# Presentation: 674035

##                 ROUND ROBIN TEST III DATA ANALYSIS                             

**      **
**    **
**  **INTERNATIONAL AIRCRAFT MATERIALS FIRE TEST WORKING GROUP** **
**                     **
**                **ROUND ROBIN TEST III DATA ANALYSIS**                             **
**                                                                **
-                                                       **Khang D. Tran, Ph.D., **
**                                                                      ****Sr. Scientist                                                            ****                   **
**   ****                                    ****The Mexmil Company, Santa Ana, California, USA.****   **
**                                            ****    ****June 2001**
-                           The International Aircraft Materials Fire Test Working Group Meeting
-                       Sedgefield, Stockton-on-Tees, Cleveland, United Kingdom, 27-28 June 2001

## ACKNOWLEDGEMENTS

- • _The Mexmil Company_
- • _Mr. David Indyke_, Materials Technology Manager, Mexmil Co.
- • _Mr. Tim Marker_, Project Manager, The FAA.
- • _Mr. Johns Brook_, Director of Research, International Aero Inc.

##                                             INTRODUCTION 

**           **
**•  **_Purpose_: To analyze data obtained from the burn-through round
-    robin test III for aircraft thermal/acoustical insulation blanket.
**•  **_Date_ : 09/2000 - 02/2001**           **
**•  **_Participants_: 8 Labs (A, B, C, E, F, G, I, J)**      **
**   **
**•**  _Burning configuration_
-    Burner type: P (Park)
-    Igniter position: 10-12 o’clock (Lab B at 12:30, Lab C at 10).
-    Turbulator-Nozzle distance: 3.75 in. (Lab C at 3.94)
-    Calorimeter manufacturer: V (Labs A and G: M)
-    Thermocouple manufacturer: (Labs A, G, I, J: X; Labs B, C, E, F: T)
-    Air Velocity Meter: O (Lab C: X)
-    Fuel: Jet A
- •  _Samples_: Fabricated by The Mexmil Company.
- _ _

## ROUND ROBIN III MATERIALS

-    ** ****Notes**

**th< 0.5 in**

**Blanket         Blanket                   Thickness         Blanket       Barrier    Estimated        Approx.        Approx. **
**     ****ID          Construction              per Layer         Density      Material   Failure           Fiberglass       Barrier**
**                                                          ****(inch)             (lb/ft****3****)                          Mode and       Required      Required**
**                                                                                                                           ****Time               (yds****2****)            (yds****2****) **
-      **A**         **2 Layer Fiberglass            1.0                   0.6              N/A      Burnthrough       214                  0 **
**                                                                                                                       ****(30-40 sec)**
-      **B **        **2 Layer Fiberglass/             1.0                 0.42           Nextel   Exceed Heat         214                107**
**                       ****Nextel Paper                                                          Paper     Flux Limit**
**                                                                                                                         ****(>300)**
-     **C**         **2 Layer Orcobloc                1.0                  0.6               N/A     Burnthrough            0                214**
**                             ****OPF                                                                                        (240)**
-      **D**         **1 Layer Fiberglass/              1.0                  0.42        Pre Ox   Burnthrough         107                107**
**                    ****1 Layer Pre Ox-               3/16                  7          PAN Felt        (190)**
**                     ****PAN Felt (7641)**
-      **E**         **1 Layer Fiberglass/         1.0/0.15          0.42/15        Basofil/   Burnthrough        107                214**
**                     ****2 Layer Basofil/                                                     Aramid         (205)**
**               ****Aramid Felt (4759R)                                                    Felt**
**                **
**      ****F         1 Layer highloft                  0.5                 0.83             N/A      Exceed Heat           0                  107**
**                  ****aramid/inorganic                                                                        Flux Limit  **
**                                                                                                                            ****(230)  **

##                         FLAME TEMPERATURE  PROFILE

**                                                ****(**observed from the burner**)**

**A**

**B**

**C**

**E**

**F**

** ****G**

**I**

**J**

**Thermocouple**
**Number**

- LAB

**Temperature T of each thermocouple was averaged over 6 calibrations for all labs.**
- The difference T is as large as 214 °F between flames from Lab A and Lab E.

