Door 11 

Test 18, Door Velocities

Time (s)

0 500 1000 1500 2000

Velocity (m/s)

-2

-1

0

1

2

Exp Time vs 320 PD15 

Exp Time vs 318 PD13 

Exp Time vs 316 PD11 

FDS Time vs BP Door 15 

FDS Time vs BP Door 13 

FDS Time vs BP Door 11 

Figure 7-56. Door Velocities, Open Door Tests 3, 5, 14, 15, and 18. 
7-70

7.2.8 Energy Budget 

There were enough temperature, heat flux and velocity measurements made in Benchmark 

Exercise 3 so that it was possible to account for all of the energy released by the fire, both in 

the experiment and in the simulation. As an example, consider the plot of the total energy 

budget shown in Figure 7-57. As the thermal environment of the compartment moves towards a steady state, the heat release rate of the fire should be balanced with the heat conducted to the walls and the heat flowing out the door. This is depicted graphically in the figure. The Total Loss (green), consisting of the rate of heat lost the walls (black) plus the rate 

of heat flowing out the door (red), should equal the heat release rate of the fire (pink). It is 

not perfect in either experiment or simulation because the compartment did not achieve 

steady-state, but it is close enough to confirm that the model conserves energy, and that the 

measurements are reasonably accurate and do account for the bulk of the heat transfer 

within the compartment. 

Test 3, Energy Budget

Time (s)

0 500 1000 1500 2000

Energy Loss/Gain (kW)

0

200

400

600

800

1000

1200

1400

1600

Exp Wall Loss

Exp Door Loss

Exp Total Loss

Exp HRR

FDS Wall Loss

FDS Door Loss

FDS Total Loss

FDS HRR

Figure 7-57. Energy budget for Test 3. 
7-71

7.3 FDS Sensitivity Analysis 

There are two types of input parameters for any fire model: numerical and physical. Physical 

parameters describe the wall materials, fuel properties, reaction stoichiometry, etc. Numerical parameters control the mathematical solution of the governing equations, the most important of which is the size of the numerical grid. The most important physical parameter in 

Benchmark Exercise 3 was the prescribed heat release rate, and there was discussion 

above about its impact on all of the results. Included below is some discussion on the sensitivity of the simulations to the wall material properties. 

7.3.1 Grid Sensitivity 

The most important numerical parameter is the grid cell size. CFD models solve an approximate form of the conservation equations of mass, momentum and energy on a numerical 

grid. The error associated with the discretization of the partial derivatives is a function of the 

size of the grid cells and the type of differencing used. FDS uses second-order accurate approximations of both the temporal and spatial derivatives of the Navier-Stokes equations, 

meaning that the discretization error is proportional to the square of the cell size. In other 

words reducing the grid cell size by a factor of 2 reduces the discretization error by a factor 

of 4. However, it also increases the computing time by a factor of 16 (a factor of 2 for the 

temporal and each spatial dimension). Clearly, there is a point of diminishing returns as one 

refines the numerical mesh. Determining what size grid cell to use in any given calculation is 

known as a grid sensitivity study. 

A modest grid sensitivity study was performed for this exercise. Shown in Figure 7-58 are 

some results for Test 3 computed on the nominally 10 cm “fine” grid and a 20 cm “coarse” 

grid. (All of the results shown above were computed on a 10 cm grid.) The coarse simulation 

of Test 3 required a few hours to complete on a single 2.4 GHz Pentium processor, whereas 

the fine required a few days. A quick glance at the sample results shows relatively little difference in the accuracy. This is not surprising because the basic conservation equations still 

ensure a reasonably good distribution of the energy from the fire on the coarse grid, and 

there are no steep gradients in the selected quantities that would have been more sensitive 

to the grid size. 

So why bother with a multi-day calculation? Consider what is not shown in Figure 7-58. The 

cable trays and other targets, which were difficult to resolve even on the fine grid, were sim-
7-72

ply too small to even include on the coarse grid. The door and vent were less accurately 

prescribed on the coarse grid, leading to greater error in the computation of the compartment 

pressure. Still worse, had the fire scenario required a prediction of the heat release rate, or 

flame spread along the cable trays, even the fine grid would not have been enough to handle 

it, never mind the coarse. 

