  This work investigated the vorticity dynamics and stability of leading-edge
vortices (LEVs) in revolving wings. Previous studies suggested that Coriolis
acceleration and spanwise flow both played key roles in stabilizing the LEV;
however, the exact mechanism remains unclear. The current study examined a
mechanism that relates the effects of Coriolis acceleration, spanwise flow, and
the tilting of the planetary vortex on limiting the growth of the LEV.
Specifically, this mechanism states that a vertical gradient in spanwise flow
can create a vertical gradient in Coriolis acceleration, which will in turn
produce oppositely-signed vorticity within the LEV. This gradient of Coriolis
acceleration corresponds to the spanwise (radial) component of planetary vortex
tilting (PVTr) that reorients the planetary vortex into the spanwise direction
therefore creating oppositely-signed LEV vorticity. Using an in-house,
immersed-boundary-method flow solver, this mechanism was investigated alongside
the other vorticity dynamics for revolving wings of varying aspect ratio (AR=3,
5, and 7) and Reynolds number (Re=110, and 1400). Analyses of vorticity
dynamics showed that the PVTr consistently produced oppositely-signed vorticity
for all values of AR and Re investigated, although other three-dimensional
phenomena play a similar but more dominant role when Re = 1400. In addition,
the relative strength of the PVTr increased with increasing AR due to a
decrease in the magnitude of advection. Finally, the effects of AR and Re on
the vorticity dynamics and LEV stability were also investigated.
