Numerical analyses of pressure fluctuations induced by interblade vortices in a model Francis turbine

Interblade vortices can greatly influence the stable operations of Francis turbines. As visible interblade vortices are essentially cavitating flows, i.e., the ones to cause interblade vortex cavitations, an unsteady simulation with a method using the RNG k- ？ turbulence model and the Zwart-Gerber-B...

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Published inJournal of hydrodynamics. Series B Vol. 27; no. 4; pp. 513 - 521
Main Author 左志钢 刘树红 刘德民 覃大清 吴玉林
Format Journal Article
LanguageEnglish
Published Singapore Elsevier Ltd 01.10.2015
Springer Singapore
Subjects
cavitation
Engineering
Engineering Fluid Dynamics
Francis turbine
Hydrology/Water Resources
interblade vortices
Numerical and Computational Physics
pressure fluctuations
Rayleigh instability
Simulation
压力波动
叶道涡
数值分析
数值模拟
涡轮机
湍流模型
稳定运行
轮叶
pressure fluctuations
Francis turbine
interblade vortices
Rayleigh instability
cavitation
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Summary:Interblade vortices can greatly influence the stable operations of Francis turbines. As visible interblade vortices are essentially cavitating flows, i.e., the ones to cause interblade vortex cavitations, an unsteady simulation with a method using the RNG k- ？ turbulence model and the Zwart-Gerber-Belamri（ZGB） cavitation model is carried out to predict the pressure fluctuations induced. Modifications of the turbulence viscosity are made to improve the resolutions. The interblade vortices of two different appearances are observed from the numerical results, namely, the columnar and streamwise vortices, as is consistent with the experimental results. The pressure fluctuations of different frequencies are found to be induced by the interblade vortices on incipient and developed interblade vortex lines, respectively, on the Hill diagram of the model runner＇s parameters. From the centrifugal Rayleigh instability criterion, it follows that the columnar interblade vortices are stable and the streamwise interblade vortices are unstable in the model Francis turbine.
Bibliography:31-1563/T
interblade vortices； pressure fluctuations； Francis turbine； cavitation； Rayleigh instability
Interblade vortices can greatly influence the stable operations of Francis turbines. As visible interblade vortices are essentially cavitating flows, i.e., the ones to cause interblade vortex cavitations, an unsteady simulation with a method using the RNG k- ？ turbulence model and the Zwart-Gerber-Belamri（ZGB） cavitation model is carried out to predict the pressure fluctuations induced. Modifications of the turbulence viscosity are made to improve the resolutions. The interblade vortices of two different appearances are observed from the numerical results, namely, the columnar and streamwise vortices, as is consistent with the experimental results. The pressure fluctuations of different frequencies are found to be induced by the interblade vortices on incipient and developed interblade vortex lines, respectively, on the Hill diagram of the model runner＇s parameters. From the centrifugal Rayleigh instability criterion, it follows that the columnar interblade vortices are stable and the streamwise interblade vortices are unstable in the model Francis turbine.
ZUO Zhi-gang , LIU Shu-hong , LIU De-min , QIN Da-qing , Wu Yu-lin （ 1. Department of Thermal Engineering, State Key Laboratory of Hydro Science and Engineering, Tsinghua University, Beijing 100084, China 2. Research and Test Center, Dongfang Electric Machinery Co. Ltd, Deyang 618000, China 3. State Key Laboratory of Hydro-power Equipment, Haerbin 150001, China）
ISSN:1001-6058
1878-0342
DOI:10.1016/S1001-6058(15)60511-X