对旋式轴流泵叶轮水力性能的研究

Study on the Impeller Hydraulic Performance for the Contra-Rotating Axial Flow Pump

为探讨前置叶轮与后置叶轮的设计方法及外特性,定义了对旋式轴流泵的比转数,提出了在原始设计参数中适当提高后置叶轮的设计扬程。通过对设计工况与非设计工况下前置叶轮与后置叶轮的进出口速度三角形的分析,提出了求解速度三角形的“耦合”条件,给出了求解公式。本文还基于速度三角形,运用升力法设计了前置叶轮与后置叶轮的几何参数,定性的分析了设计结果,预测了水力性能。设计实例表明:当前置叶轮与后置叶轮采用等扬程设计时,后置叶轮与前置叶轮相比,进出口相对速度的平均值较大,而叶栅安放角较小,并且扬程曲线要陡得多。

This paper discussed the design method and performance of the front and rear impellers of the contra-rotating axial flow pump. A definition of specific speed has been given. The design head of rear impeller was suggested to increase appropriately. By analyzing the inlet and outlet velocity triangles of the twin impellers in detail under design and off-design point, the paper gave a matching condition and formulas for working out the two triangles. Based on the velocity triangles and lift method, the geometric parameters of the twin impellers have been designed, the results have been analyzed qualitatively, and the hydraulic performance has been predicted. A practical design shows that at the same design head of the twin impellers, the relative velocity at the middle of inlet and outlet of rear impeller are larger than that of the front impeller, while the stagger angle is smaller and the head curve is much steeper.