3D Flow Field Investigations on Flapping Wing Aerodynamics

Three-dimensional, unsteady flow fields of a flapping low aspect ratio wing are investigated by means of tomographic PIV (Tomo-PIV) measurements and computational fluid dynamics (CFD). Furthermore force measurements have been done. Tomo-PIV was applied to the flow above the flat-plate-wing during the down-stroke. A high spatial resolution and a large volume thickness could be achieved by using sensitive sCMOS cameras and a traversable set-up. The CFD calculations cover the complete period of motion. Analyzing the vortex dominated flow fields provides a deeper understanding of vortex interaction and three-dimensionality of low Reynolds number (Re = 18,000 and Re = 36,000) flows. Two different Strouhal numbers (St = 0.06 and St = 0.13) are considered and their effects on the development of a leading edge and tip vortex are discussed