Simulation Study On Influence Factors Of Turbofan Engine Surge

Surge is a special situation in the use of aero-engine,which has a great threat to the safety of civil aviation aircraft and the development of the whole aviation industry.In order to make the pressurizing parts work stably without surging,it is usually required to leave enough "distance" between the working point of the pressurizing parts and the surge boundary,that is,to keep enough surge margin.According to the airworthiness safety requirements of the engine,it is required that the engine should have sufficient surge margin within the whole working envelope,but the excessive surge margin will lead to the reduction of the pressurizing capacity of the pressurizing parts of the engine.In order to achieve the best balance between high performance and surge margin,it is necessary to consider all kinds of factors affecting engine surge.Therefore,in this paper,the aero-turbofan engine is taken as the research object,and the simulation research on the influence factors of turbofan engine surge is carried out.The main research contents of this paper are as follows:(1)Taking PW4056 engine as the modeling object,using Matlab/Simulink simulation platform,based on the component characteristic data,using the variable specific heat calculation method,according to the thermodynamic principle of the turbofan engine,the thermodynamic model of each component of the engine is established;Then,based on the component model,according to the flow balance and power balance relationship between components,the engine is establishe.The steady-state model of the engine is solved by Newton Raphson method,and the simulation results at the design point and the no design point are compared with the experimental data,which proves that the steady-state model has better simulation accuracy and convergence;Finally,the dynamic model of the engine is established according to the volume dynamics and rotor dynamics,and solved by Runge Kutta method and Euler method.By changing the fuel quantity of the engine,the simulation data of performance parameters in different states are compared with the experimental data,which proves that the dynamic model has better dynamic accuracy and convergence.(2)Based on the steady-state model of engine component level,the effects of operating conditions such as atmospheric temperature,atmospheric pressure,flight Mach number,atmospheric humidity,power extraction and additional bleed of high-pressure compressor,angle of adjustable stator blade,etc.on engine supercharger and high-pressure compressor are simulated.The results show that the factors such as atmospheric temperature,atmospheric pressure,atmospheric humidity,flight Mach number,power extraction of high-pressure compressor and additional air volume can affect the surge margin of supercharger and high-pressure compressor,but the influence degree and the variation trend of surge margin are different.(3)Based on the dynamic model of the engine,this paper studies the main factors that affect the engine in the dynamic process,such as acceleration process,deceleration process,component cavity,moment of inertia and different oil supply laws.The results show that the acceleration and deceleration process,the moment of inertia and the different oil supply laws will have a significant impact on the surge margin of the supercharger and the high-pressure compressor,but the size of the external culvert,the combustion chamber and other components has little impact on the surge margin of the supercharger and the high-pressure compressor.