EXPERIMENTAL AND MODELING INVESTIGATION OF THE EFFECT OF 

VENTILATION ON SMOKE ROLLBACK IN A MINE ENTRY

John C. Edwards, Robert A. Franks, Gene F. Friel, and Liming Yuan 

National Institute for Occupational Safety and Health 

Pittsburgh Research Laboratory, Pittsburgh, PA 

Abstract 

 Diesel fuel fire experiments were conducted in 

NIOSH’s Pittsburgh Research Laboratory’s (PRL) Safety 

Research Coal Mine (SRCM) to determine the critical air 

velocity for preventing smoke rollback. Such information 

is necessary for the preplanning and implementation of 

ventilation changes during mine fire fighting and rescue 

operations. The fire intensity varied from 50 kW to 300 

kW depending upon the fuel tray area. Airflow in the 2 m 

high and 2.9 m wide coal mine entry was regulated during 

the course of each experiment; measured upwind from the 

fire as an average over the entry cross-section with an 

ultrasonic airflow sensor; and recorded dynamically with 

a mine monitoring system. The extent of smoke reversal 

was monitored with light obscuration monitors, ionization 

smoke sensors, and visual observations. Experimental 

results for the critical air velocity for smoke reversal as a 

function of fire intensity compared very well with model 

predictions based upon a computational fluid dynamics 

(CFD) fire dynamics simulator. 

Introduction 

 An underground mine fire can have devastating 

consequences for miners and the mine if not controlled in 

its incipient stage. Inhalation of the fire-generated toxic 

products-of-combustion (POC) can be injurious or fatal 

for miners, and the heat released can induce roof and rib 

collapses. Initially the thermal buoyancy forces generated 

by the fire will produce an ascending plume of fire POC. 

With sufficient ventilation, the POC will initially be 

transported downwind from the fire. Once the fire has 

evolved to sufficient intensity, the buoyancy forces will 

overcome the inertial forces of the ventilation, and the 

POC will migrate upwind along the roof counter to the 

positive ventilation. As noted by Mitchell [1], smoke 

from mine fires always rolls back in sufficiently low 

airflows, and can contain combustible gases, which are 

subject to ignition by the mine fire when diluted by air. 

This poses a risk for the firefighters. The extent of smoke 

rollback along the roof into the fresh air will be determined 

by the ventilation velocity, airway dimensions, airway 

slope, and fire intensity. Moderately small quantities of 

fuel can generate significant heat and smoke. A diesel 

fuel spill covering a 0.93 m diameter circular area would 

generate a 1 MW fire. Similarly, a conical pile of broken 

coal with a 4.57 m diameter at the base, and a height of 

1.83 m would generate a 1.5 MW fire. A wood crib 2.4 m 

high consisting of 1.22 m long timbers 0.15 m square can 

generate a 3.5 MW fire. The smoke layer above the fire 

will simultaneously thicken as the rollback occurs. Not 

only can the smoke prevent direct access to the fire, it can 

leak through stoppings into adjacent airways and thereby 

further endanger the miners. One extreme consequence 

of further increase in the fire intensity is that a sufficiently 

large heat production rate can produce flow reversal in an 

intake airway if the airway connects with parallel intake 

airways. The parallel airways could carry the balance of 

the airflow to maintain substantially the pre-fire mine 

pressure drop. 

 The use of ventilation to control the movement and 

dilution of smoke associated with an underground mine 

fire is recommended, but not quantified. Ventilation 

control, for example, is a recommended method [2] for 

the control of toxic products from shop areas in metal and 

nonmetal mines. However, a quantified ventilation 

strategy is not generally available for implementation. 

The primary reaction is egression from the mine fire 

region. Even under the best of circumstances the miners 

are often required to egress through a toxic low-visibility 

mine atmosphere produced by the mine fire. Similarly, 

any attempt to approach the fire from the intake side for 

its control and suppression will be thwarted by low 

visibility smoke conditions, and the toxic fire products, 

principally carbon monoxide (CO), associated with smoke 

backlayering. In the absence of remote real-time 

ventilation and POC monitoring, the selection of a 

ventilation change is not without unknown risks. To meet 
 

the objective of establishing a safe procedure for 

ventilation induced smoke control, an experimental and a 

computational modeling approach was undertaken to 

determine the critical ventilation velocity required to 

prevent smoke reversal from fires of specific heat 

intensities. This information will be useful for 

preplanning and implementation of ventilation changes 

under emergency conditions. Experimental studies on 

smoke backlayering from a tunnel fire and determination 

of the critical velocity to prevent smoke backlayering 

have been conducted for a large tunnel [3] with a 

hydraulic diameter of 7.75 m, and small tunnels with 

hydraulic diameters between 0.18 m and 0.40 m [4]. 

