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SSRN 2022年

作者： Li, Shuangbao Zhou, Xinxing Chen, Jianen Research Institute of Science and Technology Civil Aviation University of China Tianjin300300 China College of Science Civil Aviation University of China Tianjin300300 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

A two-degree-of-freedom nonlinear mechanical system describing a damped linear oscillator weakly coupled to a lightweight grounded bistable nonlinear energy sink is proposed to investigate the targeted energy transfer (TET) under asymmetric local nonlinear potentials. The Bogdanov-Takens bifurcations of equilibria are discussed to reflect the bistable and asymmetric characteristics of the system. Through projections of isoenergetic manifolds, the topological features of the Hamiltonian dynamics under $1:1$ internal resonance have been investigated, which induces conditions for energy localization and exchange. In the general case, the topological features of the Hamiltonian dynamics related to the nonlinear normal modes (NNMs) are classified by the Poincare map, the relations between the NNMs and the Hamiltonian dynamics have been interpreted through the frequency energy plots. The results show that introducing the asymmetric characteristics may enhance the TET and realize the complete TET. © 2022, The Authors. All rights reserved.

关键词： Degrees of freedom (mechanics)

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Understanding the Limitations of Thick Electrodes on the Rate Capability of High-Energy Density Lithium-Ion Batteries

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SSRN 2024年

作者： Xie, Wenlong Zhang, Zhengjie Gao, Xinlei Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China School of Transportation Science and engineering Beihang University Beijing100191 China Department of Mechanical Engineering Imperial College London LondonSW7 2AZ United Kingdom

As a core component of transportation electrification, lithium-ion batteries need to address two critical challenges: achieving high energy density and enabling fast charging. However, changes in electrode thickness could result in a trade-off between these two characteristics. Herein, the impact of electrode thickness on the electrochemical performance, thermal behavior, as well as energy and power density of LiNi0.8Co0.1Mn0.1O2(NCM)/graphite batteries are investigated through mathematical modeling. Underutilization of active materials of the thick electrode is identified as the primary limitation on rate capability, which can be attributed to the slow solid-state diffusion and poor electrolyte transport within the electrode, especially the enlarged concentration gradients in the solid phase and the lithium depletion in the electrolyte phase during high-rate charging. Evolutions of local current density and heat generation rate along the electrode thickness are compared, identifying the underlying mechanism of inducing uneven reaction kinetics inside the battery. The trade-off between the energy and power density as a function of electrode thickness is investigated based on the limitations of charge transfer and mass transport. Furthermore, the rate-limiting factors under various application requirements are elucidated. This study will provide guidance for the electrode design of high-energy-density batteries with fast-charging capabilities. © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Vibration Characteristics Analysis Of A Double-Suction Centrifugal Pump Identified By Intelligent Algorithms 12

Vibration Characteristics Analysis Of A Double-Suction Centr...

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12th IEEE Global Reliability and Prognostics and Health Management, PHM-Nanjing 2021

作者： Gu, Zhenyue Zhang, Mian Li, Decai Kang, Tianbo Tang, Xiuyang Wang, Zhiyuan Pei, Zhenlong Wang, Yiqiao Tianjin Key Laboratory For Advanced Mechatronic System Design And Intelligent Control School Of Mechanical Engineering Tianjin University Of Technology Tianjin300384 China China Tianjin Todelon Scicnce &TECHOLOGY CO. Ltd Tianjin China State Key Lab Of Water Resources And Hydropower Engineering Science Wuhan University Wuhan China

ISBN: (纸本)9781665401302

Due to the merits of high flow rate and high lift, double-suction centrifugal pumps are widely used for agricultural irrigation along the Yellow River in northern China. The operational conditions of the pump are highly related to the silt concentration and flow rates. Therefore, it is crucial to identify the vibration characteristics corresponding to different silt concentrations and flow rates to provide a prior guideline for pump condition monitoring. To this end, this paper explores the identification capabilities of typical intelligent models, including convolutional neural network (CNN), deep neural network (DNN), and support vector machine (SVM), to intelligently establish the connection between vibration characteristics and different flow rates and silt concentrations. Experimental studies on a double-section pump covering a range of flow rates and different silt concentrations are conducted. The results show that CNN features higher identification accuracy than DNN and SVM. © 2021 IEEE.

