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Near free surface behaviour of a submarine


Ling, X and Leong, ZQ and Duffy, J and Chin, C and Woodward, M, Near free surface behaviour of a submarine, Proceedings of the 2022 International Maritime Conference, 10-12 May 2022, International Convention Centre, Sydney, Australia, pp. 1-11. (2022) [Refereed Conference Paper]

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A well-known but poorly understood issue with submarines operating at small submergence depths is the effect of the free surface on its hydrodynamic and manoeuvring characteristics. Generally, submarines are designed only to be marginally stable for ease of manoeuvrability with the assumption that most of their operations take place while deeply submerged. Thus, off-design operations such as high speeds at small submergence depths can make them unstable. When deeply submerged, the flow field of the submarine is assumed to be unaffected by boundary effects and this greatly simplifies stability and control requirements. However, travelling near the free surface invalidates this assumption. Submarines operating near the free surface experience a submergence depth and speed dependent heave force and pitch moment, which can significantly impact the stability of the submarine.

Small changes in submergence depth combined with the effects of speed can cause significant increases in the free surface induced forces and moments. This condition warrants further study as the resulting hydrodynamic forces can overwhelm the control system in maintaining the desired trim and depth. Hence, this paper presents an evaluation of the effects of the free surface on the hydrodynamics of the bare hull geometry of a submarine. The work was carried out using Computational Fluid Dynamics (CFD) simulation models validated against experimental data for selected conditions. The investigation covers a range of speeds, submergence depths, and length-to-diameter ratios. The results show that the effects of the free surface vary with speed and diminish rapidly with submergence depth.

Item Details

Item Type:Refereed Conference Paper
Keywords:free surface, SUBOFF, CFD, length-to-diameter ratio, submergence depth
Research Division:Engineering
Research Group:Maritime engineering
Research Field:Ship and platform structures (incl. maritime hydrodynamics)
Objective Division:Transport
Objective Group:Water transport
Objective Field:Autonomous water vehicles
UTAS Author:Ling, X (Mr Xavier Ling)
UTAS Author:Leong, ZQ (Dr Zhi Leong)
UTAS Author:Duffy, J (Associate Professor Jonathan Duffy)
UTAS Author:Chin, C (Dr Chris Chin)
UTAS Author:Woodward, M (Associate Professor Michael Woodward)
ID Code:150474
Year Published:2022
Deposited By:NC Maritime Engineering and Hydrodynamics
Deposited On:2022-06-16
Last Modified:2023-01-23

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