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SSRN 2022年

作者： Wang, Zhiwei Duan, Zhongdi He, Yanping Huang, Chao Yuan, Yuchao Liu, Shiwen Li, Mingzhi State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai200240 China School of Naval Architecture Ocean & Civil Engineering Shanghai Jiao Tong University Shanghai200240 China Institute of Marine Equipment Shanghai Jiao Tong University Shanghai200240 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

The investigation of condensation-induced water hammer (CIWH) under ocean conditions is crucial to the system safety of the offshore floating nuclear plants (OFNPs). This paper establishes a CIWH numerical model under rolling conditions based on the computational fluid dynamics (CFD) code combined with user-defined functions (UDF). First, the numerical model is verified by published experimental data. Then, the transient behaviors of CIWH events under various rolling parameters are numerically investigated. The results show that the rolling motion causes a significant steam slug and enhances the steam-subcooled water contact area, which promotes the average condensation rate. The average condensation rate increases with an increase in rolling angle, decreases with an increase in rolling period. Due to the larger average condensation rate and reverse flow caused by rolling motion, the pressure peak generated by the CIWH significantly increases compared to static conditions. Similarly, the pressure peak increases as rolling angle increases, decreases as rolling period increase. Moreover, the pressure peak is proportional to steam inlet velocity, and the location of the pressure peak gradually moves back to the outlet direction as the steam velocity increases. These qualitative conclusions are useful to understand the effects of rolling motion on the CIWH and provide a reference for the CIWH simulations. © 2022, The Authors. All rights reserved.

关键词： Condensation

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Effect of Rolling Motion on Transient Behaviors of Condensation-Induced Water Hammer in an Equal-Height-Difference Passive Heat Removal system

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SSRN 2022年

作者： Duan, Zhongdi Wang, Zhiwei He, Yanping Huang, Chao Li, Mingzhi Yuan, Yuchao Liu, Shiwen State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai200240 China School of Naval Architecture Ocean & Civil Engineering Shanghai Jiao Tong University Shanghai200240 China Institute of Marine Equipment Shanghai Jiao Tong University Shanghai200240 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

The investigation of condensation-induced water hammer (CIWH) under ocean conditions is vital to the system safety of the offshore floating nuclear plants (OFNPs). This paper establishes a CIWH numerical model under rolling conditions based on the computational fluid dynamics (CFD) code combined with user-defined functions (UDF). First, the numerical model is validated with the experimental data. Then, the transient behaviors of the CIWH under various rolling parameters are numerically investigated. The results show that the rolling motion causes a significant steam slug and increases the steam-subcooled water contact area, which promotes the average condensation rate. The average condensation rate increases as the rolling angle increases and the rolling period decreases. Due to the larger average condensation rate and reverse flow induced by rolling motion, the pressure peak generated by the CIWH significantly increases compared to static conditions. Similarly, the pressure peak increases as the rolling angle increases and the rolling period decrease. Moreover, the pressure peak is proportional to the steam inlet velocity, and the location of the pressure peak gradually moves back to the outlet direction as the steam inlet velocity increases. These qualitative conclusions may serve as a reference for the CIWH simulations under ocean conditions. © 2022, The Authors. All rights reserved.

关键词： Condensation

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The statistical analyses on the bubble contact diameters in the vertical narrow channel

The statistical analyses on the bubble contact diameters in ...

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2019 Transactions of the American Nuclear Society, ANS 2019

作者： Lu, Qi Liu, Yu Liu, Wei Chen, Xi He, Hangxing Zhou, Linglan Science and Technology on Reactor System Design Technology Laboratory Chengdu610041 China Nuclear Power Institute of China Chengdu610041 China

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Experimental investigation of the transient pool boiling heat transfer on the quenching of vertical rodlet in water

Experimental investigation of the transient pool boiling hea...

