Evaluation of wavy leading edge for rotary-wing applications

Abstract

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.As a passive flow control mechanism inspired in nature, the wavy leading edge modifications have been tested here for specific rotary-wing airfoils. After examining previously studies, it was observed that these geometric devices could delay the boundary layer separation that usually occurs at high angles of attack in retreating blades, avoiding their abrupt stall. In order to evaluate if wavy leading edges could be applied successfully on helicopter blades, a series of wind tunnel tests have been performed for selected rotary-wing airfoils used in the H-60 Black Hawk aircraft. The waviness has shown a great potential to make softer the stall characteristics for the Sikorsky SC1094-R8 airfoil, a modified profile of the Sikorsky SC1095, while delaying the initial stall by up to 3◦, without a relevant increase in drag coefficient. The experimental investigation was based on force measurements (lift and drag coeficients) and oil flow visualization.