Numerical Simulation And Performance Analysis Of Francis Turbine With Long And Short Blades

As a core component of a hydropower station, hydraulic turbine plays a vital role in the integration of a station.Research on the technology of hydraulic turbine is continuously increasing with the development of water electricity. However, in many domestic and foreign hydropower station, due to some technical problems, the malfunction of the water-turbine generator set still exisrt, which may lead to the damage of flowing parts. The effieient and steady performance of Francis turbine has been taken into more consideration with its increase in capacity, size and speed. It is essential to do further research on the internal flow field simulation.Therefore, studies of steady and unsteady flowin hydraulic turbine components are of importance to deeply understand the hydraulic turbine vibration intrinsic mechanism, improve the comprehensive hydraulic performance of the hydraulic turbine, and enhance the operating stability of the water-turbine generator set.Recently, high water-head Francis turbine has been used widely with the improvement of manufacture and application of resisting erosion wear materials. But internal flow passage of high water-head nomal Francis turbine has high velocity that results in serious cavitations erosion. And it brings secondary flow at the inlet of runner under the off-design condition. Moreover, the interaction of rotating components could induce strong vibration and pressure pulse of water-turbine set.Long and short blades runner could resolve above issues effectively. It is generally approved on account of wide high-efficiency area, excellent stability and anti-cavitation capability of long and short blades runner.A hydraulic turbine of hydropower station is taken as reference in this paper. The geometric model with whole flow passage of hydraulic turbine is built at first. Then the numerical simulation of internal flow is completed under the spplication of CFD software. The internal flow features and performance of hydraulic turbine is analysed according to the results.Main work of this paper can be listed as follow:Firstly, the 3D geometric models diversion component,distributor,runner and draft tube of hydraulic turbine are done according to actual hydraulic design parameters of a specific station. Then the hydraulic turbine models are introduced into the Gambit software, and the flowing parts are meshed in sequence.Secondly, make reasearch of key steps before application of Fluent software, such as boundary setting, parameter selection, solution computation, ect. The the mesh file is introduced into software, it could be cauculated after setting boundaries. Thirdly, the cauculation results should be made post-treatment,then we could get the pressure equivalent distribution lines and velocity vector distribution. Flow state, velocity distribution and pressure variation.Finally, we could get the flowing information through compare and analyse internal flowing characteristics of hydraulic turbine.Then the performance of turbine could be evaluated quantitatively and qualitative.