10kW级氢电弧加热发动机非平衡等离子体流动过程的数值模拟

Numerical Simulation of Nonequilibrium Plasma Flow in 10 kW Hydrogen Arcjets

为对10kW级氢电弧加热发动机中的流动与传热过程进行热力学及化学非平衡数值模拟研究,采用的数学物理模型中引入重粒子和电子能量方程考察发动机喷管内等离子体流动的热力学非平衡特性;引入氢原子、氢离子组分方程,结合总体连续方程和适当的化学反应,考察发动机喷管内等离子体流动的化学非平衡特性;数值计算所需的热力学和输运性质在求解过程中按照当地条件参数计算;控制方程组采用基于Roe格式的数值方法进行离散求解。计算获得的发动机性能参数与文献报道结果相比合理符合。数值模拟结果表明,在发动机喷管内壁面,电子和重粒子的温度差远大于沿发动机轴线的二者之差,说明在发动机内壁面附近电子和重粒子偏离热平衡状况比较明显。通过对各种氢组分在发动机内分布及演化过程分析表明,在发动机出口等离子体流动处于化学非平衡状态。

A thermal and chemical nonequilibrium modeling study is performed to investigate the plasma flow and heat transfer processes in 10 kW arcjets.In this modeling,the heavy particle and electron energy equations are introduced to examine the thermal nonequilibrium characteristics,while the equations of hydrogen atom and ion species equations combined with the a global continuity equation and the suitable chemical reactions,are introduced to examine the chemical nonequilibrium characteristics of plasma flow within the arcjet nozzle.The transport properties used in this paper are recalculated according to the conditions at each point in the plasma.The Roe scheme is employed to solve the governing equations.The predicted arcjet performance agrees well with the referred experimental results.The modeling results show that the differences between the temperatures of electron and heavy particles temperatures along the interior surface of thruster nozzle are significantly larger than those along the axis of thruster,which means that there is the thermal nonequilibrium in the regions near the interior wall of nozzle.Furthermore,based on the analysis of computed hydrogen species profiles and their evolutions within the arcjet thruster,it is found that deviations from chemical equilibrium occurs downstream of the thruster nozzle.