So the lesson to be learned is that coarse grid CFD, much like zone model calculations, can 

provide reasonable predictions of certain quantities, especially those that can be traced directly to conservation equations of mass and energy, like average temperatures and pressures. However, the user has to be aware that the results are generally less reliable than 

those obtained from a finer grid, and that certain results cannot be obtained at all. 

7.3.2 Sensitivity to Wall Material Properties 

The compartment walls and ceiling were made of 2.54 cm thick Marinite I, a product of BNZ 

Materials, Inc. The manufacturer provided the thermal properties of the material used in the 

calculation: density 737 kg/m3

, conductivity 0.12 W/m/K, specific heat 1.17 kJ/kg/K at 93 °C 

ramping linearly to 1.42 kJ/kg/K at 425 °C. A testing laboratory also provided thermal properties, based on a sample provided by NIST: density 669 kg/m3

, conductivity 0.11 W/m/K at 23 

°C ramping linearly to 0.20 at 650 °C, specific heat 0.78 kJ/kg/K at 23 °C ramping to 1.22 

kJ/kg/K at 650 °C. The manufacturer’s property data was used in the FDS calculations 

merely because simulations similar to BE #3 had been performed at NIST as part of its investigation of the World Trade Center disaster, and these input files were modified for use in 

BE #3. To check the sensitivity of the simulations to the variations in the wall properties, a 

simulation was performed using the Marinite properties that were measured by the testing 

laboratory (and subsequently recommended for use by the participants of the benchmark 

exercise). 

Figure 7-59 presents the predicted ceiling temperatures using the two sets of material properties for the Marinite. There was a slight increase in temperature with the material properties from the testing lab, roughly a few percent, most likely due to the lower density and specific heat. This difference is well within the uncertainty related to the measured HRR that was 

discussed above. 
7-73

Test 3, Tree 7 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 3 (Coarse Grid), Tree 7 Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Test 3, East Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 159 TE1-1 

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Test 3 (Coarse Grid), East Wall Temperatures

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

20

40

60

80

100

120

140

160

180

200

Exp Time vs 159 TE1-1 

Exp Time vs 161 TE2-1 

FDS Time vs TC East U-1 

FDS Time vs TC East U-2 

Test 3, Oxygen Concentration

Time (s)

0 500 1000 1500 2000

Volume Fraction

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 3 (Coarse Grid), Oxygen Concentration

Time (s)

0 500 1000 1500 2000

Volume Fraction

0.12

0.14

0.16

0.18

0.20

0.22

Exp Time vs 331 O2-1 

Exp Time vs 332 O2-2 

FDS Time vs O2 1 

FDS Time vs O2 2 

Test 3, Compartment Pressure

Time (s)

0 500 1000 1500 2000

Pressure (Pa)

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Test 3 (Coarse Grid), Compartment Pressure

Time (s)

0 500 1000 1500 2000

Pressure (Pa)

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

Exp Time vs 351 CompP 

FDS Time vs Pressure 

Figure 7-58. Comparison of fine (left) and coarse (right) results for Test 3. 
7-74

Ceiling Temps; Manufacturer's Marinite Props

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Exp Time vs 191 TC1-1 

Exp Time vs 195 TC3-1 

Exp Time vs 197 TC4-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-3 

FDS Time vs TC Ceiling C-4 

Ceiling Temps; Measured Marinite Props

Time (s)

0 500 1000 1500 2000

Temperature (C)

0

50

100

150

200

250

300

350

Exp Time vs 191 TC1-1 

Exp Time vs 195 TC3-1 

Exp Time vs 197 TC4-1 

FDS Time vs TC Ceiling U-1 

FDS Time vs TC Ceiling C-3 

FDS Time vs TC Ceiling C-4 

Figure 7-59. Test 3 results for two sets of wall material properties. 

