Numerical hydrodynamic optimization of a tanker hull form

New Promising Generation of Twin-Gondola LNG Carriers Optimized with the Aid of CFD Calculations

10.5957/smc-2005-d33 ◽

2005 ◽

Author(s):

Henk V. Valkhof ◽

Eduardo Minguito ◽

Klaas Kooiker

Keyword(s):

Viscous Flow ◽

Far East ◽

Point Of View ◽

Maximum Efficiency ◽

Hull Form ◽

Overall Design ◽

Computational Fluid Dynamics Cfd ◽

New Generation ◽

Hydrodynamic Optimization ◽

Adequate Design

As natural gas is becoming an important energy source, a large fleet is needed to transport it in liquefied form across the oceans in specially designed LNG carriers from mainly the Middle East towards the Far East. During the overall design process of such a vessel the shape of the hull form and its propulsors play an important role from a hydrodynamic point of view. This paper describes the design of a twin-gondola LNG carrier for Navantia. The twingondola aft body has proven to be an adequate design concept, but due to the complexity of the flow around the aft body the design should be carried out with great care. Computational Fluid Dynamics (CFD) tools are extremely valuable in the hydrodynamic optimization process of the hull. In this design both potential flow codes and viscous flow codes have been used to obtain the optimum hull form. With the results of the PARNASSOS viscous flow calculations it was possible to make decisions with regard to the horizontal angle and the inclination of the gondolas, and the slope of the buttocks in the area between the gondolas. Special attention has been paid to avoid flow separation around the aft body. The gondolas have been oriented in such a way that maximum efficiency is achieved. The performance of the resulting design has been verified by model tests in MARIN’s Deep Water Towing Tank. Given the very promising results of this new generation of LNG carriers, achieving besides the excellent propulsive properties also a higher payload target, the yard became more competitive and is expecting quite some orders for this particular ship type.

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Hydrodynamic Optimization of a Wedge Hull

10.5957/fast-2015-020 ◽

2015 ◽

Author(s):

Lijue Wang ◽

Fuxin Huang ◽

Chi Yang ◽

Raju Datla

Keyword(s):

Hydrodynamic Performance ◽

Surface Mesh ◽

Nurbs Surface ◽

Bottom Edge ◽

Hull Form ◽

Entrance Angle ◽

Total Drag ◽

Rounded Corner ◽

Bulbous Bow ◽

Hydrodynamic Optimization

A novel wedge-shaped hull form is optimized for reduced drag using a further developed practical hydrodynamic optimization tool. The hull features a sharp entrance angle, rectilinear sides, sharp bottom edges, a triangular waterplane and a linear aftward taper from a deep bow to a shallow transom. The optimization involves two modifications of the hull form, one is to smooth out the sharp bottom edge with a rounded corner and the other is to generate a bulbous bow. In order to perform the hydrodynamic optimization of the hull, a Non-Uniform Rational BSpline (NURBS)-based hull surface modification tool, a NURBS surface mesh generator, a surrogate model and an evolutionary optimization solver are developed and integrated into the practical hydrodynamic optimization tool. The hydrodynamic performances, i.e., the total drag and the flow field near the obtained hull bodies are assessed and compared with the original wedge hull using numerical simulations. Results showed that rounding the sharp edge of the wedge hull can reduce the total drag by alleviating the flow separations around the hull body. The wedge hull with rounded bottom edge and optimized bulbous bow can achieve larger drag reduction and the flow separations are almost eliminated. The total drag of the optimal hull is compared with an earlier-optimized wedge hull that has a different type of bulbous bow, whose hydrodynamic performance has been validated by model tests.

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Hull Form Optimization of a TriSWACH for Reduced Drag

10.5957/fast-2015-038 ◽

2015 ◽

Author(s):

Fuxin Huang ◽

Lijue Wang ◽

Chi Yang ◽

Richard A. Royce

Keyword(s):

Drag Reduction ◽

Surrogate Model ◽

Objective Functions ◽

Hull Form ◽

Multi Objective ◽

Speed Range ◽

Hydrodynamic Optimization

A new methodology for hydrodynamic optimization of a TriSWACH is developed, which considers the shape of the center hull only and its optimal results are not influenced by the position configuration of side hulls. In order to accelerate the process of the optimization, a practical multi-objective hydrodynamic tool has been further developed by integrating a surrogate model to approximate the objective functions and constraints. The proposed method and the further developed tool are applied to optimize the hull form of a TriSWACH with nine possible side hull position configurations for reduced drag. A considerable drag reduction is obtained by the optimal TriSWACH for various side hull configurations and speed range.

