Numerical simulations of the cavitation phenomena in a Francis turbine at deep part load conditions

9th International Symposium on Cavitation

Wack, J.^1 ; Riedelbauch, S.^1

Institute of Fluid Mechanics and Hydraulic Machinery, University of Stuttgart, Pfaffenwaldring 10, Stuttgart

70555, Germany^1

关键词: Flow charac-teristics;    Hydraulic machines;    Minimum pressure;    Off design condition;    Operating points;    Operating ranges;    Outlet boundary condition;    Part load conditions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/656/1/012074/pdf
DOI  :  10.1088/1742-6596/656/1/012074

来源: IOP

【 摘 要 】

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.