Investigation of the Aerodynamic and Aeroacoustic Performance of Tilting Ducted Fans

This study presents a detailed experimental and numerical investigation into the aerodynamic and aeroacoustic performance of a tilting ducted fan based on a NACA 0018 airfoil. Tests were conducted in an anechoic wind tunnel under hover (varying tip Mach numbers and clearances) and cruise (varying wind speeds and angles of attack) conditions. The key findings revealed that the ducted configuration provides a significant thrust enhancement of up to 15.8% compared with an isolated propeller, without a measurable increase in overall broadband noise from reducing the tip clearance. Furthermore, the duct fundamentally altered the acoustic directivity, shifting the point of minimum noise downstream of the rotor disk due to its shielding effect. Under cruise conditions, the noise level attains a distinct peak at specific angles of attack (10°–15°), a phenomenon linked via large-eddy simulation (LES) to flow separation and vortex shedding on the duct’s outer wall. This work provides critical insights for the design and optimization of low-noise propulsion systems for electric vertical take-off and landing (eVTOL) applications.