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| 1 | Numerical analysis of fuel regression rate distribution characteristics in hybrid rocket motors with different fuel types显示文摘This paper presents three-dimensional numerical simulations of the hybrid rocket motor with hydrogen peroxide (HP) and hy-droxyl terminated polybutadiene (HTPB) propellant combination and investigates the fuel regression rate distribution charac-teristics of different fuel types. The numerical models are established to couple the Navier-Stokes equations with turbulence,chemical reactions, solid fuel pyrolysis and solid-gas interfacial boundary conditions. Simulation results including the temper-ature contours and fuel regression rate distributions are presented for the tube, star and wagon wheel grains. The results demonstrate that the changing trends of the regression rate along the axis are similar for all kinds of fuel types, which decrease sharply near the leading edges of the fuels and then gradually increase with increasing axial locations. The regression rates of the star and wagon wheel grains show apparent three-dimensional characteristics, and they are higher in the regions of fuel surfaces near the central core oxidizer flow. The average regression rates increase as the oxidizer mass fluxes rise for all of the fuel types. However, under same oxidizer mass flux, the average regression rates of the star and wagon wheel grains are much larger than that of the tube grain due to their lower hydraulic diameters. | LI XinTian TIAN Hui CAI GuoBiao | 2013 | Science China(Technological Sciences)2013,56,7: | 11 |
| 2 | Large-scale Vacuum Vessel Design and Finite Element Analysis显示文摘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. | WANG Wenlong CAI Guobiao ZHOU Jianping | 2012 | Chinese Journal of Aeronautics2012,25,2: | 10 |
| 3 | Plume aerodynamic effects of cushion engine in lunar landing显示文摘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. | He Bijiao He Xiaoying Zhang Mingxing Cai Guobiao | 2013 | Chinese Journal of Aeronautics2013,26,2: | 9 |
| 4 | Numerical and experimental investigation on the effects of aft mixing chamber diaphragm in hybrid rocket motor显示文摘This paper focuses on the investigation of an aft mixing chamber diaphragm in a hybrid rocket motor.Both numerical and experimental researches are carried out to study its effects on the motor performances.The hybrid rocket motor with star fuel grain is utilized.The 90%hydrogen peroxide(HP)oxidizer and hydroxyl terminated polybutadiene(HTPB)based fuel are adopted as propellants.The diaphragm configuration settled in the aft mixing chamber includes four circular-holes with a uniform circumferential distribution.For both motors with and without the diaphragm,three-dimensional numerical simulations with gaseous combustions considered are carried out to study the flow field characteristics and motor performances.The comparison results show that the diaphragm can improve the mixing of the oxidizer and fuel.It has evident effect on increasing the motor efficiencies.Two firing experiments are conducted with full scale motors to investigate the effects of the diaphragm.The diaphragm used in the test is composed of a central steel framework and a closed thermal insulation layer.With the diaphragm employed,the combustion efficiency increases from 93.9%to 97.34%and the specific impulse efficiency increases from 80.77%to 87.28%,which verifies the positive effect of the diaphragm.Both numerical and experimental studies indicate that the scheme of the aft mixing chamber diaphragm proposed in the paper can improve the efficiencies of the hybrid rocket motor obviously. | TIAN Hui LI XinTian YU NanJia CAI GuoBiao | 2013 | Science China(Technological Sciences)2013,56,11: | 9 |