- 1804

**TEMPERATURE****RANGE**
**PROPOSED**

- 927

- 1038

- 1149 °C

**Temperature °F**

- 1093

- 982

- A

- E

##               FLAME TEMPERATURE-FRONT HEAT FLUX CORRELATION 

**              **FLAME TEMPERATURE-FRONT HEAT FLUX CORRELATION

**Heat Flux**
**(Btu/s.ft****2****)**

**E**

-  **I**

**G**

-  **B**

-  **F**

-  **J**

**C**

**A**

**Temperature (°F)**

- - In the temperature range of 1800-2000 °F,  data from 6/8 labs showed that
-   the front heat flux-flame temperature relationship is linear.
- - A front heat flux in the (14-16 Btu/s.ft2) range could be generated when the
-   average flame temperature is in the range of (1875-1950 °F).
- - A 5% variation of flame temperature (T2- T1)/T1 yields a heat flux variation
-   (Q2- Q1)/Q1 as large as 25%.

- 2 Q = 0.8 Btu/s.ft2
- Q/Q = 3%

##    INTAKE AIR VELOCITY & FLAME TEMPERATURE CORRELATION

**Air Velocity (ft/min) + Temperature (°F)**

-         **2********T = 20 oF**

**2********V = 100 ft/min**

-    INTAKE AIR VELOCITY & FLAME TEMPERATURE CORRELATION

** ****G        B        C        I         F        J        A        E**

**Lab**

*Intake air velocity* as recorded by each lab was plotted in the
- increasing order (blue dots). The corresponding *flame temperature*
- was then correlated (green dots).
- The graph showed that an increase of *in-take air velocity* V about
- 70 ft/min could yield a *flame temperature* increase of 100 °F.

**Temperature**

**Intake air velocity**

##       TEST CELL TEMPERATURE - FLAME TEMPERATURE CORRELATION (1) 

- 70

- 95

- 120

- 145

- 170

-       TEST CELL TEMPERATURE - FLAME TEMPERATURE CORRELATION (1)** **

**Calibration/Test**

**Test cell temperature (oF)**

**Flame temperature (oF)**

**Flame Temp.(°F)**

**  ****TC Temp. (°F)**

- Data from from one lab showed that the
*flame temperature* varied in accordance
- with the *test* *cell temperature* variation.

##   TEST CELL TEMPERATURE - FLAME TEMPERATURE CORRELATION (2) 

**Test cell temperature (oF)**

**Flame temperature (oF)**

- The cell temperature was plotted in the increasing order.
- The above graph showed that, above 100 °F, the flame temperature increased with increasing cell temperature.
- This behavior was not obvious if the cell temperature is smaller than 100 °F. Indication is that a burn-through test should begin only when the cell temperature had returned to the ambient temperature.

**2********T = 20 oF**

-   TEST CELL TEMPERATURE - FLAME TEMPERATURE CORRELATION (2)** **

##    RELATIVE HUMIDITY AND FLAME TEMPERATURE

**Relative Humidity (%)**

**Lab**

- 1800

-  1850

- 1900

- 1950

- 2000

- 2050

**Flame Temperature(oF)**

-     **E         B**

-     **C         G         J          F**

-       **I          A**

**   **RELATIVE HUMIDITY AND FLAME TEMPERATURE

**2********T = 20**** **

**°F**

-  **2********H= 6 %**

- Flame temperature was plotted along with increasing humidity for each lab.
- Data does not show convincingly that the relative humidity affects flame
- temperature.
- For 6 labs from E to A (EBGJFA), the flame temperature increased with
- increasing humidity while for 4 labs from C to I the variation is reverse.

## FLAME TEMPERATURE AND BURN-THROUGH TIME CORRELATION (Graph 1)

**    ****E           I           B          G          F          J           C           A     **

**  ****A**

-   **E**

-   **C**

-   **D**

**Lab**

******t/t ~ 5-10%**

**Burn-through time (s)**

- Average burn-through time for 4 sample materials A, E, C, and D by 8 labs was
- plotted versus increasing flame temperature.
- For A and E samples, 6 over 8 labs obtained burn-through time data
- that is in agreement with temperature variation.
- For C and D samples, 4-5 labs obtained consistent data.

