Mid-fidelity analysis of unsteady interactional aerodynamics of complex Vtol configurations

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Montagnani, D.
Tugnoli, M.
Fonte, F.
Zanotti, A.
Syal, M.
Droandi, G.
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The paper presents a new flexible medium fidelity aerodynamic computational tool, developed from the collaboration between Politecnico di Milano and A3 by Airbus, and tailored to obtain reliable and fast aerodynamic simulations of new aircraft configurations like Vahana, the fully-electric vertical take-off and landing multi-rotor tiltwing aircraft built by A3 by Airbus. The proposed solution, called DUST, relies on the Helmholtz decomposition of the velocity field to recast the aerodynamic problem as a mixed boundary elements-vortex particles method. In DUST different aerodynamic elements can be combined in a single model to best capture the relevant physical phenomena, while an accelerated vortex particle model of the wakes allows for a numerically stable Lagrangian description of the free vorticity evolution. Pressure field evaluation in a rotational flow relies on an integral boundary problem for the Bernoulli polynomial obtained from the Navier-Stokes equation. The code is validated against numerical and experimental data available for conventional vehicle configurations, like airliner and helicopter models, and more complex architechtures, such as a tiltwing-rotor in hover and forward flight. Finally a comparison between flight test data and DUST computations is shown for Vahana.