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03-12-02IASFPWG – Seattle, WA Fuel Tank Ignition Experiments at Reduced Oxygen Concentrations International Aircraft Systems Fire Protection Working Group.

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Presentation on theme: "03-12-02IASFPWG – Seattle, WA Fuel Tank Ignition Experiments at Reduced Oxygen Concentrations International Aircraft Systems Fire Protection Working Group."— Presentation transcript:

1 IASFPWG – Seattle, WA Fuel Tank Ignition Experiments at Reduced Oxygen Concentrations International Aircraft Systems Fire Protection Working Group Seattle, WA March 12 – 13, 2002 Steve Summer Project Engineer Federal Aviation Administration Fire Safety Section, AAR-422

2 IASFPWG – Seattle, WA Where’s the final report?

3 IASFPWG – Seattle, WA Where’s the final report? After October conference, the decision was made to run some more experiments at a near-stoichiometric concentration, as well as some other test sets.

4 IASFPWG – Seattle, WA Objectives  Determine the Lower Oxygen Content (LOC) at altitudes ranging from 0 – 40 kft. What is the O 2 concentration, below which ignition of the ullage fuel vapors will not occur? How does this effect fuel tank inerting requirements?  Measure ignition pressure at several ‘key’ test points.  Determine the Lower Explosion Limit (LEL) of JP-8 vapors at 0 and 38 kft.

5 IASFPWG – Seattle, WA Facilities – Pressure Chamber

6 IASFPWG – Seattle, WA Facilities – Pressure Chamber  353 ft 3 pressure vessel Working pressure of 650 psi. Attached vacuum pump used to evacuate chamber to reduced pressures seen at altitude. Not capable of simulating temperatures seen at altitude.

7 IASFPWG – Seattle, WA Facilities - LOC Test Article  9 ft 3 simulated fuel tank placed inside of vessel equipped with: Bottom surface heaters. 12 thermocouples. 2 piezoresistive pressure transducers mounted behind sintered porous metal discs. Interchangeable pressure relief mechanism.  ¼-in. aluminum plate.  Foil diaphragm. Ignition source.  2 tungsten electrodes powered by 10 kV transformer operating at ~20 mA, providing 200 J/s

8 IASFPWG – Seattle, WA Apparatus – LOC Testing

9 IASFPWG – Seattle, WA Apparatus – LOC Testing

10 IASFPWG – Seattle, WA Ullage Vapor Sampling

11 IASFPWG – Seattle, WA Ullage Vapor Sampling

12 IASFPWG – Seattle, WA Test Program  JP-8 LOC Tests Mass Loading ~ 4.5 kg/m 3 Ambient pressure corresponding to altitudes of 0, 10, 20, 30 and 38 kft Ullage oxygen concentrations ranging from 21% to below the determined LOC Tests conducted with two different pressure relief mechanisms  ¼-in. aluminum plate – Ignition = movement of plate  Foil diaphragm –Ignition = rupture of foil

13 IASFPWG – Seattle, WA Results – LOC Tests (Al. Plate)

14 IASFPWG – Seattle, WA Results – LOC Tests (Foil Diaphragm)

15 IASFPWG – Seattle, WA Results – LOC Tests (Foil Diaphragm)

16 IASFPWG – Seattle, WA Test Program  Ignition Pressure Tests Tests with pressure relief (i.e. foil diaphragm)  Piezoresistive transducer placed behind sintered porous metal discs.  O 2 concentrations 1 – 1.5% above LOC.  Pressure corresponding to 0, 10, 20 & 30 kft. Tests without pressure relief (i.e. full vessel)  Diaphragm type transducer placed behind flash arrestor.  O 2 concentrations ~1.5% above LOC.  Pressure corresponding to 20 & 38 kft.

17 IASFPWG – Seattle, WA Results – Pressure Tests with Pressure Relief

18 IASFPWG – Seattle, WA Results – Pressure Tests with Pressure Relief

19 IASFPWG – Seattle, WA Results – Pressure Tests without Pressure Relief

20 IASFPWG – Seattle, WA Test Program  LEL Tests Oxygen Concentration of 21% Altitudes of 0 and 38 kft THC concentration varied to the point of non- ignition (LEL)

21 IASFPWG – Seattle, WA LEL Tests - Results

22 IASFPWG – Seattle, WA Conclusions  LOC is a linear function of altitude, going from ~12% at 0 kft to ~16% at 38 kft.  Peak pressure rise decreases in an exponential trend as a function of altitude.  Oxygen concentration has a slight effect on ignition pressure.  Time duration to reach peak pressure increases in an exponential trend as a function of altitude.  LEL shifted slightly to the right as altitude was increased from 0 to 38 kft.

23 IASFPWG – Seattle, WA Future Plans  Conduct ignition pressure tests without pressure relief at lower altitudes.  Conduct a thorough investigation of the LEL dependence on O 2 concentration and altitude.  A paper detailing the LOC tests will be composed and published shortly.


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