Sviluppo di Modelli Teorico-Numerici per L'analisi Aero-idrodinamica di Sistemi ad Ala Rotante

This paper presents a comparison among different hydrodynamic models for the analysis of the unsteady loads delivered by a marine propeller working in an axial, non-uniform inflow. Specifically, for a propeller subjected to a wake-field dominated by local high-frequency changes in space, the unsteady hydroloads predicted by the Nakatake formulation are compared with those given by the Theodorsen and Sears theories, respectively. Drawbacks and potentialities of these approaches are highlighted to assess a computationally efficient hydrodynamic solver for the analysis of operating conditions where propeller blades are significantly perturbed by a multi-harmonic onset-flow. Guidelines coming from this investigation may drive the choice of a fast and reliable unsteady propeller modeling that represents a good trade-off between accuracy of simulation and computational costs, within implementation in CFD solvers. The hydrodynamic formulations herein proposed are validated through numerical comparisons with the (accurate but computationally expensive) propeller loads predicted by a fully 3D panel-method BEM solver, suited for the analysis of propellers operating in a complex hydrodynamic environment.