Analysis Of Structural Stability Of Moving Shock Wave In Supersonic Inlet

Supersonic inlet is the key component of ramjet but the contradiction between stability and efficiency of shock wave in inlet restrict the improvement of performance of ramjet. The change of stability of shock wave is linked tightly with this restriction. The catastrophe of shock motion when inlet turn to unstart corresponds to structural unstable in dynamical system. Theref ore, the research in structural stability of dynamic shock could be helpful for finding the mathematical laws in inlet unstart and proposing methods to improve stability of shock wave. our paper sets structural stability of dynamic shock as object, analyzi ng the links and regularity between the structural stability and inlet unstart, aimed to find a method to alleviating the contradiction mentioned above.Firstly, the duct volume model describing the storage effect of inlet, the wave propagation model describing the delay and amplitude of perturbation wave, and the shock wave motion model are considered as the dominate dynamics of shock wave in inlet. Combining those dynamics, a model is built and extended to the field of magnetohydrodynamics to analyzing the magnetohydrodynamic shock wave motion.Secondly, the links between the structural stability of shock wave and inlet unstart is studied through model simulation. Two kinds of the inlet unstart is classified based on the different topological structure of system phase space and the different motion of shock wave when inlet turn to unstart is analyzed respectively. Besides, the critical condition of inlet unstart is studied in different topological structure of system.Then, the effects of magnetic field and electric filed on the structural stability of shock wave are studied respectively. The effect of magnetic field and the effect of both magnetic field and electric filed on motion of dynamic shock wave and the topological structure of system phase space are studied in two kinds of inlet unstart.Last, the theoretical method to alleviating the contradiction of stability and efficiency is studied with the central idea that electromagnetic field could enhance the stability of shock wave. Based on the critical criterion, which can be used in judging if shock wave is stable, the region of electromagnetic field in where shock wave stability is enhanced is obtained and the influence of other parameters on this region is studied.