关键词： Vibration analysis

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Acoustic indeced vibration research of dryer in steam generator 26

Acoustic indeced vibration research of dryer in steam genera...

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26th International Congress on Sound and Vibration, ICSV 2019

作者： Xianhui, Ye Fengshou, Zhang Fengchun, Cai Wenzheng, Zhang Furui, Xiong Haiyang, Song Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9781999181000

The acoustic induced vibration of dryer (also called secondary separator) in steam generator in nuclear power plants is a concern in recent years. Periodic vibrations of long-term operation can lead to fatigue damage of structural components, posing a safety hazard. In this paper, the finite element analysis model of the dryer structure in steam generator of "Hualong-1" nuclear power plant was established, and the acoustic induced vibration characteristics of the structure were studied. Firstly, the acoustic excitation of the dryer structure was discussed, and the excitation inputs were obtained, including the maximum static pressure and the maximum pressure power spectrum density. Then the finite element model was established by ANSYS and the weak parts of the dryer structure were determined by the vibration characteristics combined with the acoustic excitation characteristics analysis. Finally, the structural strength and fatigue characteristics of the dryer structure under two different inputs of the acoustic load were investigated. The analysis of vibration characteristics shows that the main weak parts of the dryer structure are the vertical partition plate and the perforated plate. The static pressure analysis shows that the stress intensity of the two weak plates is less than the limit. In the study of pressure power spectral density, the maximum dynamic stress intensity and alternating stress of the vertical partition plate and the perforated plate are also less than the limit. The research results indicate that the acoustic induced vibration response of the dryer structure is within the acceptable range © Proceedings of the 26th International Congress on Sound and Vibration, ICSV 2019. All rights reserved.

关键词： Steam generators

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Investigation of turbulent Prt model and the segmentation rule for LBE turbulent heat transfer 18

Investigation of turbulent Prt model and the segmentation ru...

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18th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2019

作者： Li, Peiying Yu, Hongxing Li, Meifu Du, Sijia Yan, Mingyu Liu, Yu Zhu, Dahuan Zhang, He Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

With liquid metal like lead-bismuth alloy(LBE) acting as a coolant for nuclear reactors, it is necessary to use a more accurate heat transfer relationship and a more reliable Prt model for the low Pr fluid. Because of the low Pr of liquid metal, the thermal conductivity is more dominant than the momentum transfer, which is quite different from ordinary fluids. In this case, the turbulent Prt can better reflect the heat transfer process. In this study, the Prt=A1+A2/Pr form is selected, and the corresponding coefficients are obtained by the renormalization group analysis method, then corrected by Pr. Furthermore, the applicable range and segmentation rule of the turbulent Prt model are discussed, and the obtained Prt segmentation theoretical model is written into CFD. The result shows that, compared with the previously unmodified model, the radial temperature distribution and Nusselt number (Nu) of the annular and bundle channel obtained by RANS method with the improved Prt model is in good agreement with experimental r esults, and the deviations are within 5%. It is proved that the turbulent Prt segmentation theoretical model proposed in this study is effective and can represent the heat transfer characteristics of liquid metal from the mechanism. © 2019 American Nuclear Society. All rights reserved.

关键词： Liquid metals

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A Service-Environment-Oriented Shape Reconstruction Method of Vehicle-borne Active Phased Array Antenna

A Service-Environment-Oriented Shape Reconstruction Method o...

