Karman vortices forming behind blades or guide vanes may induce severe vibration and noise in hydraulic machinery. To solve these problems, the trailing edge of vanes or blades is usually trimmed as a remedy. However, this type of modification is not always effective. Based on an engineering project, two sides of the tail of an asymmetric guide vane were modified respectively. The influence of the modification on the wake flow under different inflow conditions was studied using numerical simulation. The results show that, for the studied case, a 45°-bevel cut on the side of a vane with larger velocity gradient near the trailing edge can effectively suppress the Karman vortex. However, the effect of trimming on the side with smaller velocity gradient is poor. These two ways of trimming can reduce the amplitude of the vortex-excitation force by 73.6% and 35.4%, respectively. When guide vanes opening or head increases, the trimming effect is weakened. In addition, the inflow angle and velocity magnitude have a significant impact on the wake flow behind a hydrofoil. When the attacking angle decreases from 0° to –5°, the amplitude of the vortex-excitation force doubles. When the attacking angle increases to 5°, the Karman vortex street almost disappears. The strength of the Karman vortex is related to the difference between the velocity gradient on the two sides of a vane. The greater the difference, the more stable the wake flow.

在叶片或导向叶片后面形成的卡曼涡流可能在液压机械中引起严重的振动和噪声。为了解决这些问题，通常修剪叶片或叶片的后缘作为补救措施。但是，这种修改并不总是有效的。根据一个工程项目，分别对不对称导叶尾部的两侧进行了修改。利用数值模拟研究了改性对不同入水条件下尾流的影响。结果表明，对于所研究的情况，在后缘附近具有较大速度梯度的叶片侧面上的45°斜切可以有效地抑制Karman涡旋。但是，在速度梯度较小的一侧进行修整的效果较差。这两种修整方式可以将涡流激励力的幅度减小73。分别为6％和35.4％。当导叶开口或扬程增加时，修整效果会减弱。此外，流入角和速度大小对水翼后面的尾流有重要影响。当迎角从0°减小到–5°时，涡旋激励力的振幅将增加一倍。当迎角增加到5°时，卡曼涡街几乎消失了。卡曼涡旋的强度与叶片两侧的速度梯度之间的差异有关。差异越大，尾流就越稳定。涡旋激励力的振幅加倍。当迎角增加到5°时，卡曼涡街几乎消失了。卡曼涡旋的强度与叶片两侧的速度梯度之间的差异有关。差异越大，尾流就越稳定。涡旋激励力的振幅加倍。当迎角增加到5°时，卡曼涡街几乎消失了。卡曼涡旋的强度与叶片两侧的速度梯度之间的差异有关。差异越大，尾流就越稳定。