| 5 | Design and optimization of variable thrust hybrid rocket motors for sounding rockets显示文摘Besides safety and low-cost,the start/shutdown/restarting and throttling ability are the other two significant advantages of hy-brid rocket motors(HRMs) compared with liquid and solid ones.In this study,a two-stage variable thrust and non-toxic 98%HP/HTPB hybrid rocket motor(VTHRM) is designed and applied in a sounding rocket,and the design parameters of the motor are analyzed and optimized.A computational program is developed to design the motor system structure,to predict the interior ballistics and the ballistic trajectory.A star grain and a wheel grain are compared.The design of experiment(DOE),variance analysis and the main effect analysis are employed to investigate the influence of the main design parameters on mo-tor performance.The multidiscipline feasible(MDF) approach is applied to establish the optimization procedure after analyz-ing the system design structure matrix.A modified differential evolution algorithm is employed to maximize the load mass.The results indicate that the wheel grain could obtain a larger load mass and a lower length to diameter ratio,and that throttling markedly meliorates the motor and rocket performance.The conclusions drawn from the analysis and optimization could pro-vide instructive guide and theoretical basis for engineering designs. | RAO DaLin CAI GuoBiao ZHU Hao TIAN Hui | 2012 | Science China(Technological Sciences)2012,55,1: | 9 |
| 6 | Design and integrated simulation of a pressurized feed system of the dual-thrust hybrid rocket motor显示文摘A new pressurized feed system of the dual-thrust hybrid rocket motor for flight is presented in this paper.The feed system supplies 90% hydrogen peroxide (90%H 2 O 2) with two different flows of 4.5 and 2 kg s 1.The oxidizer flow is changed through regulating the mass flow of the high-pressure gas and switching the performance modes of the unique oxidizer flow control valve simultaneously.The models of the gas storage container,pressure regulator valve,control orifice,propellant tank,oxidizer flow control valve and cavitating venturi are generated and used to compute the instantaneous pressure,temperature and mass flow rate.There is a good agreement between the simulated and experimental results.Parameter sensitivity analysis is also conducted.It is found that the throat diameter of the cavitating venturi in feed line 1 is the main factor affecting the mass flow in both boost and sustaining phase.Other parameters have limited effects on the mass flow rate and the transition time of the system. | LI JunHai YU NanJia ZENG Peng CAI GuoBiao | 2013 | Science China(Technological Sciences)2013,56,4: | 9 |
| 7 | Research on vacuum plume and its effects显示文摘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. | He Bijiao Zhang Jianhua Cai Guobiao | 2013 | Chinese Journal of Aeronautics2013,26,1: | 6 |
| 8 | Multi-disciplinary design optimization with fuzzy uncertainties and its application in hybrid rocket motor powered launch vehicle显示文摘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 simulation.The 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 algorithm.The 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. | Pengcheng WANG Hui TIAN Hao ZHU Guobiao CAI | 2020 | Chinese Journal of Aeronautics2020,33,5: | 6 |
| 9 | Uncertainty analysis and probabilistic design optimization of hybrid rocket motors for manned lunar landing显示文摘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 design.Based on the results of an uncertainty analysis of HRMs,an uncertainty-based design optimization(UDO)method is also adopted to improve the design reliability.The 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 parameters.The 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 HRMs.The 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 System.The 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 throating.Comparisons of the DDO and UDO results indicate that the UDO method achieves more robust and reliable optimal designs than the DDO method.The probabilistic UDO method can be used to develop better conceptual designs for HRMs. | ZHU Hao TIAN Hui CAI GuoBiao BAO WeiMin | 2015 | Science China(Technological Sciences)2015,58,7: | 4 |
| 10 | Design of double-layer anti-sputtering targets for plume effects experimental system显示文摘在一个真空房间使用的一个电的推进器的劈啪作响背的效果在推进器,真空房间和试验性的设备上有不利效果。一个劈啪作响反的目标(著名计算机生产厂商) 能由减少劈啪作响背的免职效果扩大真空房间的操作生活。在国际设备使用的真空房间成功地合并了著名计算机生产厂商。改进著名计算机生产厂商表演,一个双层结构著名计算机生产厂商基于羽毛效果,试验性的系统(足) 被设计。结构 AST 主要结束当第二等的结束作为一个快门被设计解决象服务生活,劈啪作响的材料的背流动率,经济和系统安全那样的因素时,作为一座公寓被设计。验证双层著名计算机生产厂商的效果, AST 有或没有的劈啪作响的效果第二等结束被一个 DSMC 照片算法评估。另外,赤裸的房间的试验性的确认和目标被执行。结果显示第二等的结束石墨表能减少背流动收益约 50% 。双层著名计算机生产厂商的设计能为一个劈啪作响反的目标的设计作为一本参考书被介绍。 | SHANG ShengFei CAI GuoBiao ZHU DingQiang HE BiJiao | 2016 | Science China(Technological Sciences)2016,59,8: | 4 |
