Influence of Propeller Parameters on the Aerodynamic Performance of Shrouded Coaxial Dual Rotors in Hover

A numerical method is used to evaluate the influence of propeller parameters on the aerodynamic performance of shrouded coaxial dual rotors in hover. Compared with the open-rotor configuration, the shrouded rotors reduce the tip vortex, resulting in a higher thrust and figure of merit (FoM). The varying inflow distribution over the inlet lip of the shroud introduces a different working condition for the propellers, thereby providing an opportunity for propeller parameter optimization. The pitch length, chord length, and tip clearance are chosen as the design parameters to improve the aerodynamic performance of the rotors. When the pitch lengths of the upper and lower propellers increase, the shrouded rotors outperform the original ones in both the coefficient of thrust (Ct) and in terms of the (FoM). The results show that increasing the chord length improves the Ct but that the (FoM) is almost unaffected. Moreover, smaller tip clearance can significantly improve the aerodynamic performance of the shrouded rotors. Results presented in this work provide insights into the parametric design and optimization of shrouded rotors.