Pub Date : 2021-12-13DOI: 10.5750/ijme.v156ia1.913
R. Vijayakumar, S. Singh, V. Seshadri
The superstructure of a modern naval ship is fitted with multitude of sensors for electronic surveillance, weapon discharge, navigation, communication and varieties of deck handling equipment. Locating these electronic equipment/sensors and its integration on board is of paramount importance to achieve optimal operational performance of the naval vessel. Among the many problems in locating these sensors (like stability, EMC EMI etc.,), the presence of entrapped hot gases from the ship exhaust affects the functioning of these electronics. Hence the prediction of temperature profile and trajectories of the ship exhaust plume from the funnel around the superstructure during the design stage is a mandatory requirement for positioning the sensors on superstructure. This trajectory prediction is not amenable to theoretical analysis or empirical calculation procedures in the modern warship superstructure. Experimental and CFD studies conducted on ship superstructure are the only reliable tools that are available to estimate temperature field as well as to study the exhaust smoke superstructure interaction on ships. This paper presents the CFD simulation of the published results for two cases, namely hot jet in a cross flow and hot exhaust with a cross flow on a generic frigate. Simulations have been made using k-ɛ turbulence model with different values of turbulent Schmidt number. It has been observed that temperature field is predicted with reasonable accuracy with turbulent Schmidt number of 0.2.
{"title":"CFD PREDICTION OF THE TRAJECTORY OF HOT EXHAUST FROM THE FUNNEL OF A NAVAL SHIP IN THE PRESENCE OF SHIP SUPERSTRUCTURE","authors":"R. Vijayakumar, S. Singh, V. Seshadri","doi":"10.5750/ijme.v156ia1.913","DOIUrl":"https://doi.org/10.5750/ijme.v156ia1.913","url":null,"abstract":"The superstructure of a modern naval ship is fitted with multitude of sensors for electronic surveillance, weapon discharge, navigation, communication and varieties of deck handling equipment. Locating these electronic equipment/sensors and its integration on board is of paramount importance to achieve optimal operational performance of the naval vessel. Among the many problems in locating these sensors (like stability, EMC EMI etc.,), the presence of entrapped hot gases from the ship exhaust affects the functioning of these electronics. Hence the prediction of temperature profile and trajectories of the ship exhaust plume from the funnel around the superstructure during the design stage is a mandatory requirement for positioning the sensors on superstructure. This trajectory prediction is not amenable to theoretical analysis or empirical calculation procedures in the modern warship superstructure. Experimental and CFD studies conducted on ship superstructure are the only reliable tools that are available to estimate temperature field as well as to study the exhaust smoke superstructure interaction on ships. This paper presents the CFD simulation of the published results for two cases, namely hot jet in a cross flow and hot exhaust with a cross flow on a generic frigate. Simulations have been made using k-ɛ turbulence model with different values of turbulent Schmidt number. It has been observed that temperature field is predicted with reasonable accuracy with turbulent Schmidt number of 0.2.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48156975","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 : 2021-12-13DOI: 10.5750/ijme.v160ia4.1076
Wen-Jui Tseng, J. Ding, Yi-Chun Chen
The main purpose of this article is to apply the Analytic Hierarchy Process (AHP) method to analyse key risk factors affecting cargo damages on export operations for container shipping carriers in Taiwan. Based on the literature and experts’ opinions, a hierarchical structure with three risk aspects and eleven risk factors was constructed. We then applied the AHP procedure and AHP experts’ questionnaires to evaluate the key risk factors. The empirical results showed that: (1) ‘Shipping proxy phase’ is the most important aspect affecting cargo damages on export operations for container shipping carriers in Taiwan. (2) In order of relative importance, the top four key risk factors are “shipper’s concealed items have not been reported,” “inappropriate cargo packaging,” “insecure fixation between the container and ship deck,” and “error in printed documents.” Furthermore, some recommendations concerning effective risk management strategies and advices are provided for container shipping carriers.
