Passive control of vortex breakdown on slender delta wing using control bump and cavity at low Reynolds number

Vortex breakdown and stall are frequent occurrence on delta wings which have prompted the development of various methods to improve stability and manoeuvrability of vehicles equipped with such wings. This study investigates an in-house developed slender delta wing modified with bump and cavity geometries, examined through Reynolds-averaged Navier-Stokes (RANS) method at a Reynolds number of 1.4 × 10 5 . The modifications were applied to the suction side of the wing to analyse their effects on vortex breakdown and flow morphology. Results indicate that the bump geometrical modification alters the streamline patterns, shifting the location and structure of vortex breakdown downstream and causing drag reduction of up to 20 % in certain configurations. Although these modifications don't significantly increase the lift force, they effectively reduce the drag force in certain configurations by relocating the breakdown formation further downstream and higher up above the wing surface. The reduction in the drag force by the bump modification leads to an improvement in the aerodynamic efficiency, which translates to a reduction in fuel consumption and greenhouse gas emissions. In comparison, the cavity modification causes the formation of a vortex trap area, which moves the vortex breakdown closer to the suction surface of the wing. • The effect of surface modification on vortex breakdown structure is investigated. • The optimal geometric configuration for delta-wing flow control is identified. • Secondary vortex breakdown induced by bump modifications on delta wing is studied. • The bumpy surface reduced drag by up to 20 % by relocating the vortex breakdown. • The cavity created a vortex trapping zone, which reduced aerodynamic efficiency.