Investigation of Aerodynamic Performance of Coaxial Rotors for Mars Rotorcraft

The coaxial rotor employed by NASA's Ingenuity helicopter is a typical configuration of the Martian rotorcraft, which requires different aerodynamic characteristics due to the particular physical properties of the Martian atmosphere. This work proposes a numerical model of coaxial rotors in the Martian atmosphere and uses computational fluid dynamics methods to perform numerical simulations. Hovering experiments are then used to verify the simulation results. The results indicate that the figure of merit and power loading of the coaxial rotor increase with the increase of the rotor separation distance, and the lower rotor produces less thrust than the upper rotor while consuming more power and thus has lower aerodynamic efficiency. The numerical simulation errors of rotor thrust and power are within 15%. Under the condition that the upper and lower rotor speeds are 2300 r/min and 2141 r/min, respectively, and the separation distance is 0.3R, the torque-balanced coaxial rotor system can carry 2.0 kg on Mars and requires a power of 166.4 W. The findings of this work provide a basis for the design of Mars coaxial rotorcraft.