Numerical investigation of the impact of tubercles and wing fences on the aerodynamic behaviour of a fixed-wing, tactical Blended-Wing-Body UAV platform

Abstract

In this work, a study on the impact of passive flow control techniques on an Unmanned Aerial Vehicle (UAV) Blended Wing Body (BWB) is presented. The novel BWB layout integrates smoothly the wing to the fuselage, creating an aerodynamically superior platform. However, the lack of vertical stabilizers in the form of a tail, creates the need for aerodynamically stable and efficient wings that can withstand the spanwise flow. To that end, two passive flow control techniques are implemented in this study, namely the wing fences and the tubercles. Wing fences are vanes or airfoils attached vertically to the lifting surface and are one of the oldest flow control techniques used in aerospace applications to stop the spanwise flow. Wing fences extending from the leading edge to the trailing edge completely stop the spanwise flow. On the other hand, tubercles are sinusoidal modifications of the blade’s leading edge. This is a novel flow control technique, with the original concept inspired from the characteristic flipper of the humpback whale (Megaptera Novaeangliae). Each bump creates a set of counter-rotating vortices that acts as a virtual fence and stops the spanwise flow. The results from this comparison show that flow control techniques can offer a considerable benefit to the flying capabilities of a BWB UAV platform, by improving the lift distribution and increasing the maximum coefficient of lift.