Roles of 2-Dimensional and 3-Dimensional Vorticity Transport Mechanisms in Assisting LEV Attachment on a Revolving Wing

An aspect ratio 9.5 rectangular wing is revolved in a cylindrical domain at 45-degree angle of incidence and a Reynolds number Re_c = 300, based on the wing velocity two chord lengths from the axis of rotation (z/C = 2.0). Four cases are considered which include combinations of linearly-varying or constant inflow velocity profile, and the presence or absence of rotational accelerations, emulating pure rotation, pure translation, and two hybrid cases. Each case exhibits a strikingly different behavior of the leading-edge vortex (LEV), demonstrating that inflow shear is an important factor governing LEV behavior, in addition to the rotational accelerations. Vorticity transport analyses were conducted in chordwise planar control regions, at z/C = 2.0. There is frequently a moderate to strong correlation between the nominally two-dimensional vorticity transport mechanisms (shear-layer flux and surface diffusive flux) and between the three-dimensional transport mechanisms (spanwise convective flux and tilting flux). Although 2D fluxes typically dominate, inflow profile and rotational accelerations are shown to modify flux contributions, resulting in varied LEV strengths and trajectories.  The physical and mathematical foundations governing the observed behaviors will be discussed.