On the impact of model fidelity for the prediction of acoustic source and propagation of near-field propeller noise

To meet environmental goals in regional aviation and improve passenger comfort, propeller aeroacoustics must be integrated early into the aircraft design process. Various methods, ranging from analytical formulas to scale-resolved simulations, are available for predicting propeller noise. While previous studies have compared different noise prediction techniques, a comprehensive comparison of models that account for propagation, airframe scattering, and near-field effects in the aircraft surroundings is still lacking. As an initial step toward filling this gap, this work validates these models by applying them to the simpler case of propeller noise under static and free-field conditions. Three methods are examined for source computation: Blade Element Theory, a potential panel method, and the Lattice-Boltzmann method. For noise propagation, the frequency-domain Green's function, the Galerkin discretization of Lighthill's acoustic analogy, and Direct Noise Computation are considered. These methods are combined to form seven distinct models with varying fidelity in source computation and propagation, which are used to predict near-field noise by a 27-inch diameter propeller at different subsonic speeds, emulating the aeroacoustics of eVTOL and turboprop aircraft. Sound pressure results at the first few blade passage frequency harmonics are compared to assess the performance of each model.