Structural control of asymmetric forebody vortices over a slender body

This paper studied a combined control method based on the sensitivity of asymmetric flow over a slender body at a high angle of attack (AoA) to the tip of the nose. The control method adds a particle with a diameter of d = 0.4 mm (0.0044D) and a strake with a variable height on both sides of the tip as the artificial perturbation (AP) and artificial strake (AS), respectively, to control the behavior of forebody vortices. The height h of AS is changed from 0D to 0.055D, where D is the diameter of the slender body. The aerodynamic forces/moments, pressure distributions, and flow structures are measured using force balance, pressure scanning, and particle image velocimetry, respectively. Results show that a specific and predictable pattern of forebody asymmetric vortices is first presented at h/D = 0 because of the specific circumferential location of AP near the tip. Subsequently, as h/D increases, the forebody asymmetric vortices are changed into symmetrical first and then into the opposite asymmetric flow pattern. Thus, the corresponding side force is transformed into zero and then the opposite direction. These results indicate that the changing height of AS easily manages the pattern of forebody vortices and the corresponding side force acting on the slender body. The characteristics of associated aerodynamic forces/moments, pressure distributions, and vertical structures with increasing h are presented in detail.