Evaluating the effect of unsteady air flow on a slotted aerofoil of wind turbines

Abstract

In this study, three types of aerofoils were examined at various angles of attack and at a steady value then fluctuated of air flow. Then, the findings were compared to the XFOIL prediction results. The experimental and simulation results were consistent to some extent with the XFOIL prediction results. The shape of the chosen aerofoils was modified by making a slot through the blade the aerofoil and studying their effect on the aerodynamics of the modified shape. The slotted aerofoil shape was studied as it faced a fluctuated wind flow. The results revealed that the increase in angles of attack, the lift force increased and approximated its maximum value and then began to decrease with the slot. During the calculations, a case study for the number of elements was done to obtain the best mesh. 
The experimental and simulations were conducted by using ANSYS CFD at Reynolds number 106 and AOA equals (0°, 4°, 8°, 10°, 12°, 15°, 16°, 17°, 18°) for three shapes of aerofoils which are without a slot, two of which are symmetrical, NACA 0012 and NACA 0015, and one asymmetrical, which is NACA 4415. The slotted aerofoil (existence of an opening after 40% from the leading edge) which is the NACA 0015 aerofoil, was simulated.