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Research on vacuum plume and its effects

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Chinese Journal of Aeronautics 2013年第1期26卷 27-36页

作者： He Bijiao Zhang Jianhua cai guobiao School of Astronautics Beihang University

In vacuum environment, the exhaust flow of attitude control thrusters would expand freely and produce the plume, which possibly causes undesirable contamination, aerodynamic force and heating effects to the spacecraft. Plume work station （PWS） is developed by Beihang University （BUAA） for numerically simulating the vacuum plume and its effects. An approach which combines the direct simulation Monte Carlo （DSMC） method and difference solution of Navier-Stokes （N-S） equations is applied. The internal flows in nozzles are simulated by solving the NS equations. The flow parameters at nozzle exit are used as the inlet boundary condition for the DSMC calculation. Experimental studies are carried out in a supersonic low density wind tunnel which could simulate the 60-80 km altitude environment to investigate the plume and its effects. To demonstrate the capability of PWS, numerical simulations are performed for the vacuum plume of several typical attitude control thrusters. The research results are of great help for the engineering design.

关键词： Attitude control Effects Experiments Monte Carlo methods Vacuum plume

Investigation of non-premixed flame combustion characters in GO_2/GH_2 shear coaxial injectors using non-intrusive optical diagnostics

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Science China(Physics,Mechanics & Astronomy) 2015年第12期58卷 167-179页

作者： DAI Jian YU NanJia cai guobiao Beijing University of Aeronautics and Astronautics

Single-element combustor experiments are conducted for three shear coaxial geometry configuration injectors by using gaseous oxygen and gaseous hydrogen(GO2/GH2) as propellants. During the combustion process, several spatially and time- resolved non-intrusive optical techniques, such as OH planar laser induced fluorescence(PLIF), high speed imaging, and infrared imaging, are simultaneously employed to observe the OH radical concentration distribution, flame fluctuations, and temperature fields. The results demonstrate that the turbulent flow phenomenon of non-premixed flame exhibits a remarkable periodicity, and the mixing ratio becomes a crucial factor to influence the combustion flame length. The high speed and infrared images have a consistent temperature field trend. As for the OH-PLIF images, an intuitionistic local flame structure is revealed by single-shot instantaneous images. Furthermore, the means and standard deviations of OH radical intensity are acquired to provide statistical information regarding the flame, which may be helpful for validation of numerical simulations in future. Parameters of structure configurations, such as impinging angle and oxygen post thickness, play an important role in the reaction zone distribution. Based on a successful flame contour extraction method assembled with non-linear anisotropic diffusive filtering and variational level-set, it is possible to implement a fractal analysis to describe the fractal characteristics of the non-premixed flame contour. As a result, the flame front cannot be regarded as a fractal object. However, this turbulent process presents a self-similarity characteristic.

关键词： liquid rocket engine shear coaxial injector non-intrusive optical techniques image segmentation fractal analysis

Extension of the low diffusion particle method for near-continuum two-phase flow simulations

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Chinese Journal of Aeronautics 2013年第1期26卷 37-46页

作者： Su Wei He Xiaoying cai guobiao School of Astronautics Beihang University

The low diffusion （LD） particle method, proposed by Burt and Boyd, is modified for the near-continuum two-phase flow simulations. The LD method has the advantages of easily coupling with the direct simulation Monte Carlo （DSMC） method for multi-scale flow simulations and dramatically reducing the numerical diffusion error and statistical scatter of the equilibrium particle methods. Liquidor solid-phase particles are introduced in the LD method. Their velocity and temperature updating are respectively, calculated from the motion equation and the temperature equation according to the local gas properties. Coupling effects from condensed phase to gas phase are modeled as momentum and energy sources, which are respectively, equal to the negative values of the total momentum and energy increase in liquid or solid phase. The modified method is compared with theoretical results for unsteady flows, and good agreements are obtained to indicate the reliability of the one-way gas-to-particle coupling models. Hybrid LD-DSMC algorithm is implemented and performed for nozzle discharging gas-liquid flow to show the prospect of the LD-DSMC scheme for multi-scale two-phase flow simulations.

关键词： DSMC method Hybrid simulation Low diffusion particle method Motion relaxation Temperature relaxation Two-phase flow

Large-scale Vacuum Vessel Design and Finite Element Analysis

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Chinese Journal of Aeronautics 2012年第2期25卷 189-197页

作者： WANG Wenlong cai guobiao ZHOU Jianping School of Astronautics Beihang UniversityBeijing 100191China

The vacuum plume effects experimental system （PES） is the first experimental system designed to study the effects of vacuum plume in China. The main equipment, a vacuum chamber of 5.5 m in diameter and 12.8 m in length, and structure design of hinged door are described. The finite element method （FEM） is adopted to analyze the static strength and stability of the PES vacuum chamber. It is demonstrated that the static strength and stability are qualified. For the 5.5 m diameter vacuum chamber door, three design schemes are put forward. After comparisons are made, the single-axis-double-pin hinged door is selected. The FEM is applied to checking its static strength as well as distortions. The results show that the door’s distortion and displacement change mainly due to the gravity of the door which leads to its sinking. The calculated displacement is less than 7.8 mm, while the actual measurement is 5 mm. The single-axis-double-pin hinged door mechanism completely satisfies the design requirements. This innovative structure can be introduced as a reference for the design of large-scale hinged doors.

