Pub Date : 2023-11-22DOI: 10.1177/14750902231210047
Huirong Yang, Zhuo Sun, Peixiu Han, Mengjie Ma
To improve the energy efficiency of ships and reduce greenhouse gas (GHG) emissions, the implementation of energy-efficient operation measures is particularly important. Driven by this, this study was dedicated to improving the accuracy of ship fuel oil consumption (FOC) prediction and laying the foundation for optimizing energy-efficient operations. Firstly, we combined voyage reports and meteorological data and constructed six datasets containing different features. These features comprise navigation-related features encompassing sailing speed, displacement and trim, as well as meteorological features encompassing wind, wave, sea current, sea water salinity and sea water temperature. Secondly, we conducted experiments with 14 popular ML models on the datasets and compared the prediction performance of different models by a new scoring system. Finally, we explored the advantages and disadvantages of each dataset based on the model performance scoring results and analyzed the effects of related meteorological factors on FOC during navigation. The key findings of the proposed work were that extra trees (ET), random forest (RF), XGBoost, and LightGBM had good fitting and generalization performance. Set5, the dataset containing the most complete meteorological data, achieved the best prediction results. In particular, it had an R2 (test) of 0.9317 on the ET model, which was 1.97% higher than the R2 (test) of the dataset using only voyage reports. The conclusions can assist shipping companies in constructing a ship FOC prediction framework and developing ship fuel-saving strategies.
{"title":"Data-driven prediction of ship fuel oil consumption based on machine learning models considering meteorological factors","authors":"Huirong Yang, Zhuo Sun, Peixiu Han, Mengjie Ma","doi":"10.1177/14750902231210047","DOIUrl":"https://doi.org/10.1177/14750902231210047","url":null,"abstract":"To improve the energy efficiency of ships and reduce greenhouse gas (GHG) emissions, the implementation of energy-efficient operation measures is particularly important. Driven by this, this study was dedicated to improving the accuracy of ship fuel oil consumption (FOC) prediction and laying the foundation for optimizing energy-efficient operations. Firstly, we combined voyage reports and meteorological data and constructed six datasets containing different features. These features comprise navigation-related features encompassing sailing speed, displacement and trim, as well as meteorological features encompassing wind, wave, sea current, sea water salinity and sea water temperature. Secondly, we conducted experiments with 14 popular ML models on the datasets and compared the prediction performance of different models by a new scoring system. Finally, we explored the advantages and disadvantages of each dataset based on the model performance scoring results and analyzed the effects of related meteorological factors on FOC during navigation. The key findings of the proposed work were that extra trees (ET), random forest (RF), XGBoost, and LightGBM had good fitting and generalization performance. Set5, the dataset containing the most complete meteorological data, achieved the best prediction results. In particular, it had an R2 (test) of 0.9317 on the ET model, which was 1.97% higher than the R2 (test) of the dataset using only voyage reports. The conclusions can assist shipping companies in constructing a ship FOC prediction framework and developing ship fuel-saving strategies.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"15 ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139249322","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}
Pub Date : 2023-11-20DOI: 10.1177/14750902231210564
S. Ergin, L. Mocerino, Franco Quaranta
The emissions from ships are the key factor influencing the air quality near large ports. Although ship emissions are difficult to quantify, doing so can help port management find logistical solutions that can reduce the impact of having a large number of giant ships in a limited space. The joint study between the University of Naples and Istanbul Technical University, which focuses on the investigation of ship emissions in ports, is presented in this paper. It is expected that this study will lead to create new techniques for calculating, measuring, and validating emissions from ships at ports.
