Numerical simulations of the cavitation phenomena in a Francis turbine at deep part load conditions
Numerical simulations of the cavitation phenomena in a Francis turbine at deep part load conditions
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DOI：
10.1088/1742-6596/656/1/012074
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发表时间：
2015-12
期刊：
影响因子：
--
通讯作者：
J. Wack;S. Riedelbauch
中科院分区：
文献类型：
--
作者：
J. Wack;S. Riedelbauch
近年来，液压机的工作范围越来越大。因此，涡轮机面临着非设计条件，具有高度复杂的流动现象，如空化。在本研究中，空化叶片间涡的发生在深部分负载条件下的弗朗西斯涡轮机使用两相流模拟研究。数值模拟需要小的时间步长和精细的网格来再现所需的流动特性并解决涡核中的最小压力。此外，出口边界条件的处理是重要的，因为该操作点在尾水管中的一个扩散器通道中面临严重回流。模拟结果表明，叶间涡系是可以再现的。
In recent years, the operating range of hydraulic machines has been more and more extended. As a consequence, the turbines are facing off-design conditions with highly complex flow phenomena like cavitation. In the present study, the occurrences of cavitating inter blade vortices at deep part load conditions in a Francis turbine are investigated using two-phase flow simulations. The numerical simulations require small time steps and fine meshes to reproduce the required flow characteristics and resolve the minimum pressure in the vortex core. Furthermore, the treatment of the outlet boundary condition is important, as this operating point is facing severe backflow in one diffusor channel in the draft tube. The simulation results indicate that the inter blade vortices can be reproduced.