Study of Vortex Structures in 3D Unsteady Aerodynamics using Experiment and Simulation

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Vortical structures are amongst the most fascinating aspects of unsteady aerodynamics. Leading-edge vortices in dynamic stall (seen on helicopters and wind turbines), result in violent vibrations and mechanical failure. On the other hand, leading-edge vortices (LEVs) have been credited for being solely responsible for high-lift flight in insects and for providing high lift on aircraft employing delta wings.In both insect flight and on delta wings, a stationary leading-edge vortex on the airfoil is seen. This is very interesting, as in 2D aerodynamics, it can be mathematically shown that a stable LEV cannot exist and that it would tend to convect over the chord. In 3D however, such stationary LEVs are seen, and the conditions under which they exist are not clear. Experiments and CFD methods have shed some light on vortical structures in 3D, but because of time and expense considerations, these methods cannot be used to study the parameterspace and identify conditions where such favourable LEVs exist.Dr. Kiran Ramesh has developed a reduced-order discrete vortex method which models leading-edge vortices, but at the same time is computationally inexpensive. In this project, it is proposed to combine this methodology with a vortex-lattice formulation, so as to extend it to 3D. With the method thus developed, a range of wing kinematics and planform shapes will be studied to analyse unsteady vortical behaviour, and identify conditions where stationary LEVs may exist.Experimental work will be conducted to support the development of the reduced-order method and for validation, using the University of Glasgow's subsonic wind tunnel facilities. A range of generic model configurations will be tested using advanced flow diagnostics (Particle Image Velocimetry, Pressure Sensitive Paints, 3D LDA etc) and a 6 component sting balance.