磁场对高超声速弱电离气体流动的影响

Effect of Magnetic Field on Hypersonic Weakly Ionized Gas Flow

对偶极子磁场作用下的三维钝头体高超声速黏性绕流的化学非平衡流动进行了数值模拟。电导率利用组分公式计算,化学模型为7组元、6反应模型。应用诱导磁场方法将磁场与流场耦合,控制方程的空间离散采用有限体积法,扩散项用中心差分格式,对流项采用二阶迎风格式,时间推进采用3步Runge-Kutta法。计算结果表明,外加偶极子磁场使激波脱体距离增加,壁面摩擦系数和表面热流密度增大。与无磁场作用时相比,在0.153T外加磁场作用下,冻结流中的激波脱体距离增加约3倍,局部壁面摩擦系数最大增加63%,局部表面热流密度最大增加61%;而化学非平衡流中的激波脱体距离增加约0.5倍,局部壁面摩擦系数最大增加47%,局部表面热流密度最大增加31%,且化学非平衡流中激波层内温度的最大值约为冻结流中的64%。

Three dimensional hypersonic viscous chemical nonequilibrium flows around a blunt body under the effect of a dipole magnetic field are numerically investigated.The electrical conductivity is calculated by a species formula,with the chemical kinetics described by 7 species and 6 reactions between them.The magnetic field and the flow field are coupled by the magnetic induction equation.The finite volume method is implemented in the spatial discretization.Central difference approximation is applied to the diffusion terms while a second order upwind scheme is used for the convection terms, and a 3-stage Runge-Kutta scheme is adopted for the time integration. The results show that the shock standoff distance, skin friction coefficient and surface heat flux all increase with the strengthening of the external dipole magnetic field. When external magnetic field is 0. 153 T, the shock standoff distance, local skin friction coefficient and local surface heat flux in the frozen flow increase respectively by three times, 63% and 61%, while in the chemical nonequilibrium flow, the shock standoff distance, local skin friction coefficient and local surface heat flux increase by 50 %, 47% and 31%, respectively, as compared with the figures without the effect of the magnetic field. Meanwhile, the maximal temperature of the shock layer in the chemical nonequilibrium flow is 64 % of that in the frozen flow when external magnetic field is 0. 153 T.