Experimental Characterisation of Small-Scaled Propeller-Wing Interaction Noise

An experimental study is carried out to quantify the aerodynamic loading and the far-field noise radiation of propellers in isolated and wing-installed configurations. The effects of aerodynamic interactions between 1 propeller and an upstream wing at different positions are studied at a constant rotational speed over a range of inflow velocities. Detailed acoustic analyses such as the power spectral analysis, sound pressure levels and directivity are performed to demonstrate the dependencies of propeller acoustic signature on the upstream wing interactions. The furthest positioned wing from the propeller's hub shows the highest increase in thrust coefficient compared to the isolated propeller configuration, albeit moderately imposing a noise penalty at the propeller's blade passing frequency. Meanwhile, multiple high-amplitude tones are generated within the low and mid-frequency domain for the nearest positioned wing to the propeller's hub. The directivity contribution of tonal noise components is also studied. The results provide additional information on the apparent high directivity of tonal noise radiation in the upstream field, indicating a tonal source mechanism associated with wing-wake turbulence interaction with the propeller blade when ingested into the disc.