中文摘要：

离心叶轮设计系数的选用决定了叶轮设计的优劣，以汽蚀余量最小为目标函数对单吸式和双吸式离心叶轮的进口设计系数进行了分析，结果表明，单吸式和双吸式叶轮的进口条件不同，相应得到的进口设计系数选用曲线也不同，在低比转速条件下，以汽蚀余量最小为优化目标得到的结果小于斯捷潘诺夫的推荐值．根据对速度和扬程的要求分析了离心叶轮的出口设计系数，对于单吸式叶轮，计算结果要大于斯捷潘诺夫推荐值，而双吸式叶轮的计算结果与后者的选用值推荐非常接近，结果表明，斯捷潘诺夫的推荐曲线适用于设计效率较高的双吸式离心叶轮．

英文摘要：

The design factors for the centrifugal impeller are important during the process of impeller design. With object function of minimized NPSH, the inlet design factors were analyzed both for single suction and double suction impellers. The varied result curves show that they are smaller than that recommended by Stepanoff in the range of low specific speed. The outlet design factors were deduced according to the requirement of relative velocity and head. For single suction impeller, the results are greater than that of Stepanoff; while for double suction impeller, the calculated ones agree with the latter. It is noted that the Stepanoff curves are suitable for designing high efficiency double suction centrifugal impellers.