##      FLAME TEMPERATURE AND BURN-THROUGH TIME CORRELATION (Graph 2)

**  ****E           I           B          G           F          J           C          A     **

**Lab**

**Temperature (oF)**

**2********T = 20 oF**
**(********T/T~0.5 %)**

**2********Q = 0.8**
**(********Q/Q = 3 %)**

**     **FLAME TEMPERATURE AND BURN-THROUGH TIME CORRELATION (Graph 2)

- The flame temperatures for all labs were plotted in the increasing order to
- correlate with burn-through time data. 6/8 burner set-ups generated flame
- temperature in a pretty narrow range (1850-1950 °F).

- CURRENT
-       RANGE

##               EFFECT OF MATERIALS COMPOSITION VARIATION 

**              **EFFECT OF MATERIALS COMPOSITION VARIATION_** **_
- The shape of the heat flux curves Q = k f(T) is a characteristic of materials _composition_ .
- The rear heat flux curves of samples A, E, C, and D as independently recorded by Labs F, I, and J were utilized to examine the effect of materials composition variation.
- Below are heat flux graphs for sample E2 and A2 by labs F, J, and I where:
- (1) the E2-signals were zero for 50 seconds, then started increasing. Burn-through occurred with a sharper increase of the rear heat flux at around 95-110 s.
- (2) the A2-signals increased smoothly from nearly zero to 0.7 in t ~ 20-25 s,
- indication of a near burn-through.
-       ** **

##       HEAT FLUX CURVES OF SAMPLES E2 BY LABS F, J, AND I

**Heat Flux (Btu/ft****2****s)**

**Time (s)**

- (Ja and Jb) SAMPLE E2 - LAB J, burned through at 110 s.
- (Fa and Fb) SAMPLE E2 - LAB F, burned through at 95 **s**

** **

-     (Fa)

- (Ja)

- (Jb)

- (Fb)

-       HEAT FLUX CURVES OF SAMPLES E2 BY LABS F, J, AND I

## SAMPLE E2 - LAB I

## SAMPLE A2

**Data from LAB I**

**SAMPLE A2**

**Data from LABs **
**F and J**

- (Fa)

- (Fb)

- (Ja)

- (Jb)

- Burned-
- through

## EFFECT OF THE TEST CELL VENTILATION CONDITION 

- A strong vertical ventilation = stronger vertical air flow ---> longer burn-through time.
- A poor vertical ventilation = slower vertical air flow ---> faster burn through
-  Ventilation alters the turbulent nature of the flame, both spatially and temporally

- FLAME MODELS
- UNDER DIFFERENT
- VENTILATION
- CONDITION

##    EFFECT OF MATERIALS SHRINKAGE

-     The specimen was shrunk and/or blown towards the calorimeters.
- 1/ a failure due to an exceeding heat flux resulting from a nearer distance
-     between the hot surface of the blanket and the rear calorimeter.
- 2/ an increase of burn-through time due to a longer distance between
-     the burner cone and the blanket.

-    EFFECT OF MATERIALS SHRINKAGE

## CONCLUSION

- (1) The temperature-front heat flux relationship by 8 labs indicate that, within a 15%
-       error, flame temperature is directly proportional to the flux.
- (2) The average flame temperature required for generating a heat flux in the range of
-       14-16 Btu/s.ft2 in the range of 1875-1950 °F.
- (3) A 5% variation of average temperature (T2- T1)/T1 could yield a heat flux variation
-      (Q2- Q1)/Q1 as large as 25%. This could cause a significant difference in burn-
-      through time. Therefore, the allowable fluctuation of the average temperature
-      should be 50 °F (2.6%) instead of 100 °F (5%) (1900 ± 50 °F instead of 1900 ±
-     100 °F ).
- (4) Factors need to be controlled
-      The in-take air velocity, the cell temperature, the test cell ventilation, and the
-       shrinkage of materials.
-       Effect of humidity is not evident.
- (5) Heat flux curves indicated that materials composition variation in samples may not
-      be a significant factor affecting the burn through results.