Crossflow over cylindrical structures has been extensively studied by both academia and industry in various fields. It is responsible for in-line and transverse vibrations of marine risers. Flow-induced structural vibrations may end up with the failure of these tubular systems in oceans and seas. First experimental studies in literature signified that longitudinally grooved cylinders inspired by Saguaro trees may offer reductions both in drag and lift forces. In the present study, the performance of 2 dimensional (2D) unsteady Reynolds averaged Navier-Stokes (URANS) simulations is tested in predicting hydrodynamic force coefficients of cylinders. First, CFD runs are conducted on a smooth cylinder and a cactus-like cylinder in literature. Then flow over 8-, 10-, and 12-grooved cylinders with a diameter of 0,5 m are solved to analyze flow features in detail and evaluate the capability of 2D URANS solver for the problem at hand. k-ω SST turbulence model is employed in URANS solver. It is shown that as the number of grooves increases, mean drag slightly decreases and amplitude of drag decreases by 29%. Separation angle is significantly improved with a number of grooves from 92o to 120o. However, the amplitude of lift force increases with the number of grooves with reference to 2D CFD simulations.
圆柱结构上的横流问题在学术界和工业界的各个领域都得到了广泛的研究。它负责海洋立管的在线和横向振动。在海洋中，流体引起的结构振动可能最终导致这些管状系统的失效。文献中的第一个实验研究表明，受仙人掌树启发的纵向沟槽圆柱体可以减少阻力和升力。在本研究中，测试了二维非定常Reynolds average Navier-Stokes (URANS)模拟在预测汽缸水动力系数方面的性能。首先，CFD运行是在光滑圆柱体和仙人掌状圆柱体上进行的。然后分别求解直径为0.5 m的8槽、10槽和12槽圆柱体上的流动，详细分析流动特征，并评估二维URANS求解器对当前问题的求解能力。URANS求解器采用k-ω海温湍流模型。结果表明，随着槽数的增加，平均阻力略有减小，阻力幅值减小29%。当槽数从92°增加到1200°时，分离角明显提高。二维CFD模拟结果表明，升力的幅值随凹槽数量的增加而增大。
{"title":"Investigation of the Effect of Number of Longitudinal Rounded Grooves on Hydrodynamic Forces acting on Cylinders in Cross Flow at Re=100000","authors":"Oktay Yilmaz","doi":"10.5505/jems.2020.49354","DOIUrl":"https://doi.org/10.5505/jems.2020.49354","url":null,"abstract":"Crossflow over cylindrical structures has been extensively studied by both academia and industry in various fields. It is responsible for in-line and transverse vibrations of marine risers. Flow-induced structural vibrations may end up with the failure of these tubular systems in oceans and seas. First experimental studies in literature signified that longitudinally grooved cylinders inspired by Saguaro trees may offer reductions both in drag and lift forces. In the present study, the performance of 2 dimensional (2D) unsteady Reynolds averaged Navier-Stokes (URANS) simulations is tested in predicting hydrodynamic force coefficients of cylinders. First, CFD runs are conducted on a smooth cylinder and a cactus-like cylinder in literature. Then flow over 8-, 10-, and 12-grooved cylinders with a diameter of 0,5 m are solved to analyze flow features in detail and evaluate the capability of 2D URANS solver for the problem at hand. k-ω SST turbulence model is employed in URANS solver. It is shown that as the number of grooves increases, mean drag slightly decreases and amplitude of drag decreases by 29%. Separation angle is significantly improved with a number of grooves from 92o to 120o. However, the amplitude of lift force increases with the number of grooves with reference to 2D CFD simulations.","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"8 1","pages":"178-193"},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Is Existing Maintenance System Adequate for Sulphur 2020 Amendments?","authors":"Ahmet Yaşar Canca, Görkem Kökkülünk","doi":"10.5505/jems.2020.89421","DOIUrl":"https://doi.org/10.5505/jems.2020.89421","url":null,"abstract":"","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"8 1","pages":"302-308"},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maintenance practices are considered as the means of providing safety and security to environment and quality service, and despite increasing the costs for companies with certain increments, they contribute to their reputation and reliability. Maintenance planning of ships consists of setting priorities and planning the efficient use of the sources. One of the main objectives of this study is to bring up more profits from commercial activities by optimizing the availability of vessels. Operational capacity is ensured by adopting a systematic and proper maintenance policy that increases effectiveness and efficiency by reducing downtime. To reach at such a target, recent failure data is analyzed and through this analysis certain procedures are developed for spare parts availability and these procedures are utilized in maintenance applications. This study aims to provide an additional feature for predictive maintenance software for the analysis of the upcoming conditions of the main engine systems. In this study, the history of failure in the critical nine main engine related subsystems have been analyzed by artificial neural network method, which is consistent with condition-based maintenance applications and subsequently helps to bring out the potential breakdowns in the recorded history of failure.