Experiments in mine size tunnels with hydraulic diameter 

of 2.38 m were conducted at Buxton [4] with fire 

intensities greater than 200 kW. None of these cases were 

conducted in a mine entry, which with its rough walls 

introduces additional turbulence. This research considers 

fire intensities less than 300 kW in a coal mine entry for 

an evaluation of the critical velocity to prevent smoke 

reversal. The practical experimental limitations placed 

upon the conduct of experiments for large fire intensities 

necessitates the use of a predictive computational method 

to extrapolate limited experimental results to a range of 

fire intensities and mine entry dimensions not practically 

achievable experimentally. Modeling approaches can be 

semi-empirical analytic models, or field models which 

depend upon a numerical evaluation of the Navier-Stokes 

equations with a computational fluid dynamics (CFD) 

program. A one dimensional analytic model was 

developed by Kennedy [5] to investigate the critical 

ventilation velocity required to prevent smoke reversal. 

The model depends upon an estimate of the Froude 

number to prevent smoke reversal. Mitchell [1, p. A-2] 

has proposed a simple relationship for estimating the 

critical velocity for smoke rollback in relation to the entry 

height, but independent of fire intensity. Wu and Bakar 

[4] have used a field model to determine the dependence 

of the critical velocity upon fire intensity for laboratory 

scale tunnel fires. A CFD approach will also predict the 

length of the smoke backlayer for subcritical air 

velocities. The length of stationary smoke backlayer as a 

function of fire intensity and ventilation velocity has been 

modeled by Hwang and Edwards [6] with a CFD 

computer program. 

Experimental Procedure 

 The entry selected for the smoke reversal 

experiments was 126 m long, and had an average height 

of 2.06 m and width of 2.91 m, and was formed from a 

right angle bend with the intake portal. Figure 1 shows a 

plan view of the fire location and the doors used for 

regulating the airflow. The fire was located 40 m 

downwind from the bend. At this distance the ratio of 

the airway length to hydraulic diameter was 17, which 

assures the turbulent flow velocity was uniform. Fivepoint vane anemometer measurements made over the 

entry cross-section at the fire zone indicated this to be the 

case. The slope of the airway upwind and downwind 

from the fire was less than 0.2 o, and was thereby 

inconsequential for smoke movement along the roof. The 

fire source on the entry floor consisted of a pan containing 

diesel fuel. To control the heat release rate, the fire pan 

surface areas ranged from 0.09 m2

 to 0.49 m2 for the 

experiments. Monitoring of the smoke reversal was 

accomplished with two sensor stations located 3.05 m and 

9.14 m upwind from the fire source, as well as markers 

spaced every 1.52 m upwind from the fire along the rib 

for visual observation. At each sensor station a light 

obscuration monitor was suspended approximately 0.5 m 

from the roof, above which was positioned an ionization 

smoke sensor. Approximately 4.6 m upwind from the fire 

source, near the roof and rib, was a transmitter-receiver of 

the ultrasonic air- flow measurement sensor. The other 

transmitter-receiver was located 8.28 m upwind on the 

entry’s opposite rib near the floor. The acoustic airflow 

and smoke indication sensor outputs were sampled every 

two seconds by the mine monitoring system. 

Figure 1. Plan view of mine test section 

Measurements 

 The fire effective tray size is listed in table 1 for each 

experiment. For each experiment the tray was centered 

on the entry floor relative to the ribs with the longer side 

positioned transverse to the entry. In experiments C, E, 

and F two trays were positioned adjacent to each other to 

form the effective tray area. The fire intensities and fuel 

mass fluxes were calculated from visual observation of 

the duration of flaming combustion for known fuel 

quantities, and the physical and chemical properties of the 

diesel fuel. The diesel fuel’s mass density was 876 kg/m3

, 
 

and heat of combustion was 42.31 MJ/kg. Ignition was 

achieved by first pouring a small quantity (about 200 ml) 

of heptane on the diesel fuel. Prior to ignition, the airflow 

was measured with a vane anemometer at the fire tray. A 

five-point measurement was made at the airway center 

and corners. An average of these results was compared 

with the average acoustic measurement of the air velocity 

over the same time interval. For experiments A, B, and D 

the relative error was less than 1.2 %; for experiment C 

the relative error was 4.5%; for experiment E the relative 

error was 7.2%; and for experiment F the relative error 

was 3.6 %. 

