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In the present study, the effect of hinge position (H) has been numerically investigated to find the appropriate position for improving the aerodynamic performance of the NACA 0012 flapped airfoil. In addition, perpendicular and tangential suctions have been applied to control the flow separation and enhance the aerodynamic performance over the NACA 0012 flapped airfoil at each different hinge positions. The simulations were carried out at a Reynolds number of 5 × 10 5 (Ma = 0.021) based on two-dimensional incompressible unsteady Reynolds-averaged Navier-Stokes calculations to determine the adequate hinge position. The turbulence was modeled using the shear stress transport k-ω turbulence model. The effect of perpendicular suction (θ jet = − 90°) and tangential suction (θ jet = − 30°) was computationally studied over NACA 0012 flapped airfoil for five different hinge positions (H = 0.7c, 0.75c, 0.8c, 0.85c and 0.9c) and a flap deflection (δ f) of 15°. Based on the results, the hinge position significantly affects the aerodynamic performance of the airfoil. The lift coefficient increased clearly as the hinge position moved to the trailing edge of the airfoil. Using perpendicular suction caused to increase the lift coefficient and decrease the drag coefficient. Consequently, the maximum value of the lift-to-drag ratio (C L /C D) for perpendicular and tangential suctions was achieved about 35.8% and 25.1% higher than that of the case without suction at an angle of attack of 12° and H = 0.9c. Also, the effect of perpendicular suction was more considerable compared to the tangential suction. This caused a reduction in the size of the recirculation zone from 0.5 to 0.09 of the airfoil chord length and also transferred it from 1.13 to 1.18 of the airfoil chord length.

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In the present study, a numerical simulation of turbulent flow over the NACA 65-100 compressor cascade was conducted to control the boundary layer using both suction and blowing separately. In order to study the effects of suction and blowing over the blade, 10 slots were considered on the upper surface of the blade. The slots were considered at intervals of 5% to 95% of the blade chord length. The results showed that applying both suction and blowing caused to delay the flow separation point and move it downstream which led to increase the lift coefficient and decrease the drag coefficient. Also, it was concluded that the effect of applying suction especially in the location where is near the trailing edge was significantly more than the effect of applying blowing. So that the lift coefficient had increased about 45% at 95% of chord length for suction compared to 5% of chord length and it had increased about 10% at 95% of chord length for blowing compared to 5% of chord length. Moreover, the best location to apply suction and blowing in a compressor cascade was near the flow separation point where is near the trailing edge.