Experimental investigation on the aerodynamic characteristics of NACA 4412 Aerofoil with Curved-Edge planform

Abstract

Aircraft wings are the lifting surfaces with the chosen aerofoil sections. The lift generated by the wing sustains the weight of the aircraft to make flight in the air. Again, from an aerodynamic perspective, the main source of the airplane drag is associated with the wing. Therefore, the effects of wing shape and size are crucial to aerodynamic characteristics (lift, drag, lift to drag ratio, pitching moment, etc.) on which the efficiency as well as the performance of aircraft depend. The shape/geometry of wing can be varied span wise to search better performance. This thesis represents the experimental investigation to explore better aerodynamic performance by incorporating curvature at the leading edge and trailing edge of wing. The curvature is incorporated in the wing geometry without changing the overall surface area to reduce the chord length towards the tip of the wing. The experimental investigation is carried out in the wind tunnel to explore aerodynamic characteristics of two different wings of curved-edge planforms; one having curve at leading edge and the other having curve at trailing edge. Similar characteristics of a rectangular wing of equal span and surface area are also investigated in the same way for reference. Wooden wing models for rectangular planform and curved-edge planforms are prepared having the same span and equal surface area. All the models are tested at air speed of 85.35 kph (0.07 Mach) i.e. at Reynolds Number 1.82 x 105 in the closed circuit wind tunnel. The static pressure at different Angle of Attack (-4˚, 0˚, 4˚, 8˚, 12˚, 16˚, 20˚ & 24˚ ) are measured from both upper and lower surfaces of the wing models through different pressure tapings by using a multi-tube water manometer. The aerodynamic characteristics (Coefficient of Lift, Coefficient of Drag and Lift to Drag ratio) for different models are determined from the static pressure distribution. After analyzing the data, it is found that the curved leading edge wing planform is having higher lift coefficient and lower drag coefficient than the rectangular planform. Again, the curved trailing edge planform is having higher lift coefficient and lower drag coefficient than the curved leading edge wing. Thus, the curved trailing edge planform is having the highest lift to drag ratio among the three types of planforms. Due to reduction in the chord length near the tip of the curved-edge wings, the tip loss is also reduced. As such, aerodynamic performance of the curved edge planforms are found better than that of the rectangular planform.