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Three-dimensional numerical analysis on combustion performance and flow of hybrid rocket motor with multi-segmented grain

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Chinese Journal of Aeronautics 2020年第4期33卷 1181-1191页

作者： Hui TIAN Yu DUAN Hao ZHU School of Astronautics Beihang UniversityBeijing 100083China Key Laboratory of Spacecraft Design Optimization&Dynamic Simulation Technologies Ministry of EducationBeihang UniversityBeijing 100083China

This paper presents the combustion characteristics in hybrid rocket motors with multisegmented grain through three-dimensional numerical ***-segmented grain is composed of several thin grains with two or more *** numerical model consists of Navier-Stokes equations with turbulence,solid fuel pyrolysis,chemical reactions,a fluid–solid coupling model and a regression rate *** simulations adopt 90%Hydrogen Peroxide(HP)and PolyEthylene(PE)as the propellant *** effects of the rotation,port number,fuel grain segment number and mid-chamber length on the flow field and combustion performances are *** results indicate that the multi-segmented grain configuration can strengthen the flow field,and the regression rate and combustion efficiency are *** the cases with two grain segments and three ports for example,the regression rate is increased by 32.4%-45.1%and the combustion efficiency increases by 6%-8.6%in different rotation angles.

关键词： Combustion efficiency Hybrid rocket motor Multi-segmented grain Regression rate Rotation angle

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design and experimental research of a sub-Newton N_(2)O monopropellant thruster with inner-heater

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Chinese Journal of Aeronautics 2022年第5期35卷 309-318页

作者： Kaiyang LI Jie FANG Wei SUN Bing SUN Guobiao CAI School of Astronautics Beihang UniversityBeijing 100083China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies of Ministry of Education Beihang UniversityBeijing 100083China China Academy of Space Technology Beijing 100094China

Nitrous oxide(N_(2)O)is a green propellant with excellent application prospects.A subNewton N_(2)O monopropellant thruster with inner-heater and a N_(2)O self-pressurization stable supply system with regenerative heat compensation are designed in this *** experimental research of the thruster is described,including measurements of preheating power,activation temperature,vacuum thrust,specific impulse,life-span and pulsed operation *** inserting the heater into the catalyst-bed,preheating efficiency of the heater is significantly improved compared to the thruster with ***,the preheating power demand of the thruster is successfully reduced to around 10 *** mean vacuum thrust of 322 mN is attained and the corresponding specific impulse reaches 162s at the mass flow rate of 0.2 g/*** activation temperature of 523 K is achieved,and the activation performance of the thruster is affected by the loading factor.A long term hot-firing test longer than 12000 s is *** pulsed operation performance of the inner-preheating thruster is also studied by measuring chamber *** with different magnitudes are produced by adjusting the opening duration of the control valve.A minimum impulse of 81 mN·s is ***,the performance of the thruster is evaluated by comparison with other thrusters of the same *** results indicate that the proposed thruster with inner-heater is superior in terms of preheating power,activation temperature and specific impulse performance.

关键词： Green propellant Monopropellant thruster Nitrous oxide Regenerative heat compensation Self-pressurization

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Experiment research on regression rate of aluminized solid propellant with HMX using reconstruction techniques

Experiment research on regression rate of aluminized solid p...

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2023 International Conference on Mechanical, Aerospace and Electronic Systems, MAES 2023

作者： Wei, T.F. Cai, G.B. Tian, H. Lu, Y.D. Niu, X.T. School of Astronautics Beihang University 100191 China Key Laboratory of Spacecraft Design Optimization & Dynamic Simulation Technologies Ministry of Education China

In this research, a firing test was conducted on a Hybrid Rocket Motor (HRM) that operates using an aluminized solid propellant containing HMX and Hydrogen Peroxide (HP). The instantaneous regression rate of HRM is determined using reconstruction techniques, and the formula of regression rate is fitted by reconstruction techniques and traditional weight-loss method. The utilization of the reconstruction method presents a notable advantage, as it allows for the determination of the regression rate's sensitivity to variations in oxidizer mass flux. Additionally, this method enables the fitting of the regression rate formula based on data obtained from a single firing test. The average value of regression rate of four times firing test are 0.944, 0.529, 0.595 and 0.486 mm/s. According to the weight-loss method and reconstruction techniques, the coefficients of determination (R2) of regression rate formula fitting are 0.8867 and 0.93 respectively, indicating that the accuracy of the fitting is better than that of traditional method. Overall, this paper presents a comparison of traditional weight-loss method and reconstruction techniques for providing a critical preference for the research of regression rate of HRM. © Published under licence by IOP Publishing Ltd.

