Control of Flow Structure on Nonslender Delta Wing using Passive Bleeding: Effects of Orientation, Angle, and Solidity Ratio

Recently, we have demonstrated that the bleeding, which utilizes passages inside the wing to allow the fluid flowing from the pressure side to the suction side by using inherent pressure difference, could be used as an effective flow control method for nonslender delta wings. In the present study, this technique is investigated in detail for nonslender delta wings of 35 and 45-degree sweep angles in a low speed wind tunnel using smoke visualization, particle image velocimetry, and surface pressure measurements for broad ranges of angle of attack and Reynolds number. The effects of bleeding orientation, angle, and solidity ratio on flow structure are quantified in particular, where the solidity ratio signifies the level of bleed gap on the wing surface. The results indicate that the recovery of the leading-edge vortex with significant increases in the suction pressure coefficient, −C_p, along with the elimination of large-scale swirl pattern in near surface streamline topology are achieved with the proper bleeding configuration. Considering the effectiveness,the bleeding orientation and the solidity ratio are quite critical to achieve the successful flow control where the angles need to be adjusted according to the angle of attack of the wing to reach the utmost influence.