On the path toward fully autonomous sea vessels, forecasting a ship’s exact velocity and position during its route plays a crucial role in dynamic positioning, target tracking, and autopilot operations of the unmanned body navigating toward predetermined locations. This paper addresses the prediction of the operational performance of a free-running submarine advancing in a straight route (in surge motion). Along with the forward advancing vessel (straight-ahead motion) the study covers all possible scenarios of ship’s surge, including crash-ahead, crash-back, and astern motions. Conventional maneuvering models cannot handle motions other than forward advancement due to the absence of propeller data in all four quadrants of hydrodynamic performance map. This study proposes an approach for predicting submarine performance in all these surge conditions by utilizing four-quadrant propeller performance and resistance test data. We developed an in-house code, SMot4QP, to simulate ship speed and position in the time domain. We obtained satisfying results for the straight-ahead and crash-ahead motions, while the crash-back and astern maneuvers require further refinement due to propeller wake interaction with the hull. The proposed method is capable of predicting the motions of all types of vessels using the ship’s resistance and four-quadrant propeller test results. Thus, SMot4QP offers a fast and robust alternative to computationally expensive free-running self-propulsion simulations for operational performance prediction in broader naval applications.
{"title":"Four-quadrant propeller hydrodynamic performance mapping for improving ship motion predictions","authors":"Taner Cosgun, Mahmutcan Esenkalan, O. Kinaci","doi":"10.21278/brod75306","DOIUrl":"https://doi.org/10.21278/brod75306","url":null,"abstract":"On the path toward fully autonomous sea vessels, forecasting a ship’s exact velocity and position during its route plays a crucial role in dynamic positioning, target tracking, and autopilot operations of the unmanned body navigating toward predetermined locations. This paper addresses the prediction of the operational performance of a free-running submarine advancing in a straight route (in surge motion). Along with the forward advancing vessel (straight-ahead motion) the study covers all possible scenarios of ship’s surge, including crash-ahead, crash-back, and astern motions. Conventional maneuvering models cannot handle motions other than forward advancement due to the absence of propeller data in all four quadrants of hydrodynamic performance map. This study proposes an approach for predicting submarine performance in all these surge conditions by utilizing four-quadrant propeller performance and resistance test data. We developed an in-house code, SMot4QP, to simulate ship speed and position in the time domain. We obtained satisfying results for the straight-ahead and crash-ahead motions, while the crash-back and astern maneuvers require further refinement due to propeller wake interaction with the hull. The proposed method is capable of predicting the motions of all types of vessels using the ship’s resistance and four-quadrant propeller test results. Thus, SMot4QP offers a fast and robust alternative to computationally expensive free-running self-propulsion simulations for operational performance prediction in broader naval applications.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141690308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
He Yanru, Xingya Zhao, Huang Liwen, Luping Xu, Jinlai Liu
Due to natural and external influences in curved channels, ships frequently require adjustments in course and speed, posing challenges for existing control methods. Particularly lacking are speed control methods suitable for curved channel navigation. This study initially developed a three-degree-of-freedom MMG model incorporating external interference. It introduced an OP-PID heading controller merging optimal control strategies with traditional PID, adaptable to both external conditions and ship speed, validated through heading control simulations. The study analysed the ship's speed change process, deriving a mathematical expression for advance distance, and proposed a dichotomy-based speed control method to determine speed change points, addressing differential equations with unknown integrands. To mitigate uncertainty errors like parameter inaccuracies in ship maneuvering models and dynamic environmental disturbances, the study proposed a comprehensive control approach. This approach integrates model predictive control, feedback compensation, segment identification, and an enhanced line-of-sight (LOS) guidance method alongside the OP-PID course controller and dichotomy-based speed control. Simulation experiments in the Dongboliao Channel compared the proposed and existing methods. Results demonstrate the proposed method's capability to handle frequent course and speed adjustments effectively, even under model errors and external interference, showcasing superior track deviation and course control accuracy over existing methods.
