Aerodynamic and Aeroacoustic Optimization of Leading-Edge Undulation of a NACA 65(12)-10 Airfoil

Abstract

Experimental studies of a NACA 65(12)-10 airfoil with a sinusoidal leading-edge undulation (LEU) were carried out to simultaneously optimize its aerodynamic and aeroacoustic performances by considering the attached as well as the separated flow at the effective Reynolds number of ${10}^6$ , where the maximum lift was increased without sacrificing drag or overall noise at near- and poststall angles. Further aerodynamic and aeroacoustic tests indicated that a combination of LEU wavelength $\lambda /c=30\%$ and amplitude $h/c=6\%$ gave an optimum LEU by considering the aerodynamic performance as well as the noise reduction. Particle image velocimetry measurements of the flow over the optimized airfoil showed biperiodic velocity fluctuations downstream of the LEU peaks that were associated with unsteady stall cell structure near the trailing edge.