The Effects of Wall Boundaries on the Flow Field of a Rotating Wing

The e ect of wall boundary placement on the development of the ow around a rotating at plate wing at an angle of attack of 45 degrees and tip Reynolds number 120 is investigated using an immersed boundary numerical simulation. Force data from the numerical model indicates that a boundary placed at half a chord-length from the wingtip results in comparable lift throughout the rst wing revolution, and increased lift throughout the second wing revolution, as compared to a case with in nite boundaries. When a wall boundary was placed at ve chord-lengths from the wingtip, there was very little deviation from the case without wall boundaries. Analysis of the strength of the leading edge vortex shows a decrease in the second revolution for all boundary cases tested. Examination of the velocity eld after 630 degrees of revolution reveals a downwash in the wake of the wing that is signi cantly larger for the in nite and 5-chord boundary conditions than for the half-chord case. At the low Reynolds numbers of these simulations, wall e ects are relatively small within the rst 360 degrees of a rotating wing stroke, though tip clearances near 5 chord-lengths are required in the second wing revolution.