Analysis of Factors Affecting the Aerodynamics of Low Reynolds Number Rotating Wings

Abstract

A computational analysis was performed to address the effects of walls on wings rotating at a Reynolds number of 120. For rotation angles less than one revolution, a tip clearance of 0.5 chord-lengths is sufficient to approximate a wing rotating in an infinitely large volume of fluid. However, for a maximum rotation of two revolutions, a tip clearance of 5.0 chords is necessary. At the start of the second revolution, the wing encounters its wake, and the wake structure is significantly affected by low tip clearances.

Lift and drag forces were measured experimentally for wings rotating at a Reynolds number of 10,000 while parameters including root cutout were varied. Root cutout significantly alters the lift and drag coefficients, including the location of a second local maximum in both lift and drag. The root-relative method of force non-dimensionalization provided the best comparison of force coefficients between cases with different root cutouts.