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

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 angle. And relative fluctuation quantity of unsteady aerodynamic force increases rapidly arising from the changing angle; accounting for the blade fatigue breakdown.