包角对中比转速泵流场及无过载性能的影响

以D82-19-2型中比转速离心泵为研究对象，根据无过载叶轮约束公式确定叶轮设计方案，选取四种叶轮包角（150°、170°、190°和210°）开展中比转速泵流场及无过载性能的模拟研究。与实验结果相比，模拟所得扬程、效率和功率值误差不超过9%，模拟方法可行。结果表明：当叶片包角由150°增大到210°时，叶轮进口压力提高24%，低速区面积扩大至整个叶轮流道的1/3，叶片对流体的约束能力及抗汽蚀性能增强，但叶轮出口压力降低，大包角下导叶的湍流损失加剧了动能损耗；功率备用系数由1.145减小至1.025，且功率曲线出现极大值，泵的无过载特性更显著，但扬程和效率分别下降了15.4%和4.48%。研究结果为中比转速离心泵的无过载设计提供了理论依据。

Effects of Vane Wrap Angle on Flow Field and Non-overload Performance for Medium Specific Speed Pumps

To identify the effects of vane wrap angle for medium specific speed pumps, the centrifugal pump of D82-19-2 was chosen as the research subject. The design scheme of impeller and four impellers with vane wrap angle of 150°, 170°, 190° and 210° respectively were ascertained according to non-overload impeller constraint formula. The flow field and non-overload performance of the pumps were obtained by numerical simulations. By compared with experimental results, the deviations of simulated head, efficiency and power values are less than 9%, and the accuracy of simulation results was verified. The results show that with the increasing vane wrap angle from 150° to 210°, the inlet pressures of impeller increase by 24%, and low-velocity areas expand to one-third of the whole runner, that is, the fluid constraint ability and cavitation resistance have enhanced. However, the outlet pressures of impeller reduce and the kinetic energy losses aggravate for larger wrap angle. Meanwhile, the power reserve factor decreases from 1.145 to 1.025, and the extreme point of shaft power curve appears, so that non-overload characteristics of pump are more significant for larger wrap angle. But the pump head and efficiencies decrease by 15.4% and 4.48% respectively. The results may provide theoretical bases for non-overload design of medium specific speed centrifugal pumps.