Aerodynamic performance and wake development of airfoils with wavy leading edges

Abstract

A comprehensive numerical investigation is performed to study the aerodynamic performance and wake development of a NACA0012 airfoil with wavy leading edges (WLE). The WLEs are in the form of sinusoidal profiles with two design parameters of amplitude and wavelength. Parametric studies of the amplitude and wavelength are conducted to better understand the effect of WLEs. The chord length based Reynolds number is 400 000 and the angle of attack varies from 0° to 20°. For angles of attack less than the stall angle, steady Reynolds-averaged Navier–Stokes (RANS) computations are carried out using the SST (Shear Stress Transportation) k–ω turbulence model. For the post-stall angles of attack, unsteady simulations are carried out using the SST–SAS (Scale-Adaptive Simulation) model to solve the transient separation flow. The numerical results indicate that the aerodynamic performance of the wavy airfoil is sensitive to both the amplitude and wavelength of the WLEs. The WLE with a larger amplitude and smaller wavelength results in a worse aerodynamic performance. The drag coefficient is decreased significantly by the WLEs in the post-stall region. In addition, the wavy airfoils possess a soft stall process without the abrupt loss of the lift when the amplitude is large enough. The wake profiles for the wavy airfoils differ significantly from those for a conventional airfoil, especially for high angles of attack. In the post-stall regime of the baseline airfoil, the wavy airfoils have a higher wake deficit compared to the baseline airfoil, but the turbulence kinetic energy is reduced significantly. The leading edge separation vortex generated by the baseline airfoil is broken down into small vortices by the wavy modification, leading to a reduced lift and drag fluctuations.