RANS hydrodynamic characterization of a USV SWATH configuration including design optimization

Unmanned Surface Vehicles (USVs) are widely employed for both military and civil applications (e.g. costal raids, mine search and rescue, research activities related to sea and littoral investigations, etc.). A number of prototypes and actual operating USV designs has been developed in the last decades, providing increasing energy and stability performances. Effectiveness and efficiency (e.g. environmentally-friendly performances, maximum operative range and endurance as well as detection performances) of such vehicles have been largely improved by the enhancement, in terms of reliability and compactness, of hybrid and/or fully electric propulsion systems, of real-time and remote accessible on-board monitoring systems and high range/bandwidth transmission data devices. Within the USV PERMARE research project, CNR-INSEAN is responsible for the development of a USV system able to launch and recover autonomous vehicles of different nature (e.g. gliders, autonomous underwater vehicles, motor-gliders, wire-guided remote underwater vehicles) The cutting-edge aspects of the project are the non-conventional hull design and the propulsion system with propellers in mantle. The former consists in a SWATH (Small Waterplane Area Twin Hulls) configuration, optimized to ensure high-level resistance and sea- keeping performances (higher autonomy and operation capability). The latter combines propulsive efficiency and low noise (reduced installed power and higher efficiency in measurements). The SWATH is designed as a two torpedoes connected to the upper platform by a couple of struts. Enhanced stability performances are achieved including an active stabilization system, effective at all operational speeds. The objective of the present work is the hydrodynamic characterization of the baseline design and the subsequent design optimization for the total resistance reduction at the design speed.