EFFECT OF DIFFERENT SHAPED DIMPLES ON AIRFOILS

Abstract

The present work describes change in aerodynamic characteristics of an airfoil by applying certain surface modifications in form of dimples. At first surface modifications that are considered here have outward and inward dimples on the wing model. A comparative study of modified airfoil models showing variance in lift and drag at different angle of attacks (AOA). The surface modifications are done here by considering the different types and shapes of dimples. Dimples help in reduction of pressure drag when airfoil attains some angle of attack because that time, wake formation starts due to boundary layer separation. Application of dimples on aircraft wing works in same manner as vortex generators. They create turbulence which delays the boundary layer separation and reduces the wake and thereby reducing the pressure drag. It’s assist to enhance the lift and increase the Stall AOA. Dimples on the surface aircraft wing does not affect the pressure drag much since it is already aerodynamic in shape but it may affect its aerodynamics properties when the airfoil is at AOA that is one of the concern of this paper. A Subsonic wind tunnel (100×100×100 cm ) is used to investigate the effect of using dimples over the airfoil surface (NACA-4415) having uniform cross-section along span. For design purpose solid works software is used. Three wooden Airfoil Models with outward and inward dimples and without dimples have been constructed here. From this experimental investigation it has been observed that the flow separation on the airfoil can be delayed by using the dimples on the upper surface and the lift force and stall AOA are also increased remarkably.