Development of an Unsteady Indicial Response Model for Submarine Maneuvering

Abstract

This work focuses on the development of an indicial response model for predicting the hydrodynamic loads on a submarine in unsteady maneuvers. Traditional coefficient based models are not well equipped to predict the unsteady hydrodynamic loads resulting from the time-history of the vehicle’s state, and an investigation on the unsteady hydrodynamic loads on submarines is required for ensuring the accuracy of design codes. Indicial responses for the hydrodynamic loads on the BB2 submarine geometry have been measured by simulating impulsive accelerations in the horizontal plane with the commercial computational fluid dynamics code Ansys Fluent. Initial results show improvement over quasi-steady models for predicting the loads on the submarine in forced horizontal plane oscillations at operational frequencies. The indicial model shows particular promise for simulating the hysteresis behaviour of the out-of-plane forces, which coefficient-based methods are unable to capture.