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2020 International Conference on Nuclear Engineering, ICONE 2020, collocated with the ASME 2020 Power Conference

作者： Wang, Zefeng Deng, Jian Qian, Libo Cai, Rong Xiong, Jinbiao Zhong, Lei Ma, Yugao State Key Laboratory of Reactor System Design Technology Nuclear Power Institute of China 328 Changshun Road Shuangliu District Chengdu China School of Nuclear Science and Engineering Shanghai Jiao Tong University 800 DongChuan Road MinHang District Shanghai China

ISBN: (纸本)9780791883785

Quenching is an important phenomenon in the evaluation of an emergency core cooling system following a hypothetical loss of coolant accident (LOCA) in a nuclear reactor. In the present study, an experimental apparatus is designed and constructed with the purpose of conducting high-temperature transient pool boiling quenching experiments for zirconium (Zr-4) cylindrical test samples. Three thermocouples are inserted in the test sample to investigate the effect of axial distance on the minimum film boiling temperature. The Zr-4 rodlet is heated up to a temperature well above the minimum film boiling temperature (up to 600°C), and then plunged vertically in a quiescent pool of subcooled water. A data acquisition system is used to record the temperature of the embedded thermocouples with time. Data reduction is performed by an inverse heat conduction code to calculate the surface temperature and corresponding surface heat flux. A visualization study with a high-speed camera is conducted to record the quenching behavior on the test sample. It is found that the minimum film boiling temperature decreases with the axial distance, while the CHF temperature is relatively insensitive to the axial distance. The film boiling heat transfer coefficient decreases with surface temperature, and seems to be independent of axial distance. The quench front is observed to originate from the bottom and move upwards. It is found that the quench front velocity remains nearly constant in the lower region of the test sample, and significantly increases in the upper region. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Surface temperature

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An Efficient Digital Twin Based on Machine Learning Svd Autoencoder and Generalised Latent Assimilation for Nuclear reactor Physics

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SSRN 2022年

作者： Gong, Helin Cheng, Sibo Chen, Zhang Li, Qing Quilodrán-Casas, César Xiao, Dunhui Arcucci, Rossella SJTU-ParisTech Elite Institute of Technology Shanghai 200240 China Data Science Institute Imperial College London LondonSW7 2AZ United Kingdom Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Faculty of Sciences and Engineering Swansea University SwanseaSA1 8EN United Kingdom Department of Earth Science & Engineering Imperial College London LondonSW7 2AZ United Kingdom

This paper proposes an approach that combines reduced-order models with machine learning in order to create an digital twin to predict the power distribution over the core during the operation stage. The operational digital twin is designed to solve forward problems given input operation parameters, as well as to solve inverse problems given some observations of the power field. The forward model is realised using SVD autoencoder reduced order model and machine learning methods. The inverse model is based on a generalised latent assimilation method. The effectiveness in the sense of accuracy and real-time solver of the digital twin is illustrated through a real engineering problem in nuclear reactor physics - reactor core simulation in the life cycle of HPR1000 affected by control rod inserting step, burnup, power level and inlet temperature of the coolant, which shows potential applications for on-line monitoring purpose. © 2022, The Authors. All rights reserved.

关键词： Inverse problems

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Spatial Heterogeneity of Point Defect Properties in Refractory Multi-Principal Element Alloy with Short-Range Order: A First-Principles Study

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SSRN 2022年

作者： Shi, Tan Lyu, Sixin Su, Zhengxiong Wang, Yunpeng Qiu, Xi Sun, Dan Xin, Yong Li, Wenjie Cao, Jiang Peng, Qing Li, Yuanming Lu, Chenyang School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China School of Electronic and Optical Engineering Nanjing University of Science and Technology Nanjing210094 China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The short-range order is inherently present in the multi-principal element alloys and has a profound impact on the defect behaviour. The effect of short-range order on vacancy and interstitial formation and migration was studied in body-centered cubic multi-principal element alloy NbZrTi by first-principles calculations. Two short-range order structures created by density functional theory and Monte Carlo method at 500 K and 800 K were compared with the random solid solution structure. Both vacancy and interstitial formation energies increase with the degree of short-range order. Point defect formation energies tend to be higher in region enriched in Nb and lower in region enriched in Zr and Ti. Both vacancies and interstitials prefer to migrate towards Zr,Ti-rich regions and away from Nb-rich regions, suggesting that Zr,Ti-rich region can act as recombination center for point defect annihilation. Compared to the random solid solution, the short-range order increases the spatial heterogeneity of point defect energy landscape. Tuning the degree of short-range order can be a viable strategy to optimize the point defect behaviour to achieve enhanced radiation resistance in multi-principal element alloys. © 2022, The Authors. All rights reserved.

