Evaluation of dynamic balance of submarines by CFD method

The purpose of present article is to investigate the effects of changing the geometry on dynamic balance in submarines with sail. The concept of dynamic balance and its difference with dynamic stability is described. The purpose of dynamic balance is to maintain pitch angle at different speeds without using of control surfaces. In this article, changes of submarine geometry include 19 different geometries with changes in the bow area, the longitudinal position of the sail, the height of the sail and different changes in control surfaces. In each of these situations, the values of resistance, longitudinal moment, lift and the position of the center of pressure relative to the center of gravity have been studied. The CFD method with STAR-CCM+ software is used and validated with Suboff results in six different velocities is performed. The ideal state of dynamic balance is that the result of longitudinal moments caused by the bare hull, sail and control surfaces leads to zero longitudinal moment so that the submarine can maintain its longitudinal position and continue its path without continuous use of control surfaces. The results show that longitudinal position of the sail has the greatest effect on submarine dynamic balance.