混流式水轮机转轮设计方法改进

Improvement of the Design Method for Francis Turbine Runner

在混流式水轮机转轮设计时 ,其轴面流动一般按一元或二元假设计算 ,沿转轮进、出口边的环量分布按等值考虑。实测结果表明其轴面速度介于一元二元假设之间 ,转轮进、出口的环量分布不为常数 ,下环处大 ,上冠处小。文章建议采用介于一元二元之间的轴面流动计算方法 ,并介绍了数学模型 ,并建议在转轮出、出口按不等环量分布。经实际使用 ,这种改进取得较满意的效果。

When a Francis turbine runner is designed,the meridian flow is usually calculated according to one dimensional or two dimensional hypothesis,the circulation distributions along the inlet edge and outlet edge of runner blade are usually taken to be constants respectively.The experimental result indicates that the meridian velocity distribution is between one dimensional hypothesis and two dimensional hypothesis,and circulations along both the inlet and outlet edges of blade are not constants,they are all larger near the band and smaller near the crown.For this reasons,this paper introduces an improved design method of Francis turbine runner,in which a new calculation method,which can calculate the meridian flow between above two hypotheses,is used and the mathematical model is introduced,and unequal circulation distributions along the inlet and outlet edges of runner blade are used.Practical application indicates this improved design method can give a satisfactory result.