Numerical aerodynamic/aeroacoustic investigation of two propellers in side-by-side configuration

The increasing focus on sustainability and the need to develop less polluting aircraft models have led to the emergence of Distributed Electric Propulsion (DEP) aircraft as a revolutionary solution. The utilization of DEP systems has gained considerable traction in Electrical Vertical Take-Off and Landing (eVTOL) aircraft for urban and military applications in the modern era. These new vehicles, known for their versatility, efficiency, and technological innovation, require a detailed analysis of rotor configurations, generated noise, and performance impact. This research aims to investigate the wake development and propeller interactions in DEP systems for urban air mobility (UAM) vehicles. Specifically, the study focuses on the interaction of two side-by-side rotors positioned along the wing of the eVTOL VX4 vehicle produced by Vertical Aerospace, analyzing the evolution of tip vortices under both hover and forward flight configurations. The primary reasons behind wake evolution and tip-tip interaction with the adjacent propeller will be investigated, assessing how these phenomena can impact various performance metrics in both hover and forward flight configurations. The methodology employed is based on computational fluid dynamics (CFD) simulations. The different evolution of the wake will be analyzed through Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations for both single and side-by-side configurations. Subsequently, a comparison will be made with a high-precision Large Eddy Simulation (LES) and a low-order model to evaluate their applicability. By comparing LES results to those obtained from lower-order methods, the study aims to provide a comprehensive understanding of wake dynamics when propellers interact in close proximity. The final results will show the evolution of the wake and tip vortex in both cases: single propeller and side-by-side configuration. The impact on performance will be assessed through various graphs that illustrate the effects of the interaction in one case compared to the other, and through comparisons across the various simulations. Additionally, the research will investigate the aeroacoustic implications of these interactions, with a particular focus on tonal noise generation in the far field. This project is part of the eVTOLUTION initiative, which is designed to develop the knowledge, data, tools, and methods necessary to understand, model, and optimize aerodynamic performance and noise emissions while accounting for the complex interferences between the propulsion system and the airframe.