{"title":"Control method for the ship track and speed in curved channels","authors":"He Yanru, Xingya Zhao, Huang Liwen, Luping Xu, Jinlai Liu","doi":"10.21278/brod75307","DOIUrl":"https://doi.org/10.21278/brod75307","url":null,"abstract":"Due to natural and external influences in curved channels, ships frequently require adjustments in course and speed, posing challenges for existing control methods. Particularly lacking are speed control methods suitable for curved channel navigation. This study initially developed a three-degree-of-freedom MMG model incorporating external interference. It introduced an OP-PID heading controller merging optimal control strategies with traditional PID, adaptable to both external conditions and ship speed, validated through heading control simulations. The study analysed the ship's speed change process, deriving a mathematical expression for advance distance, and proposed a dichotomy-based speed control method to determine speed change points, addressing differential equations with unknown integrands. To mitigate uncertainty errors like parameter inaccuracies in ship maneuvering models and dynamic environmental disturbances, the study proposed a comprehensive control approach. This approach integrates model predictive control, feedback compensation, segment identification, and an enhanced line-of-sight (LOS) guidance method alongside the OP-PID course controller and dichotomy-based speed control. Simulation experiments in the Dongboliao Channel compared the proposed and existing methods. Results demonstrate the proposed method's capability to handle frequent course and speed adjustments effectively, even under model errors and external interference, showcasing superior track deviation and course control accuracy over existing methods.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141706407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The prediction of manoeuvring performance for safe navigation and effective design of ships increasingly depends on artificial intelligence (AI), mainly digital twin technology. This technology requires a digital model of the physical ship. The hydrodynamic coefficients and parameters of these models are commonly obtained through two experimental methods: the planar motion mechanism (PMM) and the circular motion test (CMT). These methods are time-consuming and expensive, which may not be feasible during the early stages of the design process. This study investigates a cost-effective alternative approach to these methods by implementing a grey box method on ships. For the first of these implementations, a full-scale tanker ship was applied with artificial training data of zigzag manoeuvres. A validation study was carried out by comparing the simulation and free-running model test results of the tanker. For the second of these implementations, a scale model of a car carrier was selected, and several numerical search methods were combined to obtain a more accurate digital model. The 3-degree-of-freedom (DOF) Manoeuvring Modelling Group (MMG) models identified through this combination were validated with simulations and compared with the free-running model test results for various manoeuvres. The contribution of this study lies in the accurate capture of the manoeuvring characteristics of the physical model, which is achieved through the use of the adjustment interval and the combination of various numerical search method of the grey box method. Consequently, the developed model can be used in future studies as a faster decision-making tool for determining the straight-line stability or instability of a ship in the ship design and in predicting the manoeuvring performance of the ship.
{"title":"Application of an offline grey box method for predicting the manoeuvring performance","authors":"Elis Atasayan, Evgeni Milanov, Ahmet Dursun Alkan","doi":"10.21278/brod75304","DOIUrl":"https://doi.org/10.21278/brod75304","url":null,"abstract":"The prediction of manoeuvring performance for safe navigation and effective design of ships increasingly depends on artificial intelligence (AI), mainly digital twin technology. This technology requires a digital model of the physical ship. The hydrodynamic coefficients and parameters of these models are commonly obtained through two experimental methods: the planar motion mechanism (PMM) and the circular motion test (CMT). These methods are time-consuming and expensive, which may not be feasible during the early stages of the design process. This study investigates a cost-effective alternative approach to these methods by implementing a grey box method on ships. For the first of these implementations, a full-scale tanker ship was applied with artificial training data of zigzag manoeuvres. A validation study was carried out by comparing the simulation and free-running model test results of the tanker. For the second of these implementations, a scale model of a car carrier was selected, and several numerical search methods were combined to obtain a more accurate digital model. The 3-degree-of-freedom (DOF) Manoeuvring Modelling Group (MMG) models identified through this combination were validated with simulations and compared with the free-running model test results for various manoeuvres. The contribution of this study lies in the accurate capture of the manoeuvring characteristics of the physical model, which is achieved through the use of the adjustment interval and the combination of various numerical search method of the grey box method. Consequently, the developed model can be used in future studies as a faster decision-making tool for determining the straight-line stability or instability of a ship in the ship design and in predicting the manoeuvring performance of the ship.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141689794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liu Liang, Zhang Baoji, Zhang Hao, Gong Jiaye, Tian Zheng, Shuhui Guo, Yuanbiao Bao, Zheng Xu
To investigate the parametric rolling motion of container ships navigating in head seas, this study utilizes the unsteady RANS approach combined with dynamic overlapping grid technology to simulate parametric roll in a container ship under the coupled motions of roll, pitch, and heave. Initially, the model was validated against experimental results, demonstrating good agreement and thus confirming the reliability of the computational method. Furthermore, the paper investigates the impacts of the initial roll angle, encounter frequency, and the addition of bilge keels on parametric rolling. The research findings indicate that the initial angles of rolling impact the duration needed to attain a steady roll condition, yet they have minimal effect on the amplitude post-stabilization. The likelihood of parametric rolling arises when the frequency of encounters doubles that of the ship's inherent roll frequency. Furthermore, the likelihood of parametric rolling escalates when the wavelengths approach the length of the ship. Installing bilge keels markedly reduces the parametric rolling movement in vessels, and the occurrence of parametric rolling is also delayed.