关键词： vacuum design finite element method buckling chamber hinges

Numerical simulation and a hybrid method of supersonic turbulent base heating

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航空动力学报 2018年第10期33卷 2442-2450页

作者： YUAN Junya cai guobiao ZHAO Lu School of Astronautics Beijing University of Aeronautics and Astronautics Beiiing 100191 China

Detached eddy simulation(DES)model was used to better capture large vortex structure and unsteady flow feature near cone *** base heating results were achieved using proper grid and numerical *** influence of inflow conditions(like Mach number,Reynolds number)and configuration(bluntness ratio of the cone)on base heating was discussed based on numerical computational *** with base heat flux,base pressure can be predicted more accurately by numerical simulation and the time consuming was shorter.A hybrid method combining numerical simulation with experimental correlation was proposed to predict supersonic turbulent base heating.A review of base heating experiment and correlations for slender cone was presented,and a revised correlation was proposed based on the above simulation *** with the experiment data,the maximum error was 24%,agood result for base heating *** proves that the hybrid method using the revised correlation performs well in predicting supersonic turbulent base heating of slender sphere cone and can meet needs of engineering design.

关键词： base heating detached eddy simulation hybrid method experimental correlation slender sphere cone

Experimental study of hydrogen-rich/oxygen-rich gas–gas injectors

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Chinese Journal of Aeronautics 2013年第5期26卷 1164-1172页

作者： Jin Ping Li Mao cai guobiao School of Astronautics Beihang University

Five types of coaxial injectors were investigated experimentally using hot hydrogen-rich gas and oxygen-rich gas, which were respectively provided by a GH2/GO2 hydrogen-rich perburner and a GH2/GO2 oxygen-rich preburner. The injectors were the shear coaxial injector, the oxidizer post expansion coaxial injector, the fuel impinging coaxial injector, the central body coaxial injector, and the shear tri-coaxial injector. The characteristic velocity efficiency and the combustor＇s wall temperatures were obtained for different design parameters through the experiments. It can be con- cluded that angles of the oxidizer post expansion and the fuel impinging have little influence on the combustion performance and the wall temperatures. The contact area between fuel and oxidizer and the mass flow rate have significant impacts on the combustion performance. The shear tri-coaxial injector has the best combustion performance but also the highest wall temperatures among the five types of injectors.

关键词： Combustion performance Experiment Gas-gas injector High mass flow rate Wall temperature

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

Multi-disciplinary design optimization with fuzzy uncertainties and its application in hybrid rocket motor powered launch vehicle

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Chinese Journal of Aeronautics 2020年第5期33卷 1454-1467页

作者： Pengcheng WANG Hui TIAN Hao ZHU guobiao cai School of Astronautics Beihang UniversityBeijing 100083China Key Laboratory of Spacecraft Design Optimization&Dynamic Simulation Technologies of Ministry of Education Beihang UniversityBeijing 100083China

In this paper,an Uncertainty-based Multi-disciplinary Design Optimization (UMDO)method combining with fuzzy theory and Multi-Discipline Feasible (MDF) method is developed for the conceptual design of a Hybrid Rocket Motor (HRM) powered Launch Vehicle (LV).In the method proposed,membership functions are used to represent the uncertain factors,the fuzzy statistical experiment is introduced to analyze the propagation of uncertainties,and means,standard deviations and credibility measures are used to delineate uncertain responses.A geometric programming problem is solved to verify the feasibility of the Fuzzy-based Multi-Discipline Feasible(F-MDF) method.A multi-disciplinary analysis of a three-stage HRM powered LV involving the disciplines of propulsion,structure,aerodynamics and trajectory is implemented,and the mathematical models corresponding to the F-MDF method and the MDF method are established.A two-phase optimization method is proposed for multi-disciplinary design optimization of the LV,including the orbital capacity optimization phase based on the Ziolkowski formula,and the scheme trajectory verification phase based on the 3-degree-of-freedom point trajectory *** correlation coefficients and the quadratic Response Surface Method (RSM) based on Latin Hypercube Sampling (LHS) are adopted for sensitive analysis of uncertain factors,and the Multi-Island Genetic Algorithm (MIGA) is adopted as the optimization *** results show that the F-MDF method is applicable in LV conceptual design,and the design with the F-MDF method is more reliable and robust than that with the MDF method.

关键词： Fuzzy theory Hybrid Rocket Motor(HRM) Launch Vehicle(LV) Sensitive Analysis(SA) Uncertainty-based Multi-disciplinary Design Optimization(UMDO)

Uncertainty analysis and probabilistic design optimization of hybrid rocket motors for manned lunar landing

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Science China(Technological Sciences) 2015年第7期58卷 1234-1241页

作者： ZHU Hao TIAN Hui cai guobiao BAO WeiMin School of Astronautics Beihang University China Aerospace Science and Technology Corporation

To obtain a conceptual design for a hybrid rocket motor(HRM)to be used as the Ascent Propulsion System in the Apollo lunar module,the deterministic design optimization(DDO)method is applied to the HRM *** on the results of an uncertainty analysis of HRMs,an uncertainty-based design optimization(UDO)method is also adopted to improve the design *** HRM design process,which is a multidisciplinary system,is analyzed,and a mathematical model for the system design is established to compute the motor performance from the input parameters,including the input variables and model *** input parameter uncertainties are quantified,and a sensitivity analysis of the model parameter uncertainties is conducted to identify the most important model parameter uncertainties for *** DDO and probabilistic UDO methods are applied to conceptual designs for an HRM to be used as a substitute for the liquid rocket motor(LRM)of the Ascent Propulsion *** conceptual design results show that HRMs have several advantages as an alternative to the LRM of the Ascent Propulsion System,including nontoxic propellant combination,small motor volume,and comparable functions,such as restarting and *** of the DDO and UDO results indicate that the UDO method achieves more robust and reliable optimal designs than the DDO *** probabilistic UDO method can be used to develop better conceptual designs for HRMs.

关键词： hybrid rocket motor deterministic design optimization uncertainty-based design optimization sensitivity analysis manned lunar landing