{"title":"Possible approaches to the study of emissions from ships during their operations in ports","authors":"S. Ergin, L. Mocerino, Franco Quaranta","doi":"10.1177/14750902231210564","DOIUrl":"https://doi.org/10.1177/14750902231210564","url":null,"abstract":"The emissions from ships are the key factor influencing the air quality near large ports. Although ship emissions are difficult to quantify, doing so can help port management find logistical solutions that can reduce the impact of having a large number of giant ships in a limited space. The joint study between the University of Naples and Istanbul Technical University, which focuses on the investigation of ship emissions in ports, is presented in this paper. It is expected that this study will lead to create new techniques for calculating, measuring, and validating emissions from ships at ports.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":" 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139254734","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}
Pub Date : 2023-11-18DOI: 10.1177/14750902231207159
D. Dong, A. Schönborn, Anastasia Christodoulou, A. Ölçer, José González-Celis
Marine fuels are the main sources of pollution from shipping industry. Hydrogen and ammonia have been suggested to be alternative fuels for shipping as these two fuels do not emit carbon dioxides in the combustion process. This study employed life cycle assessment method to compare the environmental performance of propulsion systems using hydrogen and ammonia as marine fuels to fossil fuels. 2-stroke and 4-stroke engines of tankers using fossil fuels were chosen as base case scenarios. Alternative scenarios using ‘green’ and ‘blue’ hydrogen and ammonia with the support of pilot fuel were then compared to the base case scenarios. While the performance of the coming combustion concepts for hydrogen and ammonia engines are still unknown, preliminary estimations were used in this study. The results showed that hydrogen and ammonia could substantially reduce the global warming potential, compared with the fossil fuel scenarios. Hydrogen and ammonia are also expected to be highly effective in cutting down the particulate matter and the emission of black carbon.
{"title":"Life cycle assessment of ammonia/hydrogen-driven marine propulsion","authors":"D. Dong, A. Schönborn, Anastasia Christodoulou, A. Ölçer, José González-Celis","doi":"10.1177/14750902231207159","DOIUrl":"https://doi.org/10.1177/14750902231207159","url":null,"abstract":"Marine fuels are the main sources of pollution from shipping industry. Hydrogen and ammonia have been suggested to be alternative fuels for shipping as these two fuels do not emit carbon dioxides in the combustion process. This study employed life cycle assessment method to compare the environmental performance of propulsion systems using hydrogen and ammonia as marine fuels to fossil fuels. 2-stroke and 4-stroke engines of tankers using fossil fuels were chosen as base case scenarios. Alternative scenarios using ‘green’ and ‘blue’ hydrogen and ammonia with the support of pilot fuel were then compared to the base case scenarios. While the performance of the coming combustion concepts for hydrogen and ammonia engines are still unknown, preliminary estimations were used in this study. The results showed that hydrogen and ammonia could substantially reduce the global warming potential, compared with the fossil fuel scenarios. Hydrogen and ammonia are also expected to be highly effective in cutting down the particulate matter and the emission of black carbon.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"203 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139262369","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}
Pub Date : 2023-11-14DOI: 10.1177/14750902231207133
G. Kocak, Y. Durmusoglu
Energy efficiency and environmental protection are becoming more important in the world. Almost 90% of the world trade is carried by sea which makes energy efficiency very important for the maritime sector. Exergetic method is a powerful scientific tool for measuring energy efficiency. The ships are not always cruising at maximum load conditions. The situations such as narrow water passages, maneuvering, and, hoteling etc. are partial load conditions and the exergy loss in power systems reaches maximum values at these conditions. Besides the new IMO regulation forces the sector to reduce emissions through Energy Efficiency Existing Ship Index (EEXI) and one of the most popular solutions is Engine Power Limitation (EPL). In the literature there are limited studies investigating exergy efficiencies of partial load conditions of a marine power plant. In this article, the performance analyses of a combined power system in partial load conditions are carried out using exergy method. The considered partial load conditions are maximum-ahead, full-ahead, half-ahead, slow-ahead and dead-slow-ahead loads of the engine. The results show that, the exergy efficiency of the overall system is decreasing at lower load conditions. It is observed that the maximum exergy efficiency is 51.6% which is reached at 96 rpm. The best condition considering both exergy efficiency and EEXI is 80 rpm of main engine. At slow-ahead and dead-slow-ahead conditions the exergy efficiency decreases to about 33%.
