Journal of Marine Science and Engineering

Research

14 pages, 2051 KiB

Open AccessArticle

Simulation Techniques for Design and Control of a Waste Heat Recovery System in Marine Natural Gas Propulsion Applications

by Marco Altosole, Ugo Campora, Silvia Donnarumma and Raphael Zaccone

J. Mar. Sci. Eng. 2019, 7(11), 397; https://doi.org/10.3390/jmse7110397 - 6 Nov 2019

Cited by 21 | Viewed by 3281

Abstract

Waste Heat Recovery (WHR) marine systems represent a valid solution for the ship energy efficiency improvement, especially in Liquefied Natural Gas (LNG) propulsion applications. Compared to traditional diesel fuel oil, a better thermal power can be recovered from the exhaust gas produced by [...] Read more.

Waste Heat Recovery (WHR) marine systems represent a valid solution for the ship energy efficiency improvement, especially in Liquefied Natural Gas (LNG) propulsion applications. Compared to traditional diesel fuel oil, a better thermal power can be recovered from the exhaust gas produced by a LNG-fueled engine. Therefore, steam surplus production may be used to feed a turbogenerator in order to increase the ship electric energy availability without additional fuel consumption. However, a correct design procedure of the WHR steam plant is fundamental for proper feasibility analysis, and from this point of view, numerical simulation techniques can be a very powerful tool. In this work, the WHR steam plant modeling is presented paying attention to the simulation approach developed for the steam turbine and its governor dynamics. Starting from a nonlinear system representing the whole dynamic behavior, the turbogenerator model is linearized to carry out a proper synthesis analysis of the controller, in order to comply with specific performance requirements of the power grid. For the considered case study, simulation results confirm the validity of the developed approach, aimed to test the correct design of the whole system in proper working dynamic conditions. Full article

(This article belongs to the Special Issue Advances in Marine Dynamic Simulation)

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25 pages, 24762 KiB

Open AccessArticle

Large Eddy Simulation of Flow over Wavy Cylinders with Different Twisted Angles at a Subcritical Reynolds Number

by Chunyu Guo, Hang Guo, Jian Hu, Kewei Song, Weipeng Zhang and Wei Wang

J. Mar. Sci. Eng. 2019, 7(7), 227; https://doi.org/10.3390/jmse7070227 - 18 Jul 2019

Cited by 11 | Viewed by 4536

Abstract

The deformation of the cylinder has been proved to greatly reduce the fluctuation of lift and the vortex-induced vibration. In this article, a new form of deformation mode for the smooth cylinder is proposed in order to reduce the vortex-induced vibrations, which can [...] Read more.

The deformation of the cylinder has been proved to greatly reduce the fluctuation of lift and the vortex-induced vibration. In this article, a new form of deformation mode for the smooth cylinder is proposed in order to reduce the vortex-induced vibrations, which can be applied to marine risers and submarine pipelines to ensure the working performance and safety of offshore platforms. Large eddy simulation (LES) is adopted to simulate the turbulent flow over wavy cylinders with three different twisted angles at a subcritical Reynolds number Re = 28,712. Comparing with the results of smooth cylinder, the maximum drag and lift reduction of wavy cylinder A3 with α = 40° can reach 17% and 84%, respectively, and the corresponding vortex formation length increases significantly, while the turbulence intensity decreases relatively. Meanwhile, the circumferential minimum pressure coefficient is greater than that of the smooth cylinder, which also provides a greater drag reduction for the cylinder. The surface separation line, turbulent kinetic energy distribution, and wake vortex structure indicate that the elongation of separated shear layer and wake shedding position is larger than that of the smooth cylinder, and the vorticity value in the near wake region decreases. A periodic vortex structure is generated along the spanwise direction, and a weaker and more stable Karman vortex street is reformed at a further downstream position, which ultimately leads to the reduction of drag and fluctuating lift of the wavy cylinder. Full article

(This article belongs to the Special Issue Advances in Marine Dynamic Simulation)

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15 pages, 2266 KiB

Open AccessFeature PaperArticle

Motion Control for Autonomous Navigation in Blue and Narrow Waters Using Switched Controllers

by Angelo Alessandri, Silvia Donnarumma, Michele Martelli and Stefano Vignolo

J. Mar. Sci. Eng. 2019, 7(6), 196; https://doi.org/10.3390/jmse7060196 - 25 Jun 2019

Cited by 26 | Viewed by 4401

Abstract

Autonomous ships represent one of the new frontiers of technological innovation in marine engineering, which demand the development of innovative control systems to guarantee efficient and safe navigation of vessels. A convenient control system should be able to command the several actuators installed [...] Read more.

