A COMPUTATIONAL STUDY ON AERODYNAMIC CHARACTERISTICS AND VORTEX EFFECTS OF LEADING-EDGE BEVEL IN SWIFT-INSPIRED DELTA WINGS

Based on our previous studies on the aerodynamic effects of leading-edge bluntness of swift-like delta wings, a group of bio-inspired non-slender delta wings (Λ = 50°) with different leading-edge bevel angles (β = 0°, ± 30°, ± 60°) are designed to quantitatively investigate the aerodynamic effects of the leading-edge bevel and clarify its regulation mechanism on the aerodynamic performance of bio-inspired delta wings. Numerical simulations were carried out to systematically examine the evolution of leading-edge vortex structures and overall aerodynamic forces with angle of attack (α = 0° ~ 30°) under low Reynolds number conditions (Re = 1.58 × 10⁴, 3.16 × 10⁴, 6.55 × 10⁴), with emphasis on the coupled effects of leading-edge bevel angle and Reynolds number on aerodynamic characteristics. The results show that the leading-edge bevel angle can significantly alter the strength and breakdown location of leading-edge vortices over the bio-inspired delta wing configurations, thereby exerting a pronounced influence on overall aerodynamic efficiency. Both types of beveling can effectively enhance the leading-edge vortex intensity, among which the positive bevel angle yields a more prominent strengthening effect. The positive bevel angle promotes an upstream shift of the leading-edge vortex breakdown position, while the negative bevel angle effectively suppresses the development of vortex breakdown and delays the breakdown location along the streamwise direction. Specifically, the configurations with positive bevel angle increase the pressure on the lower leading-edge surface and strengthen the vortex intensity, leading to more pronounced lift enhancement at small angles of attack. In contrast, the configurations with negative bevel angle effectively suppress premature flow separation over the wing surface and reduce pressure drag, and demonstrate better aerodynamic efficiency and stability under high angle of attack conditions. Within the Reynolds number range considered in the numerical simulations of the present study, a higher Reynolds number corresponds to weaker relative viscous effects and stronger leading-edge vortex stability, which improves the overall lift and aerodynamic efficiency of the delta wing. The conclusions of this work not only further enrich the research on aerodynamic characteristics of bio-inspired delta wings at low Reynolds numbers, but also provide theoretical basis and data support for revealing the high-efficiency flight mechanism of birds and guiding the overall aerodynamic design and performance optimization of micro bio-inspired aerial vehicles in the near future.