Aerodynamic Design Research on the Rotor System of an Electric Vertical Take-Off and Landing Aircraft

To meet the demands for efficient and agile aircraft in low-altitude and urban air mobility applications, this paper conducts a systematic investigation into the aerodynamic design, interference characteristics, and experimental validation of a quad coaxial rotor eVTOL aircraft. The study begins with a rapid preliminary rotor design using Blade Element Momentum Theory (BEMT), followed by Computational Fluid Dynamics (CFD) simulations to analyze the unsteady flow fields of coaxial rotors in hover and forward flight. Results show that in hover, the lower rotor experiences sustained downwash from the upper rotor, reducing its thrust and efficiency to approximately 75% and 80% of the upper rotor’s values, respectively. In forward flight, as airspeed increases, the coaxial system demonstrates improved total thrust and overall efficiency along with reduced total torque. Flow analysis indicates that incoming airflow alters the downwash extent and velocity of the upper rotor, thereby influencing both rotors. Bench tests validate the design and simulation outcomes, confirming the reliability of the methodology. This research establishes a comprehensive eVTOL rotor design framework and provides theoretical and practical guidance for developing high-efficiency eVTOL rotor systems.