1. FIRE MODELING OF DIFFERENT
VENTILATION SCENARIOS IN A
COMPARTMENT FIRE
Mahmood Tabaddor, PhD
Majji T. Rao
Predictive Modeling and Risk Analysis
Corporate Research
The Seventh Triennial
International Fire &
Cabin Safety
Research Conference
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2. OBJECTIVE
Assess and advance the use of CFD-based fire
modeling tools (such as Fire Dynamics Simulator by
NIST) to predict fire growth and spread within a
compartment under different ventilation conditions.
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2

3. Right
Back
Left
Front
EXTERIOR VIEW OF BASEMENT
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4. INTERIOR OF BASEMENT
View towards back
View up the stairwell
View towards front
View of stair doorway
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4

5. I-JOIST BEAM CEILING
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6. INSTRUMENTATION
Thermocouples
Velocity Probes
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7. FUEL LOAD DETAILS
Igniter
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8. MODEL OF FULLY VENTILATED BASEMENT
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9. EXPERIMENTAL HRR
6000
Experiment 1
Experiment 2
5000
Heat Release Rate (kW)
Experiment 3
Average
4000
3000
2000
1000
0
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Time (s)
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9

10. MODELING OF FUEL LOAD
3000
2500
HRR kW
2000
1500
average
FDS_HRR
1000
500
0
0
50
100
150
200
250
300
Time Sec
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10

11. BURNING BEHAVIOR OF PALLETS
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11

12. FLAME BEHAVIOR OF FUEL LOAD
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13. MESH DETAILS
•
•
•
•
FDS v. 5.5
10 x 10 x 10 cm3 cubic cell
100 x 150 x 60 = 900,000 cells
Typical computational time (serial processing) = 2-4 days
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14. THERMAL PROPERTIES
• Non-combustible floor and walls
• Combustible wood ceiling
o Specific heat
o Thermal conductivity
: 1.3 kJ/kg °C
: 0.2 W/m °C
o Density
o Ignition temperature
: 570 kg/m3
: 250 °C
o HRRPUA
: 150 kW/m2
Source: Eurocodes (EN:1995-1-2, 2006)
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15. VENTILATION SCENARIOS
• Fully Ventilated Basement (Experimental Data)
• Sequentially Ventilated
o starting with one open window
• Sequentially Ventilated
o starting from fully closed basement
• Sudden Compartmentalization
o starting from fully open basement
• Closed Basement
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16. FULLY VENTILATED BASEMENT
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17. TEMPERATURE COMPARISON
Basement Corner TC_1
Basement Center TC_1
Basement Corner TC_2
Basement Center TC_2
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17

18. VELOCITY AT STAIRWAY DOOR
25
exp-ST
Exp-STM
Exp-SM
20
Exp-SBM
Exp-SB
Sim-ST
15
Sim-STM
Velocity (m/s)
Sim-SM
Sim-SBM
10
Sim-SB
5
0
0
50
100
150
200
250
300
350
400
450
-5
-10
Time (s)
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18

19. HRR Fully Ventilated Scenario
30,000
25,000
FDS_HRR_Open
Heat Release Rate ,(kw)
FDS_HRR_Pallets
20,000
15,000
Wood Burning
(I Joist Beam )
10,000
5,000
0
0.00
50.00
100.00
150.00
200.00
250.00
300.00
Time In Seconds,T
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19

20. COMPARISON OF FLAMING BEHAVIOR
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20

21. FIRE PROPAGATION OVER TIME
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21

22. CEILING JET
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23. CEILING TEMPERATURE CONTOURS
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23

24. I-JOIST BURN THROUGH
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25. GAS TEMPERATURE CONTOUR
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26. VISUALIZATION OF FLAMES ONLY
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27. MESH REFINEMENT
Top of Basement Door
1000
900
800
Temperature (c)
700
600
500
400
10 cm mesh
5 cm mesh
300
200
100
0
0
50
100
150
Time (s)
200
250
300
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28. VARIABLE VENTILATION MODELS
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29. MODELING SUDDEN CHANGES IN OPENINGS
Initially set to zero velocity
and ambient temperature
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30. SEQUENTIALLY-VENTILATED WITH OPEN WINDOW
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31. HEAT RELEASE RATE
30,000
Front window
Opened at 230 Sec
25,000
FDS_HRR_Sequence
FDS_HRR_Pallets
Heat Release Rate ,(kw)
20,000
Top door opened
at 150Sec
15,000
Back Window
Opened at 210 Sec
10,000
Front door opened
at 180 Sec
5,000
0
0.00
50.00
100.00
150.00
Time In Seconds,T
200.00
250.00
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300.00
31

