Pub Date : 2023-08-29DOI: 10.1177/14750902231194703
Murat Mert Tekeli, Elİf Bal BeşİkÇİ, Muhammet Gul, E. Akyuz, O. Arslan
There are a wide range of chemical cargoes carried in chemical tankers. The chemical tankers are carrying hazardous chemical cargoes in their cargo tanks. When carrying hazardous chemicals in cargo tanks, the coating is required which is to provide safety barrier between the hull plate and the cargo. Therefore, capabilities of cargo tanks are of paramount importance for safe and efficient transport. Tank coatings to be applied to chemical tankers are epoxy coatings, zinc silicate coating, stainless steel coating, and marine line coating. This paper aims at conducting a numerical performance analysis of tank coatings in chemical tankers to contribute decision-making process of shipowner and safety professionals. To achieve this purpose, a multi-criterion decision-making (MCDM) tool is adopted: An Analytical Hierarchy Process (AHP) and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) under interval type-2 fuzzy set (IT2Fs) environment. The outcomes of the numerical performance analysis showed that stainless steel type tank coating has the best performance since result of closeness coefficient value c( xj) is found 0.55. The findings of the research will contribute chemical tanker ship owners, safety inspectors, naval architects, and safety professionals during decision-making process of ideal cargo tank coating.
{"title":"Application of IT2Fs-AHP and TOPSIS modeling for performance analysis of tank coatings in chemical tankers","authors":"Murat Mert Tekeli, Elİf Bal BeşİkÇİ, Muhammet Gul, E. Akyuz, O. Arslan","doi":"10.1177/14750902231194703","DOIUrl":"https://doi.org/10.1177/14750902231194703","url":null,"abstract":"There are a wide range of chemical cargoes carried in chemical tankers. The chemical tankers are carrying hazardous chemical cargoes in their cargo tanks. When carrying hazardous chemicals in cargo tanks, the coating is required which is to provide safety barrier between the hull plate and the cargo. Therefore, capabilities of cargo tanks are of paramount importance for safe and efficient transport. Tank coatings to be applied to chemical tankers are epoxy coatings, zinc silicate coating, stainless steel coating, and marine line coating. This paper aims at conducting a numerical performance analysis of tank coatings in chemical tankers to contribute decision-making process of shipowner and safety professionals. To achieve this purpose, a multi-criterion decision-making (MCDM) tool is adopted: An Analytical Hierarchy Process (AHP) and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) under interval type-2 fuzzy set (IT2Fs) environment. The outcomes of the numerical performance analysis showed that stainless steel type tank coating has the best performance since result of closeness coefficient value c( xj) is found 0.55. The findings of the research will contribute chemical tanker ship owners, safety inspectors, naval architects, and safety professionals during decision-making process of ideal cargo tank coating.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81361805","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 : 2023-07-31DOI: 10.1177/14750902231189917
N. Vladimir, I. Senjanović, Ivana Jovanović, S. Tomašević, Paul Jurišić
Large engineering structures like ships and other floating structures require reliable and complex computations to ensure their structural integrity over their lifetime. This work presents an analysis of the structural integrity of an aged single-bottom tanker during its towing from Croatia to a scrapheap in Turkey. The ship is subjected to wave loading (corresponding to the global response) and towing force (corresponding to the local response). Computations were performed by a general hydro-structure tool that combines a 3D finite element (FE) structural model and a 3D boundary element (BE) model based on the Rankine panel theory, according to the guidelines of the relevant classification society. Time domain simulations were performed to take account of Froude-Krylov nonlinearities for a wave determined within the Equivalent Design Wave (EDW) approach. After the calculation of wave loading and its transfer to the FE model of a ship structure, the stresses were calculated and compared with the allowable values. The local strength assessment of the ship forecastle deck structure was also performed, considering the prescribed towing force as an imposed load. Both the procedure and the used computational tools are general and can be applied to any kind of ship or other floating structure.
