Experimental and computational investigation into the hydrodynamics of conventional submarines

It is important to understand and optimise the hydrodynamic characteristics of a submarine in order to improve its propulsive efficiency, operational characteristics, and manoeuvring capabilities. In addition, conventional submarines are required to operate in a near surface condition further affecting the behaviour of the vessel. The Australian Maritime College (AMC) in collaboration with industry partners, are carrying out a range of numerical and experimental works aimed at identifying and optimising these hydrodynamic characteristics under various design configurations and operational conditions. Current work includes: investigating the added resistance and adverse vertical forces and moments on submarines operating near the surface, specifically quantifying the effects due to varying depths, speeds, length to diameter ratios, and different sail configurations; developing dynamic simulation models to predict the hydrodynamic characteristics of submarines during prescribed manoeuvres; and investigating the stability of surfaced submarines.

The analytical investigation is carried out using commercial and open source CFD software to develop appropriate simulation models to understand the behaviour of submarines under varying conditions. This enables the prediction of relevant hydrodynamic characteristics, including forces, moments, coefficients and flow profiles under various operational and manoeuvring conditions, thus enabling AMC to develop suitable simulation models to investigate and optimise design and operational aspects. These include modifying software and developing new models to meet the requirements unique to the operation of such vehicles. The numerical modelling is supplemented by experimental work of captive scaled models in AMC’s towing tank, model test basin and circulating water channel, including the use of a Horizontal Planar Motion Mechanism (HPMM) for underwater vehicles. The experimental data adds to the information available, whilst enabling the evaluation and validation of the numerical work. The numerical simulation models have shown agreeable correlation with experimental data. The results have provided information to improve design and operational configurations.