{"title":"Exergy efficiency and EEXI analysis of a marine power plant at partial load conditions","authors":"G. Kocak, Y. Durmusoglu","doi":"10.1177/14750902231207133","DOIUrl":"https://doi.org/10.1177/14750902231207133","url":null,"abstract":"Energy efficiency and environmental protection are becoming more important in the world. Almost 90% of the world trade is carried by sea which makes energy efficiency very important for the maritime sector. Exergetic method is a powerful scientific tool for measuring energy efficiency. The ships are not always cruising at maximum load conditions. The situations such as narrow water passages, maneuvering, and, hoteling etc. are partial load conditions and the exergy loss in power systems reaches maximum values at these conditions. Besides the new IMO regulation forces the sector to reduce emissions through Energy Efficiency Existing Ship Index (EEXI) and one of the most popular solutions is Engine Power Limitation (EPL). In the literature there are limited studies investigating exergy efficiencies of partial load conditions of a marine power plant. In this article, the performance analyses of a combined power system in partial load conditions are carried out using exergy method. The considered partial load conditions are maximum-ahead, full-ahead, half-ahead, slow-ahead and dead-slow-ahead loads of the engine. The results show that, the exergy efficiency of the overall system is decreasing at lower load conditions. It is observed that the maximum exergy efficiency is 51.6% which is reached at 96 rpm. The best condition considering both exergy efficiency and EEXI is 80 rpm of main engine. At slow-ahead and dead-slow-ahead conditions the exergy efficiency decreases to about 33%.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"1 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139276768","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}
Pub Date : 2023-11-14DOI: 10.1177/14750902231207128
Mehmet Akman, Selma Ergin
The Organic Rankine Cycle (ORC) is one of the most promising systems to recover the waste heat sourced from internal combustion engines. In this study, thermodynamic, economic and environmental analyses of the scavenge air cooling water-driven Waste Heat Recovery System (WHRS) based on the organic Rankine cycle are conducted for a dual-fuel marine engine integrated with exhaust gas recirculation (EGR) system. Zero ozone-depleting and low global warming potential working fluids; R245fa, R236ea from hydrofluorocarbons, R600a, R601a from hydrocarbons, R1234ze and R1234yf from hydrofluoroolefins are selected for the low-grade WHRS. In addition to the thermal analyses, the mass and volume of the system along with the safety factors of the working fluids are evaluated to judge the physical applicability of the system for ships. Thermo-economic performances of the fluids are analyzed, optimized and compared under various engine loads, Tier II and Tier III modes to reveal the effects of different engine operating conditions on the parameters. According to the results, scavenge air has a significant amount of waste heat at medium and heavy loads and switching the engine mode remarkably affects the performance of the WHRS. R601a shows the best thermo-economic performance, however, considering the applicability of the system R236ea is the most suitable working fluid for the ORC WHRS. The overall thermal efficiency of the power generation system can be increased by about 2.8%.
{"title":"Thermo-economic optimization of an ORC system for a dual-fuel marine engine","authors":"Mehmet Akman, Selma Ergin","doi":"10.1177/14750902231207128","DOIUrl":"https://doi.org/10.1177/14750902231207128","url":null,"abstract":"The Organic Rankine Cycle (ORC) is one of the most promising systems to recover the waste heat sourced from internal combustion engines. In this study, thermodynamic, economic and environmental analyses of the scavenge air cooling water-driven Waste Heat Recovery System (WHRS) based on the organic Rankine cycle are conducted for a dual-fuel marine engine integrated with exhaust gas recirculation (EGR) system. Zero ozone-depleting and low global warming potential working fluids; R245fa, R236ea from hydrofluorocarbons, R600a, R601a from hydrocarbons, R1234ze and R1234yf from hydrofluoroolefins are selected for the low-grade WHRS. In addition to the thermal analyses, the mass and volume of the system along with the safety factors of the working fluids are evaluated to judge the physical applicability of the system for ships. Thermo-economic performances of the fluids are analyzed, optimized and compared under various engine loads, Tier II and Tier III modes to reveal the effects of different engine operating conditions on the parameters. According to the results, scavenge air has a significant amount of waste heat at medium and heavy loads and switching the engine mode remarkably affects the performance of the WHRS. R601a shows the best thermo-economic performance, however, considering the applicability of the system R236ea is the most suitable working fluid for the ORC WHRS. The overall thermal efficiency of the power generation system can be increased by about 2.8%.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"51 15","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134902961","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}
Pub Date : 2023-11-14DOI: 10.1177/14750902231208848
Bulut Ozan Ceylan
Turbocharger fouling phenomenon was analyzed from the risk assessment perspective in this study. The research employed exhaust system and turbocharger equipment of commercial ship that equipped with a Doosan-MAN B&W 6S50 MC-C diesel engine was used as the main research materials, and utilized the fuzzy Failure Mode and Effects Analysis (FMEA) based on the expert system as a methodical approach. The experts revealed different types of turbocharger fouling failure modes (FMs), along with their respective causes and subsequent consequences. Following that, the specialists allocated an O, S, and D score to each FM. Within the framework of fuzzy logic, the process entails the establishment of input and output membership functions, as well as the construction of a fuzzy model incorporating an inference mechanism and a rule base. Based on the analysis findings, the three primary factors are as follows: low cylinder compression pressure with a Fuzzy Risk Priority Number (FRPN) score of 6.95, high main engine fuel oil consumption with a score of 6.92, and high CO, CO 2 , SO x emissions with a 6.45. The phenomenon of turbocharger fouling, being an inherent occurrence, has significant ramifications on the main engine, the vessel as a whole, and the ecological surroundings. The quantitative results presented in this study provide valuable insights into the risks associated with maritime endeavors. The data generated from this research can be used by stakeholders in the maritime industry to better understand this situation and take proactive measures to mitigate potential risks in the future. Furthermore, the findings of the research provide corroboration for the implementation of predictive maintenance procedures.