Autonomous ships represent one of the new frontiers of technological innovation in marine engineering, which demand the development of innovative control systems to guarantee efficient and safe navigation of vessels. A convenient control system should be able to command the several actuators installed on board in different conditions—for instance, during oceanic navigation, harbor approach, narrow channels, and crowed areas. Such tasks are accomplished by different switching controllers for high and low speed motion, which have to be orchestrated to ensure an effective maneuvering. An approach to the design of hierarchies of controllers for maneuvering and navigation of ships equipped with a standard propulsion configuration in both blue and narrow water is proposed. Different levels of control, from global to local, are defined and integrated to steer the vessel in such a way to increase the maneuvering capability in various scenarios. Full article

(This article belongs to the Special Issue Advances in Marine Dynamic Simulation)

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19 pages, 11792 KiB

Open AccessFeature PaperArticle

A Diesel Engine Modelling Approach for Ship Propulsion Real-Time Simulators

by Marco Altosole, Ugo Campora, Massimo Figari, Michele Laviola and Michele Martelli

J. Mar. Sci. Eng. 2019, 7(5), 138; https://doi.org/10.3390/jmse7050138 - 11 May 2019

Cited by 35 | Viewed by 6249

Abstract

A turbocharged diesel engine numerical model, suitable for real-time ship manoeuvre simulation, is presented in this paper. While some engine components (mainly the turbocharger, intercooler and manifolds) are modelled by a filling and emptying approach, the cylinder simulation is based on a set [...] Read more.

A turbocharged diesel engine numerical model, suitable for real-time ship manoeuvre simulation, is presented in this paper. While some engine components (mainly the turbocharger, intercooler and manifolds) are modelled by a filling and emptying approach, the cylinder simulation is based on a set of five-dimensional numerical matrices (each matrix is generated by means of a more traditional thermodynamic model based on in-cylinder actual cycle). The new cylinder calculation approach strongly reduces the engine transient computation time, making it possible to transform the simulation model into a real-time executable application. As a case study, the simulation methodology is applied to a high speed four stroke turbocharged marine diesel engine, whose design and off design running data are available from the technical sheet. In order to verify the suitability of the proposed model in real-time simulation applications, a yacht propulsion plant simulator is developed. Numerical results in ship acceleration and deceleration manoeuvres are shown, reducing the simulation running time of 99% in comparison with the corresponding in-cylinder actual cycle engine model. Full article

(This article belongs to the Special Issue Advances in Marine Dynamic Simulation)

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14 pages, 5202 KiB

Open AccessFeature PaperArticle

A Fast Simulation Method for Damaged Ship Dynamics

by Maria Acanfora, Ermina Begovic and Fabio De Luca

J. Mar. Sci. Eng. 2019, 7(4), 111; https://doi.org/10.3390/jmse7040111 - 19 Apr 2019

Cited by 30 | Viewed by 4371

Abstract

Ship accidents that entail flooding may lead to disastrous consequences which could be avoided or mitigated based on the knowledge of damaged ship dynamics. The dynamic behaviour of a damaged hull is a complex phenomenon involving the interaction of the flooded water and [...] Read more.

Ship accidents that entail flooding may lead to disastrous consequences which could be avoided or mitigated based on the knowledge of damaged ship dynamics. The dynamic behaviour of a damaged hull is a complex phenomenon involving the interaction of the flooded water and the ship motions. The presence of a damage opening allows water flow into and out from the compartment, which further complicates the mathematical description of the problem. A fast simulation method, based on the lumped mass approach, is developed and presented. The lumped mass path in space depends on free-surface inclinations that differ from the ship angles of the roll and pitch. The viscous effects in the floodwater dynamics are implemented based on the model for the dissipation of the energy of standing waves in rectangular rooms. The method applies to both the transient stage of flooding and to the dynamic behaviour of a flooded ship in regular waves. In the first case, viscous effects are implemented considering the water in the compartment variable with time. Several case studies are carried out on three different hull models: Transient stage of flooding, roll decay of the damaged hull, and steady state responses in waves are simulated and compared with available experimental data. Full article

(This article belongs to the Special Issue Advances in Marine Dynamic Simulation)

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16 pages, 1901 KiB

Open AccessArticle

Performance Simulation of the Transportation Process Risk of Bauxite Carriers Based on the Markov Chain and Cloud Model

by Jianjun Wu, Shenping Hu, Yongxing Jin, Jiangang Fei and Shanshan Fu

J. Mar. Sci. Eng. 2019, 7(4), 108; https://doi.org/10.3390/jmse7040108 - 18 Apr 2019

Cited by 13 | Viewed by 4241

Abstract

China imports a large quantity of bauxite each year. Bauxite in fine particles with high moisture has a high risk of liquefaction during the maritime transportation process, which is harmful to the stability and safety of the carrier. To ensure safe shipping, it [...] Read more.