Table 1. Fire pan size and interpolated fire 

intensity 

Exp Effective Tray 

Size, m Fuel, L 

Fire 

Intensity 

Q, kW 

Mass Flux,

kg/s/m2 

A 0.46 X 0.46 9.1 130 0.0147 

B 0.61 X 0.61 15.1 267 0.017 

C 1.07 X 0.46 20.8 304 0.0142 

D 0.39 X 0.23 3.8 53 0.0155 

E 0.79 X 0.23 7.6 102 0.0148 

F 0.46 X 0.39 7.6 128 0.0187 

 Figure 2 shows the responses of the light monitor 

(LIGHT) and smoke sensor (SMOKE) 3.05 m upwind 

from the 130 kW fire for experiment A, and the response 

of the ultrasonic flow measurement instrument. The 

LIGHT and SMOKE values are normalized by their prefire ambient values. Also shown are several visually 

observed positions of the smoke roll back marked by the 

curve labeled EVENT. The extent of the smoke rollback 

is noted above the EVENT curve in figures 2 and 3. The 

light monitor, as an optical device, has a faster response to 

the presence of smoke particulates and their clearing, than 

the diffusion mode smoke sensor. From 9:04 AM to 9:08 

AM the smoke was in the neighborhood of the sensors 3 

m upwind from the fire pan. Instability in the roll back of 

the buoyancy-generated smoke resulted in significant 

fluctuations in the light and smoke sensor responses. 

Over this time period the ratio of the average signal to the 

signal’s standard deviation was about 44 for the flow 

sensor, with reduced ratios of 11 for the light monitor and 

3 for the smoke sensor. This illustrates how, for even a 

relatively steady airflow, the fire’s fluctuating thermal 

effects will be amplified in the smoke movement. The 

ventilation velocity at the flow measurement device was 

0.54 m/s when the smoke backlayer extended 6.1 to 9.1 

m, 0.86 m/s when the backlayer extended 3.0 m, and 1.19 

m / s when the smoke was maintained at the fire pan. 

These velocities are converted to average velocities at the 

fire pan based upon the 5.27 m2

 entry cross-sectional area 

at the fire pan and 6.09 m2

 cross-sectional area at the flow 

monitor. The critical airflow at the fire pan for no smoke 

reversal is accordingly, 1.38 m/s. The restriction to 

human visibility posed by the smoke backlayer can be 

estimated from the output of the light obscuration 

monitor. At the reduced airflow of 0.63 m/s at the fire 

pan from 9:00 AM to 9:01:50 AM, which is a 54 % 

reduction in the ventilation velocity from its critical value, 

the average optical density of the smoke was 0.95 m-1

and 0.31 m-1 at the light monitors 3.05 m and 9.19 m 

upwind from the fire. These optical densities correspond 

to visibilities of 3.7 m and 11.3 m respectively based upon 

Jin’s [7] relationship between visibility measured relative 

to a light emitting sign and the optical density. For a light 

reflecting sign the associated visibilities are 1.4 m and 

4.2 m. Jin [7] also notes a minimum visibility of 3 m to 

5 m is required for fire-escaping personnel familiar with 

the surroundings, and a visibility of 15 m to 20 m is 

required for personnel unfamiliar with the surroundings. 

Reliance upon a cap lamp’s reflection from mine entry 

markings would be characteristic of reflection from a light 

reflecting sign. This shows the visibility limitation due to 

a relatively small 130 kW fire for someone familiar with 

the mine who, for mine escape, needs to rely upon a light 

from a cap lamp reflecting from mine entry markings. 

0

0.2

0.4

0.6

0.8

1

8:45 8:51 8:58 9:05 9:11 9:18

TIM E

LIGHT, SMOKE

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

AIR FLOW, M / S

LIGHT

EVENT

SMOKE

AIR FLOW

IGNITION

6.1 - 9.1 m 3.0 m F IR E P AN

Figure 2. Optical and smoke sensor dimensionless 

response at 3.05 m station, and airflow measurement 

for experiment A. 

