Numerical investigation into flow characteristics of tandem fan-wing configuration

Fan-wing can accelerate and rectify the air inflow through the rapid rotation of crow flow fan in the leading edge. Taking advantage of this distinguishing feature, a tandem fan-wing configuration is put forward, which is composed by double or multiple rows of fan-wings arranged in tandem with certain spacing and spatial distribution. The flow characteristics of the tandem fan-wing configuration are simulated based on two dimensional models, and the lift and thrust loads are calculated for different spacing, height disparities and row numbers. Results indicate that compared to single fan-wing, larger lift and thrust can be obtained by properly designed tandem fan-wing configuration. For instance, the four-row fan-wing with uniform spacing of one fan diameter possesses larger average lift and thrust by about 10% and 30%,respectively. The reason accounting for the improvement of lift and thrust is analyzed based on the flow filed near the fan-wings and the pressure distribution over the airfoils. These investigations can provide useful guidance for the design of future fan-wing aircraft with better low-speed large-load characteristics.