Direct and system effects of water ingestion into jet engine compresors

Water ingestion into aircraft-installed jet engines can arise both during take-off and flight through rain storms, resulting in engine operation with nearly saturated air-water droplet mixture flow. Each of the components of the engine and the system as a whole are affected by water ingestion, aero-thermally and mechanically. The greatest effects arise probably in turbo-machinery. Experimental and model-based results (of relevance to 'immediate' aerothermal changes) in compressors have been obtained to show the effects of film formation on material surfaces, centrifugal redistribution of water droplets, and interphase heat and mass transfer. Changes in the compressor performance affect the operation of the other components including the control and hence the system. The effects on the engine as a whole are obtained through engine simulation with specified water ingestion. The interest is in thrust, specific fuel consumption, surge margin and rotational speeds. Finally two significant aspects of performance changes, scalability and controllability, are discussed in terms of characteristic scales and functional relations.