Research On The Stability Of Air Defense And Anti-missile Solid Motor Based On Acoustic Resonance Simulation

In order to improve performance,the design of large loading,large aspect ratio and high pressure is applied to the air defense missile engine.However,the combustion instability occurs when the flight environment is complicated,which appears as the oscillations of engine thrust and pressure,and has a negative impact on the guidance and control of air defense missiles.Also,the combustion instability may cause the failure of mission.The combustion instability has become one of the major factors which restrict the development of new air defense missiles in our country.As a result,it is significant to study the unstable combustion of air defense missile engines.The combustion instability is a complicated problem which involves multiple disciplines.The acoustic energy resonance simulation method for evaluating the instability of engine from the perspective of acoustic response is established.The combustion instability is the result of a combination of gain and damping factors.The solid engine is regarded as a closed acoustic cavity,while the gain factors and damping factors is converted into the boundary conditions of the sound field.By analyzing the sound cavity of the solid engine,the influence rules of different structures on the acoustic response of the engine is obtained,which is able to evaluate the acoustic instability trends of the solid engine and guide the design of the air defense missile engine.The main contents of this paper are as follows:(1)Establish the acoustic energy resonance simulation method for evaluating the instability of solid engine.Calculate the model of 1/30 scale of the Ariane5 booster and obtain the conclusion that the existence of the submerged cavity is more likely to excite the pressure oscillation of the combustion chamber,which is consistent with the results of trial and simulation and verifies the feasibility of this method.(2)Implement the study of trial on the main gain and damping factors of solid engine and get the acoustic boundaries of the solid engine.Through establishing the standing wave tube experiment,the acoustic admittance which characterizes the damping effect of the thermal insulation layers will be acquired.Analyze the results of T-burner experiment from the acoustic aspect and obtain the acoustic admittance corresponding to the gain effect of propellant.(3)The front head of a certain air defense missile engine has changed,which causes the combustion instability during the test.Implement the acoustic energy resonance simulation analysis of solid engine with different configurations.The conclusion is that the changes of structure increase the acoustic response and the likelihood of combustion instability,which is consistent with the test results.(4)Implement the acoustic energy resonance simulation analysis of the double-pulse structure engine.Compared to the single-stage engine,the gain factor of the double-pulse structure engine is small while the damping factor is great.The result is that the double-pulse structure can effectively reduce the acoustic response of the engine,hich is conducive to the acoustic stability of solid engines.(5)Implement the acoustic energy resonance simulation analysis of solid engine with different structures.The changes of main structure parameters can affect the acoustic response in solid engines.The structure of large aspect ratio,conical configuration,large convergence angle and large submerged cavity increase the acoustic response,which is detrimental to the acoustic stability of the solid engine.The conclusion guides the design of structure in solid engines.