{"title":"EVALUATING KEY RISK FACTORS AFFECTING CARGO DAMAGES ON EXPORT OPERATIONS FOR CONTAINER CARRIERS IN TAIWAN","authors":"Wen-Jui Tseng, J. Ding, Yi-Chun Chen","doi":"10.5750/ijme.v160ia4.1076","DOIUrl":"https://doi.org/10.5750/ijme.v160ia4.1076","url":null,"abstract":"The main purpose of this article is to apply the Analytic Hierarchy Process (AHP) method to analyse key risk factors affecting cargo damages on export operations for container shipping carriers in Taiwan. Based on the literature and experts’ opinions, a hierarchical structure with three risk aspects and eleven risk factors was constructed. We then applied the AHP procedure and AHP experts’ questionnaires to evaluate the key risk factors. The empirical results showed that: (1) ‘Shipping proxy phase’ is the most important aspect affecting cargo damages on export operations for container shipping carriers in Taiwan. (2) In order of relative importance, the top four key risk factors are “shipper’s concealed items have not been reported,” “inappropriate cargo packaging,” “insecure fixation between the container and ship deck,” and “error in printed documents.” Furthermore, some recommendations concerning effective risk management strategies and advices are provided for container shipping carriers.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47963785","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 : 2021-12-13DOI: 10.5750/ijme.v153ia4.870
C. Leontopoulos, S. K. Lee, L. Karaminas
The demand to increase the efficiency of propellers has led to optimized propeller blade designs finding their way into the construction of high-powered commercial vessels, such as containers or LNG carriers and certain categories of passenger vessels, to mention but a few. It has become increasingly common to see the propeller tip rotate closer to the hull surface, sweeping the thick turbulent boundary layer attached to the hull, causing fluid structure interaction. At the same time, increasing the loading on marine propellers can lead to problems, such as noise, hull vibration, and cavitation. The degree above which, such phenomena as propeller cavitation can be the main perpetrators for intensive vibration during operation, their diagnosis and the solutions to mitigate this risk, such as the use of vortex generators, are discussed here, taking into account cost and longevity of the vessel as well as the involvement of classification rules.
{"title":"PROPELLER CAVITATION AND INDUCED VIBRATION","authors":"C. Leontopoulos, S. K. Lee, L. Karaminas","doi":"10.5750/ijme.v153ia4.870","DOIUrl":"https://doi.org/10.5750/ijme.v153ia4.870","url":null,"abstract":"The demand to increase the efficiency of propellers has led to optimized propeller blade designs finding their way into the construction of high-powered commercial vessels, such as containers or LNG carriers and certain categories of passenger vessels, to mention but a few. It has become increasingly common to see the propeller tip rotate closer to the hull surface, sweeping the thick turbulent boundary layer attached to the hull, causing fluid structure interaction. At the same time, increasing the loading on marine propellers can lead to problems, such as noise, hull vibration, and cavitation. The degree above which, such phenomena as propeller cavitation can be the main perpetrators for intensive vibration during operation, their diagnosis and the solutions to mitigate this risk, such as the use of vortex generators, are discussed here, taking into account cost and longevity of the vessel as well as the involvement of classification rules.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43280533","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 : 2021-12-13DOI: 10.5750/ijme.v156ia2.924
S. Youssef, Yang Seop Kim, J. Paik, S. Ince
In recent decades, the safety of ships at sea has become a major concern of the global maritime industries. Ships are rarely subject to severe accidents during their life cycle. Collision is one of the most hazardous accidents, with potentially serious consequences such as the loss of human life, structural damage and environmental damage, especially if large tankers, LNG and/or nuclear-powered vessels are involved. This study presents a Quantitative Risk Assessment (QRA) for double hull oil tankers that have collided with different types of ships. The methodology used to perform the QRA is based on the International Maritime Organization’s (IMO) definition of a Formal Safety Assessment (FSA). Using probabilistic approaches, ship-ship collision scenarios are randomly selected to create a representative sample of all possible scenarios. The collision frequency is then calculated for each scenario. As this is a virtual experiment, the LS-DYNA nonlinear finite element method (NLFEM) is used to predict the structural consequences of each scenario selected. In addition, the environmental consequences are estimated by calculating the size of each scenario’s oil spill. To assess the economic consequences, the property and environmental damages are calculated in terms of monetary units. The total risk is then calculated as the sum of the resultant structural and environmental damages. Exceedance curves are established that can be used to define the collision design loads in association with various design criteria.
