High stability control of engine based on surge margin estimation model

In order to solve the immeasurable problem of engine surge margin in super-maneuvering flight,an approach to build an engine surge margin estimation model was proposed.The modeling process consists of two parts:surge margin benchmark value model under routine flight condition and surge margin loss value model under super-maneuvering flight condition.The benchmark value model was developed using nonlinear fitting method,and the input of model was fixed by surge margin feature selection algorithm.The surge margin loss value was obtained by an angel of attack predictive model which can be used to real-timely estimate engine inlet distortion index.Based on the predictive messages of surge margin estimation model,a scheme of high stability engine control through correcting turbine expansion ratio command was designed for super-maneuvering flight.In this way, the great advantage is that the original closed-loop doesn't need changes.Finally,some surer-maneuvering flight missions with large angle of attack were imitated.The simulation results show that surge margin ranges between 11% and 13% with above stability control concept,ensuring that engine can work safely and efficiently.