导叶进出口角对能量回收水力透平性能的影响

根据不同的导叶进、出口角,设计4组带导叶的基于单级离心泵反转的能量回收水力透平模型,应用计算流体动力学软件Fluent 6.3对其进行数值模拟.结果表明：同一流量,随着导叶进口角的增大,透平的效率和水头均显著下降,在最优工况点,模型A比模型D水力效率高出7%.进口角一定,出口角大于进口角时,导叶出口速度环量减小,透平效率降低;反之,出口角小于进口角时,导叶出口速度环量增加,透平效率提高.随着进、出口角的增大,最优工况点向大流量区域偏移,转轮内部压力分布均匀性变差.因此导叶进口角对能量回收水力透平的性能有决定性作用,进口角大于出口角有利于效率的提高.对于其他基本尺寸确定的能量回收水力透平,存在最佳的导叶进、出口角,且导叶进、出口角对透平的外特性和内流场均有很大的影响.结果为能量回收水力透平的进一步研究提供了一定的理论基础.

Effect of guide vane inlet and outlet angles on performance of energy recovery turbines

Four energy recovery hydraulic turbine models were designed according to different combinations of guide vane inlet and outlet angles based on an existing single-stage centrifugal volute pump,and the fluid flows in them were simulated numerically by using software Fluent 6.3.It was shown that at the same flow rate all the turbine efficiency and head were declined markedly with increasing inlet angle; at the best efficiency point（BEP）,however,the hydraulic efficiency of model A was 7% higher than that of model D.For the same inlet angle,once the outlet angle was greater than the inlet angle,the circulation at the guide vane outlet was decreased and the efficiency of turbine was reduced;otherwise,the efficiency was raised.With increasing inlet and outlet angles,BEP was moved to a higher flow rate,and the pressure distribution in the impeller was distributed more non-uniformly.Therefore,the inlet angle plays a crucial role in determining turbine performance and a guide vane with an inlet angle larger than the outlet angle is beneficial to turbine efficiency.Especially,for a turbine in which the basic geometrical parameters of all the hydraulic components except the guide vane were fixed,there is an optimum combination between inlet and outlet angles of the guide vane.This result can provide some theoretical basis for further study on energy recovery hydraulic turbines.