曲率缓变型反弧段水流的时均特性

本文提出一种曲率缓变型反弧曲线设计方法，用激光测速系统研究了该反弧水流的时均特性，得出反弧段水流时均流速分布，壁面压强，壁面切应力及紊流边界层的沿程变化，与单圆弧反弧体型试验成果比较表明，的反弧曲率的连续缓变，使壁面压强分布和空化数变化缓和，消除了曲率突变存在的逆、顺压力梯度；过渡层紊流强度减小２０－３０％；切应力系数有所下降，反弧末端切应力系数Ｃ＇ｆ减小１０％，本文还对反弧水流紊流边界层厚度的变

The time-averaged characteristics of the flow passing through a gradually varied curvature bucket

In this paper,a disign for gradully varied curvature bucket has been proposed.The time--averaged characteristics of the flow passing th rough this bucket have been investigated deeply with 1-D and 2-D.Laser Doppler Anemometry.The velocity distribution of,the variations of wall pressure,the wall shear stress and turbulent boundary layer along the flow are obtained and compared with the experimental data of the flow passing through a single-circle curvature bucket.It has found thats the variation of the wall pressure and cavitation number are smooth;the strong favorable and adverse pressure gradients ocurred near the tangential point are eliminated; the turbulent intensity in the buf-fer layer is reduced by 20-30%;the coefficient of the shear stress drops mpderately,the cofficient Cf is declined by 10% at the end of the bucket.Some new viewpoints about the development of the tubulent boundary layer on the bucket and the second development of the boundary layer on the downstream flat apron are also suggested.