7.3.3 Radiation Parameters 

Finally, because the final simulations were run using 200 radiation angles instead of the default 100, the coarse grid simulation of Test 3 was repeated with the default settings. There 

was no noticeable change in the results, confirming in this case that the default number of 

angles would have been adequate. However, this does not mean that the default settings 

are always appropriate. Sensitivity studies like the one performed here ought to be used to 

determine if and when to change the default settings. 

Test 3, Floor Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

12 Exp Time vs 48 F1 

Exp Time vs 49 F2 

Exp Time vs 51 F4 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

FDS Time vs Floor U-4 

Test 3, Floor Heat Flux

Time (s)

0 500 1000 1500 2000

Heat Flux (kW/m2

)

0

2

4

6

8

10

12 Exp Time vs 48 F1 

Exp Time vs 49 F2 

Exp Time vs 51 F4 

FDS Time vs Floor U-1 

FDS Time vs Floor U-2 

FDS Time vs Floor U-4 

Figure 7-60. Test 3 results using 200 radiation angles (left) and 100 (right). 
7-75

7.4 Conclusions and Recommendations for FDS 

Simulations of Benchmark Exercise 3 were performed with the NIST Fire Dynamics Simulator (FDS). Because the heat release rate of the fire was given to the participants as an input 

parameter, the focus of the exercise was to predict the transport of heat and combustion 

products through a fairly large enclosure. For most deterministic fire models, including FDS, 

smoke and heat transport is the primary objective. 

The predicted gas temperatures were within 10 % of the reported measurements, with some 

exceptions due to the effect of forced ventilation and near-field inaccuracies of the model. In 

the tests with forced ventilation, a combination of the uncertainty in the measured velocity 

profile and the coarseness of the FDS grid near the vent probably were responsible for the 

discrepancies. As for near-field effects, the exact prescription of the fire’s “footprint” in the 

pan had a significant effect on the lower thermocouples of an array 10 cm away from the 

pan. 

The predicted wall, ceiling and floor temperatures were also within about 10 % of the measurements, with the larger deviations occurring at points closer to the fire, especially on the 

ceiling. The over or under-prediction of the wall temperature at a given point could not always be explained by a comparable error in the heat flux prediction. This was probably due 

to the fact that the wall temperature measurement was made with a single thermocouple, 

whereas the heat flux measurement required additional interpretation in its conversion from 

net to total. 

The accuracy of the predicted cable surface temperatures varied between 10 and 20 % depending on their location relative to the fire and the accuracy of the corresponding gas temperature and heat flux. However, as with the wall temperature predictions, it was not always 

possible to explain discrepancies solely in terms of the over or under-prediction of the local 

gas temperature and heat flux because of the effect of multiple off-setting or compounding 

errors. 

The simplified description of the cable trays was a weakness in the FDS model. There were 

no physical algorithms in the model to describe the detailed heat transfer within the bundled 

cables, nor the lateral heat transfer along the metal conductors. Nevertheless, the model did 

predict accurately the thermal environment surrounding the cables, and to a reasonable degree of accuracy it predicted the surface temperature of the cables themselves. In some 

cases, the measured temperature inside the cable was nearly the same as the surface tem-
7-76

perature, an effect captured by the model for the improvised “slab” Target E. However, more 

complicated heat transfer within the cables would not have been accounted for by the model, 

and any predictions of respectable accuracy would have simply been fortuitous. 

Predictions of oxygen and carbon dioxide were within about 10 % of the measurements in 

most cases. This level of accuracy is consistent with that of the transport of the heat from the 

fire, as both mass and energy are transported in the model with the same basis algorithm. 

The predicted smoke concentration was typically about 50 % higher than the measured 

value, most likely due to an error in the prescribed soot yield in combination with measurement error. There is no reason why the smoke and carbon dioxide predictions should not 

have been of comparable accuracy given that their prescribed yields and their respective 

measurement techniques were of comparable accuracy. 

