International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas...
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Transcript of International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas...
![Page 1: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/1.jpg)
International Aircraft Fire and Cabin Safety Conference
Fuel Tank Inerting Modeling
Ivor ThomasConsultant to FAA
1 425 455 [email protected]
![Page 2: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/2.jpg)
International Aircraft Fire and Cabin Safety Conference
Background
• Following TWA 800 the FAA undertook to examine fuel tank inerting to determine if a system could be made practical.– Two ARAC studies– FAA lab, ground and flight test programs– Computer simulations of system performance
![Page 3: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/3.jpg)
International Aircraft Fire and Cabin Safety Conference
Computer simulations of system performance
• Initial model to verify system performance in a single bay tank, using FAA Technical Center tests to confirm model.
• Flight simulation model to look at performance of an inerting system throughout a flight
• Air Separation Module (ASM) performance in flight (effects of available bleed air, system pressure drop etc.)
• Multi-bay simulations to examine in-tank performance (potential for one or more high oxygen bays when the tank average is satisfactory)
![Page 4: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/4.jpg)
International Aircraft Fire and Cabin Safety Conference
Initial Model
• Model Features:– Simple one bay tank,– Single source of Nitrogen Enriched Air, at a
fixed level of O2– Single vent overboard– Sea level conditions only
![Page 5: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/5.jpg)
International Aircraft Fire and Cabin Safety Conference
Initial Model
• Model Results:– Mixing was very rapid, and could be assumed
to be instantaneous– Starting from 21 % O2 model would predict
test results accurately
![Page 6: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/6.jpg)
International Aircraft Fire and Cabin Safety Conference
FAA Tech Center Test Data vs. Model4 %O2 NEA flow, 88 cu ft tank, 75 deg F
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0 5 10 15 20 25 30 35 40 45
Time Minutes
Ull
age
oxy
gen
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nte
nt-
per
cen
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Test; 2 cfm Flow
Test; 4 cfm Flow
Test; 5 cfm Flow
Model 2 cfm
Model 4 cfm
Model 5 cfm
![Page 7: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/7.jpg)
International Aircraft Fire and Cabin Safety Conference
Flight Model
• Model Features:– Simple one bay tank,– Single source of Nitrogen Enriched Air, at a variable
level of O2 and flow rate • Changeable for different flight conditions• Could add results of ASM performance for given
airplane/engine combination– Single vent overboard– Ground and Flight profiles can be simulated.– Fuel O2 Evolution and Fuel consumption included
![Page 8: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/8.jpg)
International Aircraft Fire and Cabin Safety Conference
Flight Model
• Model Results:– Very useful in determining effectiveness of
inerting options• Ground based inerting • Various sizes of ASM and flow modes• Substantiated concept of variable flow technique,
low flow in climb and cruise, high flow in descent
![Page 9: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/9.jpg)
International Aircraft Fire and Cabin Safety Conference
O2 and N2 Partial Pressure and %O2 in Ullage
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0 100 200 300 400 500
Time-Minutes
Pa
rtia
l Pre
ssu
res-
ps
ia, %
O2
pTOT
%o2( vol)
Case Details
Init.Oxygen Level %
Fuel Oxygen level %
Tank type
Initial Fuel Load %
21
21
CWT
0
Ground Based Inerting
![Page 10: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/10.jpg)
International Aircraft Fire and Cabin Safety Conference
Total Pressure and %O2 in Ullage
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Time-Minutes
Pa
rtia
l Pre
ssu
res-
ps
ia, %
O2
pTOT
%o2( vol)
Case Details
Init.Oxygen Level %
Fuel Oxygen level %
Tank type
Initial Fuel Load %
21
21
CWT
90
Ground Based Inerting
![Page 11: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/11.jpg)
International Aircraft Fire and Cabin Safety Conference
Total Pressure and %O2 in Ullage
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Time-Minutes
Pa
rtia
l Pre
ss
ure
s-p
sia
, %O
2
pTOT
%o2( vol)
Case Details
Init.Oxygen Level %
Fuel Oxygen level %
Tank type
Initial Fuel Load %
12
21
CWT
90
Dual-Flow On Board Inerting
![Page 12: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/12.jpg)
International Aircraft Fire and Cabin Safety Conference
Total Pressure and %O2 in Ullage
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30
0 100 200 300 400 500
Time-Minutes
Pa
rtia
l Pre
ss
ure
s-p
sia
, %O
2
pTOT
%o2( vol)
Case Details
Init.Oxygen Level %
Fuel Oxygen level %
Tank type
Initial Fuel Load %
12
21
CWT
0
Dual Flow On board Inerting
![Page 13: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/13.jpg)
International Aircraft Fire and Cabin Safety Conference
Air Separation Module (ASM)
• ASM performance strongly affected by available pressure and temperature
• Airplane bleed flow affected by airplane flight conditions.
