对称型导叶在不同攻角下的水力特性数值分析

Hydraulic Characteristic Analysis of Symmetrical Guide Blade under Different Attacking Angles

采用大涡模拟方法对对称型导叶进行了数值模拟。数值离散时 ,将时间与空间分开进行处理 ,空间上的离散采用有限体积法 ,而时间上的离散则用三阶龙格 -库塔法 ,对固壁边界的处理使用了“壁函数”法。计算结果表明导叶正压面压力系数随着攻角的增加而增大 ,而负压面的压力系数随攻角的增加而减小 ,并且在负压面上随着攻角的增加逐渐出现回流现象 ,在大攻角时 ,出现漩涡脱落现象。因此 ,建议导叶攻角范围应在 10°以内。

2D numerical simulation of flow around a symmetrical guide blade was performed by a large eddy simulation (LES) approach based on the weakly compressible hydrodynamic equation. The finite volume approach in space, the three order Runge Kutta method in time and a 'law of the wall' for the solid wall condition were used. When the attacking angle increases gradually, the pressure coefficient C p  on the positive pressure surface of the guide blade also increases, but the pressure coefficient decreases and the back flow phenomenon appears on the negative pressure surface. While the attacking angle is more than 10 degree, the flow separation appears on the negative surface. Therefore, the attacking angle of a symmetrical guide blade applied to hydraulic machine should be less than 10 degree.