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Simulation of two-phase plume field of liquid thruster

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Science China(Technological Sciences) 2012年第6期55卷 1739-1748页

作者： he XiaoYing he bijiao CAI GuoBiao School of Astronautics Beihang UniversityBeijing 100191China

When the liquid propellant thruster works,its plume field would contain many propellant liquid droplets,especially at pulse *** droplets may move along with the gas flow and deposit on the components of spacecraft as *** simulation of the plume field involving the gas molecules and liquid droplets is an important part in contamination studies of thruster *** on the PWS software developed by Beihang University(BUAA),axial-symmetric two-phase direct simulation Monte Carlo(DSMC) method is used with the liquid droplet taken as a kind of solid *** computation of gas-to-particle effect and gas reflection on the particle surface are *** inter-particle collision is also *** gas parameters at nozzle exit of 120N engine after 20 ms pulse work are taken as the entrance condition of the numerical *** test cases are conducted for comparison of different collision *** results show that the effects of liquid propellant droplets mainly concentrate near the axis line of *** particle-to-gas collision would cause evident differences in the gas field and subtle differences in the particle *** liquid droplets in the plume field are generally accelerated and convected by the gas *** DSMC method is proved to be a feasible solver to numerically simulate the two-phase flow involving solid phase and rarefied gas flow.

关键词： two-phase plume field DSMC liquid droplet liquid thruster pulse

Plume aerodynamic effects of cushion engine in lunar landing

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Chinese Journal of Aeronautics 2013年第2期26卷 269-278页

作者： he bijiao he Xiaoying Zhang Mingxing Cai Guobiao School of Astronautics Beihang University

During the second period of China ＂Tanyue＂ Project, the explorer will softland on the moon. The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground. It is necessary to study its plume effects on the explorer component. The self-developed PWS （Plume WorkStation） software based on direct simulation Monte Carlo （DSMC） method is used to simulate the plume effects of two 150 N engines. Due to the complex structure of the explorer, PWS uses a decoupling method to treat the boundary mesh, which mainly interacts with simulation particles, and has no relation with the computational grids. After the analytical expressions of plane surfaces and curved surfaces of each boundary block are given, the particle position within or without the boundary blocks can be easily determined. Finally the 3D plume field of two 150 N engines is simulated. The pressure, temperature and velocity distributions of plume field are clearly presented by three characteristic slices. The aerodynamic effects on the explorer bottom, the landfall legs and antenna are separately shown. The compression influence on the plume flow of four landfall legs can be observed.

关键词： Boundary blocks Cushion engines Lunar landing Monte Carlo methods Plume effects

Stable Runge-Kutta discontinuous Galerkin solver for hypersonic rarefied gaseous flow based on 2D Boltzmann kinetic model equations

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Applied Mathematics and Mechanics(English Edition) 2017年第3期38卷 343-362页

作者： Wei SU Zhenyu TANG bijiao he Guobiao CAI School of Astronautics Beihang University Beijing 100191 China Beijing Institute of Spacecraft Environment Engineering Beijing 100094 China

A stable high-order Runge-Kutta discontinuous Galerkin(RKDG) scheme that strictly preserves positivity of the solution is designed to solve the Boltzmann kinetic equation with model collision integrals. Stability is kept by accuracy of velocity discretization, conservative calculation of the discrete collision relaxation term, and a limiter. By keeping the time step smaller than the local mean collision time and forcing positivity values of velocity distribution functions on certain points, the limiter can preserve positivity of solutions to the cell average velocity distribution functions. Verification is performed with a normal shock wave at a Mach number 2.05, a hypersonic flow about a two-dimensional(2D) cylinder at Mach numbers 6.0 and 12.0, and an unsteady shock tube flow. The results show that, the scheme is stable and accurate to capture shock structures in steady and unsteady hypersonic rarefied gaseous flows. Compared with two widely used limiters, the current limiter has the advantage of easy implementation and ability of minimizing the influence of accuracy of the original RKDG method.

