Design Optimization Methodology of Submarine Using Multilevel Numerical CFD Models

Progress in Marine Science and Technology

Submarines bring many interesting hydrodynamic challenges that need to be properly addressed to provide precise and reliable information about their performance. Hydrodynamic performance must be evaluated at least in two main operating conditions, namely when it is deeply submerged and at snorkel depth. There are relevant differences in terms of hydrodynamic since the forward speed in the latter condition is typically much lower and of interaction with the free surface. Moreover, submarines used to sail at snorkel depth if they need to accomplish specific tasks, such as communication, that involves the use of surface piercing masts. The proposed study analyses the opportunity provided by different Computational Fluid Dynamic (CFD) approaches to correctly address submarine performance. The resistance in both conditions, masts free surface hydrodynamics and maneuvering behaviors are addressed. Ad-hoc approaches based on in-house developed numerical procedures and open-source software ...

Progress in Marine Science and Technology

Nowadays, underwater vehicles have a wide range of applications both in military, scientific, commercial and security fields. Next to Submarines, Autonomous Underwater Vehicles (AUVs) are increasingly spreading thanks to their capabilities to carry out a significant variety of missions, including interacting with underwater infrastructures, coastal and underwater inspections, intelligence gathering, environmental and fish monitoring and, of course, research and fight against underwater threats. One of the main performance characteristics of an underwater vehicle is its resistance curve. The estimation of this curve is a crucial factor in preliminary design phases in order to correctly choose and dimension the right propulsion plant and propeller and, in general, to reach operational requirements. In the last decade, with the advent of higher computing power and robust algorithms, the application of Computational Fluid Dynamics (CFD) analysis is rapidly emerging as a fast, reliable a...

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 6, 2010

Submersibles used for exploration, maintenance and naval warfare have to be both manoeuvrable and easy to control. Simulation of the trajectory for these vessels requires the accurate determination of the hydrodynamic forces and moments which are determined by model-testing, empirical methods or a combination of both. CFD can play a role here by permitting an easier and more accurate determination of these loads. In this paper we focus on the accurate prediction of the manoeuvring forces of free swimming streamlined submersibles (submarines) using CFD. We compare simulations of a standardised wellknown submarine shape (DARPA SUBOFF) for two configurations, one bare hull (AFF-1) and one fully-appended hull (AFF-8), under different inflow angles. The viscous-flow solvers used are the finite volume solver ReFRESCO developed by MARIN, and the finite element commercial solver AcuSolve. Verification studies are performed and the numerical results are validated with the experimental data available in the literature. The influence of different turbulence models is investigated and results obtained with a RANS (Reynolds-Averaged-Navier-Stokes) approach are compared with the theoretically more realistic DDES (Delayed-Detached-Eddy-Simulation) results. The influence of the appendages on the forces and flow fields is also investigated and analysed. As a last example, results of a forced pitch motion including dynamic effects are presented.

International Journal of Naval Architecture and Ocean Engineering, 2012

Autonomous Underwater Vehicles (AUVs) provide a useful means of collecting detailed oceano-graphic information. The hull resistance of an AUV is an important factor in determining the power requirements and range of the vehicle. This paper describes a procedure using Computational Fluid Dynamics (CFD) for determining the hull resistance of an AUV under development, for a given propeller rotation speed and within a given range of AUV velocities. The CFD analysis results reveal the distribution of the hydrodynamic values (velocity, pressure, etc.) around the AUV hull and its ducted propeller. The paper then proceeds to present a methodology for optimizing the AUV profile in order to reduce the total resistance. This paper demonstrates that shape optimization of conceptual designs is possible using the commercial CFD package contained in Ansys™. The optimum design to minimize the drag force of the AUV was identified for a given object function and a set of constrained design parameters.

AIP Conference Proceedings, 2019

Under Water Vehicles (UWVs) are extensively being used for variety of operations. Recently, there has been an increased interest in the design of autonomous unmanned underwater vehicles design (UUVs) as future generation submarines. The aim of this study is to investigate the effect of the various design parameters on the rotary coefficients of one such UWV i.e. a submarine SUBOFF model. The rotary coefficient has been calculated using the numerical simulations. The effect the wall roughness, linear velocity, rotation speed has been studied using the steady state Reynolds Averaged Navier-Stokes (RANS) simulations. The study helps to understand the underlying hydrodynamic phenomenon showing the dependence of these parameters on the hydrodynamics of the underwater vehicles.

Comptes rendus, 2023

More than a half century of Computational Fluid Dynamics / Plus d'un demi-siècle de mécanique des fluides numérique

Naval Engineers Journal, 2022

This paper explores the utility of an integrated physics-based digital model for the preliminary design and development of a hull-form geometry for a semi-submersible vessel (SSV). SSVs are increasingly being considered as candidate ships to improve supply-chain resilience in contested operating environments. However, formal design guidance for SSVs and an understanding of associated near-surface hydrodynamics are limited, necessitating a comprehensive technical approach that effectively integrates first principles-based design, computational modeling and simulation, and direct experimentation. The authors present a methodology that leverages gradient descent optimization to evaluate hull-form design trade-offs traceable to competing stakeholder interests, including sea-going stability, hull-form resistance, and detectability.

Journal of Ocean Engineering and Marine Energy

Traditionally, submarine hydrodynamic design has focussed mainly on requirements regarding operational range, powering performance and manoeuvring ability for deeply submerged conditions. To improve the effectiveness of the boat, attention is also paid to operating near or at the surface and fortunately, computational tools and experimental methods are available to analyse the performance of submarines at these conditions. To advance submarine hydrodynamics knowledge and tools, DMO and MARIN have conducted a wide variety of bi-lateral or collaborative studies using potential and viscous flow methods and experiments on several submarine hull forms. In this article, several examples are presented of the development and use of hydrodynamic tools available during the design and assessment process of future submarines. These examples range from experimental and numerical studies into at-surface and periscope-depth resistance and powering, periscope-depth manoeuvring, high-fidelity flow a...

2009

Abstract This paper presents finite volume method based on Reynolds-averaged Navier-Stokes (RANS) equations for computation of 2D axisymmetric flow around bare submarine hull using unstructured grid. The body used for this purpose is a standard DREA (Defence Research Establishment Atlantic) bare submarine hull. Shear Stress Transport (SST) k-ω model has been used to simulate turbulent flow past the hull surface.

This paper deals with finding the optimum fineness ratio, i.e. ratio of length to maximum diameter, of human-powered submarine of different shapes to reduce the drag force on the body using Computational Fluid Dynamics (CFD) analysis. These types of submarines are used in events like ISR and eISR. This paper focuses on finding the total drag force on submarine models with a constrained diameter and different fineness ratios. The analysis is done by using ANSYS Fluent. In this paper, only the fully submerged flow is considered on a hull without any appendages. The total drag on a body is caused in three different parts that are wave drag, skin friction drags and base drag. The analysis is done different shapes of submarines like Conic shape hull, Elliptical shape hull, Ogive shape hull and Parallel mid-body hull by flowing water at velocities of 3 m/s, 4m/s and 5 m/s. The fineness ratios at which the drag is minimum are found in all submarine shapes. The optimum value of fineness ratio, which gives minimum drag is obtained by the analysis is 6 for Conical shape hull, Elliptical shape hull and Ogive shape hull whereas for the submarine with Parallel mid-body hull shape the optimum fineness ratio is 7