{"title":"Prediction of Ship Main Engine Failures by Artificial Neural Networks","authors":"Burak Göksu, K. E. Erginer","doi":"10.5505/jems.2020.90377","DOIUrl":"https://doi.org/10.5505/jems.2020.90377","url":null,"abstract":"Maintenance practices are considered as the means of providing safety and security to environment and quality service, and despite increasing the costs for companies with certain increments, they contribute to their reputation and reliability. Maintenance planning of ships consists of setting priorities and planning the efficient use of the sources. One of the main objectives of this study is to bring up more profits from commercial activities by optimizing the availability of vessels. Operational capacity is ensured by adopting a systematic and proper maintenance policy that increases effectiveness and efficiency by reducing downtime. To reach at such a target, recent failure data is analyzed and through this analysis certain procedures are developed for spare parts availability and these procedures are utilized in maintenance applications. This study aims to provide an additional feature for predictive maintenance software for the analysis of the upcoming conditions of the main engine systems. In this study, the history of failure in the critical nine main engine related subsystems have been analyzed by artificial neural network method, which is consistent with condition-based maintenance applications and subsequently helps to bring out the potential breakdowns in the recorded history of failure.","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"8 1","pages":"98-113"},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fossil-based fuels have been decreasing all over the world and the energy requirements of power generation systems are increasing. Diesel engines are one of the most common and efficient power generation systems. However, national and international organizations impose various restrictions to reduce emissions from diesel engines. Reducing emissions and improving performance in diesel engines are one of the most common areas of work. Improvement of performance and emission parameters is possible with changes in alternative fuels, engine geometry and fuel injection systems. In this study, the effects of different injection timing and injection duration on diesel engine performance and exhaust gas emissions have been investigated with computational fluid dynamics (CFD) method. The numerical study has been carried out on a 4-stroke, single cylinder test engine and the results have been compared with the experimental results obtained from the literature. As a result of the study, combustion chamber speed profiles, fuel mass change, temperature, pressure, chemical heat release rate has been determined for the standard operating conditions. Parametric study has been performed for different injection timing and injection duration of engine. For each case, performance and emissions parameters have been determined. Analysis results has compared, and the most suitable injection parameters has been introduced.
{"title":"Analyzing the Effect of Fuel Injection Timing and Injection Duration on Performance and Emissions in Diesel Engines","authors":"Kubilay Bayramoğlu, M. Nuran","doi":"10.5505/jems.2020.99705","DOIUrl":"https://doi.org/10.5505/jems.2020.99705","url":null,"abstract":"Fossil-based fuels have been decreasing all over the world and the energy requirements of power generation systems are increasing. Diesel engines are one of the most common and efficient power generation systems. However, national and international organizations impose various restrictions to reduce emissions from diesel engines. Reducing emissions and improving performance in diesel engines are one of the most common areas of work. Improvement of performance and emission parameters is possible with changes in alternative fuels, engine geometry and fuel injection systems. In this study, the effects of different injection timing and injection duration on diesel engine performance and exhaust gas emissions have been investigated with computational fluid dynamics (CFD) method. The numerical study has been carried out on a 4-stroke, single cylinder test engine and the results have been compared with the experimental results obtained from the literature. As a result of the study, combustion chamber speed profiles, fuel mass change, temperature, pressure, chemical heat release rate has been determined for the standard operating conditions. Parametric study has been performed for different injection timing and injection duration of engine. For each case, performance and emissions parameters have been determined. Analysis results has compared, and the most suitable injection parameters has been introduced.","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"8 1","pages":"38-52"},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to increase the number of well-qualified and well experienced seafarers on ships and their employment periods, as well as providing the desired safety at work, improving/promoting the working conditions on ships, is of utmost significance. The purpose of this study is to reveal to what extent working conditions for Turkish seafarers who work on commercial ships comply with the terms of MLC (Maritime Labour Convention). For this aim, a questionnaire, an instrument of quantitative research method, was issued and conducted through 296 seafarers working on the ships owned by Turkish shipowners. The results of the comparative analysis reveal that the working condition on Turkish-owned ships is moderately compliant with the terms of MLC.
