Interblade Wortex Numerical Simulation Of Whole Flow Passage In Francis Turbine

Francis turbine is widely used,its performance directly determines the economic benefits of hydropower stations and life. Current research of francis turbine , not only to improve the efficiency of runners, and which more importantly is the stability of its operation. Large-scale francis at home and abroad to find vibration,blade cracks,and accompanied by abnormal noise,the main reason is that francis often run away from the design condition,generated from cavitation and swirl in the flow.In this paper, starting from the computational fluid mechanics,use FLUENT which is the advanced business computing software,utilize the theory and method of CFD,use the turbulent current mode of Sparlart- Allmaras,through the algorithm of SIMPLE,based on discrete incompressible N-S equation of finite volume method,for a specific station's turbine,established the turbine's whole flow passage's geometric model which use the three-dimensional modeling software,comprise volute,fixed guide vane,activity guide vane,runner,draft tube,and use the module mesh of FLUENT software,divide the over-current part's mesh and check the mesh's quality which use unstructured grid,meet the requirements of the grid paper, output file when complete initial settings of boundary conditions. Use the grid technology on a single grid paper to deal, constitute a document of whole flow,and imported into the calculation module of FLUENT software,calculated the whole flow when completion of parameter setting, calculated the whole flow unsteady three-dimensional turbulence simulation of volute,fixed guide vane,activity guide vane,runner and draft tube,when the francis turbine in the small flow condition, the design flow condition and the large flow conditions. have been the velocity spread and pressure distribution of volute,guide vane, runner and draft tube,the flowage of guide vane and runner,improve the research and analysis of the turbine's separation fluid and swirl when run in different conditions,in different cycle of same time,which between the fixed guide vanes and activity guide vanes,between the fixed guide vanes and runner blades. When small opening,there is a serious problem of water impact on the upper crown region of runner's import side,after the impact occurred,flow from crown to circle,which on the impact of blade and runner crown,at the same time,formation separation fluid in the back,and formation the interblade wortex. When the opening increases, the vortex has been rectified. Draft tube occur swirl in varying degrees when in small and large flow conditions,which with a serious off-center,into a spiral,and large pressure fluctuation. This vortex contraction after next to the runner when in the large flow conditions, the shape of vortex has larger changes when at different moments in the rotating. The vortex has been significantly improved in the design conditions.For the hydraulic optimal design of whole flow passage in francis turbine and practical guidance to hydropower station,this results of the study has important academic significance and value of engineering applications.