| The application of misaligned guide vanes (MGV) forFrancis pump-turbinebrought a new hydrodynamic research topic. With the process of the development ofpump storage plant in current China, the stability of pump-turbine unit was paid moreattention. Through the analysis of steady and unsteady flow in case of the guide vanesare not synchronized action, it is a great significance for in-depth understanding of theinherent mechanism of pump-turbine vibration, to improve the whole hydraulicperformance, improving the operation stability of pump-turbine.Through the simulation and comparison of three operation conditions of the guidevanes synchronized and unsynchronized with different opening angles at rated speedand design head, the hydraulic performance of the pump-turbine, the unsteady flowpatterns and pressure pulsation of the whole flow passage have been gained. For theguide vanes unsynchronized, the performance and the overall flow flied have beenchanged. With the increase of the angle of MGVs, the discharge and output is increasedand the efficiency has been improved.By long physical time unsteady simulation, the unsteady flow patterns, pressurepulsation and spectrum have been changed for the MGV. In the most of flow passages,the amplitude of pressure pulsation has been improved for the MGV. With the angleMGVs increased, the amplitude in the flow passage except the runner field isdecreased.Flow distribution results show that the amplitude of pressure pulsation inrunner blade channels is higher with MGV due to the velocity changed so much overtime; lead to the dynamic pressure value changedthen directly caused the pressure isfluctuation. In the other components, the MGV smooth the internal flow pattern, thusreducing the amplitude of internal pressure pulsation.In this paper, the effect of MGV for flow patterns and the inherent mechanismhave been analyzed quantitatively, and take a foundation of improve the hydraulicvibration in similar unit for further study. |
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