Study On Electromagnetic Wave Propagation Loss In Plasma Layer Based On Synthetic Jet Technology

When the high-speed aircraft passes through the atmosphere,the shock wave compression and friction high temperature form an ion sheath on its surface,which can absorb or reflect wireless remote sensing signals,resulting in a short interruption of communication between the aircraft and the ground measurement and control system.In this thesis,a synthetic jet exciter is introduced to change the distribution of the plasma sheath and enhance the local electromagnetic wave propagation ability through the flow field control method,so as to realize the active control of the electromagnetic wave in plasma.it provides a new solution for electromagnetic wave propagation in plasma layer.The main research work of this thesis is as follows:(1)Based on the Navis-Stokes flow field control equation,the k-? model and RNG k-?model for synthetic jet simulation and their solving methods are studied.(2)Based on N-S equation,the flow field distribution characteristics of piezoelectric synthetic jet actuator are studied by numerical simulation.At the same time,in order to obtain higher jet velocity,the effects of cavity structure parameters,outlet configuration and outlet angle of piezoelectric synthetic jet exciter on jet velocity are studied.The results show that the jet velocity produced by the piezoelectric synthetic jet driver is too small to penetrate the high-speed flow field.(3)The synthetic jet exciter with electric spark discharge is studied.The physical effect of spark discharge is equivalent to the process of Joule heating.The phenomenological simulation of spark discharge synthetic jet is studied by numerical simulation,and the distribution characteristics of jet field are obtained.The effects of the structure parameters,external flow field environment parameters,driving parameters and outlet configuration of the two-electrode spark discharge synthetic jet exciter on the jet velocity are studied.the simulation results show that the instantaneous peak velocity of the jet produced by the two-electrode spark discharge synthetic jet exciter reaches 300m/s at low pressure,which can penetrate the high-speed plasma flow field.(4)Based on the phenomenological simulation model of spark discharge synthetic jet,the influence of spark discharge synthetic jet on supersonic flow field is studied by numerical simulation,and the separation zone size and distribution characteristics of supersonic flow field controlled by spark discharge synthetic jet are analyzed.(5)According to the distribution characteristics of the hypersonic flow field controlled by the synthetic jet,the density distribution of the plasma region under the control of the synthetic jet is obtained,and the specific type of electromagnetic wave propagation loss in the plasma layer is studied.The simulation results show that,compared with the plasma without synthetic jet actuator,in the frequency range of 0.1-30 GHz,the propagation loss of electromagnetic wave is in the range of 7-12 GHz,and the propagation loss of electromagnetic wave is reduced by more than 2d B.It shows that it is feasible to use the flow field control method to improve the propagation ability of electromagnetic wave in plasma.(6)In the case of applying orthogonal electromagnetic fields,the propagation loss characteristics of electromagnetic waves in the plasma layer.The results show that the application of orthogonal electromagnetic field can improve the electromagnetic wave propagation characteristics.The feasibility of the applied cross electromagnetic field method is verified.