Authors
Abstract
Experimental and theoretical investigations were performed to study the effect of direct injection of air on aerodynamic characteristics for airfoil with backward facing full step. The experiments were done in a low- speed wind tunnel in order to obtain the pressure distribution on the airfoil surface and finding the aerodynamic characteristics
(Lift, drag and lift to drag ratio). Theoretically the (Fluent6.3) software was utilized for simulating the turbulent flow around the airfoils and obtaining the distribution of direction of velocity around airfoil with step. All investigations were made for the (NACA0015) basic airfoil and the other one with a step at air velocity (35m/s) and for Reynolds number (Re=4.4×105). The experimental results show that there is a considerable effect in using injection of air inside the steps on the pressure. The pressure on the upper surface of the airfoil decrease with increasing the injection ratio. This effect
leads to an increase in the lift coefficient (Cl). Due to the horizontal injection inside the full step at (Uj/U∞=8), the ((Cl)max) was increased by (12.2%) with respect to the basic airfoil, and by (6.27%) with respect to the case of step without injection. The lift to drag ratio ((Cl/Cd)max) was increased by (37.9%) with respect to the basic airfoil and by (30.65%) with respect to the case of step without injection. The theoretical results show the distribution of velocity vectors around the airfoil with step. The effect of separation
of flow was reduced with the increasing of injection ratio. The comparison between the experimental and theoretical((Cl/Cd)max) shows acceptable agreement.
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