Computational analysis of strut effects on a BB2 submarine at drift angle 0, 6, and 12°

Struts are attached to a submarine to maintain its submerged depth when conducting the model tests. While previous studies have mentioned that the attachment of the struts has a negligible effect on the performance of a submarine, it is difficult to find studies that clearly explain the effects of the struts. The present study examines the effect of struts with a circular cross-section on the resistance and propulsion performances of a submarine under both straight-ahead (β = 0°) and static-drift (β = 6° and 12°) conditions. For this analysis, the open-source computational fluid dynamics (CFD) toolkit OpenFOAM was utilized. A generic submarine Joubert BB2 was selected as a test model, which was modified by the Maritime Research Institute Netherlands (MARIN). Analyses of resistance were conducted in straight-ahead and static-drift conditions, and the flow characteristics such as pressure, velocity, vorticity, and turbulent kinetic energy were compared to identify differences caused by the struts on the BB2 submarine. The results showed that as the drift angle increased, the struts had a smaller effect on the submarine along the hull to the propeller plane. From the results, it was predicted that the effect of the struts should be considered during the design process for the submarine.