{"title":"Direct strength calculation of an aged single-bottom tanker during its towing in waves","authors":"N. Vladimir, I. Senjanović, Ivana Jovanović, S. Tomašević, Paul Jurišić","doi":"10.1177/14750902231189917","DOIUrl":"https://doi.org/10.1177/14750902231189917","url":null,"abstract":"Large engineering structures like ships and other floating structures require reliable and complex computations to ensure their structural integrity over their lifetime. This work presents an analysis of the structural integrity of an aged single-bottom tanker during its towing from Croatia to a scrapheap in Turkey. The ship is subjected to wave loading (corresponding to the global response) and towing force (corresponding to the local response). Computations were performed by a general hydro-structure tool that combines a 3D finite element (FE) structural model and a 3D boundary element (BE) model based on the Rankine panel theory, according to the guidelines of the relevant classification society. Time domain simulations were performed to take account of Froude-Krylov nonlinearities for a wave determined within the Equivalent Design Wave (EDW) approach. After the calculation of wave loading and its transfer to the FE model of a ship structure, the stresses were calculated and compared with the allowable values. The local strength assessment of the ship forecastle deck structure was also performed, considering the prescribed towing force as an imposed load. Both the procedure and the used computational tools are general and can be applied to any kind of ship or other floating structure.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89576653","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 : 2023-07-23DOI: 10.1177/14750902231188393
Bian Tao, Liu Liangliang, Cai Wenhao, Jiang Wen, Liu Zhiwen
This paper proposes a multi-objective optimization design method for shaftless rim-driven thruster (RDT) based on the ISIGHT platform. The pitch ratio, the blade area ratio and the advance coefficient of RDT were considered as the design optimization variables, the thrust and efficiency of the RDT were the optimization objectives. The multi-objective optimization design method was based on the surrogate module and the optimization module in the ISIGHT platform. Two analytical methods (response surface methodology (RSM) and radial basis function Model (RBF)) were used to build the surrogate model. The Muti-Island GA optimization algorithm was adopted in the optimization module. The paper indicates that both RSM model and RBF model are feasible to build the surrogate model, the RBF model has better accuracy and reliability than RSM model. The blade obtained by RBF method has larger thrust and smaller torque than that of the blade obtained by RSM method. For the large advance coefficient ( J > 0.6), the efficiency of the blade obtained by RBF method is slightly higher than that of the blade obtained by RSM method.
{"title":"Multi-objective optimization design of shaftless rim-driven thruster","authors":"Bian Tao, Liu Liangliang, Cai Wenhao, Jiang Wen, Liu Zhiwen","doi":"10.1177/14750902231188393","DOIUrl":"https://doi.org/10.1177/14750902231188393","url":null,"abstract":"This paper proposes a multi-objective optimization design method for shaftless rim-driven thruster (RDT) based on the ISIGHT platform. The pitch ratio, the blade area ratio and the advance coefficient of RDT were considered as the design optimization variables, the thrust and efficiency of the RDT were the optimization objectives. The multi-objective optimization design method was based on the surrogate module and the optimization module in the ISIGHT platform. Two analytical methods (response surface methodology (RSM) and radial basis function Model (RBF)) were used to build the surrogate model. The Muti-Island GA optimization algorithm was adopted in the optimization module. The paper indicates that both RSM model and RBF model are feasible to build the surrogate model, the RBF model has better accuracy and reliability than RSM model. The blade obtained by RBF method has larger thrust and smaller torque than that of the blade obtained by RSM method. For the large advance coefficient ( J > 0.6), the efficiency of the blade obtained by RBF method is slightly higher than that of the blade obtained by RSM method.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89249956","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 : 2023-07-21DOI: 10.1177/14750902231185807
P. Kundu, A. De
Generating more usable power annually from the river and tidal currents is essential to improving cost-effectiveness. Among various alternative options, the performance improvement of the blade foil has been considered in this work. When the fluid over the blade surface loses kinetic energy, flow separation occurs. The lift forces are reduced by flow separation, which finally results in less power production by the horizontal axis current turbine. To extract more power, it is necessary to overcome this flow separation. This paper presents a passive flow control method using tubes at regular intervals on the blade section to improve its performance considering its application on a horizontal axis current turbine. The tube inlet and outlet positions are determined by analyzing the force coefficients, glide ratio, and stall angle for a specific angle of attack. Finally, the performance characteristics are compared between the baseline and the modified hydrofoil. The maximum lift coefficient of the hydrofoil is increased by 15.7%. Also, the maximum glide ratios are considerably increased beyond the stall of the baseline profile. From the numerical results, it can be concluded that tubes inserted at regular intervals on the hydrofoil significantly increase its performance at a higher angle of attack.