China imports a large quantity of bauxite each year. Bauxite in fine particles with high moisture has a high risk of liquefaction during the maritime transportation process, which is harmful to the stability and safety of the carrier. To ensure safe shipping, it is necessary to pay attention to the effects of the operation of cargo, the ship’s maneuvering and the ocean environment during the whole transportation process. The simulation of the process risk helps to develop measures to intervene with the cargo behavior to keep the risk to an acceptable level. This study examined the transportation process of a bauxite carrier using the Markov Chain method at different stages of loading, unberthing, departure and sea navigation. Based on the risk transfer matrix of the operational status at different stages of transportation, a cloud simulation model was developed to analyze the transportation process risk of a ship carrying bulk bauxite. Results: the research revealed that the risk evolution rule of the solid bulk cargoes with potential liquefaction during the transportation process, especially bauxite. The risk alteration during the prophase of the transportation process conforms to the rule of the “spoon curve”. Conclusions: a simulation model of the process risk based on the Markov Chain Cloud is suitable for the simulation analysis of the transportation risk of the bulk bauxite carrier. The outcomes of this study may contribute to better safety management to prevent the occurrence of ship capsizing. Full article

(This article belongs to the Special Issue Advances in Marine Dynamic Simulation)

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20 pages, 1708 KiB

Open AccessArticle

Path Analysis of Causal Factors Influencing Marine Traffic Accident via Structural Equation Numerical Modeling

by Shenping Hu, Zhuang Li, Yongtao Xi, Xunyu Gu and Xinxin Zhang

J. Mar. Sci. Eng. 2019, 7(4), 96; https://doi.org/10.3390/jmse7040096 - 4 Apr 2019

Cited by 38 | Viewed by 5909

Abstract

Many causal factors to marine traffic accidents (MTAs) influence each other and have associated effects. It is necessary to quantify the correlation path mode of these factors to improve accident prevention measures and their effects. In the application of human factors to accident [...] Read more.

Many causal factors to marine traffic accidents (MTAs) influence each other and have associated effects. It is necessary to quantify the correlation path mode of these factors to improve accident prevention measures and their effects. In the application of human factors to accident mechanisms, the complex structural chains on causes to MTA systems were analyzed by combining the human failure analysis and classification system (HFACS) with theoretical structural equation modeling (SEM). First, the accident causation model was established as a human error analysis classification in sight of a MTA, and the constituent elements of the causes of the accident were conducted. Second, a hypothetical model of human factors classification was proposed by applying the practice of the structural model. Third, with the data resources from ship accident cases, this hypothetical model was discussed and simulated, and as a result, the relationship path dependency mode between the latent independent variable of the accident was quantitatively analyzed based on the observed dependent variable of human behavior. Application examples show that relationships in the HFACS are verified and in line with the path developing mode, and resource management factors have a pronounced influence and a strong relevance to the causal chain of the accidents. Appropriate algorithms for the theoretical model can be used to numerically understand the safety performance of marine traffic systems under different parameters through mathematical analysis. Hierarchical assumptions in the HFACS model are quantitatively verified. Full article

(This article belongs to the Special Issue Advances in Marine Dynamic Simulation)

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19 pages, 986 KiB

Open AccessArticle

The Efficient Application of an Impulse Source Wavemaker to CFD Simulations

by Pál Schmitt, Christian Windt, Josh Davidson, John V. Ringwood and Trevor Whittaker

J. Mar. Sci. Eng. 2019, 7(3), 71; https://doi.org/10.3390/jmse7030071 - 19 Mar 2019

Cited by 14 | Viewed by 4310

Abstract

Computational Fluid Dynamics (CFD) simulations, based on Reynolds-Averaged Navier–Stokes (RANS) models, are a useful tool for a wide range of coastal and offshore applications, providing a high fidelity representation of the underlying hydrodynamic processes. Generating input waves in the CFD simulation is performed [...] Read more.

Computational Fluid Dynamics (CFD) simulations, based on Reynolds-Averaged Navier–Stokes (RANS) models, are a useful tool for a wide range of coastal and offshore applications, providing a high fidelity representation of the underlying hydrodynamic processes. Generating input waves in the CFD simulation is performed by a Numerical Wavemaker (NWM), with a variety of different NWM methods existing for this task. While NWMs, based on impulse source methods, have been widely applied for wave generation in depth averaged, shallow water models, they have not seen the same level of adoption in the more general RANS-based CFD simulations, due to difficulties in relating the required impulse source function to the resulting free surface elevation for non-shallow water cases. This paper presents an implementation of an impulse source wavemaker, which is able to self-calibrate the impulse source function to produce a desired wave series in deep or shallow water at a specific point in time and space. Example applications are presented, for a Numerical Wave Tank (NWT), based on the open-source CFD software OpenFOAM, for wave packets in deep and shallow water, highlighting the correct calibration of phase and amplitude. Furthermore, the suitability for cases requiring very low reflection from NWT boundaries is demonstrated. Possible issues in the use of the method are discussed, and guidance for accurate application is given. Full article

(This article belongs to the Special Issue Advances in Marine Dynamic Simulation)

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