液力透平进口截面对水力损失及速度矩的影响

为减小液力透平各过流部件的水力损失，提高液力透平的效率，在不同蜗壳进口截面下将一单级液力透平蜗壳的基圆作为一环线，计算沿该环线的切向速度值，根据基圆半径计算出相应的速度矩，并在环线上分别设置4个监测点，利用ANSYS软件计算监测点处的速度矩随流量的变化规律，最后研究蜗壳进口截面对各过流部件水力损失的影响。结果表明:所选液力透平的蜗壳最佳进口直径为65mm，改进后液力透平的效率比原设计下的效率提高了1.83%，且在该蜗壳进口下叶轮进口的速度矩波动幅值最小；随着蜗壳进口直径的增加叶轮进口的速度矩逐渐减小，蜗壳收缩管的收缩率逐渐增加，收缩管中的水力损失逐渐减小。  

Effect of Entrance Section of Hydraulic Turbine on Hydraulic 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.