Numerical study on active flow separation control for low-pressure turbine blade

The three-dimensional viscous unsteady Reynolds-averaged Navier-Stokes equations were employed to investigate the effects of Reynolds numbers (Re) and freestream turbulence intensity (I_FSTI) on the flow separation at the suction side of the Pak-B low-pressure turbine (LPT) blade on the basis of the Menter SST turbulence model coupled with the Langtry-Menter transition model. The numerical results indicate that the turbulence simulation can predict the flow characteristics inside the LPT cascade and capture the flow separation and reattachment location at the suction side of the blade effectively. The flow separation at the suction side of the blade decreases significantly with the increase in Re or I_FSTI. The control effect of vortex generator jets (VGJs) on the flow separation at the suction side of the blade was numerically analyzed at the low Re and low I_FSTI. Applying VGJs can suppress the flow separation at the suction side of the blade and reduce the total pressure loss and wake width. There is an optimum blowing ratio (B) in the flow control by VGJs. The flow separation could not be suppressed effectively with a small B and the mixing loss of jet flow and main flow could rise with a large B. The total pressure loss decreases by 45% compared with that without the control by VGJs when B of VGJs equals 2.