高超声速飞行器等离子体成鞘特性仿真研究

Simulation of plasma sheath formation characteristics of hypersonic vehicle

高超声速飞行器周围大气因激波压缩发生高温电离,其周围产生大量等离子体,可形成等离子体鞘套,从而影响对飞行器的探测和跟踪。等离子体鞘套的形成与飞行器外形、飞行高度和速度等多个因素相关。本文中分别针对钝锥体、楔形体飞行器建立了二维仿真模型,采用双温模型和Gupta7组元空气化学反应模型,在2种飞行器典型的飞行高度和速度条件下,分别对其周围的热化学非平衡流场进行了数值模拟分析。钝锥体飞行器周围形成了等离子体鞘套,电子数密度最高达1014/cm^(3)。对于楔形体飞行器,仿真分析了6种不同条件下模型头部区域的空气温度、密度以及化学组分的分布和变化规律,结果表明:飞行高度和飞行速度对楔形体飞行器的流场物理特性有着不同程度的影响。楔形高超声速飞行器电离区域小,电离程度低,其周围不易形成等离子体鞘套。

When hypersonic vehicle is flying,a large amount of plasma is generated around the vehicle due to high temperature ionization caused by shock wave compression,which may form plasma sheath,thus affecting the detection and tracking of the vehicle.The formation of plasma sheath is related to the shape,flight altitude and speed of the aircraft.Two-dimensional geometric models are established for the blunt cone and wedge aircraft respectively,and the Two-Temperature Model and Gupta chemical reaction model are used to simulate and analyze the thermochemical non-equilibrium flow field around the aircraft at their typical flight altitude and speed.The blunt cone is surrounded by plasma sheath with an electron count density up to 1014/cm^(3).For the wedge shape vehicle,the distribution of air temperature,density,and chemical composition in the head area under six difference flight conditions are obtained by simulation.The results show that the flight altitude and flight speed have different degrees of influence on the physical characteristics of the flow field.The wedge-shaped hypersonic vehicle has a small ionization region and a low ionization degree,and it does not tend to form plasma sheath around the vehicle.