Research On The VSV Regulation Law And Surge Fault Diagnosis In Civil Aviation Engine

The surge is a very destructive failure,which seriously affects the safe operation of the engine.It is necessary to avoid the engine entering the surge area in all conditions.VSV system is one of the most important measures to prevent engine s urge.Its main function is to adjust the angle of the adjustable stator blade to make the air flow into the compressor rotor blade at the best angle of attack,avoid the eddy current and airflow obstruction,reduce the loss of air flow,and expand the stab ility of the engine.But the composition is very complex and the adjustment is very frequent.It is prone to VSV adjustment lag and unreasonable adjustment angle.And the engine will be surged when it is serious.Based on the reference air-flow entrance angle method and support vector regression machine,this paper explores the regulation of VSV,and studies the surge fault diagnosis based on SVM.First of all,according to the principle of engine,the relative velocity inlet angle of the first stage rotor of the high pressure compressor of the PW4077 D engine is taken as the reference.A regulation model of adjustable guide vane of engine is established by the method of reference air-flow entrance angle.The adjustable angle of adjustable guide vane under different state points of the engine can be obtained through the model.Second,by using the QAR data of engine health condition,establish three SVR modles for climb,cruise and descent segment to explore the VSV control law.The results show that the difference between the predictive value and the real value of the models is very small,and the precision of each model is high,and the status monitoring of the VSV position can be realized.At the same time,the advantages and disadvantages of support vector machine parameter optimization and the two modeling methods are compared.Finally,a one class support vector machine model is established based on the surge fault samples of PW4077 D engine to realize the accurate identification of surge point,and the accuracy of the model is high.Combined with the VSV regulation rule model,it can be able to determine whether surge is caused by VSV unreasonable adjustment,so as to provide help for engine fault diagnosis.