关键词： Sensitivity analysis

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Numerical Study of Pipeline Distribution Effect on the Performance of Pasty Propellant Rocket Motor

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Space(Science & technology) 2023年第1期3卷 572-584页

作者： Renjie Hu Weizong Wang Advanced Space Propulsion and Energy Laboratory(ASPEL) School of AstronauticsBeihang UniversityBeijingChina Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Ministry of EducationBeijingChina Aircraft and Propulsion Laboratory Ningbo Institute of TechnologyBeihang UniversityNingboChina

This paper reports the numerical research on PPRM(pasty propellant rocket motor)through computational fluid dynamics simulation along with pipeline design comparison based on simulation *** structure of PPRM includes feed pipelines,and the propellant is distributed in a cone shape when burnt steadily in the combustion *** a result,the internal flow field presents strong 3-dimensional characteristics,which may lead to the flow *** accurately understand the combustion flow field and flow instability in the PPRM,a numerical simulation of the combustion chamber considering propellant pyrolysis and chemical reaction,coupled with the feed system module,is employed in the *** effect of pipeline distribution,including the pipeline location and the nonuniformity of pipeline diameter on the internal combustion flow characteristics as well as the motor thrust,was *** results show that the vortex caused by the special conical shape of the burning surface leads to pressure *** adjusting the pipeline location and the nonuniformity of pipeline diameter,the distribution of vortex varies dramatically,which leads to different oscillation frequencies and *** some pipeline distribution schemes,there is almost no large vortex in the rocket motor,which greatly eliminates the flow acoustic coupling oscillation of the *** oscillation amplitude decreases from about 5.7%to less than 0.1%.The results will help guide the design of the high-performance feed system and combustion chamber of PPRM.

关键词： vortex oscillation eliminate

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Modular design of A Radial Scalled Hall Thruster for Different Magnetic Configurations

Modular Design of A Radial Scalled Hall Thruster for Differe...

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2019 IEEE Pulsed Power and Plasma Science, PPPS 2019

作者： Olano, A. Tang, H. Ren, J. Zhang, G. Li, J. Key Lab. of Spacecraft Design Optimization Dynamic Simulation Technologies of Ministry of Education School of Astronautics Beihang University Beijing100191 China Key Lab. of Spacecraft Design Optimization Dynamic Simulation Technologies of Ministry of Education School of Space and Environment Beihang University Beijing100191 China Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou Institute of Physics Lanzhou730000 China

ISBN: (纸本)9781538679692

A 100 W radial scaled Hall Thruster has been designed and manufactured using as reference design the D-55 thruster with anode layer (TAL). The magnetic field required is provided by permanent magnets following a modular design in order to compare three different magnetic field configurations: A) nominal, B) orthogonal magnetic field and C) high magnetic field. In Hall Thrusters the magnetic field is used to confine the electrons and create highly ionized plasma. Configuration A and configuration B were chosen to compare two different topographies of the magnetic field with two different magnetic field gradients and to study their influence in the plasma discharge and thruster performance. Both configurations where derived assuming Bohm diffusion as the dominant process in the plasma discharge. If instead of Bohm diffusion it is considered electron-wall collisions as main mechanism in the electron transport then a higher magnetic field is required and in consequence configuration C was designed. These three configurations are intended to provide a better understanding of the influence of the magnetic field in the thruster discharge. © 2019 IEEE.

关键词： Magnetic fields

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Mamba-based deformable medical image registration with an annotated brain MR-CT dataset

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Computerized Medical Imaging and Graphics 2025年 123卷 102566-102566页

作者： Yinuo Wang Tao Guo Weimin Yuan Shihao Shu Cai Meng Xiangzhi Bai Image Processing Center Beihang University Beijing 100191 China Center of Excellence for Smart Health (KCSH) King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Kingdom of Saudi Arabia Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technology Ministry of Education Beijing 100191 China Vision-BHU Joint AI+Computing Optics Laboratory Beijing 100191 China State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 China

Deformable registration is essential in medical image analysis, especially for handling various multi- and mono-modal registration tasks in neuroimaging. Existing studies lack exploration of brain MR-CT registration, and face challenges in both accuracy and efficiency improvements of learning-based methods. To enlarge the practice of multi-modal registration in brain, we present SR-Reg, a new benchmark dataset comprising 180 volumetric paired MR-CT images and annotated anatomical regions. Building on this foundation, we introduce MambaMorph, a novel deformable registration network based on an efficient state space model Mamba for global feature learning, with a fine-grained feature extractor for low-level embedding. Experimental results demonstrate that MambaMorph surpasses advanced ConvNet-based and Transformer-based networks across several multi- and mono-modal tasks, showcasing impressive enhancements of efficacy and efficiency. Code and dataset are available at https://***/mileswyn/MambaMorph .

