Journal of Marine Science and Engineering

Research

20 pages, 6792 KiB

Open AccessArticle

Ship Loading Influence on the Slamming Impact of Typical Sections of an S-175 Container Ship

by Guanghua He, Binyang Xie, Wei Wang, Shuang Liu and Penglin Jing

J. Mar. Sci. Eng. 2020, 8(3), 163; https://doi.org/10.3390/jmse8030163 - 3 Mar 2020

Cited by 7 | Viewed by 2620

This paper investigates the influence of ship-loading condition on slamming during water entry. Three typical sections of the S-175 container ship, namely the bow, parallel middle body and stern, under three different loading conditions are studied. Full-sized models are established and simulated by [...] Read more.

This paper investigates the influence of ship-loading condition on slamming during water entry. Three typical sections of the S-175 container ship, namely the bow, parallel middle body and stern, under three different loading conditions are studied. Full-sized models are established and simulated by commercial software LS-DYNA based on the explicit finite element method (FEM) using the arbitrary Lagrangian–Eulerian (ALE) algorithm. At first, validation is carried out by simulating the Wave Induced Loads on Ships Joint Industry Project II (WILS JIP-II) ship section entering the water and by verifying that the response is in good agreement with published experimental data. Then, nine different cases with three typical sections of the container ship and three different loadings, including the no-load (lightship weight), half-load and full-load weights of the ship, are investigated. Finally, the influence of the ship loading and sectional shape on the water impacts is analyzed and discussed. The present study is useful for the analysis of loading effects on ship slamming at the early stage of ship design. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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14 pages, 3200 KiB

Open AccessArticle

Control of Synthetic Hairpin Vortices in Laminar Boundary Layer for Skin-Friction Reduction

by Bonguk Koo and Yong-Duck Kang

J. Mar. Sci. Eng. 2020, 8(1), 45; https://doi.org/10.3390/jmse8010045 - 15 Jan 2020

Cited by 2 | Viewed by 2951

Abstract

The results of flow visualization and hot-film measurement in a water channel are presented in this paper, in which the effectiveness of controlling synthetic hairpin vortices in the laminar boundary layer is examined to reduce skin friction. In this study, hairpin vortices were [...] Read more.

The results of flow visualization and hot-film measurement in a water channel are presented in this paper, in which the effectiveness of controlling synthetic hairpin vortices in the laminar boundary layer is examined to reduce skin friction. In this study, hairpin vortices were generated by periodically injecting vortex rings into a cross flow through a hole on a flat plate. To control the hairpin vortices, jets were issued from a nozzle directly onto the head of the hairpins. The results of the flow visualization demonstrated that the jets destroyed the hairpins by disconnecting the heads from their legs, after which the weakened hairpin vortices could not develop. Therefore, the circulation around the legs was reduced, which suggests that the direct intervention on the hairpin heads resulted in the reduction of streamwise stretching. Data obtained by a hot-film sensor showed that the high-speed regions outside the hairpin legs were reduced in speed by this control technique, leading to a decrease in the associated local skin friction. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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15 pages, 4384 KiB

Open AccessArticle

A Study on the Air Cavity under a Stepped Planing Hull

by Dongmei Yang, Zhiyuan Sun, Yi Jiang and Zeyang Gao

J. Mar. Sci. Eng. 2019, 7(12), 468; https://doi.org/10.3390/jmse7120468 - 17 Dec 2019

Cited by 17 | Viewed by 4834

Abstract

Based on the FVM (finite volume method) numerical method, the flow field around the stepped planing hull in Taunton series was simulated. According to the general procedure of numerical uncertainty analysis, the numerical uncertainty in the high-speed flow field simulation of the stepped [...] Read more.

