| Ducted fan has been widely used in the field of aircraft especially in middle and small UAV. Dueto its complicated aerodynamic mechanism and low load capacity, the use of it has been limited.Theoretical analysis and study have been done on the aerodynamic characteristic of ducted fan, andthe gurney flap has been added to increase its load capacity.The blade element momentum theory is used to formulate the aerodynamic calculation model forducted fan. Vortex theory is used to formulate the aerodynamic model of the ducted fan. Bycomparing it with the related experimental data, the accuracy and reliability of the model has beentested. The aerodynamic loads for hover, vertical and forward flight have been calculated.CFD has been used to stimulate the ducted fan in hovel flight. The aerodynamic and flow fieldproperty has been analyzed, based on which, mechanism of Enhancing Lift was analyzed. Finally, aparametric study of the ducted fan has been done through numerical calculation.Due to its compact size, low weight, small shape and capability to increase lift significantly, thegurney flap is used in the ducted fan system in this paper. The calculation model of the aerodynamiccharacteristics two-dimensional airfoil with gurney flap is formulated. Then the he characteristics ofthe whole system with gurney flaps with different height have been analyzed. The results show thatthe gurney flap is able to increase the lift, hover performance and forward flight performance.In this paper, the analysis method for aerodynamic loads of ducted fan system has beenformulated. The aerodynamic characteristics of ducted fan have been analyzed systematically. Theresult of the study provides support to the design and improvement of ducted fan UAV. |
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