Flow Control over an Airfoil
Numerical study of blowing and suction slot geometry optimization on NACA 0012 airfoil
Abstract – The effects of jet width on blowing and suction flow control were evaluated for an NACA 0012 airfoil. RANS equations were employed in conjunction with a Menter’s shear stress turbulent model. Tangential and perpendicular blowing at the trailing edge and perpendicular suction at the leading edge were applied on the airfoil upper surface. The jet widths were varied from 1.5% to 4% of the chord length, and the jet velocity was 0.3 and 0.5 of the free-stream velocity. Results of this study demonstrated that when the blowing jet width increases, the lift-to-drag ratio rises continuously in tangential blowing and decreases quasi-linearly in perpendicular blowing. The jet widths of 3.5% and 4% of the chord length are the most effective amounts for tangential blowing, and smaller jet widths are more effective for perpendicular blowing. The lift-to-drag ratio improves when the suction jet width increases and reaches its maximum value at 2.5% of the chord length.
Citation: K. Yousefi, R. Saleh and P. Zahedi, Numerical Study of Blowing and Suction Slot Geometry Optimization on NACA 0012 Airfoil, Journal of Mechanical Science and Technology, Vol. 28, No. 4, pp. 1297-1310, 2014.
Three-dimensional suction flow control and suction jet length optimization of NACA 0012 wing
Abstract – A three-dimensional suction flow control study was performed to investigate the aerodynamic characteristics of a rectangular wing with an NACA 0012 airfoil section. In addition, the optimum suction jet length was determined. In this study, the Reynolds-averaged Navier–Stokes equations were employed in conjunction with a k–omega SST turbulent model. Perpendicular suction was applied at the leading edge of the wing’s upper surface, with two different types of slot distributions: i.e., center suction and tip suction. The suction jet lengths were varied by 0.25–2 of the chord length, and the jet velocity was selected to be 0.5 times the freestream velocity. Most importantly, in both cases, the results indicated that the lift-to-drag ratio increased as the suction jet length rose. However, the improvement in aerodynamic characteristics was more pronounced with center suction, and these characteristics were extremely close to those of the case considering suction over the entire wing such that the jet length was equal to wingspan. Moreover, in the center suction case, vortexes frequently abated or moved downstream. Interestingly, under similar conditions, a greater number of vortexes were removed with center suction than with tip suction. Ultimately, when the jet length is less than half the wingspan, tip suction is the better of the two alternatives, and when the jet length is greater than half the wingspan, center suction is better suited.
Citation: K. Yousefi and R. Saleh, Three-Dimensional Suction Flow Control and Suction Jet Length Optimization of NACA 0012 Wing, Meccanica, Vol. 50, No. 6, pp. 1481-1494, 2015.
Effects of Trailing Edge Blowing on Aerodynamic Characteristics of the NACA 0012 Airfoil and Optimization of the Blowing Slot Geometry
Abstract – The effects of blowing and its parameters including the jet amplitude, blowing coefficient and jet width in order to flow control was evaluated for an NACA 0012 airfoil. The flow was considered as fully turbulent with the Reynolds number of 5e5, and the Menter shear stress turbulent model was employed. Tangential and perpendicular blowing at the trailing edge were applied on the airfoil upper surface, and the jet widths were varied from 1.5 to 4 percent of the chord length, and the jet amplitude was also selected 0.1, 0.3 and 0.5. In the tangential blowing, the results showed that when the blowing amplitude increases, the lift-to-drag ratio rises by 15 percent, however, the smaller amounts of the blowing amplitude are more effective in the perpendicular blowing. Furthermore, when the blowing jet width rises, the lift-to-drag ratio increases continuously in the tangential blowing and decreases quasi-linear in the perpendicular blowing. In this study, the blowing jet width 3.5 and 4 percent of the chord length for the tangential blowing was selected as optimal values as well as smaller amounts of blowing jet width are more suitable for the perpendicular blowing. Finally, the lift-to-drag ratio was increased by 17 percent for the tangential blowing in the angle of attack of 18 degrees.
Citation: K. Yousefi and R. Saleh, Effects of Trailing Edge Blowing on Aerodynamic Characteristics of the NACA 0012 Airfoil and Optimization of the Blowing Slot Geometry, Journal of Theoretical and Applied Mechanics, Vol. 52, No.1, pp. 165-179, 2014.