Study of Flow Control Using a Slotted Blade for a Compressor Airfoil at Low Reynolds Numbers

Abstract

Flow control using a blade which is slotted from pressure surface to suction surface was studied. The effects of a slotted blade for a compressor airfoil at low Reynolds numbers were studied with the help of a linear cascade wind tunnel and a state-of-the-art multi-block flow solver. Measurements were taken in a low-speed linear cascade. The compressor cascade with a steady inflow was examined based on blade chord length at low Reynolds numbers. The experimental results showed that the slotted blade could effectively reduce the loss wake width and depth. The maximum relative reduction of wake width and depth were 48% and 45%, respectively. The numerical results at Reynolds numbers ranging from 1.2×105 to 2.1×105 showed that the airfoil aerodynamics of cascade are substantially improved by a slotted blade within this Reynolds number regime. This yields less total pressure loss and a greater flow turning angle and static pressure rise. The extensive numerical results showed that the slot inlet could capture the high pressure flow from the pressure surface, bring it into the slot, and discharge it onto the suction surface of the blade. This then blows off the boundary layer separation flow and accelerates the low energy flow, reducing the size of the separation region, or even eliminating the separation entirely on the trailing edge of blade.