Cavitation optimization of single-orifi ce plate using CFD method and neighborhood cultivation genetic algorithm

Yu Zhang,Jiang Lai,Chao He,Shihao Yang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.5

Single-orifice plate is wildly utilized in the piping system of the nuclear power plant to throttle anddepressurize the fluid of the pipeline. The cavitation induced by the single-orifice plate may cause someserious vibration of the pipeline. This study aims to find the optimal designs of the single-orifice platesthat may have weak cavitation possibilities. For this purpose, a new single-orifice plate with aconvergent-flat-divergent hole was modeled, a multi-objective optimization method was proposed tooptimize the shape of a single-orifice plate, while computational fluid dynamics method was adopted toobtain the fluid physical quantities. The reciprocal cavitation number and the developmental integralwere treated as cavitation indexes (e.g., objectives for the optimization algorithm). Two non-dominantdesigns ultimately achieved illustrated obvious reduction in the cavitation indexes at a Reynolds number Re ¼ 1 105 defined based on fluid velocity. Besides, the sensitivity analysis and temperature effectswere also performed. The results indicated that the convergent angle of the single-orifice plate dominants the cavitation behavior globally. The optimal designs of single-orifice plates result in lowerdownstream jet areas and lower upstream pressure. For a constant Reynolds number, the higher temperature of liquid water, the easier it is to undergo cavitation. Whereas there is a diametric phenomenonfor a constant fluid velocity. Moreover, the regression models were carried out to establish the mathematical relation between temperature and cavitation indexes

Research Progress of Hydrostatic Bearing and Hydrostatic-Hydrodynamic Hybrid Bearing in High-End Computer Numerical Control Machine Equipment

Xiaodong Yu,Weicheng Gao,Yanan Feng,Guangqiang Shi,Shihao Li,Minmin Chen,Ruiming Zhang,Junfeng Wang,Wentao Jia,Jianhua Jiao,Ruichun Dai 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.6

Hydrostatic bearing has the advantages of wide speed range, large bearing capacity, high precision and stability. Hydrostatic-hydrodynamic hybrid bearing can make up for the lack of stiffness of hydrostatic bearing and prevent tribological failure under the condition of high speed and heavy load. Therefore, hydrostatic bearing and hydrostatic-hydrodynamic hybrid bearing have become important bearing parts of high-end computer numerical control (CNC) machine equipment. The research on hydrostatic and hydrostatic-hydrodynamic open a new way for precision improvement of high-end CNC machine equipment. This paper reviews research progress of hydrostatic linear guideway, hydrostatic rest and ram, hydrostatic thrust bearing, hydrostatic-hydrodynamic thrust bearing and hydrostatic-hydrodynamic spindle of high-end CNC machine equipment, and discusses the influence of structure and working parameters on lubrication performance, accuracy and stability of bearing parts. Finally, the future research direction in hydrostatic bearing and hydrostatic-hydrodynamic hybrid bearing are suggested. This review provides a theoretical basis for design and development of high-end CNC machine equipment in the future.

Power-Electronics-Based Mission Profile Emulator for OBC with Simplified BP Models

Jinyu Yu,Lidan Zhou,Ke ma,Shihao Xia,Gang Yao 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

With the development and popularity of electric vehicles, the power level and power density of on-board chargers for EV charging system are constantly increasing, with the more complex status of operation. Recently, a new reliability testing method using power electronic converters to emulate the actual working conditions, which is called the mission profile emulation, has been proposed. However, this method is barely reported in the application of on-board chargers. Therefore, this paper aims to propose a novel MPE system for the testing of on-board chargers, where a power-electronics- based mission profile emulator is used to mimic the electrical characteristics of the lithium-ion battery pack. With the power electronics interface, this emulator allows plug-and-play tests for on-board chargers. Moreover, an extended series-parallel model and a small-signal linear AC impedance model of battery pack have been proposed. Simulations are realized in PLECS for comparison and verification.

Numerical investigation of the critical heat fl ux in a 5 × 5 rod bundle with multi-grid

Wei Liu,Zemin Shang,Shihao Yang,Lixin Yang,Zihao Tian,Yu Liu,Xi Chen,Qian Peng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.5

To improve the heat transfer efficiency of the reactor fuel assembly, it is necessary to accurately calculatethe two-phase flow boiling characteristics and the critical heat flux (CHF) in the fuel assembly. In thispaper, a Eulerian two-fluid model combined with the extended wall boiling model was used tonumerically simulate the 5 5 fuel rod bundle with spacer grids (four sets of mixing vane grids and foursets of simple support grids without mixing vanes). We calculated and analyzed 11 experimental conditions under different pressure, inlet temperature, and mass flux. After comparing the CHF and thelocation of departure from the nucleate boiling obtained by the numerical simulation with the experimental results, we confirmed the reliability of computational fluid dynamic analysis for the prediction ofthe CHF of the rod bundle and the boiling characteristics of the two-phase flow. Subsequently, weanalyzed the influence of the spacer grid and mixing vanes on the void fraction, liquid temperature, andsecondary flow distribution. The research in this article provides theoretical support for the design of fuelassemblies

