Effect of leading-edge protuberances on swept wing aircraft performance

Abstract

Stall is a complex phenomenon in aircraft that must be suppressed during flight. As a novel passive control method, bionic leading-edge protuberances (LEPs) have attracted widespread interest, particularly for delaying stall. Bionic protuberances at the leading edge of airfoils have been designed to control stall and increase the stability of unmanned aerial vehicles during operation, and it is the flow control mechanism associated with this application that is investigated in this study. First, numerical simulations are conducted to obtain the aerodynamic characteristics of original and bionic airfoils based on the S1223 large-lift airfoil. Next, the impact of the LEP amplitude is investigated. Finally, a vortex definition parameter, the Liutex vector, is utilized to analyze the influence of LEPs on vortices. The results show that bionic LEPs inspired by those on humpback whale flippers can improve the aerodynamic performance of airfoils under the extreme conditions that exist after stall, resulting in an ∼22% increase in the lift–drag ratio. LEPs are found to segment the flow field near the wing surface. The flow becomes bounded between adjacent protuberance structures, significantly inhibiting the development of flow separation and providing a drag reduction effect. This study thus provides a new approach for improving aircraft performance.