{"title":"Marine diesel engine turbocharger fouling phenomenon risk assessment application by using fuzzy FMEA method","authors":"Bulut Ozan Ceylan","doi":"10.1177/14750902231208848","DOIUrl":"https://doi.org/10.1177/14750902231208848","url":null,"abstract":"Turbocharger fouling phenomenon was analyzed from the risk assessment perspective in this study. The research employed exhaust system and turbocharger equipment of commercial ship that equipped with a Doosan-MAN B&W 6S50 MC-C diesel engine was used as the main research materials, and utilized the fuzzy Failure Mode and Effects Analysis (FMEA) based on the expert system as a methodical approach. The experts revealed different types of turbocharger fouling failure modes (FMs), along with their respective causes and subsequent consequences. Following that, the specialists allocated an O, S, and D score to each FM. Within the framework of fuzzy logic, the process entails the establishment of input and output membership functions, as well as the construction of a fuzzy model incorporating an inference mechanism and a rule base. Based on the analysis findings, the three primary factors are as follows: low cylinder compression pressure with a Fuzzy Risk Priority Number (FRPN) score of 6.95, high main engine fuel oil consumption with a score of 6.92, and high CO, CO 2 , SO x emissions with a 6.45. The phenomenon of turbocharger fouling, being an inherent occurrence, has significant ramifications on the main engine, the vessel as a whole, and the ecological surroundings. The quantitative results presented in this study provide valuable insights into the risks associated with maritime endeavors. The data generated from this research can be used by stakeholders in the maritime industry to better understand this situation and take proactive measures to mitigate potential risks in the future. Furthermore, the findings of the research provide corroboration for the implementation of predictive maintenance procedures.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"52 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134901877","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}
Pub Date : 2023-11-14DOI: 10.1177/14750902231209359
Qingtao Gong, Zhipeng Liu, Xin Hu, Yao Teng, Yanqing Han, Guojie Han
The robust adaptive anti-disturbance fault-tolerant control strategy for the dynamic positioning (DP) system of ships is built on the disturbance observer, the adaptive fault observer with the vectorial backstepping approach. The disturbance observer is constructed to estimate the first-order Markov disturbances. The adaptive fault observer with the projection algorithm is designed to estimate partial thruster faults. By employing the vectorial backstepping method, the robust adaptive anti-disturbance fault-tolerant control law is developed to simultaneously achieve the disturbance compensation and the partial thruster fault tolerant. It is demonstrated using the Lyapunov functions that the robust adaptive anti-disturbance fault-tolerant controller can maintain the DP of the ship’s position and heading to achieve the desired value, while guaranteeing the global stability of all signals in the DP closed-loop control system. Finally, different cases in the unknown ocean disturbance environment demonstrate the effectiveness of the robust adaptive anti-disturbance fault-tolerant control strategy.
