Sound Perception Study of Auralized Novel Propeller Design for Future Electrical Air Mobility Platforms
Roalt Aalmoes (Royal Netherlands Aerospace Centre NLR)
Kylie Knepper (Royal Netherlands Aerospace Centre NLR)
G. Margalida (TU Delft - Flight Performance and Propulsion)
T. Sinnige (TU Delft - Flight Performance and Propulsion)
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Abstract
To reduce climate impact of aviation, it is imperative to consider to introduce aircraft based on electrical engines. These electrical aircraft replace jet engines by propeller-driven propulsion systems, making the propeller the dominant noise source. A quieter and more efficient propeller blade design may generate a different noise signature, justifying a perception study to assess overall noise impact. In this study, a novel designed propeller “S2PROP” is compared with a baseline propeller “XPROP”. Both blades were measured in an aeroacoustic wind-tunnel, and wind-tunnel measurements of tonal and broadband noise were used as an input to generate fly-over sound samples of an aircraft equipped with these propellers. Atmospheric absorption, the secondary ground reflection path and Doppler effect were considered in creating a synthesized flyover sound. A noise simulator with virtual reality glasses and headphones was used to simulate both a visual and audible flyover procedure for participants of the perception study. Although a noise reduction is attained at the highest sound level around 600Hz for the S2PROP, it also generates higher broadband sounds at higher frequencies, resulting in finding no significant differences in perceived loudness or annoyance in the study between the two propeller designs.