关键词： model equation hypersonic flow discontinuous Galerkin (DG) conservative discretization positivity-preserving limiter Courant-Friedrichs-Lewy (CFL) condition

Design of double-layer anti-sputtering targets for plume effects experimental system

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Science China(Technological Sciences) 2016年第8期59卷 1265-1275页

作者： SHANG ShengFei CAI GuoBiao ZHU DingQiang he bijiao School of Astronautics Beihang University Beijing 100191 China

The back-sputtering effect of an electric thruster used in a vacuum chamber has an adverse effect on the thruster, vacuum chamber and experimental equipment. An anti-sputtering target （AST） can extend the operating life of the vacuum chamber by reducing the back-sputtering deposition effect. Vacuum chambers used in international facilities have successfully incorpo- rated ASTs. To improve an AST＇s performance, a double layer structure AST based on the plume effects experimental system （PES） was designed. The structure of primary-end of the AST was designed as a flat while the secondary end was designed as a shutter to resolve factors such as service life, back flow rate of the sputtered material, economy and system security. To veri- fy the effects of the double layer AST, the sputtering effects of the AST with and without the secondary-end were evaluated by a DSMC-PIC algorithm. Additionally, the experimental verifications of the bare chamber and the target were performed. The results indicate that the secondary end graphite sheets can reduce the back flow yield approximately 50%. The design of the double layer AST can be introduced as a reference for the design of an anti-sputtering target.

关键词： electric propulsion anti-sputtering target vacuum chamber back-sputtering deposition beam target

Experimental and numerical analysis of the heat flux characteristic of the plume of a 120-N thruster

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Science China(Technological Sciences) 2019年第10期62卷 1854-1860页

作者： ZHANG MingXing CAI GuoBiao he bijiao TANG ZhenYu ZHOU Hao Beijing Institute of Space Long March Vehicle Beijing100076China School of Astronautics Beihang UniversityBeijing100191China Beijing Institute of Spacecraft Environment Engineering Beijing100094China

The convective heat transfer of the plume of a 120-N thruster is investigated experimentally and numerically. Numerical results agree well with experimental results in that there is a nonlinear decrease in convective heat transfer with an increasing cone angle. It is also found that convective heat transfer decreases with increasing distance from the thruster outlet. Furthermore, the convective heat transfer of the plume mainly concentrates within a 35° cone angle and the heat flux decreases to the same order as solar radiation at the Earth’s surface when the cone angle exceeds 60°. The results of the study will help improve spacecraft design.

关键词： vacuum plume heat flux computational fluid dynamics/direct simulation Monte Carlo method shock wave

Investigation on aerodynamic force effect of vacuum plumes using pressure-sensitive paint technique and CFD-DSMC solution

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Science China(Technological Sciences) 2017年第7期60卷 1058-1067页

作者： WU Jing BITTER Martin CAI GuoBiao he bijiao KAEHLER Christian School of Astronautics Beijing University of Aeronautics and Astronautics R&D Center CRRC Qingdao Sifang Co. Ltd. Institute of Fluid Mechanics and Aerodynamics Bundeswehr University Munich

Pressure-sensitive paint(PSP) technique was employed to experimentally investigate the aerodynamic force effect of vacuum plume in this study. The characterization and comparison for two types of PSP were firstly conducted in an air pressure range from0.05 to 5000 Pa. The PSPs were prepared using PtTFPP as the active dye and different binders, i.e., polymer-ceramic(PC) and poly(1-trimethylsilyl-1-propyne) [poly(TMSP)]. The static calibrations showed that PtTFPP/poly(TMSP) had a higher pressure sensitivity and a lower temperature dependency compared to PtTFPP/PC in this pressure range. The pressure distributions of a single and two interacting plumes impinging onto a flat plate model were measured using PSP technique. The experimental data were compared to numerical solutions that combined both the computed fluid dynamics(CFD) and direct simulation Monte Carlo(DSMC) methods. Remarkable agreements were achieved, demonstrating the feasibility and accuracy of the numerical ***, the aerodynamic force effect of interacting plumes at different separation distances was investigated numerically.

