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Exploration of the mechanism of cavitation vortex rope and vortex development in the draft tube of tubular turbine units

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International Journal of Agricultural and Biological Engineering 2024年第1期17卷 163-171,F0002页

作者： Chuang Cheng Zhenggui Li Changrong Shen Shenglong Gu Chuchu Zeng Chuanzheng Bai Meng Liu Junfeng Hu Qinghai University of Science and Technology Xining 810000China Key Laboratory of Fluid and Power Machinery Ministry of Education(Xihua University)Chengdu 610039China South-to-North Water Diversion East Jiangsu Water Source Co. Ltd.Nanjing 210029China School of civil engineering and water resources Qinghai UniversityXining 810016China Dongyuan Branch of Shenzhen Water Planning and Design Institute Co. Ltd.Changsha 410000China

draft tube vortex rope is considered a special cavitation flow phenomenon in tubular turbine *** vortex rope is one of the most detrimental factors affecting the safety of hydraulic *** this study,ANSYS CFX software was utilized to numerically simulate the internal cavitation flow of a hydraulic turbine draft *** evolution of the cavitation vortex core was characterized by vortex line distribution and vorticity transport *** shape and number of blades influenced the revolving direction and distribution characteristics of the vortex close to the runner cone,which formed a counterclockwise-clockwise-counterclockwise distribution ***,there were many secondary flows in the draft *** cancellation and dissipation between the flows was one of the reasons for reduction in *** the cross-sectional shape of the draft tube was changed,the vorticity was distributed from the center of the vortex rope to all parts of the cross-sectional draft tube,with extreme values at the center and at the *** vortex stretching and dilatation terms played a major role in the change in vorticity,with the baroclinic torque having an effect at the center of the vortex rope,this study is helpful to understand the flow of water in the draft tube and guide the design and optimization of the draft tube in engineering application.

关键词： cavitation vortex rope vorticity transport equation vortex line draft tube

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An axisymmetric model for draft tube flow at partial load

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Journal of Hydrodynamics 2016年第2期28卷 195-205页

作者： Hosein FOROUTAN Savas YAVUZKURT Department of Mechanical and Nuclear Engineering The Pennsylvania State University

A new Reynolds-averaged Navier-Stokes （RANS） turbulence model is developed in order to correctly predict the mean flow field in a draft tube operating under partial load using 2-D axisymmetric simulations. It is shown that although 2-D axisymmetric simulations cannot model the 3-D unsteady features of the vortex rope, they can give the average location of the vortex rope in the draft tube. Nevertheless, RANS simulations underpredict the turbulent kinetic energy （TKE） production and diffusion near the center of the draft tube where the vortex rope forms, resulting in incorrect calculation of TKE profiles and, hence, poor prediction of the axial velocity. Based on this observation, a new k- c turbulence RANS model taking into account the extra production and diffusion of TKE due to coherent structures associated with the vortex rope formation is developed. The new model can successfully predict the mean flow velocity with significant improvements in comparison with the realizable k - c model. This is attributed to better prediction of TKE production and diffusion by the new model in the draft tube under partial load. Specifically, the new model calculates 31% more production and 46% more diffusion right at the shear layer when compared to the k - ~ model.

关键词： hydropower draft tube turbulence model computational fluid dynamics vortex rope

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Suspension quality and power consumption of the complex multiphase flow field in a draft-tube stirred reactor

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Particuology 2021年第3期19卷 91-102页

作者： Licheng Wang Yanxing Tian Yu Qi Yiwei Gao Mengya Wang School of Chemistry and Chemical Engineering Tianjin University of TechnologyTianjin 300384China

Experiment and simulation were used to study the flow fields of a liquid-solid-solid three-phase system in a draft-tube stirred reactor with a six-flat-bladed turbine impeller(BT)and a 45°pitched six-bladed upflow turbine impeller(PBTU45).The computational fluid dynamics(CFD)formulation was based on a 3D Eulerian multi-fluid model along with a renormalization group(RNG)k-ε turbulence model,which took into account the inter-phase momentum exchange between different *** CFD model was validated using experimental data,and the suspension quality was validated by determining the standard deviation of the solid *** solid suspension was achieved in flow fields agitated by the BT impeller at low impeller *** draft tube adversely affected solid dispersion at most impeller *** flow fields agitated by the PBTU45 impeller,good solid suspension required a faster impeller *** suspension quality with the draft tube was better than that without the draft tube under most operating *** power consumption of the BT or PBTU45 impeller with the draft tube was less than that without the draft tube at most impeller speeds.

关键词： Liquid-solid-solid Stirred reactor draft tube Computational fluid dynamics Power consumption Suspension quality

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Effect of Runner Solidity on Performance of Elbow draft tube

Effect of Runner Solidity on Performance of Elbow Draft Tube

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2011 2nd International Conference on Advances in Energy Engineering(ICAEE)

作者： Ruchi Khare Vishnu Prasad Sushil Kumar Mittal Department of Civil Engineering M.A.National Institute of Technology

The significant amount of kinetic energy comes out of runner in reaction turbines and the draft tube is used to recover this kinetic energy into useful pressure *** energy recovery in draft tube depends on its design and magnitude of velocity components at runner *** the amount of kinetic energy coming out of runner depends on the solidity of runner as well as its rotational *** draft tube is important component of turbine next to *** this paper,3D viscous turbulent flow simulation has been done in the complete flow passage of Francis turbine using commercial Computational Fluid Dynamics（CFD） code for three runner solidities at different rotational *** draft tube performance parameters in non-dimensional form are computed from simulation results and the effects of runner solidity and operating speed on draft tube performance are *** simulation results are also compared with the experimental results for validation and are found to be within reasonable accuracy.

关键词： draft tube solidity Francis turbine efficiency computational fluid dynamics

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Improving the Energy Performance of a High-Pressure Hydraulic Turbine by Researching the Flow in the Flow Part

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Journal of Power and Energy Engineering 2022年第4期10卷 27-37页

作者： Konstantin Mironov Yuliia Oleksenko Aminjon Gulakhmadov Department of Hydraulic Machines named after Academician G.F. Proskura National Technical University “Kharkiv Polytechnic Institute” Kharkiv Ukraine Ministry of Energy and Water Resources of the Republic of Tajikistan Dushanbe Tajikistan Research Center for Ecology and Environment of Central Asia Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi China Institute of Water Problems Hydropower and Ecology of the National Academy of Sciences of Tajikistan Dushanbe Tajikistan

In this study, the goal is to increase the efficiency of a high-pressure hydraulic turbine. The goal is achieved by numerical flow simulation using CFX-TASCflow. This approach reduces costs and time compared to the experimental approach and allows for improving the turbine productivity and its design. The analysis of energy losses in the flow part of the turbine Fr500, as well as the analysis of the influence of the opening of the guide vanes on changes in energy losses. The results showed that the greatest losses occur in the guide vane 3.02% based on the two-dimensional model and 2.5% based on the 3D model, which significantly affects the efficiency. The analysis was carried out using programs for calculating fluid flow in two-dimensional and three-dimensional formulations. With the help of the study, the main energy problem is solved—increasing efficiency.

关键词： Francis Turbine Efficiency Spiral Case Runner Guide Vane draft tube

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