The influence of appendages and their stall on submarine hydrodynamic loads

Global hydrodynamic loads as a function of drift angle are presented for the Defence Science and Technology Group (DST) generic submarine geometry BB2. Loads are calculated for a model-scale Reynolds number using Computational Fluid Dynamics (CFD) at angles of drift. Abrupt change in the global loads are attributed to appendage stall. Surprisingly, CFD-predicted aft-control-surface (ACS) and bridge fin stall are not easily identified from the sway force. Instead, secondary load components, such as the heave force, must be used to identify that an appendage has stalled. Identifying which ACS has stalled is not possible from global load data. Appendage pressure loads and surface flow topology are required to confirm appendage stall. The results presented will aid the interpretation of experimental load tests currently being conducted by DST.