{"title":"A Study on Working and Living Conditions of Turkish Seafarers","authors":"Ö. Tezcan, Erdem Kan, Oğuz Atik","doi":"10.5505/jems.2020.28290","DOIUrl":"https://doi.org/10.5505/jems.2020.28290","url":null,"abstract":"In order to increase the number of well-qualified and well experienced seafarers on ships and their employment periods, as well as providing the desired safety at work, improving/promoting the working conditions on ships, is of utmost significance. The purpose of this study is to reveal to what extent working conditions for Turkish seafarers who work on commercial ships comply with the terms of MLC (Maritime Labour Convention). For this aim, a questionnaire, an instrument of quantitative research method, was issued and conducted through 296 seafarers working on the ships owned by Turkish shipowners. The results of the comparative analysis reveal that the working condition on Turkish-owned ships is moderately compliant with the terms of MLC.","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"8 1","pages":"22-37"},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IMO 2020 regulations force maritime industry to look for alternative fuels for compliance. LNG is a promising option as a fuel considering today's emission control regulations and for measures to be adopted in the future. However, supply chain development for small-scale LNG is not at the expected level. The study examines the development of LNG bunkering supply chain based on different perspectives of stakeholders. The research explores the challenges regarding LNG bunkering development and aims to provide suggestions to overcome these challenges. Semi-structured interviews were conducted through purpose sampling including various representatives of LNG bunkering supply chain. The study identifies barriers in LNG bunkering development, categorizes some key approaches and links challenges from the view point of relevant stakeholders for improvement in supply chain. The research findings indicate that collaboration of stakeholders is the main driver for LNG bunkering development, public opinion, standardisation and transparency are the other outstanding factors to improve LNG bunkering supply chain.
{"title":"An exploratory study on the perceptions of stakeholders in LNG Bunkering Supply Chain","authors":"Mehmet Doymus, G. Şakar","doi":"10.5505/jems.2020.43255","DOIUrl":"https://doi.org/10.5505/jems.2020.43255","url":null,"abstract":"IMO 2020 regulations force maritime industry to look for alternative fuels for compliance. LNG is a promising option as a fuel considering today's emission control regulations and for measures to be adopted in the future. However, supply chain development for small-scale LNG is not at the expected level. The study examines the development of LNG bunkering supply chain based on different perspectives of stakeholders. The research explores the challenges regarding LNG bunkering development and aims to provide suggestions to overcome these challenges. Semi-structured interviews were conducted through purpose sampling including various representatives of LNG bunkering supply chain. The study identifies barriers in LNG bunkering development, categorizes some key approaches and links challenges from the view point of relevant stakeholders for improvement in supply chain. The research findings indicate that collaboration of stakeholders is the main driver for LNG bunkering development, public opinion, standardisation and transparency are the other outstanding factors to improve LNG bunkering supply chain.","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"1 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Risk assessment activities in maritime transportation are mostly done through fixed risk assessment forms. However, during maritime operations, many different dynamic factors such as visibility, the time period during which the operation is carried out, weather, current speed, tidal status, traffic density, etc. can increase these risks. These dynamic risks are not included in the existing risk assessment forms. In this study, the dynamic factors that increase the risks in ship operations were determined, and to what extent the variables in the operation quantitatively increased various risks was examined through the survey study conducted. Risk coefficients were collected through a survey study, as a data collection tool, conducted on seafarer who participated in ship operations. Consequently, the type of risk assessment to be performed in accordance with the dynamics was evaluated by adding dynamic risks to the possible static risks in cargo operations.