 Figure 3 shows similar results for the 304 kW fire of 

experiment C. The constant values for the measured 

airflow from 9:10 AM to 9:14 AM and from 9:28 AM to 

9:34 AM are the result of very dense smoke which causes 

attenuation and refraction of the ultrasonic acoustic 

transmissions between the transmitter and receiver. For 

experiment C the ventilation velocity at the ultrasonic 

flow measurement device was 1.28 m / s when the smoke 

was stabilized at the fire pan. This corresponds to a 1.55 

m / s flow velocity at the fire pan. A stationary roof 

smoke backlayer of 3 m developed for a ventilation of 
 

0.97 m / s indicated by the flow measurement sensor, and 

a 4.3 m to 4.6 m backlayer developed for a ventilation of 

0.93 m/s. Table 2 lists the critical velocity, Vc, at the fire 

pan to prevent smoke rollback for the six experiments. 

For the six experiments with fire intensity range from 53 

kW to 304 kW, the ratio of the critical velocity to the 

velocity representative of a 3 m backlayer was 1.25, with 

a standard deviation of 0.10. It is instructive to represent 

the relationship between critical air velocity and fire 

intensity, Q, as dimensionless quantities. The 

dimensionless critical air velocity VC

* and heat release 

rate Q*

 are defined by the equations [4]: 

VC

*

 = VC / gH (1) 

Q*

 = Q / ( ρ 0 T0 Cp

5 gH ) (2) 

where ρ 0 and T0 are the inlet ambient air density and 

temperature, Cp is the air specific heat (1.005 kJ/kg/K), 

and g is the acceleration due to gravity, 9.8 m / s2

. The 

characteristic length H is the hydraulic diameter of the 

entry. It is defined as four times the ratio of the entry 

cross sectional area to entry perimeter. For experiments C 

- F a thermal insulating material was attached to the roof 

at the fire location to protect the mine monitoring system 

data transmission cables from thermal damage. This 

reduction in the entry height at the fire pan accounts for 

variations shown for the hydraulic diameter, H, in table 2. 

Although these dimensionless variables account for the 

entry height and width through the hydraulic diameter, 

they do not account for the fire shape. 

0

0.2

0.4

0.6

0.8

1

1.2

9:00 9:06 9:13 9:20 9:26 9:33 9:40

TIME

LIGHT, SMOKE

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

AIRFLOW, M / S

LIGHT

SMOKE

EVENT

AIRFLOW

IGNITION

FIRE 

PAN

3.0 m

1.5 - 2.1 m

4.3 - 4.6 m

Figure 3. Optical and smoke sensor response at 3.05 

m station, and air flow measurement for experiment 

C. 

Table 2. Mine fire critical velocity, and dimensionless 

critical velocity and fire intensity 

Exp Fire 

Intensity, kW 

VC, 

m/s H, m Q*

 VC

* 

A 130 1.38 2.27 0.016 0.29 

B 267 1.51 2.27 0.032 0.32 

C 304 1.55 2.21 0.038 0.33 

D 53 0.92 2.15 0.0070 0.20 

E 102 1.08 2.15 0.0135 0.23 

F 128 1.32 2.15 0.0171 0.29 

Figure 4 shows the dependence of the dimensionless 

critical velocity upon the dimensionless heat release rate. 

The literature [3,8] shows a dependence of VC upon Q to 

the one-third power. The trend line in figure 4 shows a 

power dependence equal to 0.30, which is in reasonable 

agreement with the theoretical 1/3 value. The R-Squared 

value, the square of the coefficient of correlation, was 

equal to 0.89. Shown for comparison are the 

dimensionless values reported for the experiments of Wu 

and Bakar [4], and the values they report for experiments 

conducted at Buxton over the comparable Q*

 range from 

0 to 0.04. The dimensionless critical velocities for the 

SRCM experiments are higher than the Buxton and WuBakar values. Both the SRCM and Buxton experiments 

used a tunnel with comparable hydraulic diameters. For 

the Buxton gallery experiments the hydraulic diameter 

was 2.38 m, and for the SRCM experiments, the hydraulic 

value was 2.15 m, with thermal insulation at the roof, and 

2.27 m without thermal insulation at the roof. A 

significant difference between the experiments was the 

arch-shaped roof of the Buxton tunnel, and the flat roof of 

the SRCM entry. Visual observations in the SRCM 

experiments indicated the visible flames did not fill the 

entry cross-section. The small tunnels used for the Wu 

and Bakar [4] experiments had hydraulic diameters 

between 0.25 m and 0.4 m. Wall roughness is a 

significant factor in the SRCM entry, whereas the other 

tunnels were smooth walled. The fire intensities 

associated with the kerosene fires in the Buxton gallery 

were between 0.3 and 20 MW, while those for the 

propane source fires in the Wu and Bakar experiments 

were between 1.4 and 28 kW. Another factor which 

contributes to the difference in the experiments is the 

geometry of the fire source. 
 

