Extreme vortex-gust encounters by a finite wing*

This study examines the influence of wing tip vortices on the evolution of a strong gust-wing interaction. We consider flows around a NACA0015 wing impacted by an extremely strong, spanwise-oriented vortex gust at a chord-based Reynolds number of Re = 600.  An extreme gust encounter is defined as a case in which the characteristic gust velocity is larger than the free stream velocity.

We find that the tip vortices can suppress the high level of lift fluctuation generated during the gust encounters. Furthermore, the presence of the tip vortex complicates the vortical interactions with the gust and leading-edge vortex in all three directions with vortex tilting and stretching while the vortex dynamics in 2D-wing-gust interactions involve only spanwise vorticity. We also show that for particularly high gust ratios, the approaching vortex is prone to instability, the onset of which is driven by interaction with the wing tip vortex. This instability breaks down the coherent spanwise vorticity of the gust into more fine structures, leading to a mitigated lift increase on the finite wing.

The present study provides fundamental insights into the differences between a 2D and a finite wing in extreme vortex-gust wing interactions.