Numerical Boundary Layer Measurement of Different Airfoilsafter Adding Gurney Flaps

The Gurney flap is a simple device, consisting of a short strip, on the order of 1–5% of the airfoil chord in height, fitted perpendicular to the pressure surface or the chord-line along the trailing edge of a wing. The most common applications of this device are in wind turbines and UAV's. For better performance of an airfoil, there must be increased suction on the upper surface while the lower surface experiences increased pressure thus the velocity on the top surface of airfoil is an important parameter to determine the performance of the airfoil. In this paper boundary layer profiles for the upper surface of the airfoil, after adding different Gurney flap configurations in different airfoils are investigated numerically and the results are validated with experimental data. Two dimensional simulations are performed by solving the Navier-Stokes equations. By utilization of quadratic meshes, low computation time has been achieved. 2D computations agree with experimental data and shows that the addition of a Gurney flap increases the velocity on the upper surface of airfoil thus maximum lift coefficient is increased. Results make Gurney flaps more feasible in case of load limitations such as applications to wind turbine, racing-car spoilers and UAV's.

Keywords:

Gurney Flap , Boundary Layer , Numerical Investigation , Wind Turbine , NACA 0012 and 0015 Airfoil