Four-Wall Flow Separation Control Using Microvortex Generators in Supersonic Duct

Abstract

Suppression of shock-induced separation on all the walls of a rectangular duct using arrays of microvortex generators was experimentally investigated. The flowfield was analyzed using normal and inclined schlieren visualizations, surface oil flow visualization, wall static pressure distribution, and exit plane stagnation pressure distribution. The top wall and side wall array configurations were fixed, and only the bottom wall configuration was changed. It was found that control decreased the axial oscillations but increased the spanwise oscillations of the shock (oscillations in the spanwise length of the normal part of the shock). Among the control cases, as the control on the bottom wall increased, the exit plane stagnation pressure recovery, static pressure recovery across the shock, and area of the normal portion of the normal shock increased and then decreased. However, the attached flow percentage on the bottom wall increased with an increase in control. As the shock moved away from the microvortex generator arrays, the case with no control on any walls gave better results in terms of shock size and exit plane stagnation pressure recovery. Also, as the number of control devices on the bottom wall increased, the extent of flow separation on the bottom wall decreased; however, it had detrimental effects on the duct flow beyond some extent.