دانلود Numerical study of flows past airfoils with wavy surfaces

Abstract

The paper presents three-dimensional numerical studies on the aerodynamic characteristics of two different modified NACA0012 airfoils with different wavy surfaces using the large eddy simulations. Two types of wavy airfoils are investigated with wavy airfoil-A having a sinusoidal waviness on upper and lower surfaces with a constant chord length, while wavy airfoil-B having sinusoidal variation in both of the leading and trailing edges as well as on the upper and lower surfaces along the spanwise direction. The force characteristics and the flow structures are captured and compared with a corresponding standard NACA0012 airfoil with a Reynolds number of Re=1.6×105. The flow structures and surface pressure distributions on wavy airfoils were found to be significantly different from those on a conventional NACA0012 airfoil. For angles of attack less than the baseline stall angle of a NACA0012 airfoil, a slight decrease of lift coefficient was observed for both types of wavy airfoils, while the lift coefficient for the wavy airfoil-B increases up to 20% greater than that of a NACA0012 airfoil when the angle of attack is larger than the baseline stall angle of 13°. The flow over the leading edge of wavy airfoil-B remained attached at post stall angles of attack. In general, the wavy airfoil-A just exhibits a suppression the airfoil’s fluctuation force, while the wavy airfoil-B demonstrates an advantageous aerodynamic effect on the control of loss of lift in the post stall regime of a conventional NACA0012 airfoil.