关键词： Monte Carlo methods

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Large deformation and wrinkling analyses of bimodular structures and membranes based on a peridynamic computational framework

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Acta Mechanica Sinica 2019年第6期35卷 1226-1240页

作者： H.Li Y.G.Zheng Y.X.Zhang H.F.Ye H.W.Zhang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610200China International Research Center for Computational Mechanics State Key Laboratory of Structural Analysis for Industrial EquipmentDepartment of Engineering MechanicsFaculty of Vehicle Engineering and MechanicsDalian University of TechnologyDalian 116024China

In this paper,the quasi-static large deformation,wrinkling and fracture behaviors of bimodular structures and membranes are studied with an implicit bond-based peridynamic computational ***,the constant and tangential stiffness matrices of the implicit peridynamic formulations for the nonlinear problems are derived,*** former is con structed from the linearization of the bond strain on the basis of the geometric approximation while the latter is established according to the linearization of the pairwise force by using first-order Taylor’s ***,a bimodular material model in peridynamics is developed,in which the tensile or compressive behavior of the material at each point is conveniently described by the tensile or compressive states of the bonds in its ***,the bimodular material model is extended to deal with the wrinkling and fracture problems of membranes by setting the compressive micro-modulus to be *** addition,the incremental-iterative algorithm is adopted to obtain the convergent solutions of the nonlinear ***,several representative numerical examples are presented and the results demonstrate the accuracy and efficiency of the proposed method for the large deformation,wrinkling and fracture analyses of bimodular structures and membranes.

关键词： Bimodular structures Wrinkling membranes Fracture problems Peridynamics Implicit numerical algorithm

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Study on irradiation hardening of RPV steel based on modified crystal plastic finite element model

Study on irradiation hardening of RPV steel based on modifie...

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2019 Transactions of the American Nuclear Society, ANS 2019

作者： Wang, Xiaotong Yao, Weihua Luo, Ying Dong, Yuanyuan Science and Technology on Reactor System Design Technology Lab Nuclear Power Institute of China Chengdu China Nuclear Power Institute of China Chengdu China

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Study on numerical model of vortex shedding for three-way pipe 48

Study on numerical model of vortex shedding for three-way pi...

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48th International Congress and Exhibition on Noise Control Engineering, INTER-NOISE 2019 MADRID

作者： Liu, Shuai Feng, ZhiPeng Wu, WanJun Jiang, XiaoZhou Huang, Xuan Qi, HuanHuan Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China. No. 328 Changshun Avenue Shuangliu Chengdu China

ISBN: (纸本)9788487985317

The three-way pipe vortex shedding phenomenon is the main excitation source for pipe vibration, which can lead to the generation of acoustic resonance. The existing researches mainly focus on air and wet steam, however the researches on water medium is rare. In this paper, the formation mechanism of vortex shedding for three-way pipe under water medium is studied, and the influence of turbulence model, water compressibility, boundary layer and model size is discussed. A more accurate simulation model is established, The suggestions for the establishment of the three-way pipe vortex shedding simulation model are given according to the simulation results. © INTER-NOISE 2019 MADRID - 48th International Congress and Exhibition on Noise Control Engineering. All Rights Reserved.

关键词： Vortex shedding

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DC-Side Decoupling Method of DC-link Capacitor Reduction for Single Phase PWM Rectifier

DC-Side Decoupling Method of DC-link Capacitor Reduction for...

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Sustainable Power and Energy Conference (iSPEC)

作者： Jinxin Wang Peng Renyong Kailei Dai Zhiqiang Zhang Ting Zhang Junjie Zhao Qian Chen Jianjian Zhang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China Nuclear Power Institute of China Chengdu China

ISBN: (数字)9781728191645

ISBN: (纸本)9781728191652

The integrated charging system of Electric vehicle consists of a single-phase PWM rectifier and a Buck converter. When the single-phase PWM rectifier works with unit power factor, the dc-link voltage contains a large voltage harmonic of twice the grid frequency. Although the output voltage ripple can be controlled within the required range using the proper control of the Buck converter, the second-order harmonic on the dc-link capacitor is inevitable. This paper proposes a de-side decoupling method for the second-order harmonic problem of the dc-link voltage of the integrated charging system. A de-side decoupling half bridge is connected in parallel to absorb the ripple power of twice the grid frequency. This paper analyzes the operating principle of the de-side decoupling half bridge. Based on a theoretical analysis of the topology and the design procedure for controlling system, the proposed converter is designed and simulated. Finally, simulation results are given to verify the method.

关键词： Capacitors Rectifiers Bridge circuits Pulse width modulation Harmonic analysis Control systems Voltage control

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