Effects of tilting rate variations on the aerodynamics of the tilting ducted fans mounted at the wing tips of a vertical take-off and landing unmanned aerial vehicle

Abstract

Tilting ducted fans mounted at the wing tips of vertical take-off and landing unmanned aerial vehicles define new applications for these types of aerial vehicles. This new configuration gives vertical take-off and landing unmanned aerial vehicles the ability to hover like helicopters and fly forward like airplanes, which results in using any arbitrary location for take-off and landing combined with increasing range and speed. Furthermore, generating additional lift by using asymmetrical shape for the external body of the ducted fans can lead to reducing the wing area and related overall drag, which results in saving more energy. The transition between cruise mode and hovering can be done by choosing different tilting rates, which can produce instabilities in the aerodynamics of the tilting ducted fans mounted at the wing tips of the vertical take-off and landing unmanned aerial vehicles. This research provides the computational fluid dynamics simulations to investigate these instabilities and compare them for two different ducted fans. “Actuator disk model” combined with the assumption of “constant delivered power” to the propeller were used successfully to calculate the induced velocity to the rotor plane of the ducted fan in the computational fluid dynamics simulations. The effects of the flow separation on the aerodynamic coefficients were discussed and compared for both symmetrical and asymmetrical ducted fans in different tilting rates.