Technoeconomic study of engine deterioration and compressor washing for military gas turbine engines

摘要

Despite spending much of their operating life in clear air, aircraft gas turbineengines are naturally prone to deterioration as they are generally not fittedwith air filters. Engines are particularly at risk during takeoff and landing, andwhilst operating in areas of pollution, sand, dust storms, etc. The build-up ofcontaminants, especially on the compressor surfaces, leads to a dramaticreduction in compressor efficiency, which gives rise to a loss of availablepower, increased fuel consumption and increased exhaust gas temperature.These conditions can lead to flight delays, inspection failures, withdrawal fromservice, increased operating costs and safety compromises.With the growinginterest in life cycle costs for gas turbine engines, both engine manufacturersand operators are investigating the tradeoffs between performanceimprovements and associated maintenance costs.This report introduces the problem of output and efficiency degradation in twoaero gas turbine engines (the T56–A–15 and the F110–GE–129) caused byvarious deterioration factors. Their causes are broadly discussed and theeffects on powerplant performance are simulated and analyzed.One of the key factors leading to performance losses during operation ofthese engines is compressor fouling. The fouling can come from a widevariety of sources; hydrocarbons from fuel and lubricating oils; volcanic ash;pollen; marine aerosols; dust; smoke; pollution, etc. The presence of thesefouling sources acts as a bonding agent for the solid contaminants, ‘gluing’them to the compressor surfaces. Thus, the aggravation in terms of poweroutput, fuel consumption and additional time to carry out a typical mission willbe assessed and an economic analysis will be attempted in order to quantifythe effects of compressor fouling on the additional costs which arise, becauseof this specific deterioration.The effect of compressor fouling can be maintained by frequent cleaning toimprove efficiency, resulting, hence, in improved power output, fuel savingsand prolonged engine life. Compressor cleaning is thoroughly presented, andthe implementation of on-wing off-line cleaning on the performance of theF110 engine was investigated from a technical and economical standpoint.Finally, according to the results obtained, the optimal frequency of compressorwashing for the F110 engine is estimated, in order to eliminate safetycompromises, improve performance and reduce the engine’s life cycle cost.