Numerical Simulation And Analysis Of Internal Flow Of Francis Turbine In Sandy Water

China has an abundant reserve of water resources and hydropower is one of the most important energy resources. As the key part of a hydropower station, hydraulic turbine has many problems during the operation of power stations, such as cavitation and sand abrasion. These problems will affect the performance of a turbine, shorten the maintenance period, and greatly increase the expected operation cost. Therefore, the study of flow in a turbine and the predication of its hydraulic performance are very important.By using the data of a Francis turbine provided by Jinping II Hydropower Station, the whole flow passage of the turbine was modeled by using UG software. Then on the CFX platform, the three-dimensional flow fields of this model in clean water and sandy water were numerically simulated under four different conditions. The simulation results can provide theoretic basis for the operation and maintenance of Jinping II Hydropower Station and for turbine design of other hydropower stations. Major works completed in this study are as follows:1) By using the materials of the hydraulic turbine and the wood form drawings provided by Jinping II Hydropower Station, the three-dimensional geometric model of the spiral case, stay ring, runner and draft tube were established by using UG. And then, these models were assembled to establish the whole flow passage model.2) The three-dimensional model established in UG was imported into ICEM CFD which is a pre-processing module in CFX. The tetrahedral meshes were used to divide all the flow components. The mesh quality was checked and optimized until meeting the simulation requirements, and then it was exported in "cfx5" format.3) The mesh model was imported into the CFX-Pre to realize steady flow simulation in the whole flow passage in clean water under different loads. After post-processing by CFD-Post, the pressure distributions of all flow components were obtained and analyzed.4) In sandy water, the steady flow of the whole flow passage was simulated under different conditions as that in clean water while the particle sizes and sediment concentration are different. After post-processing by CFD-Post, the pressure distributions and sediment distributions of all flow components were obtained and analyzed.5) The simulation results of the flow field under the same load conditions in clean water and sandy water were analyzed and compared, which can provide reliable suggestions for the future operation of the turbine.This simulation predicts the hydraulic performance of the turbine in sandy water.