{"title":"Robust adaptive control of dynamic positioning ship under thruster faults and unknown disturbances","authors":"Qingtao Gong, Zhipeng Liu, Xin Hu, Yao Teng, Yanqing Han, Guojie Han","doi":"10.1177/14750902231209359","DOIUrl":"https://doi.org/10.1177/14750902231209359","url":null,"abstract":"The robust adaptive anti-disturbance fault-tolerant control strategy for the dynamic positioning (DP) system of ships is built on the disturbance observer, the adaptive fault observer with the vectorial backstepping approach. The disturbance observer is constructed to estimate the first-order Markov disturbances. The adaptive fault observer with the projection algorithm is designed to estimate partial thruster faults. By employing the vectorial backstepping method, the robust adaptive anti-disturbance fault-tolerant control law is developed to simultaneously achieve the disturbance compensation and the partial thruster fault tolerant. It is demonstrated using the Lyapunov functions that the robust adaptive anti-disturbance fault-tolerant controller can maintain the DP of the ship’s position and heading to achieve the desired value, while guaranteeing the global stability of all signals in the DP closed-loop control system. Finally, different cases in the unknown ocean disturbance environment demonstrate the effectiveness of the robust adaptive anti-disturbance fault-tolerant control strategy.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"51 19","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134901704","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}
Pub Date : 2023-10-31DOI: 10.1177/14750902231203443
Oleksandr L Hordiienko, Andriy V Pechenyuk
Conception of hull form and propulsion design of river-sea ships essentially depends on the restrictions of specific inland waterways. River-sea ships of the Northern Black Sea were historically designed for operation through the locks of European inland waterways of the former Soviet Union. River-sea vessels of the late Soviet Union were designed as simple and technological. After dramatic economical changes the ships of new generation acquired completely different features of general and propulsion design. The vessels had unusually full hull forms and azimuthal thrusters. As is shown in the paper, the full hull forms have sound economic grounds for the considered ship type. However, azimuthal thrusters have controversial features and are not non-alternative. Based on analysis of previous and current propulsion solutions their further development is proposed within the considered ship type. Hull forms designed with specially developed CFD methods are recommended as a further step toward propulsion optimality.
{"title":"Development of propulsion solutions for river-sea ships of the northern Black Sea","authors":"Oleksandr L Hordiienko, Andriy V Pechenyuk","doi":"10.1177/14750902231203443","DOIUrl":"https://doi.org/10.1177/14750902231203443","url":null,"abstract":"Conception of hull form and propulsion design of river-sea ships essentially depends on the restrictions of specific inland waterways. River-sea ships of the Northern Black Sea were historically designed for operation through the locks of European inland waterways of the former Soviet Union. River-sea vessels of the late Soviet Union were designed as simple and technological. After dramatic economical changes the ships of new generation acquired completely different features of general and propulsion design. The vessels had unusually full hull forms and azimuthal thrusters. As is shown in the paper, the full hull forms have sound economic grounds for the considered ship type. However, azimuthal thrusters have controversial features and are not non-alternative. Based on analysis of previous and current propulsion solutions their further development is proposed within the considered ship type. Hull forms designed with specially developed CFD methods are recommended as a further step toward propulsion optimality.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135870816","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}
Pub Date : 2023-10-31DOI: 10.1177/14750902231205349
Burak Üstündağ, Bahadir Uğurlu, Ahmet Ergin
In this study, a boundary element method (BEM) is applied to investigate acoustic radiation from a sphere vibrating in pulsating mode on the free surface of finite or infinite depth water. Effect of the free surface is introduced by employing a half-space Green’s function. A modified version of the Helmholtz integral equation (HIE) is used to calculate acoustic radiation from the sphere vibrating in pulsating mode on the free surface. Free-terms of the HIE are calculated using two different forms of integrals and “dummy” boundary elements. Moreover, to simulate finite depth fluid medium, a chain image-source method is used to derive a waveguide Green’s function. To demonstrate applicability of the method presented, calculated acoustic pressures are compared with those by finite element method (FEM) and analytical calculations. Additionally, the effects of submergence depth and vibration frequency on acoustic radiation are investigated for infinitely deep water together with those of water depth and field point distance on acoustic radiation for finite water depth medium. The calculations show that there is a good agreement between BEM, FEM and analytical solutions. Also, it is observed that field point distance significantly affects the convergence behavior of waveguide Green’s function. Furthermore, it is noted that submergence depth, domain depth and vibration frequency have pronounce influence on radiated pressure amplitude and pressure field pattern.
