One such technique is for sailors to use bodyweight movements to roll the boat about its longitudinal axis. Olympic sailors use various unsteady aerodynamic techniques when racing to increase propulsion for their boat. In this thesis, we also study new modes of NACA 0012 airfoil motions using a ``sports-mimetic'' approach, inspired by the bodyweight motions of Olympic sailors as they maneuver their sailboats when racing. ![]() Using this technique, the streamwise velocity profile is captured over 20 chord-lengths downstream of the delta wing, even when the vortex pair is in ground effect. ![]() This technique is unaffected by vortex wandering, allowing us to capture axial flow data as close as 0.03 chord-lengths apart. We study also the spatially evolving trailing vortices in the far-wake of a 75 degree leading-edge sweep-angle delta wing, using a novel technique to measure the axial flow in the vortex core. This passive, ground-based method could be a means to diminish the wake vortex hazard behind aircraft close to the ground. This leads to the formation of coherent secondary vortex structures, and an accelerated decay of the primary vortex pair. Using a vortex generator tank to produce a temporally evolving vortex pair, it is shown that the introduction of perturbations at the ground plane results in earlier localized secondary vorticity generation. When a vortex pair approaches a ground plane, the boundary layer that forms on the surface between the vortices and the wall separates, generating secondary vorticity and causing the primary vortex pair to ``rebound'' from the wall. ![]() In this work, we use a vortex generator tank and a delta wing in an XY-Towing Tank to study the dynamics of counter-rotating vortex pairs both in and out of ground effect, via PIV and flow visualization. These vortices pose an increased hazard for aircraft at airport takeoffs and landings, as following aircraft flying through a vortex wake can experience dangerous rolling moments. Understanding vortex-wall interactions has applications in the context of airplane trailing vortices, as wake vortices are an unavoidable by-product of aerodynamic lift. Download Vortex wall Interactions and Sports inspired Airfoil Motions Book in PDF, Epub and Kindle
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