Research On Design Method And Numerical Analysis Of Pump Turbine Spiral Case

In the pumped storage power station,the stability of the unit plays a decisive role in the normal operation of the power station.Especially in high head pumped storage power station,the strength and performance of volute have a great influence on the stability of pump turbine.In view of the contradiction between turbine working conditions and different performance requirements of pump working conditions in the volute design of reversible pump turbine,it is of great engineering application value to explore the design method of volute suitable for high head pump turbine.Based on the traditional design method of volute,this paper presents a design method of D-section volute(D-type volute)based on the bionic technology of egg-shaped pressure hull.The purpose is to solve the compatibility problem between the volute and the working condition of pump and turbine during the operation of pump and turbine.The main work and research results are as follows:(1)According to the different requirements of the performance of the volute in different operating conditions of pump-turbine,the design of the volute is carried out according to the pump and turbine operating conditions respectively.The research shows that the geometric parameters of the volute section designed by the two methods are quite different.The area of the volute section designed by the turbine is larger than that designed by the pump,so the former is suitable for the contraction of the turbine working conditions.Flow characteristics,and the latter is suitable for the role of pumping water.Therefore,it is difficult for these two kinds of volutes to be applied to pump turbines to meet the requirements of both pump and turbine conditions.(2)On the basis of the above analysis,the design method of D-section spiral case based on the bionic technology of egg-shaped pressure hull(D-section spiral case)is put forward.Each section of D-section spiral case adopts the shape of goose-egg section similar to elliptical section.The transition of elliptical section of D-section spiral case is smooth near the nose end,the connection between wall and seat ring is smooth,and the horizontal radius of ellipse is long.It can effectively improve the uneven distribution of pressure and reduce the hydraulic loss by providing enough space for the long and full development of flow pattern,thus solving the multiple contradictions in the design of pump turbine volute considering two different working conditions.(3)Three kinds of volute design schemes are numerically analyzed under pump and turbine operating conditions respectively.The results show that the three design methods have little influence on the efficiency of pump and turbine.Under the optimal operating conditions,the uniformity of pressure distribution in volute designed according to turbine and pump is poor,and the flow pattern in fixed guide vane is disordered.The uniform distribution of pressure in each section of D-type volute can effectively improve the flow disorder caused by the uneven distribution of pressure and the rise of local pressure in the volute,and can improve the pressure bearing capacity of the volute.In conclusion,the design of D-type pressure-resistant volute has obvious advantages in the volute design of pump-turbine.