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Evaluation of a Numerical Model for Predicting Flow and Heat Transfer in a Hexagonal Helical Cruciform Seven-Rods Bundle and Analysis of Rod Bundle Size Independence

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SSRN 2024年

作者： Jiang, Dianqiang Deng, Jian Zhang, Dalin Zhou, Xingguang Xiao, Changzhi Tian, Wenxi Qiu, Suizheng Su, Guanghui H. State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China China Institute of Atomic Energy Beijing611731 China

In this study, the accuracy and applicability of the numerical model are comprehensively evaluated based on the experimental data of a hexagonal helical cruciform (HC) seven-rods bundle. The STAR CCM+ is utilized as a tool to obtain predicted results of flow and heat transfer in different flow regions. The numerical results indicate that it is an improved method to set a negative heat flux on the hexagonal wall in the laminar flow region. The Reynolds stress transport model can accurately predict the experimental results of heat transfer in the transitional flow region, with an average wall temperature deviation of 2.8℃. The SST k-ω model with cubic constitutive option can accurately predict the experimental results of the flow resistance, and a relative error of f is 1.8%. In the turbulent flow region, the SST k-ω model with cubic constitutive option provides an accurate prediction, with an average wall temperature deviation of 3.7℃. The realizable k-Ε two-layer model can accurately predict the flow resistance, and the relative error of f is 0.1%. The preferred numerical model is used to analyze the size independence of the HC rod bundle. This work provides certain guidelines for the accurate simulation in the HC seven-rods bundle. © 2024, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Nonreciprocity of energy transfer in a nonlinear asymmetric oscillator system with various vibration states

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Applied Mathematics and Mechanics(English Edition) 2023年第5期44卷 727-744页

作者： Jian’en CHEN Jianling LI Minghui YAO Jun LIU Jianhua ZHANG Min SUN Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin 300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of TechnologyTianjin 300384China School of Aeronautics and Astronautics Tiangong UniversityTianjin 300387China Agricultural Information Institute of Chinese Academy of Agricultural Sciences Key Laboratory of Agricultural Big DataMinistry of Agriculture and Rural AffairsBeijing 100081China School of Science Tianjin Chengjian UniversityTianjin 300384China

The nonreciprocity of energy transfer is constructed in a nonlinear asymmetric oscillator system that comprises two nonlinear oscillators with different parameters placed between two identical linear *** slow-flow equation of the system is derived by the complexification-averaging *** semi-analytical solutions to this equation are obtained by the least squares method,which are compared with the numerical solutions obtained by the Runge-Kutta *** distribution of the average energy in the system is studied under periodic and chaotic vibration states,and the energy transfer along two opposite directions is *** effect of the excitation amplitude on the nonreciprocity of the system producing the periodic responses is analyzed,where a three-stage energy transfer phenomenon is *** the first stage,the energy transfer along the two opposite directions is approximately equal,whereas in the second stage,the asymmetric energy transfer is *** energy transfer is also asymmetric in the third stage,but the direction is reversed compared with the second ***,the excitation amplitude for exciting the bifurcation also shows an asymmetric *** vibrations are generated around the resonant frequency,irrespective of which linear oscillator is *** excitation threshold of these chaotic vibrations is dependent on the linear oscillator that is being *** addition,the difference between the energy transfer in the two opposite directions is used to further analyze the nonreciprocity in the *** results show that the nonreciprocity significantly depends on the excitation frequency and the excitation amplitude.

关键词： nonreciprocity strong nonlinearity energy transfer chaotic vibration higher branch of response

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The Shortest Path Algorithm Based on Geometric Symmetry for Low Earth Orbit Satellite Network

The Shortest Path Algorithm Based on Geometric Symmetry for ...