{"title":"QUANTITATIVE RISK ASSESSMENT FOR COLLISIONS INVOLVING DOUBLE HULL OIL TANKERS","authors":"S. Youssef, Yang Seop Kim, J. Paik, S. Ince","doi":"10.5750/ijme.v156ia2.924","DOIUrl":"https://doi.org/10.5750/ijme.v156ia2.924","url":null,"abstract":"In recent decades, the safety of ships at sea has become a major concern of the global maritime industries. Ships are rarely subject to severe accidents during their life cycle. Collision is one of the most hazardous accidents, with potentially serious consequences such as the loss of human life, structural damage and environmental damage, especially if large tankers, LNG and/or nuclear-powered vessels are involved. This study presents a Quantitative Risk Assessment (QRA) for double hull oil tankers that have collided with different types of ships. The methodology used to perform the QRA is based on the International Maritime Organization’s (IMO) definition of a Formal Safety Assessment (FSA). Using probabilistic approaches, ship-ship collision scenarios are randomly selected to create a representative sample of all possible scenarios. The collision frequency is then calculated for each scenario. As this is a virtual experiment, the LS-DYNA nonlinear finite element method (NLFEM) is used to predict the structural consequences of each scenario selected. In addition, the environmental consequences are estimated by calculating the size of each scenario’s oil spill. To assess the economic consequences, the property and environmental damages are calculated in terms of monetary units. The total risk is then calculated as the sum of the resultant structural and environmental damages. Exceedance curves are established that can be used to define the collision design loads in association with various design criteria.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44286182","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 : 2021-12-13DOI: 10.5750/ijme.v152ia2.828
A. Ray, D. Sen, S. Singh, V. Seshadri
The prediction of manoeuvring characteristics of underwater vehicles during design involves approximations at various stages. This paper attempts to quantify some of the uncertainties involved in the manoeuvring characteristics of underwater vehicles. The first source of uncertainty is in idealization of mathematical model selected for trajectory simulation. This is illustrated for alternative mathematical models in trajectory simulation programs. Next, the values of the hydrodynamic coefficients (HDCs) in the equations of motion have their own levels of uncertainty, depending upon the methods used to determine them. The sensitivity of trajectory simulation results to uncertainty levels in various HDCs is examined. Finally, the level of uncertainty in full-scale measurements of manoeuvres of underwater vehicles is discussed and estimated. It emerges that the cumulative errors in the prediction process during design need to be reduced further, in order to maintain their levels of uncertainty below those of the validation process.
{"title":"QUANTIFICATION OF UNCERTAINTY IN MANOEUVRING CHARACTERISTICS FOR DESIGN OF UNDERWATER VEHICLES","authors":"A. Ray, D. Sen, S. Singh, V. Seshadri","doi":"10.5750/ijme.v152ia2.828","DOIUrl":"https://doi.org/10.5750/ijme.v152ia2.828","url":null,"abstract":"The prediction of manoeuvring characteristics of underwater vehicles during design involves approximations at various stages. This paper attempts to quantify some of the uncertainties involved in the manoeuvring characteristics of underwater vehicles. The first source of uncertainty is in idealization of mathematical model selected for trajectory simulation. This is illustrated for alternative mathematical models in trajectory simulation programs. Next, the values of the hydrodynamic coefficients (HDCs) in the equations of motion have their own levels of uncertainty, depending upon the methods used to determine them. The sensitivity of trajectory simulation results to uncertainty levels in various HDCs is examined. Finally, the level of uncertainty in full-scale measurements of manoeuvres of underwater vehicles is discussed and estimated. It emerges that the cumulative errors in the prediction process during design need to be reduced further, in order to maintain their levels of uncertainty below those of the validation process.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44359125","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 : 2021-12-13DOI: 10.5750/ijme.v153ia4.869
P. Contraros, S. P. Phokas
This is the first of a series of companion papers that the authors propose to present on the effect that the new CSR Rules will have on the design of bulk carriers. Our initial focus will be on the new design framework established for the inner bottom height of such vessels, a parameter critical to their structural integrity. It examines the effect that double bottom height reduction has on the reliability of the bulk carrier structure, by applying a finite element 3D - 3 hold analysis of varying double bottom heights to a typical current Panamax bulk carrier design. The results are compared to pre and post IACS CSR[2] requirements. The conclusion reached is that the establishing of the double bottom height should not be left to direct calculations. A minimum acceptable height should be established in order to maintain a minimum level of structural reliability and safety.
