Current increasing uncertainty about potential military threats together with probable fast and unexpected changes in the nature of ongoing regional conflicts, require a continuous preventive action of surveillance and control of critical coastal areas, affected by piracy, human and arms traffics and drug smuggling. This kind of targets of interest often lead our submarines to operate in littoral scenarios, where the high risk of collision against either the bottom or other units makes a detailed design of passive survivability and a deep and accurate study of control performances fundamental.  The work presented here relates with the activities in the framework of the Research Project “Submarine Coupled 6DoF Motions Including Boundary Effects”, SUBMOTION II, financially supported by the Italian and the Norwegian MoDs, contracted through the European Defense Agency. 

The principal aim of present research is to develop a reliable and practical procedure for the analysis of submarine maneuvering qualities while operating in different operative scenarios. In this work the maneuvering behavior of a fully appended submarine have been deeply investigated by means of Computational Fluid Dynamic (CFD) simulations and experimental tests.  The model is propelled by a seven blades propeller; in the numerical simulations the effect of the propeller is taken into account by means of the modified Hough and Ordway model. Operative conditions are identified by a Reynolds and Froude numbers based on the submarine length and advancement speed of Re=6.65 Million and Fr=0.21, respectively.

Two arrangement of the aft planes were tested, namely the cruciform and the X rudder configurations. As it will be shown in the paper, the numerical simulations carried out are suitable to provide insights in the maneuverability of the submarine. In particular, the different maneuvering characteristics of the two configurations will be exploited. Comparison with available experimental data will be provided as well.