The increasing interest in Micro-Air-Vehicles pushed the research and adaption of biology inspired membrane wing structures of bats. Their thin and flexible wing design can improve aerodynamic fight performance at low to medium Reynolds numbers. Membrane wings can combine vehicle agility, enlarged maximum stall angle, extended maximum lift and smooth gust reaction. The main source of their benefits is suggested to rely on their inherent membrane oscillations which can energise the weak boundary layer to enforce longer flow attachment. In addition, membrane vibrations are known to enhance leading edge vortex shedding, forming large roll up vortices of low pressure content which can significantly contribute to the total lift enhancement at high incidences.
The experimental wind tunnel study examines flow structure interactions of membrane wings in high and low altitude. Emphasis is on aspect ratio and the vicinity of the ground. The operation of membrane wings close to a surface could be one further option to gain efficiency and therefore range of MAVs by maintaining the aerodynamic and weight benefits of (passive) membrane wings. A force transducer is used to capture time resolved force measurements whereas Digital Image Correlation (DIC) is selected to resolve membrane motions and Particle Image Velocimetry (PIV) is used to show time resolved modifications in the flow.
Project leader : Robert Bleischwitz
Main supervisor(s): Prof Ganapathisubramani, Dr Roeland De Kat
taken from here