Tonal noise emission of a lift propeller in unsteady flow conditions

Abstract

Advanced air mobility (AAM) vehicles produce significant noise due to unsteady aerodynamics and transient flight conditions. This paper introduces a methodology to predict unsteady noise emission from a harmonically excited propeller, which represents oblique inflow conditions. The approach combines a high-fidelity CFD RANS simulation with a low-fidelity aeroelasto-acoustic solver to model the propeller’s response under unsteady inflow conditions. The inflow field is generated via CFD and fed into a time-marching reduced order coupled solver based on blade element theory, Timoshenko beam theory, and Farassat’s 1A formulation. The simulation results are compared with experimental data for a two-bladed propeller. While in-plane forces correlate well with measurements, axial forces show discrepancies due to test bench effects. The analysis reveals that unsteady loading causes a noise increase of up to 24 dB(A), with negligible influence from blade elasticity. The findings confirm the model’s capability to predict unsteady hub forces and tonal noise emission, supporting its use in future AAM noise studies.