OTTIMIZZAZIONE DETERMINISTICA IDRODINAMICA DEL MEZZO SWATH CON MODELLI PER FLUSSI A POTENZIALE

The objective of the present work is the design optimization of a Small-Waterplane-Area Twin Hull (SWATH) USV - formed by two torpedoes connected by a couple of twin struts to the upper platform - by potential flow simulations aimed at resistance reduction in cruise condition. A preliminary hydrodynamic characterization of the SWATH is presented using an in-house steady potential flow solver (WARP). The flow is computed with a Neumann-Kelvin linearization approach and the wave resistance is calculated by pressure integral. The frictional resistance is estimated using a flat-plate approximation based on the local Reynolds number. Grid converged potential flow results are compared to RANSE computations performed with an in-house code X-NAVIS revealing a reasonable agreement in the speed range evaluated. Parametric study varying the struts clearance and the interaxis distance is shown (by potential flows), in order to investigate different configurations of the SWATH. Design modifications of the fore and the aft fairings, sensitivity analysis to shape modifications and deterministic design optimization aimed at reducing the total resistance reduction - performed using Particle Swarm Optimization algorithm - are illustrated. A parametric performance analysis of the optimized design is also presented and commented.