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2021 CIE International Conference on Radar, Radar 2021

作者： Xu, Pengying Xu, Xiaoxian Wang, Yan Teng, Yucheng Wang, Congsi Ge, Dongming Kang, Mingkui Yuan, Shuai Wang, Xuezi Xidian University Key Laboratory of Electronic Equipment Structure Design Ministry of Education Xi'an China School of Information and Control Engineering Xi'an University of Architecture and Technology Xi'an China Beijing Institute of Spacecraft System Engineering Beijing China No.771 Institute of China Aerospace Science and Technology Corporation Xi'an China China Electronics Technology Group Corporation No.38 Research Institute Hefei China

ISBN: (纸本)9781665498142

Modern electronic equipment has been moving towards large scale and increased complexity. Affected by such factors as complex working environments, the performance of a large number of structures in engineering is degraded or even destroyed. Therefore, structure shape estimation is of great significance. The complexity of the structure, however, makes it impossible for a single deformation evaluation algorithm to evaluate the structure comprehensively and accurately. In this paper, a modal-approximate curve (M-AC) method, using a small amount of strain data, is proposed for block shape estimation of structures. Three typical wind load experiments are carried out on the finite element model (FEM) of the vehicle-borne active phased array antenna, and the effectiveness of the algorithm is verified. Under the wind speed of 28 (m/s), the deformation of antenna front is 104.70 mm and the estimation accuracy of the M-AC method is 87.43%, which is 16.47% higher than that of the modal approach. The results indicate that the estimated displacement is consistent well with the simulation results of the finite element method. © 2021 IEEE.

关键词： active phased array antenna Fiber Bragg grating mode shapes sensor shape estimation

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Effects of core peripheral components melting on corium pool configuration in lower plenum of ACP1000 27

Effects of core peripheral components melting on corium pool...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Chen, Liang Yu, Hongxing Liu, Lili Dong, Huaping Deng, Jian Zhang, Hang Hou, Liqiang Wang, Xiaoji Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9784888983051

The MAAP5 code and CFD method are adopted to estimate the melting behavior of core peripheral components for an Advanced China PWR, called ACP1000 after a large break accident to determine the amount of stainless steel relocating into the corium pool. The results suggest that larger portion of peripheral components melting in CFD method because of considering the radiation of fuel rods on shroud and barrel before core melting and ignoring the cooling of steam on the components in core. Effects of different configurations of corium pool on heat flux imposed on the vessel wall are also investigated in this work. The heat flux in light metal layer for the corium pool that obtained by MAAP5 code could be higher than that of CFD case due to its thinner light metal layer. Copyright © 2018-2019 by JSME

关键词： Heat flux

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A new turbulent Prandtl number model for forced fully-developed pipe heat transfer of liquid metals 27

A new turbulent Prandtl number model for forced fully-develo...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Peiying, Li Hongxing, Yu Sijia, Du Yaou, Shen Mingyu, Yan Hongsheng, Yuan Yu, Liu Xiaoli, Wu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9784888983051

With the proposal of liquid metals as coolant of the reactors, the use of accurate heat transfer correlation and reliable turbulent prandtl number（Prt）model of these low prandtl number fluids in turbulent flow is essential. The heat transfer of Liquid metals differ from traditional coolants for their good molecular heat conductivity and this property leads to a separation of the spatial extension of thermal and viscous boundary layers. A constant turbulent prandtl number is proved to be inappropriate for complex conditions for it depends on the Reynolds and molecular Prandtl number. This paper proposes a new turbulent prandtl number model Prt=C+B/Pet, which can be used for accurately predicting the heat transfer for liquid metal flows. The constants C and B of the expression are obtained from the analytic solution of renormalization group procedure. B is further corrected with the physical properties for different liquid metals. The results are in a good agreement with experimental data over the range of experimentally accessible Prandtl numbers. The Nusselt numbers calculated using the proposed model with the Lyon integral are found to be well consistent with the experimental data for forced fully-developed pipe flows with constant heat flow boundary conditions. Computational fluid dynamics(CFD) analysis is also carried out for pipe geometries. With the proposed model for turbulent prandtl number, CFD codes using RANS approach give similar results for local Nusselt numbers measured in the experiments. Copyright © 2018-2019 by JSME

关键词： Liquid metals

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Research on the vibration reduction and sound radiation index properties of the cabin with internal equipment 26

Research on the vibration reduction and sound radiation inde...