{"title":"Performance analysis of a horizontal axis current turbine blade section with inserted tube","authors":"P. Kundu, A. De","doi":"10.1177/14750902231185807","DOIUrl":"https://doi.org/10.1177/14750902231185807","url":null,"abstract":"Generating more usable power annually from the river and tidal currents is essential to improving cost-effectiveness. Among various alternative options, the performance improvement of the blade foil has been considered in this work. When the fluid over the blade surface loses kinetic energy, flow separation occurs. The lift forces are reduced by flow separation, which finally results in less power production by the horizontal axis current turbine. To extract more power, it is necessary to overcome this flow separation. This paper presents a passive flow control method using tubes at regular intervals on the blade section to improve its performance considering its application on a horizontal axis current turbine. The tube inlet and outlet positions are determined by analyzing the force coefficients, glide ratio, and stall angle for a specific angle of attack. Finally, the performance characteristics are compared between the baseline and the modified hydrofoil. The maximum lift coefficient of the hydrofoil is increased by 15.7%. Also, the maximum glide ratios are considerably increased beyond the stall of the baseline profile. From the numerical results, it can be concluded that tubes inserted at regular intervals on the hydrofoil significantly increase its performance at a higher angle of attack.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89877311","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 : 2023-07-10DOI: 10.1177/14750902231184096
JaeHyeck Lee, Yoon-Seo Nam, Yuming Liu, Hee-Joo Yang
In this study, the predictability of ocean wave fields is considered based on marine radar measurement data. Phase-resolved components obtained by applying 3D FFT-based reconstruction to a sequence of radar images are utilized for wave field prediction, and two different prediction approaches are introduced: (i) snapshot data-based prediction through the adjustment of the frequency and phase of each component, and (ii) spatiotemporal data-based prediction through the data assimilation for reconstructed wave fields. Furthermore, the time evolution of a predictable zone is derived for different shapes of measurement domains including rectangular and ring-shaped domains. To validate the proposed wave propagation modeling method, numerical simulations are conducted on synthetic radar images created by reflecting geometrical shadowing effects, and the prediction accuracy is examined in relation to the derived predictable zone. Lastly, the forecasting performance, which is represented by the predictable time range at a radar location, is discussed with respect to the prediction techniques, specifications of the reconstruction domain, and moving measurements.
{"title":"Study on predictability of ocean wave fields based on marine radar measurement data","authors":"JaeHyeck Lee, Yoon-Seo Nam, Yuming Liu, Hee-Joo Yang","doi":"10.1177/14750902231184096","DOIUrl":"https://doi.org/10.1177/14750902231184096","url":null,"abstract":"In this study, the predictability of ocean wave fields is considered based on marine radar measurement data. Phase-resolved components obtained by applying 3D FFT-based reconstruction to a sequence of radar images are utilized for wave field prediction, and two different prediction approaches are introduced: (i) snapshot data-based prediction through the adjustment of the frequency and phase of each component, and (ii) spatiotemporal data-based prediction through the data assimilation for reconstructed wave fields. Furthermore, the time evolution of a predictable zone is derived for different shapes of measurement domains including rectangular and ring-shaped domains. To validate the proposed wave propagation modeling method, numerical simulations are conducted on synthetic radar images created by reflecting geometrical shadowing effects, and the prediction accuracy is examined in relation to the derived predictable zone. Lastly, the forecasting performance, which is represented by the predictable time range at a radar location, is discussed with respect to the prediction techniques, specifications of the reconstruction domain, and moving measurements.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90884820","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 : 2023-06-24DOI: 10.1177/14750902231183198
Ankit Nehra, V. Rajagopalan
The twin island concept is the most recent innovation in the top-deck architecture of an aircraft carrier. The carrier’s bluff body design presents the pilot with a number of difficulties, with landing on deck posing the biggest problem. The goal of the current study is to carry out the numerical analysis of the aerodynamic behaviour of twin island structure on Generic Aircraft Carrier. The flow characterization has been performed utilizing the normalized axial velocity and turbulent kinetic energy as aids for establishing pilot workload along the glideslope line. In this paper, multiple transverse planes cut across perpendicular to the flow direction are used to analyse the flow across the flight deck of twin island GAC and its downstream. The impacts of the two islands’ longitudinal translations with regard to the initial GAC position were then investigated and the results were analysed and compiled with reference to the landing approach path of the aircraft. The results show that the twin island designs are preferable to a single island. The maximum advantage in terms of turbulence reduction is achieved when the bifurcated islands are longitudinally repositioned forward of the original single island design position. The modified design not only achieves a 72% reduction in peak turbulence but also provides an additional time advantage to the pilot for assessing the environmental conditions while he is approaching the carrier flight deck for landing thus aiding to efficiently and effectively manage the workload. The findings of this study can act as a driving force for the integration and application of twin island concept in future design plans for floating structures and further studies in the field.
