On the high-lift characteristics of a bio-inspired, slotted delta wing

Abstract

A bio-inspired, slotted delta wing was abstracted from a multi-vane propulsor geometry ubiquitous in nature, and analysed to investigate aerodynamic performance during acceleratory and steady-state motions. Evolutionary convergence of slotted geometries in nature suggests an aerodynamic benefit in manoeuvrability, as exemplified in the fins and wings of a broad range of extant and extinct swimmers and flyers, respectively. Through direct force measurements and stereoscopic particle image velocimetry, it was found that the abstracted, slotted geometry exhibited a region of steady-state lift and drag enhancement at angles of attack greater than 25° when compared to a reference profile based on a delta-wing plate. At an angle of attack of 30°, the lift and drag measured on the abstracted model were 15.3% and 17.0% higher than the delta-wing model, respectively. In contrast, these shapes showed little difference in performance during an acceleration-from-rest manoeuvre. It was found that the secondary and tertiary vanes of the abstraction encouraged the formation of additional leading-edge vorticity. The formation of these additional leading-edge vortices was confirmed by an increase in streamwise circulation measured near each effective leading edge along the length of the chord. As such, this configuration provides lift augmentation appropriate for the development of high-performance control surfaces.