{"title":"Study on numerical simulation and mitigation of parametric rolling in a container ship under head waves","authors":"Liu Liang, Zhang Baoji, Zhang Hao, Gong Jiaye, Tian Zheng, Shuhui Guo, Yuanbiao Bao, Zheng Xu","doi":"10.21278/brod75305","DOIUrl":"https://doi.org/10.21278/brod75305","url":null,"abstract":"To investigate the parametric rolling motion of container ships navigating in head seas, this study utilizes the unsteady RANS approach combined with dynamic overlapping grid technology to simulate parametric roll in a container ship under the coupled motions of roll, pitch, and heave. Initially, the model was validated against experimental results, demonstrating good agreement and thus confirming the reliability of the computational method. Furthermore, the paper investigates the impacts of the initial roll angle, encounter frequency, and the addition of bilge keels on parametric rolling. The research findings indicate that the initial angles of rolling impact the duration needed to attain a steady roll condition, yet they have minimal effect on the amplitude post-stabilization. The likelihood of parametric rolling arises when the frequency of encounters doubles that of the ship's inherent roll frequency. Furthermore, the likelihood of parametric rolling escalates when the wavelengths approach the length of the ship. Installing bilge keels markedly reduces the parametric rolling movement in vessels, and the occurrence of parametric rolling is also delayed.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141711848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to investigate the impact of marine propeller wake fields on sediment siltation in shallow water channels, this study employs the unsteady RANS approach and the Volume of Fluid model. A full-scale numerical self-propulsion test was conducted on a 50,000 DWT oil tanker under the influence of a free surface. The research includes forecasting the effect of propeller wakes on sediment redeposition following the dredging of the approach channel to Jiaxing Port in the China Sea. Initially, uncertainty research was carried out on the full-scale ship and propeller system, and the credibility of the computational results was quantified. The simulated results based on the sediment transport numerical model were then compared and validated against actual data from monitoring stations. The self-propulsion performance and the velocity distribution of the propeller wake were examined under three different propeller speeds. Scenarios simulated included no ship navigation, daily single-ship navigation, and daily two-ship navigation, evaluating the siltation distribution within the channel over one month. The results demonstrate that ship propeller wakes positively influence the reduction of channel sedimentation, with the maximum monthly siltation reduction reaching 0.108 m during single-ship tidal navigation and 0.11 m during two-ship tidal navigation.
{"title":"Study on the effect of marine propeller wake on sediment siltation in a shallow water channel","authors":"Liu Liang, Zhang Hao, Chaonan Zhang, Jinbiao Chen, Zhang Baoji, Xiangen Bai, Shengyao Song, Chen Qian, Weijia Zhang","doi":"10.21278/brod75308","DOIUrl":"https://doi.org/10.21278/brod75308","url":null,"abstract":"In order to investigate the impact of marine propeller wake fields on sediment siltation in shallow water channels, this study employs the unsteady RANS approach and the Volume of Fluid model. A full-scale numerical self-propulsion test was conducted on a 50,000 DWT oil tanker under the influence of a free surface. The research includes forecasting the effect of propeller wakes on sediment redeposition following the dredging of the approach channel to Jiaxing Port in the China Sea. Initially, uncertainty research was carried out on the full-scale ship and propeller system, and the credibility of the computational results was quantified. The simulated results based on the sediment transport numerical model were then compared and validated against actual data from monitoring stations. The self-propulsion performance and the velocity distribution of the propeller wake were examined under three different propeller speeds. Scenarios simulated included no ship navigation, daily single-ship navigation, and daily two-ship navigation, evaluating the siltation distribution within the channel over one month. The results demonstrate that ship propeller wakes positively influence the reduction of channel sedimentation, with the maximum monthly siltation reduction reaching 0.108 m during single-ship tidal navigation and 0.11 m during two-ship tidal navigation.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141844347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jinfeng Liu, Guoqing Feng, Jiaying Wang, Tianwei Wu, Chen Xu, Kai Yang
The liquefied natural gas (LNG) fuel tank in a large container ship is loaded with liquid LNG at an ultra-low temperature (-163°C), there is a significant temperature difference in the cargo hold area where the entire fuel tank is located, which will have an important impact on the steel grade design and structural safety of the cargo tank in container ship. This paper develops two heat transfer models using Computational Fluid Dynamics method (CFD method) and an analytical method to analyze the temperature distribution in a large container ship equipped with Type-B LNG fuel tank. These models incorporate the arrangement and heat transfer characteristics of LNG fuel tanks. The temperature field analysis is conducted under typical the environmental conditions specified in the Code for the Construction and Equipment of Ships Transporting Liquefied Gas in Bulk (IGC Code) and the United States Coast Guard Code (USCG Code), based on the CFD method and the analytical method, and the results of temperature field distribution are compared. Additionally, a parametric analysis of the hull temperature field is further carried out, the results show that the thermal conductivity of the insulation layer in LNG storage tanks and the types of the loaded liquid cargo have a limited impact on the final temperature field distribution in hull structure. However, the selection of steel grade in the local structure of the cargo hold, especially in the inner hull part, may lead to significant changes.