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Information Communication Technologies Conference (ICTC)

作者： Benchu Zhang Zaiyue Yang School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China Shenzhen Key Laboratory of Control Theory and Intelligent Systems and the School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China

ISBN: (数字)9798350373523

ISBN: (纸本)9798350373530

Since the Low Earth Orbit (LEO) satellite communication system has the advantages of low latency, global coverage, and rapid reconstruction, it has become the main networking method of satellite networks [1]. Routing is the basis for realizing satellite communications. Because the complexity of the shortest path algorithm basically determines the computational complexity of the routing algorithm, the shortest path algorithm is the core of the routing problem. This paper attempts to use the laws of LEO satellite network topology to calculate the shortest path between the source satellite and the destination satellite. First, we derive the function of inter-satellite link (ISL) length with time and establish the geometric model of the satellite network. Then, on the basis of this model, we establish the shortest path algorithm between source-destination pairs (SD pairs) - the symmetric geometry algorithm (SGA). In addition, in order to ensure the optimality of the path, we extend the applicable scene of the model from the two-dimensional plane to the three-dimensional sphere. The simulation test results show that compared with the traditional Dijkstra’s algorithm, SGA can greatly improve the calculation speed of the shortest path while ensuring the optimality of the path.

关键词： Geometry Solid modeling Satellites Network topology Geometric modeling Low earth orbit satellites Routing

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Effect of Hydrogen, Helium and Dose Rate on the Evolution of Dislocation Loop in Pure Iron During In-Situ Irradiation

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SSRN 2024年

作者： Wu, Mengjie Huang, Jiyong Cao, Ziqi Ding, Yifan Zhong, Qinghong Zhao, Yanli Ran, Guang College of Energy Xiamen University Xiamen361102 China Fujian Research Center for Nuclear Engineering Xiamen361102 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

Simulating neutron irradiation with ion irradiation requires considering the comprehensive effects of hydrogen, helium and dose rate to fully understand the microstructure evolution of material in an irradiated environment. Here, the characterization and evolution of dislocation loops in pure iron were investigated under heavy ion irradiation with four different injected gas ion types (Fe+, Fe+ & H2+, Fe+ & He+ and Fe+ & H2+ & He+) and under Fe+ & He+ irradiation with four different dose rates using in-situ transmission electron microscopy at 723 K. Compared to the Fe+ single-beam irradiation, the additional injection of H or He, or co-injecting H & He, mainly promoted the nucleation of dislocation loops at the early stage of irradiation and enhanced loop growth after that. Among them, the simultaneous irradiation of Fe+ & H2+& He+ triple beams were most pronounced. Moreover, Fe+ & H2+ & He+ triple-beam irradiation resulted in the highest fraction of loops and the highest ratio of the rotation of loop habit-plane. Under Fe+ & He+ dual-beam irradiation, the results demonstrated that as the dose rate increases, the loop density increased and the loop size decreased. Moreover, the fraction of loops at low dose rate was noticeably greater than that at high dose rate. The results of the current work provide important references for a better understanding of the effectiveness of ion irradiation in simulating neutron irradiation. © 2024, The Authors. All rights reserved.

关键词： Neutron irradiation

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Thinning air-water films stabilized by bacterial particles

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Acta Mechanica Sinica 2021年第1期37卷 27-34,I0001页

作者： Song Wu Yuehua Yang Hongyuan Jiang Hefei National Laboratory for Physical Science at the Microscale CAS Key Laboratory of Mechanical Behavior and Design of MaterialsDepartment of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei230026China

The ability of particles to stabilize liquid films has broad applications in many fields,such as drug delivery,biofuel catalysis,and crude-oil *** mechanism of particles to stabilize emulsions has been widely ***,how particles affect the stability of suspension films is still ***,the dynamics of bacterial particles on free liquid films during evaporation is obtained by direct microscopic *** find that the initial concentration of the bacterial solution affects the evolution of the shapes and stabilities of liquid *** liquid film with a low bacterial concentration exhibits a drainage and rupture process similar to pure water,and bacteria would be evacuated during the evaporation of liquid ***,when the bacterial concentration is high,bacteria form a single-layer array in the center of the film and greatly enhance the stability of the liquid *** demonstrate that these two distinct film evaporation dynamics are caused by the difference in the lateral capillary force of the particles at different positions on the liquid film,which is not affected by the active motility of ***,our research reveals the critical role of bacteria concentration in stabilizing suspension liquid film.

