COMPUTATIONAL INVESTIGATIONS FOR AERODYNAMIC PERFORMANCE OF BIO-INSPIRED DELTA-WING BASED ON SWIFT-WING

Aiming at aerodynamic configuration for micro aerial vehicle at the low-Reynolds number flow regime, a group of bio-inspired non-slender delta wings (\varLambda =50^\circ) similar to swift wings with different leading edge bluntness was designed. To quantitatively investigate the aerodynamic effect caused by the trailing edge tapering of the delta wing, a set of generic delta wings with the same sweep angle was designed for comparisons. In order to deeply investigate the evolution characteristics of the leading edge vortex and the overall aerodynamic characteristics of the bio-inspired delta wing, the numerical simulation method was used to explore the leading edge vortex structure and the overall aerodynamic characteristics at different angles of attack in detail under low Reynolds number flow (Re=1.58\times 10^4). Computational results show that, the leading edge bluntness and trailing edge tapering have significant effect on the vortex intensity and vortex breakdown position of the leading edge vortex of the generic delta wing and swift delta wing. Compared to the blunt leading edge, the sharp leading edge increased the pressure difference between the upper and lower surfaces, so it has more pronounced vortex intensity and more significant lift enhancement for models with sharp leading edge. Comparing to generic delta wing configuration, the bevel angle of the leading edge of the bio-inspired delta wing results in higher drag, and the trailing edge tapering makes the vortex breakdown position fixed at the trailing edge, so the entire upper wing surface remains at low pressure, resulting in greater overall lift. Since the lift increases more obviously at low angles of attack, the aerodynamic efficiency of the bionic delta wing is significantly greater than that of generic delta wing at low angles of attack. These conclusions are of great values in revealing the flight mechanism of birds and the design of bionic micro aerial vehicles in the near future.