Based on the FVM (finite volume method) numerical method, the flow field around the stepped planing hull in Taunton series was simulated. According to the general procedure of numerical uncertainty analysis, the numerical uncertainty in the high-speed flow field simulation of the stepped planing hull was discussed. Combined with the wave-making characteristics of the hull, the generation mechanism, shape evolution of air cavity, and the pressure distribution characteristics under the influence of the cavity, focuses on the variation of the flow around the stepped planing when the hull is in the triangle planing stage. Numerical results suggest that, as the air cavity enlarges, the cover rate of the air cavity can rise up to 77.8% of the whole wetted surface of the planing hull bottom. While, in the triangle planing stage, there is additional wetting at the aft bilge, which leads to the decrease of the air cavity rate and the increase of the wetted area. At the same time, the pressure distribution concentrates to the center of gravity. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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20 pages, 8343 KiB

Open AccessArticle

Numerical Investigation on the Scale Effect of a Stepped Planing Hull

by Lei Du, Zhuang Lin, Yi Jiang, Ping Li and Yue Dong

J. Mar. Sci. Eng. 2019, 7(11), 392; https://doi.org/10.3390/jmse7110392 - 5 Nov 2019

Cited by 5 | Viewed by 4102

Abstract

This article discusses the scale effects on a planing boat, utilizing the computational fluid dynamics method. The simulation is compared with a tank test for verification and validation. The planing boat sails use both aerodynamics and hydrodynamics. Studying the performances and wave patterns [...] Read more.

This article discusses the scale effects on a planing boat, utilizing the computational fluid dynamics method. The simulation is compared with a tank test for verification and validation. The planing boat sails use both aerodynamics and hydrodynamics. Studying the performances and wave patterns of different dimensions of the models is the best way to investigate the scale effect without using experimental data. The resistance is discussed in two parts, namely residuary resistance and friction resistance, and is compared to the calculated data using the international towing tank conference (ITTC) formula. The computational fluid dynamics (CFD) calculations of the model are increased by 4.77% on average, and the boat computations are also increased by 3.57%. The computation shows the scale effect in detail. The residuary resistance coefficients at different scales are approximately equal, and the friction resistance coefficients show the scale effect. The scale effect for longitudinal steadiness is also captured for the period of the porpoising behavior. The rational for the full-scaled boat oscillation period and the model is the root of the scales. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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25 pages, 10427 KiB

Open AccessArticle

Experimental and Numerical Research on the Influence of Stern Flap Mounting Angle on Double-Stepped Planing Hull Hydrodynamic Performance

by Jin Zou, Shijie Lu, Yi Jiang, Hanbing Sun and Zhuangzhuang Li

J. Mar. Sci. Eng. 2019, 7(10), 346; https://doi.org/10.3390/jmse7100346 - 1 Oct 2019

Cited by 33 | Viewed by 6423

Abstract

In the current hydrodynamic research relating to planing hulls, the stern flap and steps are generally considered to be two independent resistance reduction measures. Limited research has focused on the coupled effects of flaps and steps. Therefore, experimental and numerical simulation methods are [...] Read more.

In the current hydrodynamic research relating to planing hulls, the stern flap and steps are generally considered to be two independent resistance reduction measures. Limited research has focused on the coupled effects of flaps and steps. Therefore, experimental and numerical simulation methods are carried out in this paper to explore the influence of the flap mounting angle coupled with the steps. A series of model towing tests were implemented for a double-stepped planing hull with 2°, 3° and 4.5° flap angles. The test results show that, as the mounting angle increased, the low speed resistance performance was improved and the porpoising critical speed was delayed, with a slight resistance cost. Based on the tests, a numerical simulation method was established with volume Froude numbers ranging from 0.88 to 5.20. The simulated hull flow field showed good agreement with the testing data. The simulation results suggest a cavity induces the negative pressure after the steps; the cavity core region is the air phase, and this expands with the air–water mixture flow. The cavity also causes wetted surface reduction and pressure distribution changes. Finally, comparisons of cavities after-steps and load coefficients of different planing surfaces among models were considered. Numerical results analysis gave distinct interpretations for the experimental phenomenon of porpoising critical speed increasing with a slight resistance increment. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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16 pages, 5484 KiB

Open AccessArticle

Temporal Model for Ship Twin-Propeller Jet Induced Sandbed Scour

by Yonggang Cui, Wei Haur Lam, Tianming Zhang, Chong Sun, Desmond Robinson and Gerard Hamill

J. Mar. Sci. Eng. 2019, 7(10), 339; https://doi.org/10.3390/jmse7100339 - 27 Sep 2019

Cited by 10 | Viewed by 2377

Abstract

This research paper proposes the use of empirical equations to estimate the temporal maximum scour that is induced by twin-propeller (

ε_{t w i n} = Ω_{t} {[l n (t)]}^{Γ_{t}}

) when acting over non-cohesive [...] Read more.

