With the application of large eddy simulation (LES) and structural hexahedral mesh

the unsteady numerical model of the low-pressure high-lift turbine Pak B cascade was established. The mechanism and influence of the flow separation control using synthetic jet were discussed in detail. The separation zone of flow becomes larger when Reynolds number decreases and angle of attack increases without synthetic jet. The separated flow has not reattached on the cascade when the angle of attack is 5°. After using synthetic jet control method

the flow separation under different flow parameters is controlled effectively. Meanwhile

the effects of synthetic jet control with different jet pitch angles were compared

and there exists an optimal jet pitch angle 30° which leads to the best flow control effect. The location of separation on the boundary layer of the cascade is delayed with synthetic jet

but the reattachment location moves forward and the size of separation bubble decreases. The adverse pressure gradient zone decreases evidently. The shear layer at the suction side moving downstream is not uplifted fully and it adheres to the wall of blade quickly

which avoids the formation of large scale vorticity and controls the flow separation.