Hydraulic Design And Internal Lfow Field Analysis Of Pump-turbine

To achieve the necessary adjustment ability of the network, at least5%of the totalcapacity of pumped storage power station should be installed in the power system and10%to achieve better adjustment ability. Experts of pumped-storage plan in"12th Five-Year" believed that the inadequate domestic capacity of pumped-storagefacilities had increased the investment costs and influenced the development ofpumped-storage power station.Pump-turbine’s two conditions don’t coincide, so whether the design or selectionof the runner requires some compromise. Based on the determined basic parameters, acondition was calculated using existing hydraulic design methods from the start andchecked by another condition. In this paper, the runner which can meet theperformance requirements was designed on the basis of this concept and attempted tostudy the pump’s hydraulic performance during different operating conditions.The runner design uses the design principle of low specific speed Francisturbine’s blade, then hydraulic design,3D modeling and ICEM meshing were carriedon a pump-turbine with given parameters. Taking into account the factors of highstrain rate and curvature over the stream surface, RNG k-model was used to solveN-S equations. The finite volume method was used to discrete and SIMPLECalgorithm was used to solve pressure-speed coupling equations. By simulating themodel with the software of Fluent and correcting repeatedly, the efficiency ofpump-turbine under design condition was predicted. Besides, the changes of thepressure field and velocity field in volute, runner and draft tube were analyzed duringdifferent operating conditions, then the paper illustrated the influence of internalwhirlpool’s generation causes to the pressure field and velocity field.This design method has provided a new reference for pump-turbine runner’shydraulic design and made up for the lack of empirical data by using CFD technologyto give a direct-viewing reflection of hydraulic performances simultaneously,Numerical experiment results show that the optimal efficiency of turbine’s operatingcondition can reach91%and the optimal efficiency of pump’s can reach82%.Therewill be a further improvement if modify the model repeatedly. There are greatturbulent flow,secondary injection,swirl and flow separation in the volute.This canprovide a new method for the quantitative analysis of sudden change pressure duringthe transition when electricity goes off at Pump working and give some enlightenment for the calculation of other transition process. It’s valuable for pump-turbine runner’sdesign and structural optimization.