| 11 | Theoretical development for DSMC local time stepping technique显示文摘The direct simulation Monte Carlo(DSMC) method is the most mature and wildly used approach for nonequilibrium gas flow simulation.The phenomenological nature of this method brings flexibility to the computation algorithms.In this study,the theoretical foundations to decouple the molecular motion and collision within a time step are discussed in detail,which can be treated as criterions for the DSMC algorithms.Based on the theoretical developments,an improved local time stepping scheme is proposed,which specifies the movement time attribute and the collision time attribute for each representative particle.A free flow about a sphere body is considered as an example,which is compared with the calculations using the published local time stepping technique.The results show that the improved local time scheme is valid and is promising in realizing flow structures with strong variations. | CAI GuoBiao SU Wei HOU FengLong | 2012 | Science China(Technological Sciences)2012,55,10: | 4 |
| 12 | Effects of axial gap and nozzle distribution on aerodynamic forces of a supersonic partial-admission turbine显示文摘The turbine in an LH2/LOX rocket engine is designed as a two-stage supersonic partialadmission turbine. Three-dimensional steady and unsteady simulations were conducted to analyze turbine performance and aerodynamic forces on rotor blades. Different configurations were employed to investigate the effects of the axial gap and nozzle distribution on the predicted performance and aerodynamic forces. Rotor blades experience unsteady aerodynamic forces because of the partial admission. Aerodynamic forces show periodicity in the admission region, and are close to zero after leaving the admission region. The unsteady forces in frequency domain indicate that components exist in a wide frequency region, and the admission passing frequency is dominant.Those multiples of the rotational frequency which are multiples of the nozzle number in a fulladmission turbine are notable components. Results show that the turbine efficiency decreases as the axial gap between nozzles and the 1 st stage rotor(rotor 1) increases. Fluctuation of the circumferential aerodynamic force on rotor 1 blades decreases with the axial gap increasing. The turbine efficiency decreases as the circumferential spacing between nozzles increases. Fluctuations of the circumferential and axial aerodynamic forces increase as the circumferential spacing increases. As for the non-equidistant nozzle distribution, it produces similar turbine performance and amplitudefrequency characteristics of forces to those of the normal configuration, when the mean spacing is equal to that of the normal case. | Jinpeng JIANG Jiawen LI Guobiao CAI Jue WANG Qiyan LIN | 2017 | Chinese Journal of Aeronautics2017,30,6: | 4 |
| 13 | Uncertainty analysis and design optimization of hybrid rocket motor powered vehicle for suborbital flight显示文摘In this paper, we propose an uncertainty analysis and design optimization method and its applications on a hybrid rocket motor(HRM) powered vehicle. The multidisciplinary design model of the rocket system is established and the design uncertainties are quantified. The sensitivity analysis of the uncertainties shows that the uncertainty generated from the error of fuel regression rate model has the most significant effect on the system performances. Then the differences between deterministic design optimization(DDO) and uncertainty-based design optimization(UDO) are discussed. Two newly formed uncertainty analysis methods, including the Kriging-based Monte Carlo simulation(KMCS) and Kriging-based Taylor series approximation(KTSA), are carried out using a global approximation Kriging modeling method. Based on the system design model and the results of design uncertainty analysis, the design optimization of an HRM powered vehicle for suborbital flight is implemented using three design optimization methods: DDO, KMCS and KTSA. The comparisons indicate that the two UDO methods can enhance the design reliability and robustness. The researches and methods proposed in this paper can provide a better way for the general design of HRM powered vehicles.In this paper,we propose an uncertainty analysis and design optimization method and its applications on a hybrid rocket motor(HRM)powered vehicle.The multidisciplinary design model of the rocket system is established and the