﻿ 离子推力器羽流热效应仿真分析<sup>*</sup>
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Simulation analysis of ion thruster plume thermal effect
ZHANG Jianhua, LI Jinghua, YOU Fengyi, ZHENG Hongru
School of Astronautics, Beijing University of Aeronautics and Astronautics, Beijing 100083, China
Received: 2017-12-25; Accepted: 2018-01-05; Published online: 2018-01-31 13:52
Corresponding author. ZHANG Jianhua, E-mail:zjh@buaa.edu.cn
Abstract: The plume ejected from a working ion thruster collides with the surface of spacecraft, which may cause thermal effects such as thermal deformation of the sensitive material and lead to the failure of the space mission in severe cases. In this paper, the plume thermal effect of LIPS-200 ion thruster developed by Lanzhou Institute of Space Physics was simulated. The particle in cell (PIC) method is employed to process the plasma motion, the direct simulation Monte Carlo (DSMC) method is employed to deal with the collision between particles, and the Maxwell model is employed to deal with the energy exchange between the particle and the surface. Part of the measuring points in the experiment of electric propulsion plume thermal effect was numerically simulated. The results show that the simulation results are in good agreement with the experimental data. The error between simulation results and experimental data of the stagnation heat flow on the outlet axis of the thruster is less than 17.0%. In addition, the influence of the heat flow meter on the flow field is mainly concentrated within 0.1 m near the heat flow meter, which has little impact on the overall flow field.
Keywords: electric propulsion     plume     thermal effect     PIC-DSMC method     numerical simulation

1 仿真方法

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2 实验系统

 图 1 离子推力器羽流热效应测量系统示意图 Fig. 1 Schematic diagram of ion thruster plume thermal effect measurement system
 图 2 两种热流传感器实物图 Fig. 2 Photo of two kinds of heat flow sensor

3 网格及边界条件

 图 3 计算域示意图 Fig. 3 Schematic diagram of computational domain
 图 4 推力器与模拟热流计相对位置示意图 Fig. 4 Schematic diagram of relative position of thruster and simulated heat flow meter

 粒子种类 流率/s－1 温度/K 速度/(m·s-1) Xe 5.69×1017 300 325 Xe+ 4.609×1018 46400 39000 Xe++ 5.12×1017 46400 55154

 图 5 羽流场电流密度仿真与实验对比 Fig. 5 Comparison of current density in plume flow field between simulation and experiment
4 计算结果分析

 图 6 轴向位置热效应实验和仿真对比 Fig. 6 Comparison of thermal effect in axial direction between simulation and experiment

 图 7 距离推力器出口0.5 m和0.9 m处径向热流对比 Fig. 7 Comparison of radial heat flow at 0.5 m and 0.9 m from thruster exit

 图 8 距离推力器出口0.9 m处放置热流计时的一价Xe离子和Xe原子分布 Fig. 8 Number density distribution of Xe atom and monovalent xenon ion when heat flow meter is located at 0.9 m away from thruster exit

 图 9 距离推力器出口0.9 m处放置热流计时的一价Xe离子、Xe原子及无热流计时数密度对比 Fig. 9 Comparison of xenon atom and monovalent xenon ion number density distribution on axis with or without heat folw meter located at 0.9 m away from thruster exit
5 结论

1) 采用混合PIC-DSMC方法可以对电推进羽流热效应进行有效的数值模拟分析，推力器出口轴线上滞止热流仿真与实验对比，误差小于17.0%。

2) 在进行径向热效应仿真时，由于粒子具有一定的出射速度，热适应系数不是恒定不变的，而是应随着角度的升高而减小。

3) 在进行三维粒子模拟时，模拟热流计的介入对流场整体影响较小。对Xe离子的影响主要集中在热流计后方0.1 m范围内，并出现了小范围内数密度为0的区域。热流计后方Xe离子数密度低于无热流计时的流场。

4) 模拟热流计对于Xe原子的影响同时存在于热流计前方和后方，在热流计前方中性粒子数密度升高约2个量级，与推力器出口附近的数密度相近。热流计后方Xe原子数密度低于无热流计时的流场。

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文章信息

ZHANG Jianhua, LI Jinghua, YOU Fengyi, ZHENG Hongru

Simulation analysis of ion thruster plume thermal effect

Journal of Beijing University of Aeronautics and Astronsutics, 2018, 44(10): 2028-2034
http://dx.doi.org/10.13700/j.bh.1001-5965.2017.0802