32. FIRE PROPAGATION OVER TIME
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32

33. GAS TEMPERATURE CONTOUR
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33

34. TEMPERATURES
Corner Temperature_TC_1
Corner Temperature_TC_4
900
900
150 sec
180 sec
Temperature In deg Celsius
800
ThermoCouple_
Corner_01
700
600
500
400
300
200
230 sec
100
0
800
700
ThermoCouple_
Corner_04
600
500
400
300
200
100
0
0
50
100
150
200
Time In Second
210 sec
250
300
0
50
Center Temperature_TC_1
150
200
Time In Second
250
300
250
300
Center Temperature_TC_4
900
1,000
800
900
Temperature In deg Celsius
Temperature In deg Celsius
100
700
ThermoCouple_
Center_01
600
500
400
300
200
100
800
ThermoCouple_
Center_04
700
600
500
400
300
200
100
0
0
50
100
150
200
Time In Second
250
300
0
0
50
100
150
200
Time In Second
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35. SEQUENCE OF EVENTS
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35

36. MODEL OF SEQUENTIALLY-VENTILATION IN INITIALLY
CLOSED BASEMENT
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36

37. HEAT RELEASE RATE
25,000
20,000
FDS_HRR_Sequence
HRR,(kw/m2)
FDS_HRR_Pallets
15,000
Right Window
Opened at 160 Sec.
Top Door Opened at
90 Sec.
10,000
Back Window
Opened at 60Sec.
Front Door Opened at
120 Sec.
5,000
0
0.00
50.00
100.00
150.00
200.00
250.00
300.00
Time In Seconds,T
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37

38. FIRE PROPAGATION OVER TIME
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38

39. SEQUENCE OF EVENTS
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39

40. SEQUENTIALLY-VENTILATED IN CLOSED BASEMENT
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40

41. SUDDEN COMPARTMENTALIZATION
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42. HEAT RELEASE RATE
All Doors and Windows are
Closed at 150-160sec.
16,000
14,000
12,000
Heat Release Rate in kw
FDS_HRR_Compartment
FDS_HRR_Pallets
10,000
8,000
6,000
4,000
2,000
0
0.00
50.00
100.00
150.00
200.00
250.00
300.00
Time In Seconds,T
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42

43. OXYGEN CONCENTRATION
0.25
0.20
Oxygen Concentration in mol/mol
X_O2_Conc_Cent_Top
X_O2_Conc_Cent_Middle
X_O2_Conc_Cent_Bottom
0.15
0.10
0.05
0.00
0
50
100
150
Time In Second, Sec
200
250
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300
43

44. FIRE PROPAGATION
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45. SEQUENCE OF EVENTS
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45

46. MODEL OF CLOSED BASEMENT
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46

47. HEAT RELEASE RATE
10,000
9,000
8,000
FDS_HRR_Compartment
7,000
FDS_HRR_Pallets
HRR,(kw/m2)
6,000
5,000
4,000
3,000
2,000
1,000
0
0.00
-1,000
50.00
100.00
150.00
200.00
250.00
300.00
Time In Seconds,T
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48. FIRE PROPAGATION OVER TIME
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48

49. OXYGEN CONCENTRATION
0.25
0.20
Oxygen Concentration in mol/mol
X_O2_Conc_Cent_Top
X_O2_Conc_Cent_Middle
X_O2_Conc_Cent_Bottom
0.15
0.10
0.05
0.00
0
50
100
150
Time In Second, Sec
200
250
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300
49

50. HRR FOR VENTILATION SCENARIOS
30,000
Fully_Ventilated_Basement
Sequentially_Ventilated_Open Window
25,000
Sequentially_Ventilated_Fully_Closed_Basement
Sudden Compartmentalisation
HRR,(kw/m2)
20,000
Closed_Compartmentalisation
15,000
10,000
5,000
0
0.00
50.00
100.00
150.00
200.00
250.00
300.00
Time In Seconds,T
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50

51. REMARKS
• Modeling of changing ventilation conditions
o Do not place openings/closings on the boundary of computational
domain
o Simplified model in FDS is very good start
o Stability issues when configuration changes too much at once
• It is very important that fire tests consider the needs of model
validation when selecting an instrumentation scheme.
• Modeling tools are the key to advancing fire safety research and
engineering
o Data rich
o Efficient and economic
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52. THANK YOU
Reports available at
www.ul.com/fireresearch