design uncertainties are quantified.The sensitivity analysis of the uncertainties shows that the uncertainty generated from the error of fuel regression rate model has the most significant effect on the system performances.Then the differences between deterministic design optimization(DDO)and uncertainty-based design optimization(UDO)are discussed.Two newly formed uncertainty analysis methods,including the Kriging-based Monte Carlo simulation(KMCS)and Kriging-based Taylor series approximation(KTSA),are carried out using a global approximation Kriging modeling method.Based on the system design model and the results of design uncertainty analysis,the design optimization of an HRM powered vehicle for suborbital flight is implemented using three design optimization methods:DDO,KMCS and KTSA.The comparisons indicate that the two UDO methods can enhance the design reliability and robustness.The researches and methods proposed in this paper can provide a better way for the general design of HRM powered vehicles. | Zhu Hao Tian Hui Cai Guobiao Bao Weimin | 2015 | Chinese Journal of Aeronautics2015,28,3: | 4 |
| 14 | Hybrid uncertainty-based design optimization and its application to hybrid rocket motors for manned lunar landing显示文摘Design reliability and robustness are getting increasingly important for the general design of aerospace systems with many inherently uncertain design parameters.This paper presents a hybrid uncertainty-based design optimization(UDO) method developed from probability theory and interval theory.Most of the uncertain design parameters which have sufficient information or experimental data are classified as random variables using probability theory,while the others are defined as interval variables with interval theory.Then a hybrid uncertainty analysis method based on Monte Carlo simulation and Taylor series interval analysis is developed to obtain the uncertainty propagation from the design parameters to system responses.Three design optimization strategies,including deterministic design optimization(DDO),probabilistic UDO and hybrid UDO,are applied to the conceptual design of a hybrid rocket motor(HRM) used as the ascent propulsion system in Apollo lunar module.By comparison,the hybrid UDO is a feasible method and can be effectively applied to the general design of aerospace systems. | Zhu Hao Tian Hui Cai Guobiao | 2017 | Chinese Journal of Aeronautics2017,30,2: | 3 |
| 15 | Investigation on aerodynamic force effect of vacuum plumes using pressure-sensitive paint technique and CFD-DSMC solution显示文摘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 approach.Finally, the aerodynamic force effect of interacting plumes at different separation distances was investigated numerically. | WU Jing BITTER Martin CAI GuoBiao HE BiJiao KAEHLER Christian | 2017 | Science China(Technological Sciences)2017,60,7: | 3 |
| 16 | Experimental and numerical analysis of the heat flux characteristic of the plume of a 120-N thruster显示文摘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. | ZHANG MingXing CAI GuoBiao HE BiJiao TANG ZhenYu ZHOU Hao | 2019 | Science China(Technological Sciences)2019,62,10: | 3 |
| 17 | Extension of the low diffusion particle method for near-continuum two-phase flow simulations显示文摘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. | Su Wei He Xiaoying Cai Guobiao | 2013 | Chinese Journal of Aeronautics2013,26,1: | 3 |
| 18 | Numerical Simulation of 2D Supersonic Magnetohydrodynamic Channel and Study on Hall Effect显示文摘In this research effort,numerical simulation of two-dimensional magnetohydrodynamic(MHD) channel is performed and Hall effect is studied.The computational model consists of the Navier-Stokes(N-S) equations coupled with electrical-magnetic source terms,Maxwell equations and the generalized Ohm's law.Boundary conditions for the electrical potential equation considering Hall effect are derived.To start with,the MHD channel with single-pair electrodes is studied and flow of the electric current is in accordance with physical principle.Then the MHD channel with five-pair electrodes is numerically simulated.The results show that the electrical current concentrates on the downstream of the anode and the upstream of the cathode due to Hall effect,and the flow field becomes asymmetrical.At the current value of the magnetic interaction parameter,the electrical-magnetic force affects the flow remarkably,decreasing the outlet Mach number and increasing the outlet pressure;what's more,the flow structure in the channel becomes extremely complex.Performances of MHD channels with continual electrodes and segmented electrodes are compared.The results show that performance of the MHD channel with segmented electrodes is better than that with continual electrodes with the increase of Hall parameter. | ZHENG Xiaomei LU Haoyu XU Dajun CAI Guobiao | 2011 | Chinese Journal of Aeronautics2011,24,2: | 3 |