The predictions of compartment pressure were within experimental uncertainty except in two 

tests where the door was closed but the ventilation system was turned on. In these cases, 

the model used prescribed volumetric flow rates and could not account for the variations in 

mass flow rate as a result of changing compartment temperature. A change in the model 

boundary conditions would have rectified this situation. 

If Benchmark Exercise 3 were a design fire scenario, FDS, or any CFD model, would have 

been sufficiently accurate. Indeed, it was shown that a calculation performed on a grid 

whose cells were twice as large as those used in the study produced results of comparable 

accuracy, at least for the bulk temperatures and heat fluxes. However, if the exercise were 

part of a forensic reconstruction of a fire that erupted from an accidental fuel spill and then 

ignited power cables within steel trays, FDS would not have been accurate enough to produce a blind prediction of the heat release rate, heat flux to the cables, and fire spread along 

the trays. It could have produced a qualitative description of the events, but with nothing 

near the accuracy shown above. 

There is no reason why a more detailed sub-model of the cables could not be included in 

FDS since the gas and solid phase need only exchange mass and energy. However, the fact 

that the predicted heat flux to the cable surface was at times only 20 % accurate calls into 

question the added value of a more detailed heat transfer algorithm for the cables. It is not 

clear whether the extra work in model development, and the added complexity of model use 

and code maintenance, would benefit the larger community of users. 
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The most valuable measurements were those that combined multiple measurements at a 

given location/target. This allowed for a better assessment of the model’s performance. Often in predicting a target’s temperature, a model can over-predict the gas temperature and 

under-predict the heat flux, or vice verse, resulting in a deceptively accurate prediction. It is 

best to make sure that each accurate prediction of a target temperature is “traceable”, that 

is, that it can be shown that the thermal properties, local gas temperature, and heat flux are 

all accurate as well. 

7.5 References 

Hamins, A., A. Maranghides and G. Mulholland. 2003. The Global Combustion Behavior of 1 

MW to 3 MW Hydrocarbon Spray Fires Burning in an Open Environment. NISTIR 

7013. National Institute of Standards and Technology, Gaithersburg, Maryland, 

USA. 

McGrattan, K., J. Floyd, G. Forney, H. Baum and S. Hostikka. 2003. Improved Radiation and 

Combustion Routines for a Large Eddy Simulation Fire Model. Fire Safety Science -- Proceedings of the Seventh International Symposium. International Association for Fire Safety Science. 

McGrattan, K. (ed.) 2004. Fire Dynamics Simulator (Version 4) Technical Reference Guide. 

NIST Special Publication 1018. National Institute of Standards and Technology, 

Gaithersburg, Maryland, USA. 

McGrattan, K. and G. Forney. 2004. Fire Dynamics Simulator (Version 4) User’s Guide. 

NIST Special Publication 1019. National Institute of Standards and Technology, 

Gaithersburg, Maryland, USA. 

Quintiere, J.G. 1998. Principles of Fire Behavior. Delmar Publishers, Washington, DC, USA. 

Walton, W.D. and P.H. Thomas. 2003. Estimating Temperatures in Compartment Fires. Fire 

Protection Handbook, 3rd Ed. National Fire Protection Association, Quincy MA. 

Welsh, S. and P. Rubini. 1997. Three-Dimensional Simulation of a Fire-Resistance Furnace. 

Fire Safety Science – Proceedings of the Fifth International Symposium. International Association for Fire Safety Science. 
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8 Summary of Conclusions from Individual Contributions 

This final chapter summarizes the conclusions of the individual modelers who participated in 

the Benchmark Exercise. Note that it is difficult to summarize in a simple way the accuracy 

of the models, as each participant chose different quantities to analyze, some performed 

calculations before the test data was released, some after. All of the participants agreed that 

the approximate forms of the conservation equations for mass, momentum and energy in the 

various fire models evaluated provide a “reasonable” prediction of the hot gas layer temperature, depth and product concentration. Other issues are discussed individually below. 

