Control of asymmetric flow over a blunt-nosed slender body

An innovative control device for the asymmetric flows over a blunt-nosed slender body is studied at a high angle of attack (α = 50°). The control device is composed of a micro-particle and a blowing device. Experimental tests are conducted to study the control of asymmetric flow. Particle-image velocimetry, surface oil-flow visualizations, and pressure scanning are used to present the vortical structures, flow separations, and pressure distributions. A blow hole with a diameter of d_b = 0.005D and a particle with a diameter of d_p = 0.006D are placed on both sides of the nose as the micro-blowing perturbation and micro-particle perturbation (MPP), respectively, to control the behavior of the asymmetric vortices. The blowing coefficient (C_μ) through the blow hole is 0-9.42 × 10^-5. Results show that a certain and predictable pattern of asymmetric flow is first presented at C_μ = 0, owing to the certain location of MPP on the nose. Subsequently, as C_μ increases, the asymmetric flow is changed into symmetrical first and then into the opposite asymmetric flow pattern. As a result, the corresponding side-force is changed into zero and then the opposite direction. These results indicate that the pattern of asymmetric vortices and their corresponding side-forces are easily managed by changing the blowing coefficient. The evolutions of associated pressure distributions, flow separations, and vortical structures with the increase in blowing coefficient are presented in detail.