Experimental Studies of the Boundary Conditions Leading to Oil Fire in the Bearing Chamber and in the Secondary Air System of Aeroengines

The continuous increase of the temperature and pressure levels in modern aeroengines has significantly increased the demands on the design of the lubrication system. Among other things the oil/air system of a gas turbine engine has to ensure that engine operation does not permit oil coking or oil fires in order to guarantee high reliability and safety of the engine. To improve existing and develop new design rules, a fundamental study of the conditions leading to oil firing within an oil contaminated environment has been initiated. Three ignition mechanisms relevant for the triggering of an oil fire in the bearing chamber or in the secondary air system are investigated in detail: the spontaneous ignition of the lubricant (autoignition), the ignition of the lubricant near a hot surface (hot surface ignition) and the propagation of a flame within a vent pipe into the bearing chamber (vent pipe flashback). The present paper focusses on the experimental approach and procedure. The different test rigs are presented and their functioning is demonstrated by means of initial results.