A simulation using unsteady Reynolds-averaged viscous turbulent equations was carried out.The results show that the flow in the separation region and wake region is characterized as periodic or quasi-periodic vortex shedding and the frequency of vortex shedding is varied with incidence and Mach number.At same Mach number

the frequency of vortex shedding decreases with the increase of incidence.Yet

the frequency increases with the increase of Mach number keeping incidence unchanged.In the same situation

the frequency of vortex shedding differs along the span of the cascades.The frequency is lower at the middle of the span than that at the hub.