Mid-fidelity approach to aerodynamic simulations of unconventional VTOL aircraft configurations

A new flexible medium-fidelity open source computational tool was developed with the purpose of obtaining fast and reliable aerodynamic simulations of unconventional Vertical Take-Off and Landing (VTOL) aircraft configurations, such as the emerging category of eVTOLs. This tool, called DUST, ensures quick simulations and provides reasonably accurate results when the need for numerous evaluations rules out an extensive use of CFD due to its high computational cost, while maintaining robustness in the complex interactional aerodynamic phenomena typical of the novel eVTOL configurations. The paper first presents the analytical formulation of the tool, based on different potential boundary elements and vortex particles wake integrated in a common formulation. Then, the results obtained with the novel code are compared with experimental data and CFD results of a half-span tiltwing tiltrotor model and an eVTOL multi-rotor tiltwing aircraft, both in hover and forward flight mode. The comparisons show that DUST produces results that are as accurate as the results obtained with CFD, except for massively separated conditions, at a computational cost orders of magnitude lower. The results highlight the effectiveness of this approach for the preliminary design of a vehicle and for the preliminary study of the flow physics related to the aerodynamic interactions between rotor wakes and solid bodies as wings.