The application of biomimetic principles to enhance wind-turbine and micro aerial vehicle performance in gusty environments

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Advancements in wind-turbine as well as Micro Aerial Vehicle (MAV) design are currently limited by the unsteady, gust-induced structural loadings incurred on their respective blades and wings. By studying how animals swim and fly in unsteady environments, improvements to gust performance can be achieved. Such biomimetic research takes advantage of millions of years of evolutionary optimization. One elegant example is found in the efficient flapping kinematics, shape and flexibility of seagull wings, all of which are fundamental to the animal's survival in gusty environments. An investigation into the influence of gust fields on the formation of separated, vortical structures - described as regions around the blade or wing dominated by strong unsteady and viscous effects - is proposed here. Such unsteady, separated flows are often dominated by coherent vortex structures, which are known to affect instantaneous blade and wing loadings tremendously. This examination will be undertaken using an array of numerical and experimental techniques including Scale-Adaptive Simulations (SAS), Particle Image Velocimetry (PIV) and Three-Dimensional Particle Tracking Velocimetry (3D-PTV). The simplest case of a longitudinal gust can generate a rapid yet non-uniform change in incidence along the span of a blade/wing, thus generating separated regions with strong three-dimensionality. In the past there has also been great speculation as to the influence of rotation - both centripetal and Coriolis contributions - on the spanwise flows within these separated regions. Therefore the current research program looks to uncover the underlying physics of these vortical flows by examining three aspects of increasing complexity, i.e. the influence of aspect ratio, the influence of rotation and finally, the influence of spanwise flexibility. It is expected that once these fundamental aspects of the problem are properly understood, advancements to future wind-turbine and MAV blade/wing shapes, structures and materials can be undertaken.