| 19 | Effects of axial gap on aerodynamic force and response of shrouded and unshrouded blade显示文摘Forced response analysis of a rocket engine turbine blade was conducted by a decoupled fluid-structure interaction procedure.Aerodynamic forces on the rotor blade were obtained using 3D unsteady flow simulations. The resulting aerodynamic forces were interpolated to the finite element(FE) model through surface effect elements prior to conducting forced response calculations.Effects of axial gap on aerodynamic forces were studied. In addition, influence of axial gap on the response of the shrouded blade was compared with that on the response of the unshrouded blade. Results demonstrated that as the axial gap increases,time-averaged pressure on the blade surface changes very little, while the pressure fluctuations decrease significantly. Pressure and aerodynamic forces on the blade surface display periodic variation, and the vane passing frequency component is dominant.Amplitudes of aerodynamic forces decrease with increasing axial gap. Restricted by the shroud, deformation and response of shrouded blade are much lower than those of the unshrouded blade. The response of unshrouded blade shows obvious beat vibration phenomenon, while the response of the shrouded blade does not have this characteristic because the shroud restrains multiple harmonics. Blade response in time domain was converted to frequency domain using fast Fourier transformation(FFT).Results revealed that the axial gap mainly affects the forced harmonic at the vane passing frequency, while the other two harmonics at natural frequency are hardly affected. Amplitudes of the unshrouded blade response decrease as the axial gap increases, while amplitudes of the shrouded blade response change very little in comparison. | JIANG JinPeng LI JiaWen CAI GuoBiao WANG Jue | 2017 | Science China(Technological Sciences)2017,60,4: | 2 |
| 20 | Steady-state coupled analysis of flowfields and thermochemical erosion of C/C nozzles in hybrid rocket motors显示文摘A hybrid rocket can be used in various applications and is an attractive propulsion system.However,serious erosion of nozzles is common in motor firing operations,which could restrict the application of hybrid rocket motors.Usually,the serious erosion is attributed to the high concentration of oxidizing species in hybrid motors,while the details of flowfields in the motors are not paid special attention to.In this paper,first the thermochemical erosion of C/C nozzle is simulated coupled with the flowfields in a 98%H2O2/hydroxyl-terminated polybutadiene(HTPB)hybrid rocket motor.The simulation is made on a typical axisymmetric motor,including a pre-combustion chamber,an aft-combustion chamber and nozzle structures.Thermochemical reactions of H2O,CO2,OH,O and O2with C are taken into account.Second,the change of flowfields due to fuel regression during motor firing operations is considered.Nozzle erosion in different flowfields is evaluated.Third,the results of nozzle erosion in the coupled simulation are compared with those under uniform and chemical equilibrium flow and motor firing test results.The results of simulation and firing tests indicate that the thermochemical erosion of nozzles in hybrid motors should be calculated coupled with flowfields in the motor.In uniform and chemical equilibrium flowfields,the erosion rate is overestimated.The diffusion flame in hybrid motors protects the nozzle surface from the injected oxidizer and high temperature products in flowfields,leading to a relatively fuel-rich environment above the nozzle.The influence of OH and the geometry of motor should also be considered in the evaluation of nozzle erosion in hybrid motors. | ZHAO Sheng TIAN Hui WANG PengFei YU NanJia CAI GuoBiao | 2015 | Science China(Technological Sciences)2015,58,3: | 2 |