An Application of Amiet’s Model for Turbulence Ingestion to eVTOL Propellers

Abstract

The proliferation of multirotor and eVTOL vehicles has intensified the importance of predicting broadband noise, particularly Turbulence Ingestion Noise (TIN), which can dominate the overall noise of these vehicles during edgewise flight. TIN can be predicted using high-fidelity Computational Fluid Dynamics (CFD), though its computational cost often precludes its use as a design-stage tool without access to a huge amount of computational resources. This paper investigates a hybrid prediction framework coupling CFD-derived turbulence statistics with Amiet’s analytical model for leading-edge noise to predict the farfield broadband noise of a 21% scale Joby Aviation eVTOL propeller operating in edgewise flow. The results are compared using turbulence intensity and integral length scales statistically extracted from a high-fidelity blade-resolved Delayed Detached Eddy Simulation (DDES) against the lower cost actuator line Reduced Order Aerodynamic Model (ROAM) built into CREATETM-AV Helios. The extracted parameters are applied and compared to canonical turbulence spectra, primarily von Kármán and Gaussian models. Results show that inputting the turbulence parameters extracted from the DDES simulation into von Kármán spectra yields sound pressure level predictions that closely match experimental measurements. In contrast, the actuator line approach produced a very different incident turbulence field, more concentrated along the Blade-Vortex Interaction locations, which resulted in a higher sensitivity to length scale. Ultimately, the study suggests that with some model improvements, informing Amiet’s leading-edge noise model with turbulence extracted from a CFD simulation can make the reduced-order actuator line approach viable for low-cost TIN modeling.