热化学模型对高超声速磁流体控制数值模拟影响分析

Numerical analysis of influence of thermochemical model on hypersonic magnetohydrodynamic control

针对等离子体流场的模拟准确性问题及其对高超声速磁流体控制的影响,通过数值求解三维非平衡Navier-Stokes流场控制方程和Maxwell电磁场控制方程,建立了三维低磁雷诺数磁流体数值模拟方法及程序,分析了不同空气组分化学反应模型和壁面有限催化效率等因素对高超声速磁流体控制的影响.研究表明:不同空气组分化学反应模型对高超声速磁流体流场结构、气动力/热特性控制的影响不容忽视;对于本文计算条件,Park化学反应模型在组分模型一致性、等离子体模拟准确性等方面具有一定优势;磁控热防护效果,受壁面有限催化复合系数影响较大,两者呈非线性关系,不同表面区域差异较大;磁场对磁阻力伞及其磁阻力特性影响,受壁面催化效应的影响相对较小.

In hypersonic flow,extremely high temperature due to shock aerodynamic heating leads plasma flow to form.By adding energy and momentum to the plas-ma flow field through the magnetic field on aircraft,the control of plasma flow field around aircraft can be realized.This has a broad prospect of applications in hypersonic aerodynamic control,aerothermal protection,and plasma distribution adjustment.Very recently,chemical reaction model and thermodynamic model were suggested to study the hypersonic magnetohydrodynamic control.However,the influence of different models and surface catalytic efficiency on hypersonic magnetohydrodynamic control are rarely analyzed in depth.In this study,a comparison of different chemical reaction models and the influence of surface catalytic efficiency are discussed.Three-dimensional(3 D)nu-merical simulation method and program of extra magnetic field coupled with reentry plasma flow under the assumption of low magnetic Reynolds number are developed by solving 3 D chemical non-equilibrium Navier-Stokes equations and Maxwell electromagnetic field governing equations.Based on this method,the influence of different gas component models,chemical reaction models,and surf ace catalytic efficiency on hypersonic magnetohydrodynamic control are analyzed.The results show that the conductivity of plasma,calculated by different gas component models and chemical reaction models,can be quite different from each other,thus can influence the accurate study on the structure of hypersonic magneto flow field as well as the aerothermal and aerodynamic characteristics.Based on the calculation conditions in this paper,the Park chemical model has advantages in the consistency and accuracy in numerical simulation.The magnetic thermal protection is greatly influenced by the surface catalytic efficiency and the correlation between the magnetic thermal protection and the surface catalytic efficiency is nonlinear and can be quite different in different region.As the surface catalytic efficiency increases,the influence of magnetic field on heat flux at stagnation point drops drastically,then increases slowly,which is a joint result of thermal conduction and chemical component diffusion.The influence of magnetic field on magnetohydrodynamic drag character is less affected by the surface catalytic efficiency.As the catalytic efficiency increases,the influence of magnetic field on magnetohydrodynamic drag character drops slowly.