{"title":"Numeric assessment of the effect of the twin island design on the airflow dynamics around a generic aircraft carrier","authors":"Ankit Nehra, V. Rajagopalan","doi":"10.1177/14750902231183198","DOIUrl":"https://doi.org/10.1177/14750902231183198","url":null,"abstract":"The twin island concept is the most recent innovation in the top-deck architecture of an aircraft carrier. The carrier’s bluff body design presents the pilot with a number of difficulties, with landing on deck posing the biggest problem. The goal of the current study is to carry out the numerical analysis of the aerodynamic behaviour of twin island structure on Generic Aircraft Carrier. The flow characterization has been performed utilizing the normalized axial velocity and turbulent kinetic energy as aids for establishing pilot workload along the glideslope line. In this paper, multiple transverse planes cut across perpendicular to the flow direction are used to analyse the flow across the flight deck of twin island GAC and its downstream. The impacts of the two islands’ longitudinal translations with regard to the initial GAC position were then investigated and the results were analysed and compiled with reference to the landing approach path of the aircraft. The results show that the twin island designs are preferable to a single island. The maximum advantage in terms of turbulence reduction is achieved when the bifurcated islands are longitudinally repositioned forward of the original single island design position. The modified design not only achieves a 72% reduction in peak turbulence but also provides an additional time advantage to the pilot for assessing the environmental conditions while he is approaching the carrier flight deck for landing thus aiding to efficiently and effectively manage the workload. The findings of this study can act as a driving force for the integration and application of twin island concept in future design plans for floating structures and further studies in the field.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89273535","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 : 2023-06-22DOI: 10.1177/14750902231181505
Sunil Hansda, K. Debnath, D. Pal
An experimental study has been carried out in a laboratory flume to characterize the turbulence structure and turbulence anisotropy in the boundary layer over smooth and rough side walls for both current alone and wave-current combined flow situations. The rough side wall of the flume comprises a train of circular ribs (diameter, k) attached vertically maintaining uniform spacing p along the streamwise direction. The experiments are performed for smooth surface and rough (ribbed) surfaces with p/k = 2, 3, and 4 to reproduce different cases of d-type rib roughness. The effect of wave-current interaction has been investigated by superposing waves of two different frequencies. Time series data of three velocity components are obtained using Acoustic Doppler Velocimeter. At the near wall region, roughness with higher p/k value enhances the level of turbulent intensity and Reynolds stress significantly. In a channel with smooth side wall, the wave-current combined flow produces lesser turbulence intensity than the current alone flow near the wall. However, for a ribbed wall case, the effect is completely opposite that is, wave-current interacting flow induces higher intensities compared to the reference current alone flow. Substantial decline in the turbulent length scales at the near wall region are observed for ribbed walls, which reveals the strong effect of roughness elements on the turbulent structure. Superposition of wave reduces the length scales even more for both smooth and rough wall cases. As the spacing between two ribs ( p/ k ratio) increases, the energy dissipation rate increases. The analysis of anisotropy invariant map demonstrates a reduction of anisotropy in the vicinity of ribbed wall compared to that for a smooth wall. For wave-current combined flow, the anisotropy invariant data of Reynolds stress tensor varies dramatically within the boundary of map, reflecting significant changes in the state of turbulence.
