Contribution of spanwise and cross-span vortices to the lift generation of low-aspect-ratio wings: Insights from force partitioning

Karthik Menon, Rajat Mittal

Published 2022-05-09Version 1

This study reports on the vortex-induced lift production mechanisms in low Reynolds number flows over a low aspect-ratio rectangular wing. We use a rigorous force partitioning method which allows for the estimation of the pressure-induced aerodynamic loads due to distinct flow features or vortex structures in the flow around the wing. The specific focus of this work is on distinguishing the effect of spanwise and cross-span oriented vortex structures on pressure-induced lift production. We quantify the lift induced on the wing by these different vortices, and also estimate their influence within different regions of the flow-field around the wing and in the wake. We show that for this low aspect-ratio wing, the spanwise vorticity contributes only about 26% of the total lift whereas 60% of the lift is generated by cross-span oriented vortices. Furthermore, the spanwise vorticity in the near wake is capable of producing net negative lift on the wing and this is explained by separating and quantifying the influence of vortex cores and regions of strain in the wake. The results demonstrate the utility of the force partitioning method for dissecting the flow physics of vortex dominated flows.