Research On Internal Pressure Pulsation Of High-head Water Pump Turbine

The stable operation of high-head pump turbines is very important.Pressure pulsation is one of the important parameters that affect the stability of pump turbines.It is a typical source of vibration that induces energy storage units and plant and vibration.In this paper,the model experiment and numerical simulation are used to study the internal pressure pulsation of the pump-turbine.The model pump-turbine with proportional scale is used as the research object.Through model tests and CFD methods,the pressure fluctuations in the active guide vane area of low specific speed pump turbines were studied,and the effects of different operating conditions,different guide vane openings and different flow rates on the guide vane area pressure fluctuations were studied.There is a further understanding of the pressure pulsation in the guide vane area of the specific speed pump turbine,which provides a reference for the stable operation of the unit.The high-head pump turbine model test device was modified to replace four ordinary activities with special movable guide vanes.The new movable guide vanes are evenly arranged with 4 pressure sensors at 1/2 of the height of the guide vanes,each consisting of 2 movable guide vanes A flow channel is used to monitor the pressure pulsation in the movable guide vane area.At the same time,the 3D CFD model of the flow component is established.The three-dimensional constant value simulation is used to numerically calculate the four turbulence models of SST,k-?,k-?,and RNG k-?.By comparing the numerical simulation with the new guide vane model,the external characteristics are tested.The results show that when the turbulence model is SST,the numerical simulation results are closer to the test results of the active guide vane area of the high head pump turbine model,and the average pressure distribution at the active guide vanes is obtained.At the optimal operating point of the pump,the flow field velocity vector obtained from the PIV test is compared with the flow field obtained by numerical simulation.The results show that the SST turbulence model is more suitable for the numerical simulation of the pump and turbine in terms of the external characteristics and the simulation of the internal flow field in the movable vane area.The three-dimensional unsteady Reynolds average method is used to simulate the pressure fluctuations in the pump turbine.The results show that the closer to the runner inlet along the fluid flow direction of the movable guide vane,the more obvious the dynamic and static interference between the movable guide vane and the runner.The larger the amplitude is,and the frequency characteristics of the monitoring point also change with the distance between the monitoring point and the runner inlet;the flow path composed of No.1 guide vane and No.3 guide vane and No.2 guide vane and No.4 guide vane The flow channels are 180° apart,and the monitoring points on the guide vanes on the same side of different flow channels have the same change rule,that is,the change rules of guide vanes 1 and 2 are similar,and the change rules of guide vanes 3 and 4 are similar.The comparative study of model test and CFD flow analysis can fill the shortage of existing research results.Under the condition of hydraulic turbine,n11=34.05r/min,20mm guide vane opening,the numerical simulation results of the monitoring points at different positions are compared with the model test results,and the ?H/H values obtained from the numerical simulation and model tests of the monitoring points at different positions under different guide vane openings There are deviations,which are not completely consistent,but the numerical simulation results at different monitoring points are basically consistent with the model test results.From the numerical simulation results,the numerical simulation results of the pressure pulsation at the monitoring points at the guide vanes 1 and 3 near the inlet of the volute are closer to the measured values of the model test.Under the pump operating conditions,the results of numerical simulation and model test are analyzed and compared at the pump-6 operating point.At each monitoring point on the four guide vanes,the numerical simulation results can better reflect the pressure in the active guide vane area.The pulsation characteristic is not much different from the model test result.The numerical simulation result of pressure pulsation can better reflect the measured value of the model test.The propagation characteristics of the leafless area obtained by numerical simulation and model test along the entire flow channel under the conditions of the turbine and the pump are analyzed.The results show that the numerical simulation can more accurately reflect the propagation characteristics of the pressure pulsation in the bladeless area of the pump turbine.