Effect of Airfoil-Preserved Undulations on Wing Performance

Abstract

The effect of undulation placement (leading edge, trailing edge, leading and trailing edge) on the wing performance and the wingtip vortex was investigated. Experiments were performed at the University of Dayton Low Speed Wind Tunnel (UD-LSWT) on undulated wings where the NACA 0012 airfoil crosssection is preserved along the wingspan. Sensitivity studies were done on the undulation wavelength along the span (λ/c 0.31, 0.21 and 0.15) and undulation placement (leading edge, trailing edge, and both leading and trailing edge). The leading edge undulations delayed stall until higher angles of attack, however, the maximum aerodynamic efficiency was reduced. The trailing edge undulated wing on the other hand increased the maximum aerodynamic efficiency but was not successful in stall mitigation. Wings with both leading and trailing edge undulations showed improvement in aerodynamic efficiency as well as delayed stall. The effect of the undulations on the wingtip vortex was also investigated through Particle Image Velocimetry (PIV). For the same coefficient of lift, the undulated wing cases reduced the wingtip vortex circulation by 25%. Investigations into the wingtip vortex core RMS and aerodynamic efficiency revealed a direct relationship where a higher vortex core RMS resulted in a higher aerodynamic efficiency and viceversa. Dedication or Acknowledgements The author acknowledges the partial funding from Henry Luce Foundation through the Clare Boothe Luce Scholars Program for the work presented in this thesis. The author would also like to acknowledge the Ohio Space Grant Consortium (OSGC) for partially funding the primary author for performing undergraduate research. The author would also like to thank UD wind tunnel technician, Jielong Cai, and research partner, Michael Mongin, for helping with manufacturing wind tunnel models and performing experiments.