ACTIVE FLOW CONTROL BY MICRO-BLOWING AND EFFECTS ON AERODYNAMIC PERFORMANCES. AHMED BODY AND NACA 0015 AIRFOIL

Flow control is a very promising solution for improving the performance of aerial and terrestrial vehicles. Among the various existing techniques, blowing is effective in reducing or delaying the detachment near a wall by restoring energy to the moving fluid. The control solution proposed in this work relates to steady blowing through a micro-hole series in the case of an NACA 0015 airfoil and a simplified Ahmed body geometry. An experimental study was conducted in a subsonic wind tunnel for several incidences of the airfoil, two inclinations of the Ahmed body rear window, and a range of flow speeds (15-30 m/s). The investigation also took into account the effect of the blowing flow rate and the Reynolds number. The results showed interesting improvements in aerodynamic coefficients. Indeed, for a rear window tilted 20° in the case of Ahmed body, a reduction in drag of 3.6% is reached when applying minimum blowing with Cμ = 0.28%, whereas 15% is obtained by complete blowing at Cμ = 4.79%. On the other hand, at a high-drag regime corresponding to a 30° rear window slant, a 19% drag reduction is achieved with Cμ = 5%. As for the NACA 0015 airfoil, an improvement in lift of around 49%, a significant decrease in drag by 69%, and a delay in stall by 4° are obtained.