Numerical Simulation Of Plasma Sheath And The Interaction With Electromagnetic Wave

Since the first hypersonic flight, researches on hypersonic flight attract much attention and keeps improving. Hypersonic flight in reenrty of aerocrafts and high dynamic aircaft brings advances as well as disadvantages.Because of the extramly high temperature procuding in the hypersonic flight, reactions such as dissociations and ionizations of the air molecules, make the flow field a group of ionized gas which called plasma sheath. The affection of interaction between electronmagnetic wave and the plasma sheath on commucation and the radar’s detection can not be ignored. Some time even result in communication black out, which is a hidden danger in hypersonic flight.In order to improve this problem,works have done by researches. Most of the work is about the formation machanism, composition and simulating method of the plasma sheath.Basing on these, researches on the interaction between electronmagnetic wave and plasma sheath are done.This work is based on the finite volum method. The multiblocks grids are formulated as the computating grids. The flow field are simulated by solving the integral form of the controal functions. The LU-SGS time marching method is used to simulate the three diamention viscous flow. And the simulationg program is formed based on these. The difference schemes in AUSM family are involed in the program and some anylyses are made throught the classic Reminne problem..The simulation program is improved to make it possible computing the thermodynamic nonequilibrium and chemical nonequilibrium flow. The two temperature model is introduced as well as different chemical reaction models. Comparisions are also made among the reaction models. The reliablility of the computaion program is valided by computaion and experimental results.Interaction between the electronmagnetic wave and plasma layer are calculated. Transmission parameter, reflection parameter and absorption parameter are use to investigate the interaction. The influences of non-uniformity of plasma layer and the applied magnetic field are discussed. As a possible method to improve the communication black out, the frequency of EM wave is improved to terahertz range to offerd refercences to improved the communication black out problem.The flow field around sphere in different cases are calculated. The cases are different in Mach number and height of flight. The variation of plasma stheath with the flight height and Mach number is analysed. The electron density in different flight cases are also calculated, as well as the collision frequency of plasma and the plasma frequency.The flow field around blunted cone in different flight cases are also calculated. And the frequency and electron dinsity. The characteritics of flow field along the stagnation polint line are extracted and translated to dielectric coefficient. The propagation of EM wave along the stagnation line is calculated as well. Different pathes of propagation are introduced to make comparison.