Effect of Entrance Section of Hydraulic Turbine onHydraulic Loss and Velocity Torque

The diffusion tube of volute outlet becomes the shrinkable tube of hydraulic turbine when centrifugal pump acts as hydraulic turbine. The energy loss between the diffusion tube and shrinkable tube is different, as well as the effect of the shrinkable tube of different shrinkage rate on hydraulic loss and velocity torque of hydraulic turbine. In order to reduce hydraulic loss of each the flow components in hydraulic turbine and improve the efficiency of hydraulic turbine, the base circle of volute of a single stage hydraulic turbine is regarded as a loop line under the different entrance section. The tangential velocity along the loop line is calculated. Correspondingly, the velocity torque is work out with the radius of base circle. Four monitoring points in the loop are set up. At the points, the velocity torque varies with the flow rate. The varieties are analyzed with ANSYS software and effect of the entrance section of volute on hydraulic loss of each the flow components is studied. The results show that the optimum entrance diameter of volute of hydraulic turbine is equal to 65 mm. Compared to the original design, the efficiency of improved hydraulic turbine increases by 1.83%. Fluctuant amplitude of velocity torque of impeller entrance is minimum in the volute entrance. With increasing volute entrance diameter, velocity torque of impeller entrance and the hydraulic loss is gradually decreased. Meanwhile the shrinkage rate of shrinkable tube in volute gradually increases.