{"title":"Research on temperature distribution in container ship with Type-B LNG fuel tank based on CFD and analytical method","authors":"Jinfeng Liu, Guoqing Feng, Jiaying Wang, Tianwei Wu, Chen Xu, Kai Yang","doi":"10.21278/brod75302","DOIUrl":"https://doi.org/10.21278/brod75302","url":null,"abstract":"The liquefied natural gas (LNG) fuel tank in a large container ship is loaded with liquid LNG at an ultra-low temperature (-163°C), there is a significant temperature difference in the cargo hold area where the entire fuel tank is located, which will have an important impact on the steel grade design and structural safety of the cargo tank in container ship. This paper develops two heat transfer models using Computational Fluid Dynamics method (CFD method) and an analytical method to analyze the temperature distribution in a large container ship equipped with Type-B LNG fuel tank. These models incorporate the arrangement and heat transfer characteristics of LNG fuel tanks. The temperature field analysis is conducted under typical the environmental conditions specified in the Code for the Construction and Equipment of Ships Transporting Liquefied Gas in Bulk (IGC Code) and the United States Coast Guard Code (USCG Code), based on the CFD method and the analytical method, and the results of temperature field distribution are compared. Additionally, a parametric analysis of the hull temperature field is further carried out, the results show that the thermal conductivity of the insulation layer in LNG storage tanks and the types of the loaded liquid cargo have a limited impact on the final temperature field distribution in hull structure. However, the selection of steel grade in the local structure of the cargo hold, especially in the inner hull part, may lead to significant changes.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141709810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hong Shi, Rui Wang, Yi Xiao, Xiaojian Zhu, Rentong Zheng, Caiyue Song, Zhenrong Liu
To attain high-performance ejector configurations, an ejection characteristic testing system was established initially to validate the reliability of the Realizable k-ε turbulent model. Subsequently, optimization investigations were conducted on lobed nozzle ejectors with various structural parameters. The effects of four key structural parameters, including lobed nozzle expansion angle α, lobed nozzle width d, number of lobes in the nozzle n, and height of the square-to-circle section h, were systematically studied. Furthermore, the CRITIC method was employed for multi-objective evaluation to identify the optimal design configuration for the casing ejector. The research findings revealed that among the structural parameters, the lobed nozzle expansion angle α exerted the greatest influence on the ejection coefficient and pressure loss coefficient. The weights of the evaluation criteria were determined by the CRITIC method as follows: ejection coefficient (49.38%) < pressure loss coefficient (50.62%). The optimal design configuration determined by the CRITIC method included α = 45°, d = 150 mm, n = 14, and h = 600 mm. The resulting enclosure design ensures smooth airflow within the system, preventing the backflow of high-temperature mainstream fluid and heating the enclosure. It also maintains a temperature distribution in the typical cross-section that meets specified requirements. Additionally, it facilitates improved mixing of mainstream and secondary fluid and reduces exhaust gas temperature.