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26th International Congress on Sound and Vibration, ICSV 2019

作者： Wenzheng, Zhang Bihao, Wang Xiaozhou, Jiang Bin, Lan Haiyang, Song Fengchun, Cai Xianhui, Ye Jiabin, Feng Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9781999181000

Suitable vibration and noise indices which provide technical direction for vibration and noise reduction, play a very important role in structure analysis and validated test. The contribution of foundation impedance is studied by analyzing the vibration reduction index of a single degree of freedom system. The finite element method (FEM) and boundary element method (BEM) are applied to simulate the vibration and noise indices of a cabin along with internal equipment. The vibration reduction and sound radiation indices of the internal isolator have been calculated to analyze the variation trend with frequency. The results indicate that the difference between vibration level difference and insert loss is very small in most frequency band. Interestingly, the power flow difference and radiated sound power are opposite in phase in middle and high frequency band, which have been proved to be appropriate elements to evaluate the vibration and noise indices of the cabin. The analysis method and procedure can be used to objectively evaluate the vibration reduction property of similar vibration isolators © Proceedings of the 26th International Congress on Sound and Vibration, ICSV 2019. All rights reserved.

关键词： Finite element method

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Liquid Metal Manifold Microchannel Heat Sink for Ultra-High Heat Flux Cooling

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SSRN 2024年

作者： Zhang, Mingkuan Gao, Qi Zhao, Zhiyuan Guo, Luna Li, Xuan Zhang, Chao Zhang, Xudong Rao, Wei Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China School of mechanical engineering Tianjin University of Commerce Tianjin300134 China Institute of Refrigeration and Cryogenics Shanghai Jiao Tong University Shanghai200240 China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering Mechanics Tsinghua University Beijing Beijing100084 China CAS Key Laboratory of Cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences China Beijing Key Lab of CryoBiomedical Engineering and Key Lab of Cryogenics Beijing100190 China

The reduction in transistor dimensions and advancements in chip integration have led to a dramatic increase in the heat flux of chip. Advanced heat dissipation technology has become the pivotal in ensuring the normal operation of chips and fully utilizing chip performance. Room temperature liquid metal convection cooling technology has demonstrated its efficacy as a viable approach for addressing high heat flux heat dissipation. However, the smaller specific heat capacity of liquid metal leads to a large temperature rise, imposing a constraint on the progression of liquid metal cooling technology. To overcome this drawback, this paper proposed a liquid metal manifold channel structure designed to convert the continuous long-range flow into a segmented short-range flow. The good matching between liquid metal and manifold structures is adequately demonstrated through a comparison with alternative coolant and channel structure. The simulation results demonstrate the effectiveness of liquid metal manifold channel cooling in dealing with a heat flux of 1000 W/cm², ensuring that the maximum temperature of the chip remains below 351.7 K. Moreover, the convective heat transfer coefficient even reaches 106 W/(m2·K), which is ten times larger than that of water conventional microchannel heat sink. The orthogonal experiments were conducted to analyze how the structural parameters affect the dissipation performance, including the height of the microchannel, ratio of manifold length to fin length, length of fin in manifold, width of channel, and ratio of fin with to channel width. It concluded that the height of the microchannel has been identified as the most critical factor. This manifold structure mitigates the inherent limitation of the lower specific heat capacity of liquid metal, paving the way for effective thermal management of electronic devices subjected to ultra-high heat flux. © 2024, The Authors. All rights reserved.

关键词： Heat flux

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