Exploring the aerodynamic characteristics of a blown annular wing for vertical/short take-off and landing applications

Abstract

This article explores, theoretically and experimentally, a new wingform, based on an annular wing wrapped around a radial flow generator, potentially creating a vehicle with no external moving parts, reduced vehicle aerodynamic losses compared to previous vertical/short take-off and landing technologies, and substantially eliminating induced drag. Concentrating on hovering and slow flight, it is shown that such a wing works best with a thick aerofoil section and appears to offer greatest potential at a micro-aerial vehicle scale. Experimental methods are described along with results, and this work shows that wing efficiency can be substantially improved by the use of upper surface blowing technology and the Coanda effect. The main causes of efficiency loss are annular flow expansion and problems with achieving acceptable slot heights. Experimental efficiency remains below theoretical efficiency, partly due to flow asymmetry but possibly also other factors. This work is also very early in the development of this technology, and so recommendations are made for future work.