• Model combined airplane/engine bleed data with ASM performance data to predict ASM performance in flight, which could then be used in the inerting flight model.
![Page 14: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/14.jpg)
International Aircraft Fire and Cabin Safety Conference
Screen Dump of ASM Model
Permeable Membrane Inerting System PerformanceUser Notes Heat ExchangerTo run a case, input values in Yellow Cells and click "Solve for exit pressure" button. Loss Coefficient 0.7
Don't change any other cells or program may not run correctly.Control OrificesFlow Mode 1(1= Descent, 2 = Cruise)
Input Required Waste/Vent outflow Input Orifice and tank dataAltitude 18,000 ft Pressure 7.34 psia Orifice coefficient 7Bleed Pressure 30.22 psia OEA flow 1.31 Lb/min Orifice Delta P 4.40 psigAir temperature 180 Deg F OEA O2 Level 28.3 % Tank Pressure 0.5 psig
ASM Inlet Data Outflow DataAmbient Pressure 7.34 psia NEA Flow 0.79 lb/minHeat Exchanger loss 2.74 psi NEA O2 Level 10.08 %
temperature 170 Deg FAir Flow 1.98 lb/min Outlet Pressure 12.2 psiaInlet Pressure 20.14 psig Outlet Pressure 4.90 psigInlet Pressure 27.48 psia Recovery 51.7 %Inlet Temperature 180 Deg F
ASM Delta P 10.59 psi
Solve for exit pressure
![Page 15: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/15.jpg)
International Aircraft Fire and Cabin Safety Conference
NEA Performance During Descent
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0.00 5.00 10.00 15.00
Ambient Pressure psia
NE
A O
2 L
evel
, %
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
NE
A F
low
, L
b/M
in
NEA O2 Level
NEA Flow, lb/min
Typical Single ASM Performance
![Page 16: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/16.jpg)
International Aircraft Fire and Cabin Safety Conference
Multi-bay simulations
• Background:
• The performance of an inerting system can be estimated with the inerting flight model at a gross tank level.
• In-tank effects needed to be examined to understand the potential for bays of a tank to be left at a high O2 state even though the tank average O2 was acceptable.
![Page 17: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/17.jpg)
International Aircraft Fire and Cabin Safety Conference
Multi-bay simulations
• Model Features:– Specific airplane /tank set-up
• Bay sizes• Interconnect flow areas • vent geometry,
– Multiple NEA insertion points– Ground and Flight Operation– Leakage
![Page 18: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/18.jpg)
International Aircraft Fire and Cabin Safety Conference
Multi-bay simulations
• Model Approach:– Establish bay to bay flow paths, vent flow
paths and any leakage flows– Determine mass changes in each bay for
each time increment, based on NEA flow and altitude change and temperature change
– Solve for flows between bays and compute resultant O2 level in each bay
– Iterate along flight path
![Page 19: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/19.jpg)
International Aircraft Fire and Cabin Safety Conference
Typical Flight Profile, Oxygen Content by Bay
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0 20 40 60 80 100 120 140Time, Minutes
Oxy
gen
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ten
t %
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10000
15000
20000
25000
30000
35000
40000
45000
50000
Alt
itu
de
ft
Bay 0
Bay 1
Bay 2
Bay 3
Bay 4
Bay 5
Bay 6
Inerting Limit
Altitude
![Page 20: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/20.jpg)
International Aircraft Fire and Cabin Safety Conference
Current Status
• FAA Multi-bay model developed for specific tanks
• NOT available to public as the model uses specific airplane data
• Specific model allows examination of different distribution techniques to minimize bay-to-bay O2 variation, particularly at Landing.
![Page 21: International Aircraft Fire and Cabin Safety Conference Fuel Tank Inerting Modeling Ivor Thomas Consultant to FAA 1 425 455 1807 fuelsguy@msn.com.](https://reader035.fdocuments.us/reader035/viewer/2022062621/551be289550346be588b5ea5/html5/thumbnails/21.jpg)
International Aircraft Fire and Cabin Safety Conference
Conclusions
• FAA computer models, together with a large amount of testing to verify the assumptions in the models have allowed the FAA to understand the potential for On-board inerting systems and has allowed FAA to go forward towards an NPRM to address high flammability fuel tanks.