Effect of Angle of Attack on Lift, Drag, Pitching Moment and Pressure Distribution of NACA 4415 Wing

This experiment was conducted to determine the effects of angle of attack on lift, drag, pitching moment and pressure distribution during the flow of NACA 4415 wing model of chord length of 200mm, leading edge radius of 4.96mm and span of length 450 mm using a low speed open return wind tunnel with test section of 0.47m width, 0.47m height and 1.27m length. The wing model was subjected to several tests at two different speeds of 15m/s and 25m/s which corresponds to two different Reynolds numbers of 1.8×10 5 and 3.1×10 5 respectively. The result showed that for both speeds, the coefficient of lift increased as angle of attack increased and the maximum lift coefficient was 1.45 at 15m/s while at 25m/s, the coefficient of lift is 1.40, which is slightly less than that at 15m/s. The coefficient of drag also increased as the angle of attack increased from 0 0 to 18 0 and the maximum drag was 0.15 at 15m/s, while at 25m/s, the coefficient of drag is approximately 0.2 which showed that the wing has a very low drag coefficient. For pressure distribution, it was observed that there was no flow separation at low angle of attacks from -6˚ to 0˚ , but the flow began to separate at moderate angle of attack of 3 0 to 9 0 and fully separated at high angle of attacks of 12 0 to 18 0 with vortices for both speeds.