Impact analysis of design parameters and flow mechanism of ducted fan

Abstract The ducted fan has become one of the most promising electric propulsion devices for aviation electrification due to its high aerodynamic efficiency, excellent safety, and low aerodynamic noise. An accurate numerical calculation method for electrically driven ducted fans is established based on the Reynolds-averaged Navier-Stokes equation (RANS) and the multiple reference frame (MRF) method, with validation of the computational results against NASA’s wind tunnel test for ducted fans. Based on the method, the effects of duct lip shape, tip clearance, and inflow velocity on the aerodynamic performance of the ducted fan, as well as the intrinsic mechanism, are investigated. The result shows that the curvature of the duct lip and the vertex position jointly affect the negative pressure area, thus affecting the additional thrust of the duct; the increasing tip clearance weakens the inhibitory effect on the tip vortex, leading to decreased aerodynamic efficiency. The thrust contribution of the duct in the cruise state is significantly lower compared to the hover state. As the inflow velocity increases, the thrust of the ducted fan decreases, while the propulsion efficiency first increases and then decreases.