Spontaneous ignition of kerosene (avtur) fuel vapour within a 4 inch cylindrical vessel

Spontaneous ignition of kerosene (avtur) fuel vapour within a 4 inch cylindrical vessel

White, R.G.
Macdonald, J.A.

Royal Aircraft Establishment RAE

1963-06-30

Further laboratory tests using a 4 inch diameter stainless steel cylinder 12 inches long have been done to explore the risk of spontaneous ignition in uniformly heated zones containing Avtur fuel vapour. The effects of temperature, pressure and mixture strength have been investigated over ranges applicable to supersonic aircraft and missiles, a number of tests being done at varying pressures in simulation of the changes experienced when descending from high altitude at rates between 0.025 and 0.79 psi/sec. The minimum spontaneous ignition temperature rises only from 230°C to 240°C as the pressure is reduced from 14·7 psia to 4 psia, but changes rapidly to 340°C as the pressure approaches 1 psia. The magnitude of the resulting pressure rise is not necessarily great, being dependent on the absolute pressure level before ignition and on the fuel concentration. The presence of a large excess of fuel vapour can inhibit ignition altogether, while the presence of 70% to 90% by weight can limit the resulting pressure rise to 2 psi. For ignitions at the same pressure, the inspiration of air in a dive yields generally lower pressure rises than are obtained in tests where the pressure is initially steady. A "safe" diva rate giving ignition pressure rises less than 2 psi for the range of temperatures covered is about 2 psi/min. Using the minimum ignition delays obtained in static tests a relationship has been obtained which gives reasonable results when applied to the dive tests.

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Ministry of Aviation, Royal Aircraft Establishment, RAE Farnborough

Campus only

RAE Technical Note No. Mech Eng 379

Aerospace Engineering Reports

report

© 1963 Ministry of Aviation, Royal Aircraft Establishment