{"title":"EFFECT OF DOUBLE BOTTOM HEIGHT ON THE STRUCTURAL BEHAVIOUR OF BULK CARRIERS","authors":"P. Contraros, S. P. Phokas","doi":"10.5750/ijme.v153ia4.869","DOIUrl":"https://doi.org/10.5750/ijme.v153ia4.869","url":null,"abstract":"This is the first of a series of companion papers that the authors propose to present on the effect that the new CSR Rules will have on the design of bulk carriers. Our initial focus will be on the new design framework established for the inner bottom height of such vessels, a parameter critical to their structural integrity. It examines the effect that double bottom height reduction has on the reliability of the bulk carrier structure, by applying a finite element 3D - 3 hold analysis of varying double bottom heights to a typical current Panamax bulk carrier design. The results are compared to pre and post IACS CSR[2] requirements. The conclusion reached is that the establishing of the double bottom height should not be left to direct calculations. A minimum acceptable height should be established in order to maintain a minimum level of structural reliability and safety.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42874478","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 : 2021-12-13DOI: 10.5750/ijme.v153ia4.866
P. Stott, P. Wright
In 2014 the Panama Canal Authority is scheduled to bring into commission new locks that will eliminate the long standing Panamax beam constraint of 32.2m. The expansion of the canal is aimed at increased capacity for container transits but will clearly have consequences for all types of vessel. There is an emerging demand for dry bulk carriers that are larger than the current Panamax limit of around 85,000 dwt but smaller than the Capesize class of around 160,000 dwt and the expansion of the canal will facilitate this development. Larger vessels will permit economies of scale and greater efficiency in the dry bulk shipping sector compared to what is currently possible with conventional Panamax ships. The relaxation of the constraint will additionally permit the development of more efficient hull forms than is possible within the existing beam constraint and the expansion of the Panama Canal’s locks will therefore (eventually) contribute directly to the reduction of CO2 produced by dry bulk shipping. The use of the Panamax constraint is far wider than the dry bulk sector, however, and the potential for reduction in carbon emissions for other sectors currently constrained to 32.2m beam is recommended for further study to evaluate the total carbon reduction ‘windfall’ that could result from the expansion of the Canal.
{"title":"OPPORTUNITIES FOR IMPROVED EFFICIENCY AND REDUCED CO2 EMISSIONS IN DRY BULK SHIPPING STEMMING FROM THE RELAXATION OF THE PANAMAX BEAM CONSTRAINT","authors":"P. Stott, P. Wright","doi":"10.5750/ijme.v153ia4.866","DOIUrl":"https://doi.org/10.5750/ijme.v153ia4.866","url":null,"abstract":"In 2014 the Panama Canal Authority is scheduled to bring into commission new locks that will eliminate the long standing Panamax beam constraint of 32.2m. The expansion of the canal is aimed at increased capacity for container transits but will clearly have consequences for all types of vessel. There is an emerging demand for dry bulk carriers that are larger than the current Panamax limit of around 85,000 dwt but smaller than the Capesize class of around 160,000 dwt and the expansion of the canal will facilitate this development. Larger vessels will permit economies of scale and greater efficiency in the dry bulk shipping sector compared to what is currently possible with conventional Panamax ships. The relaxation of the constraint will additionally permit the development of more efficient hull forms than is possible within the existing beam constraint and the expansion of the Panama Canal’s locks will therefore (eventually) contribute directly to the reduction of CO2 produced by dry bulk shipping. The use of the Panamax constraint is far wider than the dry bulk sector, however, and the potential for reduction in carbon emissions for other sectors currently constrained to 32.2m beam is recommended for further study to evaluate the total carbon reduction ‘windfall’ that could result from the expansion of the Canal.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43381707","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 : 2021-12-13DOI: 10.5750/ijme.v156ia4.936
K. Chang, C. L. Chang, C. C. Hung, A. S. Chiou
Repeated casualties caused by inadvertent release of lifeboat release hooks during drills and inspections have attracted the attention of the International Maritime Organization, which correspondingly amends the Life-Saving Appliance (LSA) Code in the international convention for the Safety of Life at Sea. This study proposes novel installations of locked-position monitors on release hooks for monitoring and safety checks. With the installation of locked-position monitors near unsealed pull rod, upon lifting the lifeboat from the water, the sensors can initiatively detect whether the release hooks are in a locked position. If the release hooks are not in the locked position for any reason, audible alarms are activated, warning lifeboat operators to cease operations and wait for further inspection. The example provided in this research indicates that locked-position monitors can be implemented on lifeboats to reduce accidents resulting from malfunctioning lifeboat release hooks, thereby promoting a safer working environment for all seamen at sea.
