叶栅安装角异常的非定常流场数值模拟

Numerical simulation of unsteady flow field on abnormal stagger angle of cascade

采用商用软件NUMECA对叶栅安装角异常进行二维流场定常和非定常数值模拟,并进行对比分析,得到了因叶栅安装角异常造成通道堵塞对该叶片以及相邻叶栅通道流场结构和非定常气动力的影响.结果表明:安装角异常角度大于0°时,主要对沿吸力面方向叶栅通道流场结构影响较大,随着安装角异常角度的增大,气流不断恶化,出现大面积的附面层分离,尾涡脱落主频率随着安装角异常角度的增大而减小,次频率随着安装角异常角度的增大而增大;并导致叶片非定常气动力相对脉动量迅速增大,这可能是导致叶片疲劳破坏的原因之一.

Tow-dimensional steady and unsteady numerical simulation was predicted by commercial softwave NUMECA when the stagger angle of cascade was abnormal. The main aim is to investigate cascade passage block resulting from abnormal stagger angle affecting the flow field and unsteady aerodynamic force of the blade and the adjacent cascade passage. The results show that it has an effect on the cascade field passage along the suction side when abnormal stagger angle is positive. With the increase of abnormal stagger angle, the flow is more deteriorated and the large scale of boundary layer separation is generated. The main frequency of vortex shedding decreases with the increase of abnormal stagger angle; but the secondary frequency of vortex shedding increases with the increase of abnormal stagger an- gle. And relative fluctuation quantity of unsteady aerodynamic force increases rapidly arising from the changing angle; accounting for the blade fatigue breakdown.