 Vc*= 0.92 Q* 0.3

0

0.1

0.2

0.3

0.4

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04

Q*

VC

*

SRCM BUXTON

WU-BAKAR (KENNEDY ET.AL. FR=4.5) MODEL

(KENNEDY ET.AL. FR=0.75) MODEL MITCHELL

CFD POWER (EXPERIMENTAL DATA)

Figure 4. Dimensionless critical velocity dependence 

upon dimensionless heat release rate 

 Associated with smoke reversal is the roof layer’s 

elevated temperature, which is characteristic of the 

smoke’s buoyancy. For experiment E, the 102 kW fire, 

when the smoke had stabilized 12.2 m upwind from the 

fire, the smoke temperature at the roof was 66 oC above 

the fire, and 59 and 54 oC respectively 1.52 m and 3.05 m 

upwind from the fire. For experiment F, the 128 kW fire, 

when the smoke had stabilized 7.62 m upwind from the 

fire, the smoke temperature near the roof was 80 oC above 

the fire, and 61 and 58 oC respectively 1.52 m and 3.05 m 

upwind from the fire. At a location 10.2 m downwind 

from the fire the air temperature near the roof was 41 oC. 

The ambient temperatures were 22 and 20oC for 

experiments E and F respectively. This corresponds to 

Thomas’s [8] observation that reverse flow is associated 

with hot smoke, and not cold smokeThis condition can be 

quantified by the Froude number. The Froude number Fr 

is defined as 

Fr = g h (1- T / Tf) / V2

 (3) 

where Tf is the hot gas layer temperature, T is the ambient 

temperature in degrees K, h is the tunnel height, g is the 

gravitational acceleration, and V is the ventilation 

velocity. Application of mass and energy conservation 

equations with the Froude numbers equal to 4.5 by 

Kennedy et.al. [5] leads to the predicted values shown in 

figure 4 for critical velocity. The selection of Froude 

number equal to 4.5 was based upon scale-model tests in 

ducts by Lee et. al. [9-10]. The SRCM fire tests results 

are more realistically modeled with Fr = 0.75, as shown in 

figure 4. 

 Mitchell [1, p.A-2] presents a rule-of-thumb for the 

critical velocity to prevent smoke rollback. Expressed in 

units of fpm, the critical velocity is equal to 100 h , 

where h is the entry height in units of ft. When converted 

to dimensionless units with the identification of the 

hydraulic diameter with the entry height, the expression is 

V*

 = 0.29. This value is independent of the heat release 

rate, and is shown as a constant value curve in figure 4. 

For Q*

 values less than 0.022, the Mitchell estimate 

provides adequate ventilation for the prevention of smoke 

rollback for the SRCM fires. For Q* values greater than 

0.022, the Mitchell result underestimates the required 

ventilation for the prevention of smoke rollback. A Q*

value equal to 0.022 corresponds to a 135 kW fire for an 

entry with a 2 m hydraulic diameter. 

Modeling 

 NIST [11] has developed a CFD model of fire-driven 

fluid flow. NIST’S Fire Dynamics Simulator (FDS) is a 

numerical simulator for low Mach number flows with 

special applications to heat and smoke transport. The 

program solves the Navier-Stokes equations numerically 

for fluid flow with a mixture fraction combustion model. 

A significant feature of the program is the large scale 

eddy simulation (LES) method for turbulence. FDS was 

applied to a simulation of the six fire experiments 

conducted in the SRCM at PRL. The dimensions for the 

fuel tray and entry average cross-section were entered in 

detail. A 50 m length of tunnel section was used in the 

simulation with the fire located 30 m downwind from the 

entrance. The critical velocity for the experiment is 

determined from the analysis of the airflow at the roof. 

When the airflow at the roof does not extend upwind from 

the leading edge of the fire source, the inlet flow is at the 

critical velocity. For these computations a twenty second 

time average over the last twenty seconds of a five minute 

time interval was used to define the stationary state. 

These values were determined to be close to two minute 

time interval computations. Figure 4 shows good 

agreement between the SRCM experimentally determined 

critical velocity and the CFD predictions with FDS. 

