Analysis of the Interactional Aerodynamics of the Vahana eVTOL Using a Medium Fidelity Open Source Tool

This paper presents the results of a series of aerodynamic simulations of the Vahana demonstrator carried out using a new medium fidelity open source software, called DUST. This tool, developed from the collaboration between Politecnico di Milano and A3 by Airbus LLC, exploits the Object Oriented paradigms of the latest Fortran standards to obtain a coherent formulation of the aerodynamic problem governing the flow field around one or more arbitrary bodies. Such formulation enables DUST to be used for comprehensive aerodynamic analysis on any vehicle configuration, including conventional airplanes, helicopters and new eVTOLs, flying in any flight condition. A series of test cases of increasing complexity are analyzed in the paper to assess the accuracy and the limits of such a new medium fidelity numerical software. Test cases range from the simple Vahana 3-bladed isolated fan in hover to the full vehicle flying at different attitudes. Aerodynamic simulations carried out using DUST are compared and validated against both experimental measurements and high-fidelity numerical simulations to assess the validity of the approach and the limits of the new solver in simulating the most challenging flight conditions for an eVTOL. The model of Vahana is developed using doublet-source singularity panels to represent the fuselage, the canard and the wing, while lifting lines with tabulated aerodynamic characteristics of airfoils are used to capture the compressibility and viscosity effects of the rotating blades of the fans.