Influence of Wall Effect on Comprehensive Controllability for Ducted Fan Aircraft

A novel coaxial ducted fan structure aircraft is proposed to enable the aircraft near vertical walls at high altitudes. The state space equation of the system can be obtained by correlation deduction and identification of the whole prototype model. Based on the duct test bench experiment and computational fluid dynamics (CFD) simulation analysis, the expressions between the different distances d_WE from the rotor center of the prototype to the wall and the thrust, reaction torque, and tilting moment of the system under hovering conditions are obtained. The influence of the wall effect of the prototype is incorporated into the system model to analyze the relationship between distance d_WE and the comprehensive controllability of the system. The results show that the system comprehensive controllability vector of other channels changes little with the decrease of the distance d_WE, and only the controllability vector of the rolling channel increases significantly. At the same time, the tilting moment also increases significantly, which strengthens the tendency of the prototype to tilt towards the wall.