{"title":"Investigation of acoustic radiation from a sphere vibrating on the free surface of a finite depth water using a boundary element method","authors":"Burak Üstündağ, Bahadir Uğurlu, Ahmet Ergin","doi":"10.1177/14750902231205349","DOIUrl":"https://doi.org/10.1177/14750902231205349","url":null,"abstract":"In this study, a boundary element method (BEM) is applied to investigate acoustic radiation from a sphere vibrating in pulsating mode on the free surface of finite or infinite depth water. Effect of the free surface is introduced by employing a half-space Green’s function. A modified version of the Helmholtz integral equation (HIE) is used to calculate acoustic radiation from the sphere vibrating in pulsating mode on the free surface. Free-terms of the HIE are calculated using two different forms of integrals and “dummy” boundary elements. Moreover, to simulate finite depth fluid medium, a chain image-source method is used to derive a waveguide Green’s function. To demonstrate applicability of the method presented, calculated acoustic pressures are compared with those by finite element method (FEM) and analytical calculations. Additionally, the effects of submergence depth and vibration frequency on acoustic radiation are investigated for infinitely deep water together with those of water depth and field point distance on acoustic radiation for finite water depth medium. The calculations show that there is a good agreement between BEM, FEM and analytical solutions. Also, it is observed that field point distance significantly affects the convergence behavior of waveguide Green’s function. Furthermore, it is noted that submergence depth, domain depth and vibration frequency have pronounce influence on radiated pressure amplitude and pressure field pattern.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"49 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135863158","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}
A Dynamic Positioning system automatically maintains both the position and heading of a vessel by using its thrusters in the presence of external disturbances. This goal is ensured by a controller that compensates for the environmental disturbances and computes the proper set-points for each actuator. The core of such a system is composed of force and thrust allocation modules that tailor the required forces and moment over the available actuators. The propulsion systems used are often over-actuated and the thrust allocation algorithm implies an infinite number of solutions since it is impossible to solve analytically the problem. Over the years efforts from the research community dealt with the optimization in terms of accuracy, energy consumption, and maintenance with innovative allocation strategies were investigated. However, no publications or rules indicate the procedure for the evaluation of exhaust gas emission during dynamic positioning operations. For such a reason, the paper aims to develop an optimization procedure that includes an ad-hoc objective function with relative non-linear constraints for the thrust allocation logic that tends to minimize the actuators’ thrust. The procedure accounts for non-linear hydrodynamic effects on the thrust generation, including thruster-thruster and thruster-hull interactions, to obtain the most realistic results as possible. Moreover, following the IMO suggestions, the production of greenhouses gases emissions is evaluated in probabilistic terms. The proposed approach provides indicators in terms of yearly operability, fuel consumption, and environmental footprint during dynamic positioning operations that could be used for proper decisions in ship deployment.
{"title":"Probabilistic operability and greenhouse gas assessment during dynamic positioning operations","authors":"Camilla Fruzzetti, Silvia Donnarumma, Francesca Maggiani, Michele Martelli","doi":"10.1177/14750902231203441","DOIUrl":"https://doi.org/10.1177/14750902231203441","url":null,"abstract":"A Dynamic Positioning system automatically maintains both the position and heading of a vessel by using its thrusters in the presence of external disturbances. This goal is ensured by a controller that compensates for the environmental disturbances and computes the proper set-points for each actuator. The core of such a system is composed of force and thrust allocation modules that tailor the required forces and moment over the available actuators. The propulsion systems used are often over-actuated and the thrust allocation algorithm implies an infinite number of solutions since it is impossible to solve analytically the problem. Over the years efforts from the research community dealt with the optimization in terms of accuracy, energy consumption, and maintenance with innovative allocation strategies were investigated. However, no publications or rules indicate the procedure for the evaluation of exhaust gas emission during dynamic positioning operations. For such a reason, the paper aims to develop an optimization procedure that includes an ad-hoc objective function with relative non-linear constraints for the thrust allocation logic that tends to minimize the actuators’ thrust. The procedure accounts for non-linear hydrodynamic effects on the thrust generation, including thruster-thruster and thruster-hull interactions, to obtain the most realistic results as possible. Moreover, following the IMO suggestions, the production of greenhouses gases emissions is evaluated in probabilistic terms. The proposed approach provides indicators in terms of yearly operability, fuel consumption, and environmental footprint during dynamic positioning operations that could be used for proper decisions in ship deployment.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":"97 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135871706","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：