Wavy leading edge phenomena on transonic flow regime

Resumo

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.This work investigates wavy leading edge phenomena at transonic flow regime. Pressure sensitive paint measurements are performed over upper surface airfoil at transonic flow regime. The experimental investigation was conducted at a transonic wind tunnel at Reynolds number of 1,000,000, Mach number from 0.6 to 0.7, and angle of attack from 0 to 4 degrees. Two sets of airfoil were used, a smooth NACA0012 profile as baseline model and a wavy leading edge NACA0012 profile with amplitude of 3% and wavelength of 11% both related to chord of the airfoil. The models were manufactured using a 3D rapid prototyping which significantly improved time and cost, and also the feasibility and accuracy of such complex wavy leading edge airfoil. Pressure sensitive paint measurements indicates an impressive modification on flow pattern caused by tubercles when compared to baseline airfoil. If on hand, the baseline airfoil presents lambda-shock wave pattern, on the other hand, the wavy leading edge model changes this flow pattern avoiding shock wave structure. A likely explanation for tubercles avoid shock wave is related to possible counter-rotating vortex generated by wavy configuration upstream of the shock wave line. Thus, the results presented here indicates a potential to apply tubercles in commercial aircraft wings at transonic regime in order to decrease drag rise.