关键词： Bacterial concentration Evaporation dynamics Film stability Lateral capillary force

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Thermochemical non-equilibrium flow characteristics of high Mach number inlet in a wide operation range

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Chinese Journal of Aeronautics 2023年第12期36卷 164-184页

作者： Chunliang DAI Bo SUN Lianjie YUE Shengbing ZHOU Changfei ZHUO Changsheng ZHOU Jianyi YU School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China College of Aerospace Engineering Chongqing UniversityChongqing 400044China Beijing System Design Institute of Electro-mechanic Engineering Beijing 102308China

The high-temperature non-equilibrium effect is a novel and significant issue in the flows over a high Mach number(above Mach 8)air-breathing ***,this study attempts to investigate the high-temperature non-equilibrium flows of a curved compression two-dimensional scramjet inlet at Mach 8 to 12 utilizing the two-dimensional non-equilibrium RANS ***,the thermochemical non-equilibrium gas model can predict the actual high-temperature flows,and the numerical results of the other four thermochemical gas models are only used for comparative ***,the thermochemical non-equilibrium flow fields and work performance of the inlet at Mach 8 to 12 are ***,the influences of high-temperature non-equilibrium effects on the starting characteristics of the inlet are *** results reveal that a large separation bubble caused by the cowl shock/lower wall boundary layer interaction appears upstream of the shoulder,at Mach *** separation zone size is smaller,and its location is closer to the downstream area while the thermal process changes from frozen to non-equilibrium and then to *** the increase of inflow Mach number,the thermochemical non-equilibrium effects in the whole inlet flow field gradually strengthen,so their influences on the overall work performance of the high Mach number inlet are more *** vibrational relaxation or thermal non-equilibrium effects can yield more visible influences on the inlet performance than the chemical non-equilibrium *** inlet in the thermochemical non-equilibrium flow can restart more easily than that in the thermochemical frozen *** work should provide a basis for the design and starting ability prediction of the high Mach number inlet in the wide operation range.

关键词： Non-equilibrium Scramjet inlet Starting ability Thermochemical Work performance

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Flow and thermal modeling of liquid metal in expanded microchannel heat sink

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Frontiers in Energy 2023年第6期17卷 796-810页

作者： Mingkuan ZHANG Xudong ZHANG Luna GUO Xuan LI Wei RAO Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin 300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of TechnologyTianjin 300384China Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084China School of Mechanical Engineering Tianjin University of CommerceTianjin 300134China Institute of Refrigeration and Cryogenics Shanghai Jiao Tong UniversityShanghai 200240China Beijing Key Laboratory of CryoBiomedical Engineering and Key Laboratory of Cryogenics Beijing 100190China

Liquid metal-based microchannel heat sinks (MCHSs) suffer from the low heat capacity of coolant, resulting in an excessive temperature rise of coolant and heat sink when dealing with high-power heat dissipation. In this paper, it was found that expanded space at the top of fins could distribute the heat inside microchannels, reducing the temperature rise of coolant and heat sink. The orthogonal experiments revealed that expanding the top space of channels yielded similar temperature reductions to changing the channel width. The flow and thermal modeling of expanded microchannel heat sink (E-MCHS) were analyzed by both using the 3-dimensional (3D) numerical simulation and the 1-dimensional (1D) thermal resistance model. The fin efficiency of E-MCHS was derived to improve the accuracy of the 1D thermal resistance model. The heat conduction of liquid metal in Z direction and the heat convection between the top surface of fins and the liquid metal could reduce the total thermal resistance (Rt). The above process was effective for microchannels with low channel aspect ratio, low mean velocity (Um) or long heat sink length. The maximum thermal resistance reduction in the example of this paper reached 36.0%. The expanded space endowed the heat sink with lower pressure, which might further reduce the pumping power (P). This rule was feasible both when fins were truncated (h_(2) < 0, h_(2) is the height of expanded channel for E-MCHS) and when over plate was raised (h_(2) > 0).

关键词： liquid metal cooling heat sink expanded microchannel flow and thermal modeling

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Mechanically Stable and Damage Resistant Freestanding Ultrathin Silver Nanowire Films with Closely Packed Crossed-Lamellar Structure

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Precision Chemistry 2024年第12期2卷 634-643页

