Optimum L/D for Submarine Shape

Abstract

This paper discusses about an optimum length on diameter (L/D) for hydrodynamic shape of submarine with parallel (cylindrical) middle body hull. L/D parameter is an important hydrodynamic parameter that plays a unique role in submarine hydrodynamic design. In addition, the amount of L/D is depended on the internal architecture and general arrangements of submarine. Submarines have two major categories for hydrodynamic shape: tear drop shape and cylindrical middle body shape. For tear drop shape, the optimum hydrodynamic L/D in several scientific references is mentioned, equal to 7. However most real and naval submarines and ROV's have cylindrical middle body shape. This paper wants to propose an optimum L/D for this type of shape by CFD method and Flow Vision software. Major parameter in hydrodynamic design is resistance. The focus of this paper is on resistance at fully submerge mode without free surface effects. For this purpose, the total volume of shape is supposed constant and only varies L/D ratio.