叶片出口安放角对单叶片泵性能的影响

Effects of blade outlet angle on performance for single blade pumps

为改善单叶片泵的性能,采用数值模拟与外特性试验相结合的方法分析了叶片出口安放角对泵性能的影响.基于SIMPLEC算法和RNG k-ε湍流模型,通过ANSYS CFX软件求解三维N-S方程,对叶片出口安放角分别为10°,14°,18°,22°和26°的单叶片泵内部流场进行了数值分析,得到了泵的速度场、压力场,并获得了泵外特性及所受径向力,数值计算所得扬程与试验结果具有较好的一致性.结果表明单叶片泵扬程、功率、效率均随叶片出口安放角增大而提高,但叶片出口安放角增大到18°以后,由于叶轮内流动滑移加剧,变化不再显著;不同叶片出口安放角单叶片泵内流场整体分布相似,但叶片压力面前端脱流区随叶片出口安放角的增加而增大,压力面的相对速度随叶片出口安放角的增加而减小,隔舌处的流动随叶片出口安放角的增加而变得顺畅;叶轮及蜗壳所受径向力随叶片出口安放角的增加而增大,叶轮所受径向力在设计点工况附近最小,而蜗壳所受径向力随流量增加而减小.

In order to improve the performance of single blade pumps, effects of blade outlet angle on the performance for a single blade pump were investigated based on numerical simulation and perfor- mance test. A single blade pump was designed, with different blade outlet angles β2 including to 10°, 14°, 18° ,22° , and 26°. ANSYS CFX was adopted to calculate the flow field, and SIMPLEC arithmetic and RNG k - e turbulence model were adopted to solve the N - S equations. The flow velocity, pres- sure distribution, radial force and performance curve were obtained. The simulated H - Q was in good agreement with the experimental result. The numerical simulation results show that the blade outlet an- gle affects the performance curve greatly, the head, power and efficiency are all improved with the blade outlet angle increasing, however, the change is no longer significant after the blade outlet angle increased to 18~. As the main parameters of the single blade pump are basically the same, the overall flow fields are similar in the single blade pump with different blade outlet angles, however, the flow separation in front of the pressure surface becomes serious with the blade outlet angle increasing. The relative velocity at the pressure surface decreases sing the efficiency of the single blade pump. The radial force of impeller and volute increase with the blade outlet angle increasing, moreover, the radial force of impeller is minimum near the design condi- tions and the radial force of volute decreases with the flow rate increasing.