作者： Si-Chao Zhang Huai-Ling Ga Long Zhang Yin-Bo Zhu Ya-Dong Wu Jian-Wei Liu Li-Bo Mao Mei Feng Liang Dong Zhao Pan Xiang-Sen Meng Yang Lu Shu-Hong Yu Department of Chemistry New Cornerstone Science LaboratoryInstitute of Biomimetic Materials&ChemistryAnhui Engineering Laboratory of Biomimetic MaterialsDivision of Nanomaterials&ChemistryHefei National Research Center for Physical Sciences at the MicroscaleUniversity of Science and Technology of ChinaHefei 230026China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei 230027China Anhui Key Laboratory of Controllable Chemical Reaction and Material Chemical Engineering School of Chemistry and Chemical EngineeringHefei University of TechnologyHefeiAnhui 230009P.R.China Institute of Innovative Materials(I2M) Department of ChemistryDepartment of Materials Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China

One-dimensional(1D)functional nanowires are widely used as nanoscale building blocks for assembling advanced nanodevices due to their unique ***,previous research has mainly focused on nanowire functionality,while neglecting the structural stability and damage resistance of nanowire assemblies,which are critical for the long-term operation of *** achieve excellent mechanical stability and damage resistance through sophisticated structural ***,we successfully prepared a mechanically stabilized monolamella silver nanowire(Ag NW)film,based on a facile bubblemediated assembly and nondestructive transfer strategy with the assistance of a porous mixed cellulose ester substrate,inspired by the hierarchical structure of *** to the closely packed arrangement of Ag NWs combined with their weak interfaces,the monolamellar Ag NW film can be transferred to arbitrary substrates without ***,freestanding multilamellar Ag NW films with impressive damage resistance can be obtained from the monolamellar Ag NW film,through the introduction of bioinspired closely packed crossed-lamellar(CPCL)*** CPCL structure maximizes intra-and interlamellar interactions among Ag NWs ensuring efficient stress transfer and uniform electron transport,resulting in excellent mechanical durability and stable electrical properties of the multilamellar Ag NW films.

关键词： Biomimetics hierarchical structure structural stability damage resistance functional nanowire assemblies

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A Dynamic Recognition Method of Metamorphic Relation Identification 13

A Dynamic Recognition Method of Metamorphic Relation Identif...

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13th International Conference on Reliability, Maintainability, and Safety, ICRMS 2022

作者： Hong, Jie Zhang, Jie Qiu, Qi Ma, Angang Li, Meng Yan, Shiyu Gong, Helin School of Computing University of South China Hunan Hengyang China Engineering and Technology Research Center Software Evaluation and Testing for Intellectual Equipment of Hunan Province Hunan Hengyang China CNNC Key Laboratory on High Trusted Computing Hunan Hengyang China Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu China

ISBN: (数字)9781665486903

ISBN: (纸本)9781665486903

Metamorphic testing is one of the effective methods to alleviate the test oracle problem. Metamorphic relation is the core of metamorphic testing, and there is no effective automatic identification technology. This paper transforms the metamorphic relation recognition issue into a symbolic expression regression problem. The test input pairs are generated using the preset input pattern, and the output pattern is mined by gene expression programming. After reduction and verification, a valid metamorphic relation is obtained. Experiments show that this method can identify the relation obtained by static analysis and a more significant number. At the same time, compared with existing technologies, it has apparent advantages in effectiveness, reliability, and performance. © 2022 IEEE.

关键词： Static analysis

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A statistical sensing method by utilizing Wi-Fi CSI subcarriers:Empirical study and performance enhancement

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Journal of Information and Intelligence 2024年第4期2卷 365-374页

作者： Tao Deng Bowen Zheng Rui Du Fan Liu Tony Xiao Han Wireless Technology Laboratory Huawei Techologies Co.Ltd.Shenzhen 518000China School of System Design and Intelligent Manufacturing(SDIM) Southern University of Science and TechnologyShenzhen 518000China

In modern Wi-Fi systems,channel state information(CSI)serves as a foundational support for various sensing ***,existing CSI-based techniques exhibit limitations in terms of environmental *** such,optimizing the utilization of subcarrier CSI stands as a critical avenue for enhancing sensing *** the OFDM communication framework,this work derives sensing outcomes for both detection and estimation by harnessing the CSI from every individual measured subcarrier,subsequently consolidating these *** contrasted against results derived from CSI based on specific extraction protocols or those obtained through weighted summation,the methodology introduced in this study offers substantial improvements in CSI-based detection and estimation *** approach not only underscores the significance but also serves as a robust exemplar for the comprehensive application of CSI.

关键词： CSI Subcarrier Wi-Fi sensing

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