速度矩分布规律对混流泵叶轮设计的影响

根据Ωu=0二元设计理论,提出了采用四次多项式表示叶片速度矩沿轴面流线的分布规律,进而通过理论分析,确定用其中一个参数控制叶片速度矩的分布规律,以减小设计结果对经验的依赖程度.由此确定的速度矩分布规律包括＂S＂型、反＂S＂型和＂L＂型3类.采用不同的叶片速度矩分布规律,比较分析了对应的叶片出口边位置、包角等设计结果,并基于正问题分析,对不同叶片速度矩分布规律下的叶轮效率预测值和叶片表面载荷分布进行了比较.结果表明：对于Ωu=0的设计方法,采用四次多项式描述叶轮轮缘边速度矩分布规律是合理的;对于给定的混流泵轴面流道,部分＂S＂型速度矩分布规律能合理地满足叶片表面扭曲和混流泵结构设计的要求;采用合理的＂S＂型速度矩分布规律设计的叶轮效率最高,叶片表面载荷分布更加光滑.结果可为混流泵叶轮设计提供参考.

Effects of velocity moment distribution law on design of mixed-flow pump impeller

According to the two-dimensional Ωu=0 design theory,a four-order polynomial was proposed to describe the velocity moment distribution along one blade streamline.The distribution was controlled only by one polynomial parameter through further theory analysis.This reduced the depen-dency of design results on design experience.In this way,there produced three types of distributions,which named ＂S＂ type,inverse ＂S＂ type and ＂L＂ type.For different velocity moment distributions,related design results such as blade outlet position and blade wrap angle were compared and analyzed.Then impeller efficiencies and blade surface loadings were compared based on numerical simulation.The results show that the method of applying four-order polynomial to describe the shroud velocity moment is practicable.For given mixed-flow pump impeller meridional flow path,there are part of reasonable ＂S＂ type velocity moment distributions satisfying requirements of both blade twist and pump structure design.For these reasonable ＂S＂ type distributions,their impeller efficiencies are higher and blade surface loadings are smoother than those of other two types.So the results can be given as a reference for mixed-flow pump impeller designers.