Roll Attitude Control for Flying Wing via Apex Vortex Perturbation

A flying-wing configuration offers high aerodynamic efficiency, but the absence of lateral-directional stability makes roll-attitude control challenging. An active flow control method based on apex vortex perturbation is proposed, using an inward jet at the apex. To accommodate asymmetric flow structures, two strategies are defined: upward and downward control. Free-to-roll experiments demonstrate effective roll-attitude modulation for both strategies, with momentum coefficient C_μ as the key parameter. As C_μ increases, upward control first increases the roll angle, then decreases it, and finally reverses the roll direction, whereas downward control reduces the roll angle monotonically. Flowfield measurements show that the jet forms a jet-induced vortex (JIV) that reorganizes the leading-edge vortex– shear-layer–recirculation-zone (LEV–SL–RZ) system and redistributes loading between the wings. For upward control, the JIV drives the LEV toward the surface and entrains SL-shed vortices into the RZ to promote reattachment, producing moment reversal at higher C_μ. For downward control, the opposite JIV rotation lifts the LEV and shifts the SL termination upward, with weak RZ changes, yielding a positive roll moment. The results demonstrate an apex-vortex-perturbation approach that maintains strong roll-control authority in severely separated flow and establishes a foundation for virtual aerodynamic surface control.