{"title":"Effect of d-type rib roughness on the turbulent structure of side wall boundary layer for wave-current combined flow","authors":"Sunil Hansda, K. Debnath, D. Pal","doi":"10.1177/14750902231181505","DOIUrl":"https://doi.org/10.1177/14750902231181505","url":null,"abstract":"An experimental study has been carried out in a laboratory flume to characterize the turbulence structure and turbulence anisotropy in the boundary layer over smooth and rough side walls for both current alone and wave-current combined flow situations. The rough side wall of the flume comprises a train of circular ribs (diameter, k) attached vertically maintaining uniform spacing p along the streamwise direction. The experiments are performed for smooth surface and rough (ribbed) surfaces with p/k = 2, 3, and 4 to reproduce different cases of d-type rib roughness. The effect of wave-current interaction has been investigated by superposing waves of two different frequencies. Time series data of three velocity components are obtained using Acoustic Doppler Velocimeter. At the near wall region, roughness with higher p/k value enhances the level of turbulent intensity and Reynolds stress significantly. In a channel with smooth side wall, the wave-current combined flow produces lesser turbulence intensity than the current alone flow near the wall. However, for a ribbed wall case, the effect is completely opposite that is, wave-current interacting flow induces higher intensities compared to the reference current alone flow. Substantial decline in the turbulent length scales at the near wall region are observed for ribbed walls, which reveals the strong effect of roughness elements on the turbulent structure. Superposition of wave reduces the length scales even more for both smooth and rough wall cases. As the spacing between two ribs ( p/ k ratio) increases, the energy dissipation rate increases. The analysis of anisotropy invariant map demonstrates a reduction of anisotropy in the vicinity of ribbed wall compared to that for a smooth wall. For wave-current combined flow, the anisotropy invariant data of Reynolds stress tensor varies dramatically within the boundary of map, reflecting significant changes in the state of turbulence.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75418590","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 : 2023-06-06DOI: 10.1177/14750902231177337
Shaik Abdul Shareef, Nasar Thuvanismail, Sai Kiran Naik E, M. Vijaykumar
Global aquaculture is in exponential trend to fulfil the demand for seafood due to the rise in world population. Most countries have implemented nearshore farming and reached their limits, which impacts water quality parameters. Offshore farming is the alternative option to counteract this nearshore farming issue and balance the aquaculture demand and supply. The present study construes on the numerical study of the porous wall fencing offshore fish cage subjected to regular waves. The numerical analysis is carried out for four cages by varying porous hole diameters from 0.5 to 0.7 m and without porosity. All the cages are placed at the same water depth of 200 m, interacting with a constant wave height of 6m with wave periods ranging from 6.92 to 19.05 s. Both frequency and time domain analysis are conducted to study the variation of hydrodynamic parameters, namely added mass, wave excitation forces, radiational potential damping, motion responses, and mooring line tension. Among all cage configurations, the cage with 0.5 m diameter porous hole fencing performs better for all wave conditions considered. Also, a scaled model of 1:75 was considered in both experimental and numerical studies for the purpose of validation. It is learnt that experimental parameters such as motion responses and mooring line tension are in good agreement.
