长短叶片混流式水轮机内部流动数值预测

为研究长短叶片混流式水轮机的内部流动特性,基于CFX软件平台,运用N-S方程和SST湍流模型,对HLA542-LJ-130长短叶片水轮机全流道典型小流量工况进行三维湍流计算,得到了水轮机各过流部件内流场的流动信息.计算结果表明,从固定导叶到活动导叶出口,速度矢量随压力降低而均匀增大,而且压力和速度分布在圆周方向的周向性较好,从叶片进水边到出水边,长短叶片压力变化为均匀减小,压力分布比较合理,叶片工作面表面没有明显的回流和二次流,流线分布较为流畅,尾水管进口压力、速度分布基本对称,压力沿径向分布比较均匀,尾水管肘管之前有与转轮旋转方向相同的涡带,涡带在尾水管中发展至尾端,但没有明显的偏心,在扩散段内逐渐减弱.研究结果对高水头水电站的水轮机选择和设计具有重要的指导意义.

Numerical prediction of flow in Francis turbine with long and short blades

The 3D turbulent flow in HLA542-LJ-130 turbine runner under the typical small flow rate condition was simulated in CFX by solving the 3D N-S equation with SST turbulent model. The flow information in various flow passage components was obtained. The calculation results show that the pressure reduces uniformly from the volute inlet to the outlet of the guide vane,while the velocity vector increases uniformly. In addition,the symmetry of velocity and pressure distributions on the circumferential direction is good. The pressure reduces uniformly on the long and short blades from the inlet edge to the outlet edge of the blade,and the pressure distribution is relatively reasonable. There is no obvious recirculation and secondary flow on the working surface of the blade. The streamline distribution is smooth,and the pressure and velocity distributions on the inlet of the draft tube are basically symmetrical,while the pressure is uniformly distributed along the radial direction. There are vortexes in the straight taper section of the draft tube which has the same rotation direction with the runner.These vortexes develop to the end of the draft tube without obvious eccentricity,and they are weakened in the diffuser section. This study has important guiding significance for the selection and design of turbines in high-head hydropower stations.