Techsburg - News Archives - September, 2023

Techsburg and Virginia Tech selected for a NASA Phase I STTR contract entitled "Acoustics and Performance Scaling of a Low-Noise Tiltrotor for Urban Air Mobility Applications"

ABSTRACT: The team of Techsburg, AVEC, and Virginia Tech propose a program that directly complements the NASA/Joby Aviation 2021 flight test program by studying an isolated low tip speed tiltrotor noise in detail, with an initial primary objective of the development and validation of scaling methods to extend tests and models to full-scale applications, including noise sources due to ingestion of naturally occuring turbulence at low speeds and hover conditions. The Phase I/Phase II program will make use of test methods in an outdoor environment in addition to numerical methods based on the PowerFLOW LBM flow solver as developed by the Techsburg, AVEC, and Virginia Tech team. Our goal is the development of a family of low-noise propulsors for eVTOL applications. These airframe-agnostic propulsors would have thoroughly documented aerodynamic and acoustic characteristics, measured in real atmospheric conditions with atmospheric turbulence, thereby removing approximations in understanding the future vehicle performance and noise signature in early design phases. By supplying these as “off-the-shelf” products to the eVTOL industry, much of the expensive R&D related to high performance propulsors could eventually be eliminated and commodified for the industry.

With our experience in full-aircraft modeling, we believe there is a compelling case for individual component testing. Full aircraft modeled even in simple hover cases with no relative wind or turbulence result in a very complex flowfields with rotor-rotor and rotor-airframe component interactions. Despite this complexity, some of these phenomena may not be the dominant noise source producers, and it is difficult to learn or gain insight and understand primary noise generation mechanisms in this manner. By focusing on the single most important noise source for these vehicles, detailed study and documentation of the acoustic characteristics of isolated rotors with naturally occurring turbulence ingestion will greatly advance overall understanding of eVTOL noise production by helping to avoid overly complex aerodynamic interactions, even for simple hover cases.