Modelling and Simulating Unsteady Six Degrees-of-Freedom Submarine Rising Maneuvers

Abstract : DRDC Atlantic is collaborating with ANSYS Canada and the University of New Brunswick to develop an unsteady, six degrees-of-freedom, Reynolds Averaged Navier-Stokes (RANS) submarine maneuvering simulation capability. Initially, this is being used to evaluate emergency rising maneuvers. During these maneuvers, high negative angles of attack can occur which result in a roll instability not previously predicted by quasi-steady modelling. The objective of the RANS simulation is to reproduce the instability and investigate mitigation strategies. Models for weight and buoyancy when blowing, high incidence propulsion, and appendage and propulsion activation are presented and tested. A high incidence, quasi-steady, coefficient based hydrodynamic model used in previous stability analyses is also presented. These models are used for evaluating stability, testing the system models, and investigating different maneuvering scenarios in preparation for carrying out the computationally intensive RANS simulations. These preliminary investigations suggest the initial roll angle prior to blowing ballast, coupled with the roll instability and low pitch angles, plays an important role in the emergence roll angle.