8.1 Modeling the Fire 

In this exercise, the flow rate of fuel into a pan was specified as an input parameter, and a 

fixed heat of combustion was assumed. This is not unusual in fire model validation exercises, especially when the intent is not to predict the heat release rate, but rather the transport of hot gases throughout the compartment. However, the size and shape of the fire has 

an impact on the predicted radiative flux from the fire plume. A variety of techniques were 

used to model the fire, ranging from a point source in the zone models to simple combustion 

models in the field (CFD) models. Several participants did sensitivity studies to assess the 

effect of various modeling inputs: the radiative fraction, area of the fire “footprint” in the pan, 

point source vs surface radiation assumptions. 

8.2 Fire Extinction 

The fires in two of the fifteen tests (Test 13 and 16) self-extinguished due to lack of oxygen. 

The oxygen concentration measured near the fire close to the floor of the compartment was 

about 15 % at the time of extinction, consistent with the lower oxygen limit (LOL) that is often 

included in the various fire models as an indicator of a fire’s viability in an under-ventilated 

environment. Although the LOL concept is fairly crude and glosses over the complexity of 

the combustion processes that occur in these types of fires, it was sufficient in these two 

cases to predict extinction. In other words, an accurate prediction of the fire’s extinction in 

Tests 13 and 16 is based on the appropriate LOL assumption and an accurate calculation of 

oxygen transport. 
8-2

8.3 Heat Flux 

The heat flux to walls and targets is predicted by the different models using a variety of 

methods. The zone models typically use a point source model, in which the radiative energy 

from the fire is assumed to emanate from a single point, in combination with the summation 

of radiative contributions from the hot walls and hot gas layer. This method works so long as 

the radiative fraction of the fire is chosen appropriately and the temperature of the hot gas 

layer predicted accurately. It is important to note that the radiation heat flux from the hot gas 

layer is a function of the (absolute) temperature raised to the fourth power. Thus, the uncertainty in the heat flux prediction is expected to be larger (by roughly a factor of 2) than the 

uncertainty in the hot gas layer temperature. 

Field models typically do not rely on point source radiation models, but rather compute solutions to the radiative transport equation. While this is potentially more accurate than the point 

source method, it is important to define the emission and absorption of the fire and the hot, 

smoke-laden gases. 

8.4 Target Model 

A detailed heat transfer model for cables bundled in a tray is fairly complex. The fire models 

used in this benchmark exercise did not have the capability of modeling such complex cable 

configurations. Most of the codes used for the benchmark exercise had a one-dimensional 

slab model for targets. Some had simple models, such as a plate-type model with a conductor blanketed with insulation, a cylindrical model composed of two insulating materials, or the 

cable tray was modeled as a homogenous slab of cable insulation. For models in which the 

target is represented as a rectangular slab, the orientation of the slab is an issue. 

8.5 Carbon Monoxide and Soot 

The fire models that were exercised in the benchmark exercise do not have the capability to 

model the production of soot or carbon monoxide in the combustion process. The models 

use a constant yield input to the codes for these combustion products. The yields of carbon 

monoxide and soot, products of incomplete combustion, vary depending on the extent of 

under ventilation of the fire, and the size of the fire. This limitation was evident in the comparison of predictions with experimental data for the under-ventilated tests. 
8-3

8.6 Mechanical Ventilation 

Most models used did not include the coupling of the fire compartment with the mechanical 

ventilation system. This limitation led to discrepancies in the predictions of supply and exhaust flow rates. The accurate prediction of the direction of supply flow was another issue. 

The prediction of the mixing of the supply air with gases in the compartment for underventilated environments determines the oxygen levels in the compartment. Generally larger 

discrepancies were noted for predictions of oxygen concentrations for under ventilated environments with forced ventilation, even with CFD codes. Most models predicted less oxygen 

depletion than measured. 

8.7 Compartment Pressure 

The computation of compartment over pressure for closed door cases is highly dependent 

on the assumed leakage, as discussed in Chapter 4. The accuracy of the predictions of the 

over pressure varied, with several codes over-predicting the pressure increase. The computation of the over pressure had an impact on the convergence of solutions in some CFD 

codes, especially when the leakage was assumed to be from a hypothetical orifice. 
 A - 8-4