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Numerical and experimental study on hydrodynamic bulbous bow hull-form optimization for various service conditions due to slow steaming of container vessel

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1177/1475090218811782 ◽

2018 ◽

Vol 233 (4) ◽

pp. 1103-1122

Author(s):

Xun-bin Yin ◽

Yu Lu ◽

Jin Zou ◽

Lei Wan

Keyword(s):

Optimization Design ◽

Optimization Technique ◽

Experimental Studies ◽

Design Stage ◽

Probability Density Distribution ◽

Hull Form ◽

Slow Steaming ◽

Service Conditions ◽

Bulbous Bow ◽

Hydrodynamic Optimization

In this article, an innovative hydrodynamic optimization design of bulbous bow hull-form under various service conditions resulting from the slow steaming of container vessel is presented, improving the overall performances for the real multi-variant usage situations more practical than the single specification of design, which includes both numerical computation and experimental validation. Effects of slow steaming–based statistical analysis of the actual operative occurrence during the lifetime is conducted, obtaining a combined probability density distribution of speed and displacement ushering in the evaluation of objective function. Three main component elements of the hydrodynamic optimization procedure that comprises parametric design of bulbous bow hull-form variation part, hydrodynamic numerical solver part, and optimization technique part are established and integrated. The proposed optimization process is subsequently applied to find the optimal bulbous bow of a container carrier for the hipping demand of different speeds and displacement distributed utilization, reducing significantly total conditions resistance of the hull, on a higher level decreasing the operative cost as well as gas emissions of the ship. Finally, there is an experimental campaign carried out between the optimal and original models to validate the numerical optimization computations. The compared investigation has provided a good agreement from the perspective of both numerical and experimental studies, as a result confirming the success of the present optimization framework and the utility value of the proposed optimization consideration on various service conditions during ship design stage.

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Hull Form Optimization Based on an NM+CFD Integrated Method for KCS

International Journal of Computational Methods ◽

10.1142/s0219876220500085 ◽

2020 ◽

Vol 17 (10) ◽

pp. 2050008

Author(s):

Aiqin Miao ◽

Decheng Wan

Keyword(s):

Optimization Design ◽

Model Building ◽

Computational Cost ◽

Hull Form ◽

Integrated Method ◽

Computational Fluid Dynamics Cfd ◽

Hull Forms ◽

Main Components ◽

Hydrodynamic Optimization ◽

High Computational Cost

This paper concerns development and illustration of a hydrodynamic optimization tool, OPTShip-SJTU, which contains four main components, i.e., hull form modifier, performance evaluator, surrogate model building, and optimizer module. It has been further developed by integrating a new method into the performance evaluator module, which combines the Neumann–Michell (NM) theory with computational fluid dynamics (CFD) technology, in order to reduce the high computational cost. To illustrate the practicality of further extension, OPTShip-SJTU was applied to optimize the hull form of KCS by simultaneously reducing drags at two speeds. A drag reduction was obtained by the optimal KCS of different hull forms. It turns out the presented method for ship optimization design is effective and reliable.

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Multi-Objective Hydrodynamic Optimization of the DTMB 5415 for Resistance and Seakeeping

10.5957/fast-2015-034 ◽

2015 ◽

Author(s):

Matteo Diez ◽

Andrea Serani ◽

Emilio F. Campana ◽

Omer Goren ◽

Kadir Sarioz ◽

...

Keyword(s):

Computational Methods ◽

Task Group ◽

Test Case ◽

Multi Objective Optimization ◽

Hull Form ◽

Multi Objective ◽

Average Improvement ◽

Hull Forms ◽

Hydrodynamic Optimization

The paper presents recent research conducted within the NATO RTO Task Group AVT-204 “Assess the Ability to Optimize Hull Forms of Sea Vehicles for Best Performance in a Sea Environment.” The objective is the improvement of the hydrodynamic performances (resistance/powering requirements, seakeeping, etc.) of naval vessels, by integration of computational methods used to generate, evaluate, and optimize hull-form variants. Several optimization approaches are brought together and compared. A multi-objective optimization of the DTMB 5415 (specifically the MARIN variant 5415M) is used as a test case and results obtained so far using low-fidelity solvers show an average improvement for resistance and seakeeping performances of nearly 10 and 9%, respectively.

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