 Although the instability of the smoke reversal made it 

difficult to define with great certainty the extent of smoke 

reversal for different ventilation velocities, a reduction of 

the data with dimensionless variables makes the trend 

more apparent. For the smoke reversal length L achieved 

for different ventilation velocities Vin and heat release 

rates Q, a pair of dimensionless variables, X and Y, can 

be defined as 

X = /( ) 0

3 Q AVin ρ and (4) 
 

Y = 

( ) C T T0

gH

H

L

p f − (5) 

where Tf is the flame temperature in degrees K. Figure 5 

shows the parameters X and Y for the available 

experimental data. For this evaluation the flame 

temperature was set to 1,600 K. The correlation between 

X and Y satisfies the simple relationship Y=0.0238 ln (X) 

-0.0479 with a R-Squared value, the square of the 

coefficient of correlation, equal to 0.68. The constant 

coefficients will change inversely with the selected flame 

temperature. The clustering of the data for the six 

different fire intensities near X = 11, in the range 7.8 to 

14.1 for L=0, is representative of the approximate onethird power law dependence of the critical velocity upon 

the fire intensity noted above. 

Y = 0.0238 Ln(X) - 0.0479

0

0.02

0.04

0.06

0.08

0.1

0.12

1 10 100 1000

X

Y

EXPERIMENTAL DATA

Log. (EXPERIMENTAL DATA)

Figure 5. Dimensionless correlation of smoke reversal 

length with fire intensity 

Conclusions 

 It was demonstrated with fire smoke reversal 

experiments in the NIOSH SRCM that for a range of fire 

intensities between 50 and 300 kW in a mine entry 2 m 

high and 2.9 m wide that the critical velocity for 

preventing the development of a smoke layer upwind 

from the fire is proportional to the fire intensity to the 

0.30 power. This is in substantial agreement with other 

researchers who posit a one-third law dependence upon 

the fire intensity. The development of visibility 

obscuration 9 m upwind from a small 130 kW fire when 

the ventilation velocity was reduced by 54% from its 

critical value demonstrated the importance for 

maintaining the critical ventilation velocity for smoke 

control. For the fires considered, the results are in 

approximate agreement with an empirical result which is 

independent of fire intensity. CFD modeling of the 

dependence of the critical air velocity upon fire intensity 

showed good agreement with measured values. 

References 

1. Mitchell, DW (1996), “Mine Fires Prevention, 

Detection, Fighting,” (Intertec Publishing Inc, 

Chicago, IL), pp.19-20 

2. Code of Federal Regulations, 30CFR, Part 57.4761. 

Office of the Federal Register, National Archives and 

Standards Administration, U.S. Government Printing 

Office, Washington, D.C., July 1, 2002. 

3. Massachusetts Highway Department, (Boston, Mass), 

“Memorial Tunnel Fire Ventilation Test Program, 

Test Report”, 1995 

4. Wu Y and. Bakar, M.Z.A. (2000), “Control of Smoke 

Flow in Tunnel Fires Using Longitudinal Ventilation 

Systems—A Study of the Critical Velocity”, Fire 

Safety Journal, vol. 35, pp.363-390 

5. Kennedy, WD, Gonzales, JA, and Sanchez, JG, 

(1996), “Derivation and Application of the SES 

Critical Velocity Equations”, ASHRAE Transactions: 

Research, vol. 102, no.2, pp.40-44 

6. Hwang, CC and Edwards, JC, (2001),“CFD 

Modeling of Smoke Reversal “Proceedings of the 

International Conference on Engineering Fire 

Protection Design” (Society of Fire Protection 

Engineers, Bethesda, MD) pp.376-387 

7. Jin, T (1977), “Visibility through Fire Smoke”, J. of 

Fire & Flammability, vol.9, pp. 135-155. 

8. Thomas, PH (1970), “Movement of Smoke in 

Horizontal Corridors against an Airflow” Inst. Fire 

Engrs. Q. vol. 30, pp.45-53. 

9. Lee, CK, Chaiken, RF, and Singer, JM (1979), 

“Interaction between Duct Fires and Ventilation: An 

Experimental Study” Combustion Science and 

Technology vol. 20, pp.59-72 

10. Lee, CK, Hwang, CC, Singer, JM, and Chaiken, RF 

(1979), “Influence of Passageway Fires on 

Ventilation Flows” Second International Mine 

Ventilation Congress , Reno, NV 

11. McGrattan, KB, Forney, GP, Prasad, KFloyd, , JE, 

and Hostikka, S. (2002), “Fire Dynamics Simulator 

(Version3)-User’s Guide”, U.S. Dept. of Commerce, 

National Institute of Standards and Technology.