This research paper proposes the use of empirical equations to estimate the temporal maximum scour that is induced by twin-propeller (

ε_{t w i n} = Ω_{t} {[l n (t)]}^{Γ_{t}}

) when acting over non-cohesive bed materials. A purpose built experimental apparatus is used to obtain the measurement data required for the calculation of the empirical constants. The output from rigorous experimental investigations demonstrates that the maximum scour depth produced from the operation of twin-propeller (

ε_{t w i n}

), within the confines of a harbour basin, varies as a logarithmic function of time. A dimensional analysis of the standard single propeller configuration is used as the foundation upon which the scour equation is postulated. This is extended to include the influence of the operating distance between the twin-propeller configurations for the first time. The division of scours by twin-propeller and single-propeller (

ε_{twin} / ε_{m}

) enables the establishment of mathematical relation to calculate C₁, C₂, A, and B. The constants are

C_{1}

= 366.11,

C_{2}

= 0.3376, A = 0.859, and B = 0.1571. The proposed scour equation is more reliable within the time zone up to two hours based on the experimental data. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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18 pages, 4930 KiB

Open AccessArticle

Numerical Analysis on the Effect of Artificial Ventilated Pipe Diameter on Hydrodynamic Performance of a Surface-Piercing Propeller

by Zeyang Gao, Dongmei Yang, Ping Li and Yue Dong

J. Mar. Sci. Eng. 2019, 7(8), 240; https://doi.org/10.3390/jmse7080240 - 24 Jul 2019

Cited by 4 | Viewed by 2949

Abstract

Under the condition of large water immersion, surface-piercing propellers are inclined to be heavy loaded. In order to improve the hydrodynamic performance of the surface-piercing propeller, the installation of a vent pipe in front of a propeller disc is more widely used in [...] Read more.

Under the condition of large water immersion, surface-piercing propellers are inclined to be heavy loaded. In order to improve the hydrodynamic performance of the surface-piercing propeller, the installation of a vent pipe in front of a propeller disc is more widely used in the propulsion device of high speed planning crafts. Based on computational fluid dynamics (CFD) method, this paper studied the influence of diverse vent pipe diameters on hydrodynamic performance of the surface-piercing propeller under full water immersion conditions. The numerical results show that, with the increase of vent pipe diameters, the thrust and torque of the surface-piercing propeller decrease after ventilation, and the efficiency of the propeller increases rapidly; the low pressure area near the back root of the blade becomes smaller and smaller gradually; and the peak of periodic vibration of thrust and torque can be effectively reduced. The numerical results demonstrate that the installation of artificial vent pipe effectively improves the hydrodynamic performance of surface piercing propeller in the field of high speed crafts, and the increase of artificial vent pipe diameter plays an active role in the propulsion efficiency of the surface-piercing propeller. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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24 pages, 8893 KiB

Open AccessArticle

Numerical Simulation of Seakeeping Performance on the Preliminary Design of a Semi-Planing Craft

by Yu-Hsien Lin and Chia-Wei Lin

J. Mar. Sci. Eng. 2019, 7(7), 199; https://doi.org/10.3390/jmse7070199 - 27 Jun 2019

Cited by 11 | Viewed by 4507

Abstract

This study established a seakeeping program to evaluate the motion responses of a high speed semi-planing craft and to develop a database for future route planning. A series 62 mono-hull was chosen for the test cases, comparing seakeeping performances with full-scale on-board measurements. [...] Read more.