{"title":"A LOCKED-POSITION MONITOR FOR IMPROVING SAFETY OF RELEASE HOOKS IN ENCLOSED LIFEBOATS","authors":"K. Chang, C. L. Chang, C. C. Hung, A. S. Chiou","doi":"10.5750/ijme.v156ia4.936","DOIUrl":"https://doi.org/10.5750/ijme.v156ia4.936","url":null,"abstract":"Repeated casualties caused by inadvertent release of lifeboat release hooks during drills and inspections have attracted the attention of the International Maritime Organization, which correspondingly amends the Life-Saving Appliance (LSA) Code in the international convention for the Safety of Life at Sea. This study proposes novel installations of locked-position monitors on release hooks for monitoring and safety checks. With the installation of locked-position monitors near unsealed pull rod, upon lifting the lifeboat from the water, the sensors can initiatively detect whether the release hooks are in a locked position. If the release hooks are not in the locked position for any reason, audible alarms are activated, warning lifeboat operators to cease operations and wait for further inspection. The example provided in this research indicates that locked-position monitors can be implemented on lifeboats to reduce accidents resulting from malfunctioning lifeboat release hooks, thereby promoting a safer working environment for all seamen at sea.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49495862","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 : 2021-12-13DOI: 10.5750/ijme.v157ia4.968
M. Ozkok
Plate bending is one of the major processes in shipbuilding. The plates which are cut in specific dimensions are sent to plate bending work shop and they are curved by using various methods. These curved plates constitute bilge turn plates of a vessel which are curvilinear. In this study, plate bending work shop was considered and its simulation model was created by using SIMIO software. The aim of the study is to see the effects of some alterations on available situation of plate bending work shop and present some recommendations in order for the plate bending work shop to operate effectively. In this work, there are number of four alterations including the changing of bending processing time, number of cranes and bending machine. At the end of the study, the values of the most suitable crane number, bending machine number, and the bending operation processing time were recommended. It is believed that the plate bending work shop will operate in effective way if the shipyard administration implement the recommendations presented in this study.
{"title":"WORK ANALYSIS OF PLATE BENDING WORKSHOP IN SHIPBUILDING INDUSTRY","authors":"M. Ozkok","doi":"10.5750/ijme.v157ia4.968","DOIUrl":"https://doi.org/10.5750/ijme.v157ia4.968","url":null,"abstract":"Plate bending is one of the major processes in shipbuilding. The plates which are cut in specific dimensions are sent to plate bending work shop and they are curved by using various methods. These curved plates constitute bilge turn plates of a vessel which are curvilinear. In this study, plate bending work shop was considered and its simulation model was created by using SIMIO software. The aim of the study is to see the effects of some alterations on available situation of plate bending work shop and present some recommendations in order for the plate bending work shop to operate effectively. In this work, there are number of four alterations including the changing of bending processing time, number of cranes and bending machine. At the end of the study, the values of the most suitable crane number, bending machine number, and the bending operation processing time were recommended. It is believed that the plate bending work shop will operate in effective way if the shipyard administration implement the recommendations presented in this study.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45969671","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 : 2021-12-13DOI: 10.5750/ijme.v152ia4.838
J. W. English
The cause of the severe propeller excited broadband vibration on a twin screw ship’s stern was investigated in a cavitation tunnel using conventional modelling methods. At first sight the results did not indicate anything untoward about the stern and propeller designs tested, apart from some unusual cavitation patterns in the propellers’ slipstreams. The fluctuating pressure levels on the model hull varied considerably depending on the propeller designs and loading conditions used in the tests, but these did not provide an explanation for the vibration on the ship. Some unusual patterns in the relative levels of the harmonic pressures on the stern were noticed in addition to the presence of a large cavitation disturbance in a propeller trailing vortex that was captured in a single frame of a video recording. This latter observation led to a plausible explanation for the broadband vibration on the ship’s stern.
{"title":"A SOURCE OF PROPELLER EXCITED BROADBAND VIBRATION ON A HIGH-SPEED TWIN SCREW SHIP","authors":"J. W. English","doi":"10.5750/ijme.v152ia4.838","DOIUrl":"https://doi.org/10.5750/ijme.v152ia4.838","url":null,"abstract":"The cause of the severe propeller excited broadband vibration on a twin screw ship’s stern was investigated in a cavitation tunnel using conventional modelling methods. At first sight the results did not indicate anything untoward about the stern and propeller designs tested, apart from some unusual cavitation patterns in the propellers’ slipstreams. The fluctuating pressure levels on the model hull varied considerably depending on the propeller designs and loading conditions used in the tests, but these did not provide an explanation for the vibration on the ship. Some unusual patterns in the relative levels of the harmonic pressures on the stern were noticed in addition to the presence of a large cavitation disturbance in a propeller trailing vortex that was captured in a single frame of a video recording. This latter observation led to a plausible explanation for the broadband vibration on the ship’s stern.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46108788","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：