Low Reynolds number flight frequently involves aggressive maneuvers or rotating wings at a high angle of attack. In these conditions a leading-edge vortex (LEV) forms, augmenting the force produced by the wing. In order to accurately predict the force on the wing, some estimation of the LEV's circulation is necessary. This study tests a simple method for estimating the circulation of the LEV during the early stages of its formation on both a rotating and a translating wing. We begin with an integral analysis of the circulation growth of the LEV. This analysis assumes that the LEV growth is entirely due to the convection of the leading edge shear layer into the vortex and that said shear layer is dominated by the wing and/or freestream velocity. The result of this analysis was a linear relationship between normalized circulation (LEV circulation normalized by the current velocity and chord length) and the number of chord lengths traveled. To determine the validity of this analysis, planar PIV measurements of the flow at four radial stations on an impulsively started rotating wing with a tip Reynolds number of 1400 were used to measure the circulation of the LEV at various locations. Similar measurements from a prior experiment on a surging, aspect ratio 8 wing at a variety of Reynolds numbers and acceleration distances were used to measure growth of LEV circulation in a nominally two dimensional case. The normalized circulations in both cases were found to have a linear relationship with the local distance traveled from 0.1 chords traveled to 1.5 chords traveled.
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