A review on the risk, prevention and control of cooling water intake blockage in coastal nuclear power plants

Heshan Lin,Shuyi Zhang,Ranran Cao,Shihao Yu,Wei Bai,Rongyong Zhang,Jia Yang,Li Dai,Jianxin Chen,Yu Zhang,Hongni Xu,Kun Liu,Xinke Zhang Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.2

In recent decades, numerous instances of blockages have been reported in coastal nuclear power plants globally, leading to serious safety accidents such as power reduction, manual or automatic power loss, or shutdown of nuclear power units. Loss or shortage of cooling water may compromise the reliability of the cooling water system, thus threatening the operational safety of power plants and resulting in revenue reduction. This study provides a comprehensive review of the current state of cooling water system safety in coastal nuclear power plants worldwide and the common challenges they face, as well as the relevant research on cooling water system safety issues. The research overview and progress in investigation methods, outbreak mechanisms, prevention and control measures, and practical cases of blockages were summarized. Despite existing research, there are still many shortcomings regarding the pertinence, comprehensiveness and prospects of related research, and many problems urgently need to be solved. The most fundamental concern involves understanding the list of potential risks of blockages and their spatially distributed effects in surrounding waters. Furthermore, knowledge of the biological cycles and ecological habits of key organisms is essential for implementing risk prevention and control and for building a scientific and effective monitoring system.

CRISPR/Cas9-mediated knockout of the Vanin-1 gene in the Leghorn Male Hepatoma cell line and its effects on lipid metabolism

Xu Lu,Wang Zhongliang,Liu Shihao,Wei Zhiheng,Yu Jianfeng,Li Jun,Li Jie,Yao Wen,Gu Zhiliang 아세아·태평양축산학회 2024 Animal Bioscience Vol.37 No.3

Objective: Vanin-1 (VNN1) is a pantetheinase that catalyses the hydrolysis of pantetheine to produce pantothenic acid and cysteamine. Our previous studies have shown that the VNN1 is specifically expressed in chicken liver which negatively regulated by microRNA-122. However, the functions of the VNN1 in lipid metabolism in chicken liver haven’t been elucidated. Methods: First, we detected the VNN1 mRNA expression in 4-week chickens which were fasted 24 hours. Next, knocked out VNN1 via CRISPR/Cas9 system in the chicken Leghorn Male Hepatoma cell line. Detected the lipid deposition via oil red staining and analysis the content of triglycerides (TG), low-density lipoprotein-C (LDL-C), and highdensity lipoprotein-C (HDL-C) after VNN1 knockout in Leghorn Male Hepatoma cell line. Then we captured various differentially expressed genes (DEGs) between VNN1- modified LMH cells and original LMH cells by RNA-seq. Results: Firstly, fasting-induced expression of VNN1. Meanwhile, we successfully used the CRISPR/Cas9 system to achieve targeted mutations of the VNN1 in the chicken LMH cell line. Moreover, the expression level of VNN1 mRNA in LMH-KO-VNN1 cells decreased compared with that in the wild-type LMH cells (p<0.0001). Compared with control, lipid deposition was decreased after knockout VNN1 via oil red staining, meanwhile, the contents of TG and LDL-C were significantly reduced, and the content of HDL-C was increased in LMH-KO-VNN1 cells. Transcriptome sequencing showed that there were 1,335 DEGs between LMH-KO-VNN1 cells and original LMH cells. Of these DEGs, 431 were upregulated, and 904 were downregulated. Gene ontology analyses of all DEGs showed that the lipid metabolism-related pathways, such as fatty acid biosynthesis and long-chain fatty acid biosynthesis, were enriched. KEGG pathway analyses showed that “lipid metabolism pathway”, “energy metabolism”, and “carbohydrate metabolism” were enriched. A total of 76 DEGs were involved in these pathways, of which 29 genes were upregulated (such as cytochrome P450 family 7 subfamily A member 1, ELOVL fatty acid elongase 2, and apolipoprotein A4) and 47 genes were downregulated (such as phosphoenolpyruvate carboxykinase 1) by VNN1 knockout in the LMH cells. Conclusion: These results suggest that VNN1 plays an important role in coordinating lipid metabolism in the chicken liver.