{"title":"Optimization of exhaust ejector with lobed nozzle for marine gas turbine","authors":"Hong Shi, Rui Wang, Yi Xiao, Xiaojian Zhu, Rentong Zheng, Caiyue Song, Zhenrong Liu","doi":"10.21278/brod75303","DOIUrl":"https://doi.org/10.21278/brod75303","url":null,"abstract":"To attain high-performance ejector configurations, an ejection characteristic testing system was established initially to validate the reliability of the Realizable k-ε turbulent model. Subsequently, optimization investigations were conducted on lobed nozzle ejectors with various structural parameters. The effects of four key structural parameters, including lobed nozzle expansion angle α, lobed nozzle width d, number of lobes in the nozzle n, and height of the square-to-circle section h, were systematically studied. Furthermore, the CRITIC method was employed for multi-objective evaluation to identify the optimal design configuration for the casing ejector. The research findings revealed that among the structural parameters, the lobed nozzle expansion angle α exerted the greatest influence on the ejection coefficient and pressure loss coefficient. The weights of the evaluation criteria were determined by the CRITIC method as follows: ejection coefficient (49.38%) < pressure loss coefficient (50.62%). The optimal design configuration determined by the CRITIC method included α = 45°, d = 150 mm, n = 14, and h = 600 mm. The resulting enclosure design ensures smooth airflow within the system, preventing the backflow of high-temperature mainstream fluid and heating the enclosure. It also maintains a temperature distribution in the typical cross-section that meets specified requirements. Additionally, it facilitates improved mixing of mainstream and secondary fluid and reduces exhaust gas temperature.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141697008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The maritime industry is a significant component of the transportation sector. Ships are the major element of the maritime industry, and propulsion power comes from fossil fuels, such as heavy fuel oil or marine diesel oil. These fossil fuels are used in conventional marine diesel engines and result in high levels of harmful emissions. These emissions contribute to the greenhouse effect and global warming, which is why efforts have been made to regulate and limit them within specific boundaries through various rules and regulations. However, with current technology, it is not possible to stay within these regulations. Therefore, the maritime sector has embarked on the quest for alternative power sources, and as a result, alternative fuels and fuel cells have gained importance. Hydrogen, one of these alternative fuels, is a promising solution with a carbon-free structure for the maritime industry to move toward sustainability. However, ships are considered high-risk areas, which is why specific standards need to be established for the use of hydrogen and fuel cell technology in ships. Hydrogen bunkering, onboard storage, and power system design, limits, and operational aspects must be properly elaborated. Although there are several substantial international standards and regulations for gas, liquid, and dangerous cargo, there is a lack of specific and detailed regulations for the use of fuel cells and hydrogen fuel onboard ships. This paper reviews the relevant regulations and standards while showing the regulatory gap concerning hydrogen and fuel cells by discussing the main barriers and highlights the current and future agenda of the industry toward decarbonization vision.
{"title":"Decarbonization of shipping: Hydrogen and fuel cells legislation in the maritime industry","authors":"Omer Berkehan Inal","doi":"10.21278/brod75205","DOIUrl":"https://doi.org/10.21278/brod75205","url":null,"abstract":"The maritime industry is a significant component of the transportation sector. Ships are the major element of the maritime industry, and propulsion power comes from fossil fuels, such as heavy fuel oil or marine diesel oil. These fossil fuels are used in conventional marine diesel engines and result in high levels of harmful emissions. These emissions contribute to the greenhouse effect and global warming, which is why efforts have been made to regulate and limit them within specific boundaries through various rules and regulations. However, with current technology, it is not possible to stay within these regulations. Therefore, the maritime sector has embarked on the quest for alternative power sources, and as a result, alternative fuels and fuel cells have gained importance. Hydrogen, one of these alternative fuels, is a promising solution with a carbon-free structure for the maritime industry to move toward sustainability. However, ships are considered high-risk areas, which is why specific standards need to be established for the use of hydrogen and fuel cell technology in ships. Hydrogen bunkering, onboard storage, and power system design, limits, and operational aspects must be properly elaborated. Although there are several substantial international standards and regulations for gas, liquid, and dangerous cargo, there is a lack of specific and detailed regulations for the use of fuel cells and hydrogen fuel onboard ships. This paper reviews the relevant regulations and standards while showing the regulatory gap concerning hydrogen and fuel cells by discussing the main barriers and highlights the current and future agenda of the industry toward decarbonization vision.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140356252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ming Wang, D. Qiao, Xiangbo Zhou, Guoqiang Tang, Lin Lu, Jinping Ou
Submerged floating tunnel (SFT) may be subjected to sudden impact loads such as submarine and shipwreck. Besides the local damage caused by impact, the overall transient dynamic response may also affect its driving safety. Based on the dynamic impact finite element software, the full-length model, and the locally truncated accurate model with solid element of the SFT are established respectively. By applying different spring stiffness constraints on the boundary of the truncated model, its first three modes are consistent with the full-length model, thus their dynamic characteristics are basically the same. The truncated model is further used to simulate the impact of a massive object on the SFT under different impact velocities, impact mass, impact angles and impact positions. The velocity and mass of the impact object have positive influences on the peak contact force, the displacement amplitude of the tube and the length of the damaged area. When the impact angle is perpendicular to the SFT tube, the contact force, displacement amplitude and the damaged area are the largest. The change of the impact position has little effect on the contact force and the damage area, but it will affect the distribution of displacement amplitude.
