Numerical Simulation Of Hypersonic Plasma Flowfield And Electromagnetic Wave Propagation With Magnetic Interference

When a hypersonic aircraft reenters the upper atmosphere,the surface temperature of the aircraft will rise sharply due to the boundary layer effect due to severe friction with the air,resulting in a high-temperature effect of hypersonic flow.As the temperature rises,atmospheric molecules will dissociate,ionize,and a series of other complex physical and chemical reactions,and finally form a plasma sheath on the surface of the aircraft.When the ground communicates with the aircraft,the plasma sheath will prevent the propagation of electromagnetic waves,causing the communication interruption or “black barrier”phenomenon.The communication “black barrier” problem caused by the plasma flow field during the reentry of the hypersonic vehicle is an important issue that plagues the aerospace field,and the application of a magnetic field is one of the potential black barrier technologies.In this paper,a numerical simulation of the turbulent flow field of a hypersonic vehicle is carried out first,and then a simulation analysis is carried out on the distribution characteristics of the plasma flow field and the propagation characteristics of electromagnetic waves under the control of a magnetic field.The research content of the paper is as follows:1.Established a thermochemical non-equilibrium calculation model for the plasma flow field of a hypersonic vehicle.Numerical simulation research on the plasma flow field of RAMC-Ⅱ blunt body aircraft at different heights is carried out,and the distribution characteristics of the flow field at different heights are analyzed.At the same time,the distribution map of the characteristic quantities such as the electron density and temperature of the plasma flow field is obtained,and the reliability of the calculation model in this paper is verified by comparing and analyzing with the flight test data and the data of other research documents.2.Established a calculation model of the plasma flow field considering the chemical reaction under an externally distributed periodic magnetic field,and analyzed the electron density distribution law of the plasma flow field under the periodic magnetic field applied to different positions of the RAMC-II aircraft.The simulation results show that the single-coil periodic distribution magnetic field will affect the plasma flow field to produce periodic flow,which makes the plasma flow field appear vortex-like structure,and the vortex tip position of the flow field will form a low electron density area;the double-coil periodic distribution The simulation results of the magnetic field show that different magnetic field intensity distributions will affect the electron density distribution of the plasma flow field to a large extent.The position of the double coil simulated in this paper makes the electron density in the stagnation point region of the plasma flow field decrease.3.The calculation model of electromagnetic wave propagation in plasma flow field under the control of magnetic field is established.The whistle wave propagation mode of the electromagnetic wave in the magnetized plasma is analyzed,and the black barrier phenomenon is alleviated under the condition of an external magnetic field.Calculate the energy density of the electromagnetic wave on the surface of the RAMC-Ⅱ aircraft,analyze the different magnetic field strengths,different frequency of the electromagnetic wave and the external magnetic field to alleviate the influence of electromagnetic wave propagation.The simulation results show that the electromagnetic wave signal can pass through the plasma in the form of a whistle wave with an external magnetic field.Body sheath,and electromagnetic wave signals can be recovered well on the surface of the aircraft.When the magnitude of the applied magnetic field is the same,the smaller the electromagnetic wave frequency,the better the penetration effect of the plasma sheath;when the electromagnetic wave frequency is the same,the larger the magnetic field,the better the penetration effect.At the same time,the external magnetic field will converge electromagnetic waves in the fixed area of the aircraft wall,which also provides suggestions for the design of the antenna on the aircraft.