{"title":"Quantitative Analysis of Dynamic Risk Factors for Shipping Operations","authors":"Serap Göksu, O. Arslan","doi":"10.5505/jems.2020.63308","DOIUrl":"https://doi.org/10.5505/jems.2020.63308","url":null,"abstract":"Risk assessment activities in maritime transportation are mostly done through fixed risk assessment forms. However, during maritime operations, many different dynamic factors such as visibility, the time period during which the operation is carried out, weather, current speed, tidal status, traffic density, etc. can increase these risks. These dynamic risks are not included in the existing risk assessment forms. In this study, the dynamic factors that increase the risks in ship operations were determined, and to what extent the variables in the operation quantitatively increased various risks was examined through the survey study conducted. Risk coefficients were collected through a survey study, as a data collection tool, conducted on seafarer who participated in ship operations. Consequently, the type of risk assessment to be performed in accordance with the dynamics was evaluated by adding dynamic risks to the possible static risks in cargo operations.","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"8 1","pages":"86-97"},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Donatus Eberechukwu Onwuegbuchunam, M. Aponjolosun, S. Buhari, D. Ojo
This paper assessed the performance of jetty operations in Warri Refining and Petrochemical Company (WRPC). Primary data for the study consisted of ship turn round times, volume of cargo and number of vessels handled at the jetties for years 2004 to 2018. These variables served as key performance assessment criteria. In addition, copies of questionnaires on postulated factors affecting terminal performance were administered to a random sample of WRPC staff. Our findings showed that the jetties were being operated at less than optimum level. Trend analysis of the key performance indicators showed existence of continuous decline in operational performance of WRPC over the years covered in the study. Significant factors accounting for this performance outcome were found to include: inadequate berthing facilities, shortage of manpower supply, pipeline vandalisation, inadequate maintenance of jetty facilities and poor documentation process. The study recommended deployment of trained workforce to jetty operations, maintenance of berthing facilities, adequate funding and improved documentation of processes during jetty operations.
{"title":"Analysis of Operational Performance of Crude Oil Refining and Petrochemical Jetties in Nigeria","authors":"Donatus Eberechukwu Onwuegbuchunam, M. Aponjolosun, S. Buhari, D. Ojo","doi":"10.5505/jems.2020.98705","DOIUrl":"https://doi.org/10.5505/jems.2020.98705","url":null,"abstract":"This paper assessed the performance of jetty operations in Warri Refining and Petrochemical Company (WRPC). Primary data for the study consisted of ship turn round times, volume of cargo and number of vessels handled at the jetties for years 2004 to 2018. These variables served as key performance assessment criteria. In addition, copies of questionnaires on postulated factors affecting terminal performance were administered to a random sample of WRPC staff. Our findings showed that the jetties were being operated at less than optimum level. Trend analysis of the key performance indicators showed existence of continuous decline in operational performance of WRPC over the years covered in the study. Significant factors accounting for this performance outcome were found to include: inadequate berthing facilities, shortage of manpower supply, pipeline vandalisation, inadequate maintenance of jetty facilities and poor documentation process. The study recommended deployment of trained workforce to jetty operations, maintenance of berthing facilities, adequate funding and improved documentation of processes during jetty operations.","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"1 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Weighting Key Factors for Port Congestion by AHP Method","authors":"P. Bolat, Gizem Kayisoglu, Emine Gunes, Furkan Eyup Kizilay, Soysal Ozsogut","doi":"10.5505/jems.2020.64426","DOIUrl":"https://doi.org/10.5505/jems.2020.64426","url":null,"abstract":"","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"11 1","pages":"252-273"},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dimensions of the Port Performance: A Review of Literature","authors":"U. Bucak, Ibrahim Basaran, Soner Esmer","doi":"10.5505/jems.2020.76598","DOIUrl":"https://doi.org/10.5505/jems.2020.76598","url":null,"abstract":"","PeriodicalId":41280,"journal":{"name":"Journal of Eta Maritime Science","volume":"8 1","pages":"214-240"},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71090355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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