低功率氮氢电弧加热发动机非平衡数值模拟  

Non-equilibrium numerical simulation of a low power nitrogen/hydrogen arcjet

作　　者：魏延明[1,2] 何青松[3] 王海兴[3] 

机构地区：[1]北京控制工程研究所,北京100190 [2]哈尔滨工业大学,哈尔滨150001 [3]北京航空航天大学宇航学院,北京100191

出　　处：《中国空间科学技术》2016年第3期15-23,共9页Chinese Space Science and Technology

基　　金：国家自然科学基金(11575019,11275021);民用航天项目(混合模式推进系统优化技术)

摘　　要：文章对低功率氮氢电弧加热发动机进行了双温度化学非平衡数值模拟研究,模型中包含总的能量方程和电子能量方程,等离子体组分包括分子、原子、离子和电子等7个组分,采用的化学动力学模型中包含了氮氢组分解离、电离等重要的动力学过程,气体的物性根据当地的组分和温度实时计算。通过计算获得了发动机内部气体温度及各组分数密度分布。结果表明,发动机轴线附近等离子体接近热力学平衡,而在发动机阳极壁面电弧贴附区域等离子体明显偏离热力学平衡;计算获得的组分分布表明电弧加热发动机内存在反混合过程,即发动机内各组分分布与入口浓度分布明显不同。氢组分由发动机中心到阳极壁面沿径向呈现先减小后增大的趋势;而氮组分的浓度分布趋势与氢组分相反;进一步的分析表明,发动机内各组分的扩散主要受到气体解离和电离过程引起的浓度梯度所驱动。Thermal and chemical nonequilibrium modelings study were performed on a low power nitrogen/hydrogen arcjet.Separate energy equations were formulated for the electrons and total species,and seven-species nitrogen/hydrogen plasma composition of molecules,atoms,ions and electrons was assumed.Some important chemical kinetic processes of dissociation and ionization were considered in the chemical nonequilibrium model.The plasma properties were calculated according to the local species number density and temperature.The distribution of temperature and the number density of each species in the arcjet were obtained. The results show that the axis of arcjet is close to thermal equilibrium and significant deviation from thermal equilibrium is found in the arc attachment region.It is shown that the species distributions of nitrogen and hydrogen are significantly different from those at the inlet of thruster,which indicates that there exist the demixing processes inside thruster.It is found that the hydrogen species decrease at first and then increase along the radial direction from the center to the inner wall of thruster,while the nitrogen components show the opposite trend.Further analysis shows that the species diffusions inside arcjet are driven by mole fraction gradients which are due to the dissociation and ionization of nitrogen and hydrogen species.

关 键 词：氮氢电弧加热发动机 非平衡 数值模拟 化学动力学 电推进 

分 类 号：V439[航空宇航科学与技术—航空宇航推进理论与工程]