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vortex structures of dynamic pure yaw test using DDES approach and vortex identification method

Journal of Hydrodynamics 2022年第2期34卷 226-233页

作者： Wei-wen Zhao Qing-jie Meng De-cheng Wan Yi-qian Wang Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Wuhan Second Ship Design and Research Institute Wuhan430205China School of Mathematical Science Soochow UniversitySuzhou215006China

Considered as the building blocks,vortex structures with variety of sizes and intensity are widely recognized in the viscous flow field around *** this paper,the computational fluid dynamics(CFD)solver,naoe-FOAM-SJTU,coupled with delayed detached-eddy simulation(DDES)is adopted to analyze the vortex structures around the benchmark model Yupeng Ship in dynamic pure yaw tests,which are captured by third generation of vortex identification *** good agreement of the predicted force/moment by DDES method with the experimental data indicates that the present numerical schemes are reliable and *** vortex identification methods,Q-criteria,Ω_(R) and Liutex,are used to capture the vortex structures around the *** large separated flow is able to be investigated by these three methods,in which more vortex structures are captured byΩ_(R) approach and Liutex method with scalar,vector and tensor form seems to be more suitable for analyzing the flow mechanism around the hull in dynamic pure yaw *** general,each vortex structure corresponds to a dominant positive/negative axial Liutex and a bound vortex *** streamlines are spiral in the large separated flow,indicating that the flow in corresponding region is *** the rotation of the flow is not directly related to the intensity of Liutex.

关键词： Dynamic pure yaw test delayed detached-eddy simulation(DDES) vortex identification method vortex structure flow mechanism

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vortex identification based on the Liutex method and its effect on fish passage upstream

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Journal of Hydrodynamics 2024年第1期36卷 130-141页

作者： Chun-ying Shen Rui-guo Yang Xiao-tao Shi Ming-ming Wang Shi-hua He Faculty of Electrical Power Engineering Kunming University of Science and TechnologyKunming650500China Hubei International Science and Technology Cooperation Base of Fish Passage China Three Gorges UniversityYichang443002China Shanghai Investigation Design and Research Institute Co.LtShanghai200434China

Fishway research is important for mitigating the fragmentation of river habitats caused by hydraulic *** vertical slit fishway is a broadly used fishway type because of its high efficiency and adaptability to water ***,the resulting vortex current disrupts the fish passage hence directly affecting fish *** study aims to accurately capture the vortex structure in the fishway and analyze the effect of vortex elements(vortex structure,vortex intensity,etc.)on *** conducted an analysis of the 3-D current flow field in the fishway through the utilization of an experimental model and the large eddy simulation(LES)***,we captured the vortex information in the fishway at different flow rates using the Liutex vortex identification method and investigated the effect of the vortex on fish *** results revealed that the structures inside the fishway pool occupy most of the room,however,the areas with higher vortex strength were primarily located in the vortex near the vertical seam and the mainstream,the vortex strength inside the fishway gradually increases with increasing flow,suppressing fish *** experienced significantly increased resistance when encountering strong *** suggests that the vortex may act as a physical barrier to fish *** findings highlight the potential negative effects of vortex on fish movement and reiterate the importance of understanding vortex dynamics for aquatic environmental *** an effective tool for identifying vortices in fluid flow,the Liutex method demonstrates features of vortex within the fishway,thereby providing important insights into the interaction between fluid dynamics and aquatic organisms.

关键词： Vertical slit fishway vortex identification method Liutex large eddy simulation(LES) fish experiment computational fluid dynamics

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Influence of upstream disturbance on the draft-tube flow of Francis turbine under part-load conditions

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Journal of Hydrodynamics 2018年第1期30卷 131-139页

作者：陈婷郑祥豪张宇宁 Shengcai Li Key Laboratory of Condition Monitoring and Control for Power Plant Equipment Ministry of EducationSchool of EnergyPower and Mechanical EngineeringNorth China Electric Power University School of Science Wuhan Institute of Technology School of Engineering University of Warwick Key Laboratory of Fluid and Power Machinery Ministry of Education Xihua University National Research Center of Pumps Jiangsu University

Owing to the part-load operations for the enhancement of grid flexibility, the Francis turbine often suffers from severe low-frequency and large-amplitude hydraulic instability, which is mostly pertinent to the highly unsteady swirling vortex rope in the draft tube. The influence of disturbances in the upstream（e.g., large-scale vortex structures in the spiral casing） on the draft-tube vortex flow is not well understood yet. In the present paper, the influence of the upstream disturbances on the vortical flow in the draft tube is studied based on the vortex identification method and the analysis of several important parameters（e.g., the swirl number and the velocity profile）. For a small guide vane opening（representing the part-load condition）, the vortices triggered in the spiral casing propagate downstream and significantly affect the swirling vortex-rope precession in the draft tube, leading to the changes of the intensity and the processional frequency of the swirling vortex rope. When the guide vane opening approaches the optimum one（representing the full-load condition）, the upstream disturbance becomes weaker and thus its influences on the downstream flow are very limited.

关键词： Francis turbine vortex identification method instability vortex rope part-load condition swirl number

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