Analysis and Evaluation of Aerodynamic Noise Characteristics of Toroidal Propeller

Toroidal propellers, a new type of drone propellers capable of significantly reducing noise, offer new possibilities for future low-altitude flying platforms. In this study, a numerical model was established to analyze the aerodynamic noise of the toroidal propeller under normal atmospheric conditions. The aerodynamic calculations for the toroidal and benchmark propellers were performed to obtain noise source information using a transient large eddy simulation. The hybrid computational aeroacoustic method was employed to calculate the noise spectrum at different speeds and locations. Moreover, an experimental system for propellers was designed and built within an anechoic chamber to investigate the aerodynamic performance and noise characteristics at various speeds. The noise reduction effect of the toroidal propeller compared to the benchmark propeller was analyzed, taking into account the sound pressure level, lift coefficient, and figure of merit. At the same thrust level, the lift coefficient of the toroidal propeller increased by 187% relative to the benchmark propeller. The radial and axial sound pressure levels decreased by 5.2 dB(A) and 19.6 dB(A), respectively. The toroidal propeller significantly reduced noise while improving aerodynamic performance. This study provides a theoretical basis, experimental methods, and data support for the aerodynamic and noise calculations of toroidal propellers. It has significant engineering implications for the development of low-noise propellers for drones.