Surrogate Modeling Based Aeroacoustic Optimization Of An Evtol Propeller In Cruise Flight Conditions

Abstract

A surrogate-based optimization (SBO) framework was implemented to optimize the aerodynamic efficiency and tonal aeroacoustics of an eVTOL propeller in cruise flight conditions. An exemplary analysis was performed for a parameterized five-bladed propeller geometry, to study the combined influence of the propeller chord, twist, sweep and anhedral distributions on the multi-objective design criteria. The propeller aerodynamics are simulated using a computational fluid dynamics (CFD) model in ANSYS Fluent. The tonal aeroacoustics noise emission is evaluated at multiple receiver locations around the propeller using the Ffowcs-Williams and Hawkings (FWH) acoustics model. To enable a direct comparison with competing designs, all cases are trimmed to the same target thrust condition by iteratively adjusting the rotational speed. Surrogate modeling techniques are utilized to improve the candidate selection process to reduce the number of function evaluations required for the design task and decrease the overall computational cost. The current work discusses the optimization-problem formulation and solution process. Furthermore, insights into three different designs are provided by comparing designs that are generated based on different design targets, namely, maximum aerodynamic efficiency, minimum overall sound pressure level, and a weighted combination of both.