Coupling Analysis Of Sound Field And Combustion In SRM Under External Excitation

As early as the early 1960 s,it has been found that solid rocket motors with a larger aspect ratio(L/D)occasionally have unstable combustion after external influences during operation.That is to say,the engine at ordinary times can be stable work,and in a certain range of turbulence,it will suddenly become unstable.This comes from the outside world of spontaneous motivation can be divided into two kinds,the engine internal motivation and external shell incentive,this article selects the former as the research content,using the numerical calculation method and theory analysis,by means of impulse excitation for pressure coupling and vortex sound coupling mechanism to explore the inner cause of unstable combustion.The main achievements are as follows:1.A numerical calculation method for analyzing acoustic vortex coupling and pressure coupling is established;The software of engine instability linear prediction is developed.The modified equation of flame model for NWR-11 composite propellant was obtained.2.Calculate the acoustic mode of the model engine by using the finite element method;Using the LES method,the acoustic vortex resonance characteristics of the engine under various conditions are calculated.Based on the study of the pressure pulse wave of UDF applied to the flow field in different combustion chamber,specific conclusions about the effect of pulse disturbance on the acoustic vortex coupling are obtained.3.The theoretical analysis method was adopted to separate and discuss the parameters of linear engine estimation technology,judge the influence characteristics of gain factor and damping factor,and find the development law of each parameter in the combustion process;The parameters that cannot be theoretically analyzed are studied by numerical method alone and specific conclusions are drawn.4.Based on the influence law of pressure pulse disturbance on the flow field in the combustion chamber,the internal causes and specific action mechanism of impulse excitation triggering unstable combustion are found.