关键词： vacuum plume plume interaction aerodynamic force effect pressure-sensitive paint CFD-DSMC

Experiment of Hall thruster plume effects on different ground experimental conditions

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航空动力学报 2019年第7期34卷 1568-1576页

作者： SU Yang CAI Guobiao he bijiao SHANG Shengfei LIU Peng LIANG Wei School of Astronautics Beijing University of Aeronautics and AstronauticsBeijing100191China Science and Technology on Reliability and Environmental Engineering Laboratory Beijing Institute of Spacecraft Environment EngineeringChina Aerospace Science and Technology CorporationBeijing100094China Electric Propulsion Department Shanghai Institute of Space PropulsionChina Aerospace Science and Technology CorporationShanghai201112China

Reducing the influence of back-sputtering effect can effectively improve the accuracy of the measurement of the Hall thruster plume *** crystal microbalance(QCM)was used to measure the deposition and sputtering distribution of heT-40 thruster plume on two different experimental conditions:case1,using liquid nitrogen heat sinks and case 2,without using liquid nitrogen heat ***,X-ray photoelectron spectroscopy(XPS)was used to analyze the composition of the QCM surface after two *** results of the two experiments showed that the sputtering rate under the condition of case 1 was slightly higher than case *** within the range of 90°to 110°relative to the thruster axis,case 1 experiment result showed sputtering effect,while case 2 experiment showed deposition *** analysis of the experimental results,it can be found that using liquid nitrogen heat sink to reduce the temperature of the inner wall surface of vacuum chamber can effectively adsorb the particles sputtered by the plume and reduce the concentration of back-sputtering particles,leading to the above phenomenon.

关键词： vacuum exhaust plume sputtering effect deposition effect Hall thruster heT-40

Three-dimensional particle simulation of ion thruster plume flows with EX-PWS

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Plasma Science and Technology 2018年第10期20卷 118-126页

作者： Hongru ZheNG Guobiao CAI Hongyue WANG Lihui LIU bijiao he School of Astronautics Beihang UniversityBeijing 100191People＇s Republic of China Beijing Institute of Aerospace Testing Technology Beijing 100074People＇s Republic of China

Ion thruster plumes from a multi-thruster array of different working configurations are simulated by a hybrid fluid-particle software. The particle in cell method is employed to model the transports of ions. The direct simulation Monte Carlo method is used to model momentum and charge exchange （CEX） collisions. The software is based on unstructured grids which make it easy to handle with complex geometry. The results of chamber simulation are compared with experimental data in ion current density and number density, which show good agreements. The maximum difference of current density along the thruster centerline is less than 9.30%. The interaction effects of plumes when multiple thrusters are operating in vacuum are predicted. Distributions of single charged xenon ions are significantly different in the near-field plume flow, however, merge into one in the far downstream region. Moreover, the interaction effect on the spatial distribution of CEX xenon ions is displayed as well.

关键词： electric propulsion multi-thruster array PIC-DSMC method ion thruster plume

Taylor-Couette流的DSMC数值模拟

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北京航空航天大学学报 2010年第3期36卷 353-356页

作者：何小英贺碧蛟蔡国飙北京航空航天大学宇航学院北京100191

使用圆柱坐标系网格的三维DSMC(Direct Simulation Monte Carlo)模型,对同轴圆柱间Taylor-Couette流中Taylor涡的形成进行了数值模拟,并分析了不同计算域和边界条件下稳定流场中Taylor涡的轴向排列结构.在网格设置和流场参数不变的情况... 详细信息

使用圆柱坐标系网格的三维DSMC(Direct Simulation Monte Carlo)模型,对同轴圆柱间Taylor-Couette流中Taylor涡的形成进行了数值模拟,并分析了不同计算域和边界条件下稳定流场中Taylor涡的轴向排列结构.在网格设置和流场参数不变的情况下,使用轴对称DSMC模型对Taylor涡进行数值模拟,所得Taylor涡的稳定过程与三维结果一致,验证了使用三维DSMC方法来解决微尺度低速的稀薄气流问题的可行性.三维模拟结果表明Taylor涡以较大的圆周速度绕轴旋转,二维模拟则无法体现.对不同的内圆柱旋转速度进行数值模拟,确定了能够产生Taylor涡的临界速度值.

关键词： Taylor涡直接模拟蒙特卡罗三维轴向排列