Aeroacoustic design and optimisation of an all-electric ducted fan propulsion module for low-noise impact

This paper discusses the aeroacoustic aspects of the design, construction and testing of an all-electric ducted fan propulsion module for future electric aircraft. An overview of the propulsor aerodynamic design is provided. Acoustic measurements made with a prototype sub-scale unit in an anechoic chamber are reported, and measurement results are presented for far-field spectra, tonal and broadband directivities at a range of rotational speeds. It is shown that broadband noise is the dominant contributor to the sub-scale unit noise. A psychoacoustic investigation of the measured far-field radiation is conducted using selected Sound Quality Metrics, and it is shown that both Zwicker's Psychoacoustic Annoyance and Loudness scale with rotational speed at all angles.