Evaluation of submarine motions under irregular ocean waves by panel method

1485-1495This paper utilizes the Panel method to evaluate the effect of submerged depth in ocean waves on submarine motions. At the depth called the "wave base", the effects become so small that motions are almost negligible. The present research aims at recommending a safe depth for calm and stable motions of a submarine. Depth of λ/2 could be considered as an absolutely calm depth but a depth of 0.1λ is recommended as an operationally safe and approximately calm depth for submarines. To achieve the objectives of the study, a naval submarine was analyzed at some depths accompanied by regular surface wave. By increasing the depth, the reductions in submarine motions are evaluated. The obtained results from the study might have beneficial outcomes for AUVs, and research in submersibles and naval submarines. As mentioned, the analysis is performed by Panel method and the results are compared with those of a CFD method

Concepts in submarine shape design

100-104This paper uses CFD method for analysis of six different models of submarines. The resistance coefficients of each shape are presented and compared so that could understand the reason of submarine shape selection with tapered stern and curved bow. Focus of this paper is on the cylindrical middle body submarine such as the most of naval submarines and ROVs. Determination of diameter and length of submarine is related to the L/D ratio that is somewhat discussed here by CFD modeling. The tools of CFD modeling is Flow Vision (v.2.3) software that is known as a skilled software in CFD modeling

Optimum L/D for Submarine Shape

38-43This 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

Wave making system in submarines at surface condition

44-53In this paper the critical Froude numbers of the wave making system of submarines are evaluated at surface condition.. Focus of this paper is on finding out the hump and hollow of the wave making diagram, and related critical Froude number. Range of maximum Froude number in submarines is extracted statistically. For the study of this phenomenon, three methods are employed; CFD method, Experimental method and Analytical formulas. CFD analysis is performed for a bare hull of a submarine by Flow Vision (V.2.3) software, which is based on the solution of RANS equations. Experiments are conducted in the towing tank of Isfahan University of Technology (IUT) on two models with appendages and different bows (Tango and DREA)