关键词： Deformable medical image registration Multi-modal brain registration State space model Medical image analysis

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Coupling plasma plume of a low-power magnetically shielded Hall thruster with a hollow cathode

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Chinese Journal of Aeronautics 2020年第12期33卷 3018-3026页

作者： Guangchuan ZHANG Junxue REN Wei LIANG Ning OUYANG Chao LU Haibin TANG School of Space and Environment Beihang UniversityBeijing 100083China School of Astronautics Beihang UniversityBeijing 100083China Shanghai Institute of Space Propulsion Shanghai 201112China Key Laboratory of Spacecraft Design Optimization&Dynamic Simulation Technologies Ministry of EducationBeijing 100083China Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information TechnologyBeijing 100083China

The coupling region of a Hall thruster with a hollow cathode is the region between the cathode and the thruster *** characteristics of plasma in that region are complicated and strongly associated with the thruster working conditions and the cathode *** this paper,a laboratory 100 W class magnetically shielded Hall thruster was coupled with a hollow *** imaging and electrostatic probe were employed to monitor and scan the plasma *** characteristics in the coupling region in non-self-sustained mode and self-sustained mode were *** of the coupling plume with the cathode position was *** show that,when turning the thruster into self-sustained mode or moving the cathode further away axially,the discharge current can be reduced by 6.4–10.6%restraining the electron current and improving *** particular,when the cathode is moved further,the electron conduction near the channel walls is *** electron current is reduced by 27.4%and the ion beam current is increased by 7%.Overall,this work shows that the working mode of the thruster and the position of the cathode greatly affect the coupling plasma *** play an important role in improving the utilizations of propellant and current.

关键词： Coupling region Electron conduction Hall thruster Hollow cathode Utilizations of propellant and current

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Infrared Small Target Detection Based on Prior Weighed Sparse Decomposition 18th

Infrared Small Target Detection Based on Prior Weighed Spar...

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18th Chinese Conference on Image and Graphics technology and Application Conference, IGTA 2023

作者： Yang, Dongning Zhang, Haopeng Xie, Fengying Jiang, Zhiguo School of Astronautics Beihang University Beijing102206 China Beijing Key Laboratory of Digital Media Beijing102206 China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Ministry of Education Beijing102206 China

ISBN: (纸本)9789819975488

Infrared small target detection is a critical topic and research focus in target detection. Compared to visible light and radar detection, infrared imaging-based detection can effectively avoid illumination limitations and potential exposure risks. However, detecting small infrared targets with complex backgrounds and significant noise is challenging, and existing algorithms often have low detection rates, high false alarm rates, long calculation times, and unsatisfactory performance. To address these issues, we proposes an infrared small target detection algorithm based on sparse representation. The algorithm enhances target sparsity through multi-scale contrast saliency mapping and global gray value fusion, leveraging the low rank of the background. We evaluate the proposed method on SIRST dataset and compare its performance with traditional and recent algorithms. The results demonstrate the superiority of our algorithm in terms of detection rate, false alarm rate, and calculation time. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Image resolution

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Bearing Failure optimization of Composite Double-Lap Bolted Joints Based on a Three-Step Strategy Marked By Feasible Region Reduction and Model Decoupling

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Computers, Materials & Continua 2020年第2期62卷 977-999页

作者： Fengrui Liu Wanting Yao Xinhong Shi Libin Zhao Jianyu Zhang School of Astronautics Beihang UniversityBeijing100191China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Ministry of EducationBeihang UniversityBeijing100191China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an710049China Institute of Solid Mechanics Beihang UniversityBeijing100191China College of Aerospace Engineering Chongqing UniversityChongqing400044China

To minimize the mass and increase the bearing failure load of composite double-lap bolted joints,a three-step optimization strategy including feasible region reduction,optimization model decoupling and optimization was *** feasible region reduction,the dimensions of the feasible design region were reduced by selecting dominant design variables from numerous multilevel parameters by sensitivity analyses,and the feasible regions of variables were reduced by influence mechanism *** model decoupling,the optimization model with a large number of variables was divided into various sub-models with fewer variables by variance *** the third step,the optimization sub-models were solved one by one using a genetic algorithm,and the modified characteristic curve method was adopted as the failure prediction *** on the proposed optimization method,optimization of a double-lap single-bolt joint was performed using the ANSYS®*** results show that the bearing failure load increased by 13.5%and that the mass decreased by 8.7%compared with those of the initial design of the joint,which validated the effectiveness of the three-step optimization strategy.

关键词： Composite bolted joints sensitivity analysis optimization

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A simple artificial neural network for fire detection using landsat-8 data 24

A simple artificial neural network for fire detection using ...

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2020 24th ISPRS Congress - Technical Commission III

作者： Liu, Z. Wu, K. Jiang, R. Zhang, H. Department of Aerospace Information Engineering School of Astronautics Beihang University Beijing102206 China Beijing Key Laboratory of Digital Media Beijing102206 China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies Ministry of Education Beijing102206 China

Fixed threshold models have been widely used in active fire detection products. However, its accuracy is limited due to the complexity of setting up thresholds. Artificial neural network (ANN) is capable of learning from data and can decide weights automatically. Given enough data, an ANN model is able to optimize itself and quickly find an optimal solution. In this work, a simple ANN model is implemented to classify fire pixels from Landsat-8 data. Experimental results show that our ANN model effectively achieves fire detection and performs better than fixed threshold model in certain circumstances. © 2020 International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives.

关键词： Landsat

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