Aerodynamic performance of a ducted fan in high-altitude, high-speed electric aircraft via a data-driven method

Studying the propulsion performance of ducted fans in electric aircraft is crucial for achieving zero emissions in next-generation electrically propelled general aviation. Existing research lacks an understanding of aerodynamic performance regulation for high-altitude, high-speed electric propulsion systems. This study examines the impact of blade pitch angle (BPA) on the aerodynamic performance and unsteady flow behaviors in high-speed ducted fans. The results show that as true airspeed increases from 0 to 300 km/h, the effective angle of attack decreases from 10° to 3°, and the total thrust drops from 1784.43 N to 234.53 N (an 86.86% reduction). Increasing the BPA significantly enhances total thrust under high True Airspeed with a 1096.70 N increase when adjusting from 0° to 20°. Meanwhile, the BPA significantly affects the evolution of flow disturbance characteristics. As the BPA increases from 0° to 10°, the dominant disturbance frequency increases from 168.076 to 193.375 Hz. For the case of 0°, the first-order dynamic mode decomposition mode aligns closely with the blade tip vortex structure. For the case of 10°, leading-edge flow separation becomes the main disturbance source, overshadowing tip leakage unsteadiness. When the BPA increases to 20°, the frequency drops sharply to 101.783 Hz due to flow reattachment and the restoration of tip leakage dominance. The competition between leading-edge separation and tip leakage intensity determines unsteady disturbance characteristics under BPA adjustments. This study aims to provide theoretical foundations for adaptive variable-pitch control of ducted fans, advancing the design of high-stability electric propulsion systems.