On the Flow Origins of Tonal Aeroacoustic Signatures in a Small-Scale APC Propeller

With the rapid growth of electric aerial vehicles, propeller noise has become a critical engineering challenge, particularly in urban environments. This study presents a detailed numerical investigation of the aerodynamic and aeroacoustic characteristics of a two-bladed APC ۱۰×۷E propeller operating at an advance ratio of. The unsteady flow field is simulated using the Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations coupled with the SST turbulence model. Acoustic propagation is predicted using the Ffowcs Williams–Hawkings (FW-H) analogy based on an impermeable surface formulation, focusing on deterministic monopole (thickness) and dipole (loading) noise sources. The aerodynamic performance is validated against experimental measurements, showing excellent agreement with less than ۸% error in thrust and torque coefficients. Spectral analysis reveals a strongly tonal noise signature dominated by the Blade Passage Frequency () and its higher harmonics. A key contribution of this study is the directional analysis of tonal noise attenuation, demonstrating that higher-order BPF harmonics exhibit distinct decay rates in the radial and axial directions. The results show that high-frequency tonal components remain more pronounced in the rotation plane, while they attenuate more rapidly in the downstream wake, reflecting the different radiation characteristics of thickness- and loading-dominated noise mechanisms. The inverse-square law attenuation is further confirmed in the intermediate field (), supporting the reliability of the numerical framework. These findings provide physical insight into the flow-induced origins and directional behavior of tonal noise in small-scale propellers and offer an efficient computational approach for UAV noise prediction.

کلیدواژه ها:

UAV Propeller ، APC ۱۰×۷E ، Aeroacoustic ، FW-H analogy