Colloquia

Samenvatting

This thesis builds upon the work done by Zarri et al. (2024) to develop a low-fidelity model that predicts the aerodynamic loading and tonal noise emissions of isolated propellers (single propeller) and distributed propeller systems (multiple propellers) in cruise flight configuration. A low-order, semi-analytical model is developed to calculate the aerodynamic loading on a propeller disk in a distributed propeller system, where multiple propellers are arranged in series and co-rotate either in-phase or out-of-phase. The model is based on the aerodynamic loading due to steady flow phenomena and fluctuating flow phenomena that are induced by the wake of each propeller in the propeller distribution. The propeller wake is modeled as a helical vortex filament that convects downstream. We were able to derive closed-form expressions for variables detrimental to model, and desingularize certain aspects of the propeller wake. Three different loading models are compared: one primarily relies on fundamental aerodynamic theories, such as thin airfoil theory, and the other two primarily rely on higher-order frequency transfer functions, such as a gust response model. Using the aerodynamic loads on the propeller disk, we computed the tonal noise emissions of these distributed propeller systems using a rotating dipole model, which yields the sound directivity and the sound pressure level. The results of the low-order model are compared with those of high-fidelity numerical models. Two different propeller geometries are analyzed to check the general applicability of the low-order model. To validate one of these geometries, unsteady Reynolds-averaged Navier-Stokes simulations were conducted in this thesis. Ultimately, the low-order model is extended to include hover flight configurations for isolated propellers. To mark the achievement of developing a low-fidelity model that can predict the aerodynamic loading and tonal noise emissions of isolated propellers and distributed propeller systems in cruise and isolated propellers in hover within a matter of minutes on a regular laptop.