1 / 23

Fuel Tank Ignition Experiments at Reduced Oxygen Concentrations

Fuel Tank Ignition Experiments at Reduced Oxygen Concentrations. Steve Summer Project Engineer Federal Aviation Administration Fire Safety Section, AAR-422. International Aircraft Systems Fire Protection Working Group Seattle, WA March 12 – 13, 2002. Where’s the final report?.

deirdre-holman
Download Presentation

Fuel Tank Ignition Experiments at Reduced Oxygen Concentrations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

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

  3. 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. IASFPWG – Seattle, WA

  4. Objectives • Determine the Lower Oxygen Content (LOC) at altitudes ranging from 0 – 40 kft. • What is the O2 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. IASFPWG – Seattle, WA

  5. Facilities – Pressure Chamber IASFPWG – Seattle, WA

  6. Facilities – Pressure Chamber • 353 ft3 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. IASFPWG – Seattle, WA

  7. Facilities - LOC Test Article • 9 ft3 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 IASFPWG – Seattle, WA

  8. Apparatus – LOC Testing IASFPWG – Seattle, WA

  9. Apparatus – LOC Testing IASFPWG – Seattle, WA

  10. Ullage Vapor Sampling IASFPWG – Seattle, WA

  11. Ullage Vapor Sampling IASFPWG – Seattle, WA

  12. Test Program • JP-8 LOC Tests • Mass Loading ~ 4.5 kg/m3 • 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 IASFPWG – Seattle, WA

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

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

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

  16. Test Program • Ignition Pressure Tests • Tests with pressure relief (i.e. foil diaphragm) • Piezoresistive transducer placed behind sintered porous metal discs. • O2 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. • O2 concentrations ~1.5% above LOC. • Pressure corresponding to 20 & 38 kft. IASFPWG – Seattle, WA

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

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

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

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

  21. LEL Tests - Results IASFPWG – Seattle, WA

  22. 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. IASFPWG – Seattle, WA

  23. Future Plans • Conduct ignition pressure tests without pressure relief at lower altitudes. • Conduct a thorough investigation of the LEL dependence on O2 concentration and altitude. • A paper detailing the LOC tests will be composed and published shortly. IASFPWG – Seattle, WA

More Related