Comprehensive Acoustic Analysis for Distributed Electric Propulsion Aircraft

A major innovative thrust in urban air mobility (UAM) is underway that will potentially transform how we travel by providing on-demand, affordable, quiet, and fast passenger-carrying operations in metropolitan areas. As cited in the NASA SBIR A1.06 topic solicitation, “Growth of UAM is dependent on affordable, low-noise VTOL configurations, which may be enabled by electric aircraft propulsion technologies.” To support this, NASA implemented the DELIVER (Design Environment for Novel Vertical Lift Vehicles) program to help “… bring 100 years of aeronautics knowledge to the new entrepreneur’s desktop with a design environment for emerging vertical lift vehicles.” DELIVER identified a key gap in technology required by UAM vehicle developers – “no current ability to account for noise in conceptual design”. The proposed effort is directed toward filling this technology gap by enhancing state-of-the-art rotary-wing aeroacoustics analysis with the key additional modeling capabilities needed for comprehensive acoustic prediction of Distributed Electric Propulsion (DEP) aircraft noise. The new tool will provide fast, accurate prediction of all the acoustic characteristics associated with DEP aircraft, including (1) noise generated by the simultaneous operation of multiple, variable RPM lifting and propelling rotors and props, (including stacked and counter-rotating blades), (2) interacting propeller/duct/airframe noise, (including strut noise and prop/wing interaction noise), (3) full-spectrum broadband noise modeling pertinent to this new class of aircraft, and (4) electric motor noise. The new software will also include auralization capabilities to enhance evaluation of community annoyance due to various acoustics characteristics beyond A-weighted sound pressure level.