This paper aims at understanding how the aerodynamic performance of a hovering microrotor is affected by horizontal and vertical wall proximity. Toward that end, experiments are performed to extract aerodynamic loads and velocity flow fields from strain gauges and high-definition stereoscopic particle image velocimetry measurements, respectively. The results show that horizontal wall boundary conditions contribute to enhancing aerodynamic performance, whereas vertical boundary conditions have a negligible impact. Enhancement of aerodynamic performance arises from distinct flow physics, such as rotor wake expansion or Venturi effects, that depend on the configuration considered. These results open the path toward the development of micro air vehicles dedicated to the exploration of highly confined environments.

International audienceThe present study experimentally investigates the hydrodynamic behaviour of 2-D NACA (15%, 25% and 35%) symmetric hydrofoils at Reynolds number 0.5×106. Particular attention was paid to the hysteretic behaviour at the static stall angle, and a detailed cartography of the boundary layer structures (integral quantities and velocity profiles) is given to support the detachment mechanism and the onset of von Kármán instability for thick hydrofoils

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Flight time of micro-UAVs battery size they can carry. Typically, they n recharged after about 10 minutes. This paper p for wirelessly charging the UAV battery when the need to remove it and replace it. The sys light-weight flexible rectenna array mounted o and micro-controller driven power managem enables efficient battery charging. In this wor 5.9GHz is chosen as a compromise between efficiency. The UAV battery is charged from th field with about 5W of transmit power.