{"title":"Dynamic responses analysis of submerged floating tunnel under impact load","authors":"Ming Wang, D. Qiao, Xiangbo Zhou, Guoqiang Tang, Lin Lu, Jinping Ou","doi":"10.21278/brod75208","DOIUrl":"https://doi.org/10.21278/brod75208","url":null,"abstract":"Submerged floating tunnel (SFT) may be subjected to sudden impact loads such as submarine and shipwreck. Besides the local damage caused by impact, the overall transient dynamic response may also affect its driving safety. Based on the dynamic impact finite element software, the full-length model, and the locally truncated accurate model with solid element of the SFT are established respectively. By applying different spring stiffness constraints on the boundary of the truncated model, its first three modes are consistent with the full-length model, thus their dynamic characteristics are basically the same. The truncated model is further used to simulate the impact of a massive object on the SFT under different impact velocities, impact mass, impact angles and impact positions. The velocity and mass of the impact object have positive influences on the peak contact force, the displacement amplitude of the tube and the length of the damaged area. When the impact angle is perpendicular to the SFT tube, the contact force, displacement amplitude and the damaged area are the largest. The change of the impact position has little effect on the contact force and the damage area, but it will affect the distribution of displacement amplitude.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140353933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dejiang Li, Qiutong Tan, Jiwei Liu, Long Zheng, Chao Hu
Offshore assembly and disassembly operations represent a multi-billion-dollar market potential. Collaborative lifting by multiple vessels has emerged as a new operating paradigm for integrated offshore facilities assembly and disassembly. Hence, this paper investigates the hydro-dynamic interaction of dual lifting vessels in collaborative lifting operations. The coupled motions during multi-body operations are simulated using the commercial software SESAM. The feasibility of the numerical model for coupled motions in collaborative lifting is verified by comparing the numerical results of topside motions, vessel motions, and vertical lifting arm loads against experimental measurements. The effects of wave heading and period on the hydrodynamic responses of the topside module, dual lifting vessels, and lifting arms during collaborative operations are studied. Their influence patterns and mechanisms are analysed in detail. The results show that transverse waves and head wave induce significant heave and pitch motions of the topside module and vessels, but the maximum vertical loads on the lifting arms occur in oblique waves. The motion responses of the topside module and vessels increase with longer wave periods under the oblique sea condition, and roll motions are more sensitive to large periods compared to the gradual rise in heave and pitch.
{"title":"Coupled response analysis of dual lifting vessels during collaborative lifting topside module","authors":"Dejiang Li, Qiutong Tan, Jiwei Liu, Long Zheng, Chao Hu","doi":"10.21278/brod75206","DOIUrl":"https://doi.org/10.21278/brod75206","url":null,"abstract":"Offshore assembly and disassembly operations represent a multi-billion-dollar market potential. Collaborative lifting by multiple vessels has emerged as a new operating paradigm for integrated offshore facilities assembly and disassembly. Hence, this paper investigates the hydro-dynamic interaction of dual lifting vessels in collaborative lifting operations. The coupled motions during multi-body operations are simulated using the commercial software SESAM. The feasibility of the numerical model for coupled motions in collaborative lifting is verified by comparing the numerical results of topside motions, vessel motions, and vertical lifting arm loads against experimental measurements. The effects of wave heading and period on the hydrodynamic responses of the topside module, dual lifting vessels, and lifting arms during collaborative operations are studied. Their influence patterns and mechanisms are analysed in detail. The results show that transverse waves and head wave induce significant heave and pitch motions of the topside module and vessels, but the maximum vertical loads on the lifting arms occur in oblique waves. The motion responses of the topside module and vessels increase with longer wave periods under the oblique sea condition, and roll motions are more sensitive to large periods compared to the gradual rise in heave and pitch.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140355422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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