MAV Propulsion System Using the Coanda Effect

Abstract

In an effort to to fill the micro aerial vehicle (MAV) performance gap between efficient cruise (fixed wing) and hover (rotary), a Coandǎ type propulsive platform is proposed. A jet, deflected by a curved surface is used for hover, while the curved surface can also be used as a wing for efficient cruise. The principles allowing the attachment of the flow are not clear and therefore efficient sizing of the surface and jet is difficult. For this purpose design rules are proposed and validated by Reynolds averaged Navier-Stokes and latticeBoltzmann models. The efficiency of converting the jet into thrust was in the order of 60 to 80 percent with respect to the predicted ideal thrust for the tested configurations. The correspondence in predicted and calculated pressure coefficient for circular surfaces was adequate, with the exception of the expansion of the jet and the stagnation point at separation. Measurements are, therefore, still needed for further validation of the computations.