Numerical Simulation And PIV Tests Of Internal Flow In Francis Turbine Runner

In recent years,the level of turbine design and manufacture has been greatly improved in China and has entered the advanced level in the world.But there is a certain gap between the domestic turbine design level and the international level,especially in the energy characteristics and cavitation performance of the runner.Francis turbine is one of the most widely used types of turbines in China.The study of vortex flow and cavitation in the runner of Francis turbines is of great significance.A Francis turbine was taken as the research subject.The entire flow passage was numerically simulated and tested after modeling.First,The internal flows at seven operating conditions were numerically simulated to study the channel vortex.And then the cavitation model was used to study the cavitation in the runner.Meanwhile,the PIV was use to observe the channel vortexes in the turbine runner.This technology was used to test the flow velocity in the runner to explore feasible test measures.Major works completed in this study are as follows:Firstly,a 3D geometrical model was established for the selected turbine,and good quality meshes were generated.The meshes of various flow components were pretreated in ANSYS,including designating area,setting up boundary conditions,interfaces and the computational accuracy.Then the entire flow passage of the turbine was numerically simulated.Secondly,the channel vortexes were numerically simulated at large opening and small opening conditions.The channel vortexes in the runner at the same opening but different unit speeds and at the same unit speed but different openings were compared.Thirdly,the cavitation was numerically calculated at large opening and small opening conditions.The cavitations in the runner at the same opening but different unit speeds and at the same unit speed but different openings were compared.Fourthly,the PIV speed measuring device was set on the test stand of the turbine to test the internal flow state and observe the channel vortexes.Through image data processing,the streamline,velocity vector and other data of flow in the turbine runner were obtained.