Research On Aeroengine Model Switching Based On Inertial Sliding Mode Method

The aero-engine research is costly and time-consuming.The major method is computer simulating.Each application and various states about aero-engine can be studied by establishing mathematical model.Generally,there are several problems to simulate the aero-engine model: the state variable model has small application range,the nonlinear model is complex and its speed very long time.Therefore,in this paper,in the light of those problems,the inertial sliding model method was applied to solve the models switching.The major research contents are as follows:(1)In this paper,take the DGEN380 engine as research object.Based on the thermodynamic principle of aero-engine,the component-level thermodynamic model of DGEN380 engine was established by using the component-level method.Flow balance equations and power balance equations at steady state were established to form the steady state model solved by N-R method.The steady state model was verified by comparing test data with simulating data.At the same time,flow balance equations and rotor dynamics equations were established to form the dynamic state model solved by N-R method and Euler method.(2)The DGEN380 engine state variable model was gained by linearizing nonlinear thermodynamic model at the cruise point and design point(the maximum continuous thrust operating point).The state variable model was verified by compared nonlinear response data with linear response data at the 1% fuel step.(3)sensitivity analysis and independence analysis of aero-engine were carried out based on quasi-steady state assumption.And number of quasi-steady-state points inserted between cruise point(PLA=43%)and design point(PLA=74%)can be determined.The sliding surface assembly was established based on the number.The effects of speed variation on aero-engine acceleration can be obtained by dynamic characteristic analysis,so that the dynamic trend between points is obtained.(4)The results of model switching of DGEN380 engine show that the aero-engine model can be switched smoothly by applied the inertial sliding mode method under different engine states.And compared experimental data with simulation data,the state difference is within 3%,which satisfies the model accuracy requirement.On the basis of satisfying the model accuracy,under the same change(43%-74%)in throttle angle,the calculation time of the component-level model is about 20 minutes,and the calculation time of the aero-engine model established by applying the inertial sliding mode method is about 6s.