Abstract
The simulations of submarine sailing near the free surface with long-crested waves have been conducted in this study using an in-house viscous URANS solver with an overset grid approach. First, the verification and validation procedures were performed to evaluate the reliability, with the results showing that the generation of irregular waves is adequately accurate and the results of total resistance are in good agreement with EFD. Next, three different submerged depths ranging from 1.1D to 3.3D were selected and the corresponding conditions of submarine sailing near calm water were simulated, the results of which were then compared with each other to investigate the influence of irregular waves and submerged depths. The simulations of the model near calm water at different submerged depths demonstrated that the free surface will cause increasing resistance, lift, and bow-up moments of the model, and this influence decreases dramatically with greater submerged depths. The results of the irregular wave simulations showed that irregular waves cause considerable fluctuations of hydrodynamic force and moments, and that this influence remains even at a deeper submerged depth, which can complicate the control strategies of the submarine. The response spectrum of hydrodynamic forces and moments showed slight amplitudes in the high-frequency region, and the model showed less sensitivity to high-frequency excitations.
Highlights
It is necessary to evaluate the sailing performance parameters of a submarine to ensure its safe navigation before sea trials
Compared with the encounter wave spectrum, the amplitudes of the response spectrum have considerable differences to those of the encounter wave spectrum in high-frequency regions, which demonstrates that the response produces nonlinear characteristics compared with the encounter wave spectrum, and the hydrodynamic force and moments acting on the model are less sensitive to high frequency excitations
The numerical simulations of a SUBOFF model sailing near the free surface in calm water and long-crested waves at different submerged depths using URANS codes have been presented in this study, and the comparison between the different surface conditions at different submerged depths has been conducted, which is aimed to investigate the influence of irregular waves on the hydrodynamic performance of the model at different submerged depths
Summary
It is necessary to evaluate the sailing performance parameters of a submarine to ensure its safe navigation before sea trials. Carrica et al [15] and Wang et al [16] conducted experiments and simulations for the self-propulsion of a submarine near the free surface The former paid attention to the force and moment coefficients of the submarine and performance parameters of the propeller in different control strategies. The present study focuses on the hydrodynamic performance of a submerged vehicle based on the viscous flow method, considering the effects of the initial surface wave, and the ITTC wave spectrum is discretized numerically to simulate the irregular waves, which could be used to provide support for the development of control strategies for a vehicle sailing near the free surface with realistic seaway conditions.
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