Toward high-efficiency low-noise propellers: A numerical and experimental study

Abstract

This work presents a high-efficiency low-noise propeller design for unmanned aerial vehicles. Three different blade configurations are first investigated, using the computational aeroacoustic approach to recognize the flow around propellers and the noise emissions. The flow simulation is obtained by an acoustic-wave preserved artificial compressibility method, and the far-field noise is extrapolated by solving the Ffowcs-Williams and Hawkings equations. Experiments are also conducted to validate numerical simulations and the design philosophy. The comparison between numerical and experimental results confirms an encouraging agreement regarding aerodynamic efficiency, noise spectra and differences between propellers. The results show that two designed propellers can simultaneously improve aerodynamic efficiency and reduce noise emissions compared to the baseline propeller. It is observed that using a longer chord length and shorter propeller radius can reduce flow separation at the trailing edge. Furthermore, a qualitative noise-source analysis shows that broadband noise sources are primarily ascribed to the time-derivative of blade surface pressure and occur at the trailing edge near the tip.