Aerodynamic characteristics of nonplanar quadrotors with rotor failure

This study investigates the aerodynamic performance of a nonplanar quadrotor subject to one rotor failure. Experiments (α = 0°–50°) and computational fluid dynamics simulations reveal a counter-intuitive “Aerodynamic Relief” phenomenon, where the gains in Thrust Coefficient and Figure of Merit for the remaining rotors reach or approach their peak values at α = 20°. Numerical analysis elucidates that this relief effect stems from a geometric threshold that triggers a topological transition from a “blocked” to a “vented” state. At this critical angle, the tilted geometry effectively “directs” the high-momentum downwash away from adjacent disks and the central airframe, facilitating significant blockage release. This redirection triggers a pressure-gradient-driven flow and lateral stream tube expansion into the failure void. This flow reconfiguration reduces induced velocity and redistributes blade loading, where a substantial load surge at the blade tips (r/R = 0.95) outweighs inboard (r/R = 0.75) unloading. These findings provide a fluid dynamic basis for utilizing passive flow control to enhance fault tolerance unmanned aerial vehicle.