A stationary Leading-Edge-Vortex (LEV) formed over the upper wing surface is one of the primary mechanisms to achieve high lift force on wings. While most applications of LEVs have utilized the phenomenon to enhance the lift of slender wings, evidence in nature suggests that stationary LEVs can also exist on high aspect ratio (AR) wings.
This study investigates the analytical potential flow modeling of a stationary LEV above a high AR wing for lift enhancement. The main objective of this research is to study and characterize the phenomenon for designing large AR wings with high lift due to the LEV.
The novelty of the flow model we developed is in the three-dimensional aspects of the LEV, which are considered in two ways:
- satisfying conservation of mass and vorticity within the LEV core;
- using a combination of both the strip theory and the lifting-line theory, in order to account for the effect of the wing shape and induced flow on the formation of a stationary LEV.
Our pseudo-three-dimensional flow model is studied for several wing configurations, in order to evaluate the resulting LEV characteristics and aerodynamics coefficients. Our results shed extensive insight on the physical mechanisms responsible for generating and maintaining a stationary LEV structure on a non-slender wing. The wing planform shape and sweep are shown to have a major role in determining the characteristics of the LEV- which can result in significant lift enhancement of over 70% for a given planform. The flow model can serve as a preliminary tool in designing new high AR wings that utilize the stationary LEV phenomenon to improve performance at high angles of attack.
