Papers by Davide Montagnani
The paper presents a new flexible medium fidelity aerodynamic computational tool, developed from ... more The paper presents a new flexible medium fidelity aerodynamic computational tool, developed from the collaboration between Politecnico di Milano and A 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 A 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 valida...
Mid-fidelity approach to aerodynamic simulations of unconventional VTOL aircraft configurations
Aerospace Science and Technology, 2021
Abstract A new flexible medium-fidelity open source computational tool was developed with the pur... more Abstract 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.
Experiments in Fluids, 2015
The purpose of this work is to develop an innovative procedure for reconstructing the pressure fi... more The purpose of this work is to develop an innovative procedure for reconstructing the pressure field from PIV velocity measurements of unsteady, incompressible flows. The proposed technique is based on a generalization of the Glowinski-Pironneau method for the uncoupled solution of the incompressible Navier-Stokes equations written in primitive variables and exploits a finite element discretization of the measurement grid. By virtue of the underlying mathematical formulation, the method is stable and more accurate than the other techniques proposed so far in the literature. The method is first applied to an exact solution of the Navier-Stokes equations, showing second order convergence of the L ∞ error for the pressure variable. The robustness of the method with respect to stochastic perturbations in the velocity field is then tested and the results compared with other techniques proposed in the literature. Finally, the proposed technique is applied to both phase-averaged and time-resolved PIV velocity measurements of the flow around a pitching airfoil employed to investigate the dynamic stall. The reconstructed pressure is compared with direct pressure measurements, showing very encouraging results.
Reconstructing Pressure from PIV Velocity Measurements: a Novel Approach
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Papers by Davide Montagnani