{"title":"Dynamic analysis of a porous wall fencing offshore fish cage subjected to regular waves","authors":"Shaik Abdul Shareef, Nasar Thuvanismail, Sai Kiran Naik E, M. Vijaykumar","doi":"10.1177/14750902231177337","DOIUrl":"https://doi.org/10.1177/14750902231177337","url":null,"abstract":"Global aquaculture is in exponential trend to fulfil the demand for seafood due to the rise in world population. Most countries have implemented nearshore farming and reached their limits, which impacts water quality parameters. Offshore farming is the alternative option to counteract this nearshore farming issue and balance the aquaculture demand and supply. The present study construes on the numerical study of the porous wall fencing offshore fish cage subjected to regular waves. The numerical analysis is carried out for four cages by varying porous hole diameters from 0.5 to 0.7 m and without porosity. All the cages are placed at the same water depth of 200 m, interacting with a constant wave height of 6m with wave periods ranging from 6.92 to 19.05 s. Both frequency and time domain analysis are conducted to study the variation of hydrodynamic parameters, namely added mass, wave excitation forces, radiational potential damping, motion responses, and mooring line tension. Among all cage configurations, the cage with 0.5 m diameter porous hole fencing performs better for all wave conditions considered. Also, a scaled model of 1:75 was considered in both experimental and numerical studies for the purpose of validation. It is learnt that experimental parameters such as motion responses and mooring line tension are in good agreement.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82713382","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 : 2023-05-15DOI: 10.1177/14750902231172821
R. Nicholls-Lee
This work aimed to test the feasibility, both experimentally and numerically, of a novel concept for a robust Wave Energy Converter (WEC) operating in the near-shore region. The converter uses a series of non-return valves, constrained by a tapered pipe, where the incoming wave builds up pressure in each compartment and finally drives a turbine onshore with the pressurised water. The device is aimed at remote communities, to gain energy security and reduce dependence on imports. The device facilitates local engagement, and it is intended that local people are trained to perform most maintenance tasks using low cost, readily available, parts. This work assessed the feasibility of the WEC through physical testing, the results of which were compared to initial numerical models. The device was shown to capture energy and, through a case study of Ushant Island off the coast of France, was shown to have the potential to become part of the future energy mix for remote communities.
{"title":"Development of a novel, robust, near-shore, wave energy converter for energy security in remote communities","authors":"R. Nicholls-Lee","doi":"10.1177/14750902231172821","DOIUrl":"https://doi.org/10.1177/14750902231172821","url":null,"abstract":"This work aimed to test the feasibility, both experimentally and numerically, of a novel concept for a robust Wave Energy Converter (WEC) operating in the near-shore region. The converter uses a series of non-return valves, constrained by a tapered pipe, where the incoming wave builds up pressure in each compartment and finally drives a turbine onshore with the pressurised water. The device is aimed at remote communities, to gain energy security and reduce dependence on imports. The device facilitates local engagement, and it is intended that local people are trained to perform most maintenance tasks using low cost, readily available, parts. This work assessed the feasibility of the WEC through physical testing, the results of which were compared to initial numerical models. The device was shown to capture energy and, through a case study of Ushant Island off the coast of France, was shown to have the potential to become part of the future energy mix for remote communities.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89074058","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 : 2023-05-09DOI: 10.1177/14750902231173470
F. Del Pero, C. A. Dattilo, Alessandro Giraldi, M. Delogu
Sustainable development, one of the main challenges of our time, is a policy focused on the perfect balance between three fundamental pillars: environmental, economic and social sustainability. As regards the environmental protection, the Life Cycle Assessment (LCA) methodology allows to evaluate the sustainability profile of the overall Life-Cycle (LC) of products, processes and services, based on an inventory (in terms of materials/energy consumption and emissions/waste production) referred to all LC stages. The paper describes an application of LCA in the maritime transportation field, after a careful analysis of the state of the art. In particular, the case study consists in the environmental comparison of two alternative design solutions for the superstructure of a Azimut-Benetti yacht, designed by Corporate R&D department and manufactured in one of Benetti botyards. The competing construction options are a Glass Fiber reinforced Vinylester-isophthalic Resin (GFVR) and a Carbon Fiber reinforced Epoxy Resin (CFER) component, and they are assessed in terms of Global Warming Potential through the CML2001 Life Cyle Impact Assessment (LCIA) method. The study takes into account the entire LC of the superstructure component, divided into production (including raw materials, manufacturing and transportations), use (including both fuel consumption and exhaust air emissions) and End-of-Life (EoL). The Life Cycle Inventory (LCI) is mainly based on primary data (materials and energy consumption for manufacturing) directly provided by the construction company; missing data are retrieved from secondary sources (literature and LCI database provided by the GaBi6 environmental software). Results show that, despite the higher impact in production stage, the innovative solution allows achieving a significant quota of GWP over the entire LC (more than 16%), which is mainly associated with decreased amount of fuel needed and lowered CO2 exhaust emissions during operation. The sensitivity analysis reveals that the environmental advantage provided by the CFER design becomes bigger as both component life-time and yacht consumption increase.
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