This study established a seakeeping program to evaluate the motion responses of a high speed semi-planing craft and to develop a database for future route planning. A series 62 mono-hull was chosen for the test cases, comparing seakeeping performances with full-scale on-board measurements. The statistical results were obtained using spectral analysis, which combines the International Towing Tank Conference (ITTC) spectrum with the response amplitude operator (RAO) responses of each wave heading for a given sailing speed. The speed polar diagram was made to illustrate five degree-of-freedom (DOF) motion responses between sailing speeds and wave heading angles in a particular sea state. Although the craft has different trim angles at high speeds (because of dynamic lift) under various loading and draft conditions, this study only investigated the trim angles of 0° (even keel), 1° by the stern, and 2° by the stern, to understand the difference between their seakeeping performances. The results in this study provide a useful guideline for evaluating operational regulations and safety for high speed semi-planing crafts in the future. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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21 pages, 2684 KiB

Open AccessArticle

Investigation on a Novel Support System for Automatic Ship Berthing in Marine Practice

by Van Suong Nguyen

J. Mar. Sci. Eng. 2019, 7(4), 114; https://doi.org/10.3390/jmse7040114 - 22 Apr 2019

Cited by 14 | Viewed by 4013

Abstract

For safe ship berthing, all steps involved, from bringing the ship to the fairway area to directing it to the final wharf position at a desirable speed, need to be performed properly. In this article, a support system is proposed to automatically bring [...] Read more.

For safe ship berthing, all steps involved, from bringing the ship to the fairway area to directing it to the final wharf position at a desirable speed, need to be performed properly. In this article, a support system is proposed to automatically bring the ship into the berth after completing the maneuvering process. This proposed system requires no involvement of a shipmaster, enabling automatic ship berthing in marine practice. Three fuzzy controllers are proposed to conduct different tasks of berthing. The first controller is designed to control the movement of the ship in a longitudinal direction towards the wharf while the second controller stabilizes the relative bearing error with respect to the tugboat. The final controller is responsible for bringing the ship into a wharf according to crabbing motion with bow thruster and tugboat simultaneously. Compared to other approaches, ours has a wider range of adoption, better generalization capability, and is more suitable for marine practice. Comprehensive experiments in numerical simulations are carried out, showing the superior performance of the proposed support system for automatic ship berthing. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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20 pages, 5890 KiB

Open AccessArticle

A Potential Flow Theory and Boundary Layer Theory Based Hybrid Method for Waterjet Propulsion

by Lei Zhang, Jia-Ning Zhang and Yu-Chen Shang

J. Mar. Sci. Eng. 2019, 7(4), 113; https://doi.org/10.3390/jmse7040113 - 21 Apr 2019

Cited by 6 | Viewed by 3962

Abstract

A hybrid method—coupled with the boundary element method (BEM) for wave-making resistance, the empirical method (EM) for viscous resistance, and the boundary layer theory (BLT) for capture of an area’s physical parameters—was proposed to predict waterjet propulsion performance. The waterjet propulsion iteration process [...] Read more.

A hybrid method—coupled with the boundary element method (BEM) for wave-making resistance, the empirical method (EM) for viscous resistance, and the boundary layer theory (BLT) for capture of an area’s physical parameters—was proposed to predict waterjet propulsion performance. The waterjet propulsion iteration process was established from the force-balanced waterjet–hull system by applying the hybrid approach. Numerical validation of the present method was carried out using the 1/8.556 scale waterjet-propelled ITTC (International Towing Tank Conference) Athena ship model. Resistance, attitudes, wave cut profiles, waterjet thrust, and thrust deduction showed similar tendencies to the experimental curves and were in good agreement with the data. The application of the present hybrid method to the side-hull configuration research of a trimaran indicates that the side-hull arranged at the rear of the main hull contributed to energy-saving and high-efficiency propulsion. In addition, at high Froude numbers, the “fore-body trimaran” showed a local advantage in resistance and thrust deduction. Full article

(This article belongs to the Special Issue Ship Hydrodynamics)

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