Abstract Ships and offshore structures operate in a severe corrosion degradation environment and face difficulty in providing long-lasting corrosion protection. The Classification Societies recommend regular thickness measurements leading to structural component replacements, to ensure structural integrity during service life. The measurements are usually performed using ultrasonic thickness gauges and such an approach requires multiple measurements of the corroded structural components. Otherwise, the collected data are insufficient to precisely assess the corrosion degradation level. This study aims to perform numerical and experimental analyses to verify the use of guided ultrasonic waves in defining the corrosion degradation level of the corroded structural components of a ship. The study incorporates the fundamental antisymmetric Lamb mode, excited by piezoelectric transducers attached at the pre-selected points on stiffened panels, representing typical structural ship components. The specimens are exposed to accelerated marine corrosion degradation, the influence of the degree of degradation on the wave time of flight being analysed. The study indicates that guided waves are a promising approach for diagnosing corroded structural components. The signals characterised by a high signal-to-noise ratio have been captured, even for relatively long distances between the transducers. This proves that the proposed approach can be suitable for monitoring more extensive areas of ship structures by employing a single measurement.
{"title":"Guided Waves in Ship Structural Health Monitoring – A Feasibility Study","authors":"Emil Roch, B. Zima, K. Woloszyk, Y. Garbatov","doi":"10.2478/pomr-2023-0023","DOIUrl":"https://doi.org/10.2478/pomr-2023-0023","url":null,"abstract":"Abstract Ships and offshore structures operate in a severe corrosion degradation environment and face difficulty in providing long-lasting corrosion protection. The Classification Societies recommend regular thickness measurements leading to structural component replacements, to ensure structural integrity during service life. The measurements are usually performed using ultrasonic thickness gauges and such an approach requires multiple measurements of the corroded structural components. Otherwise, the collected data are insufficient to precisely assess the corrosion degradation level. This study aims to perform numerical and experimental analyses to verify the use of guided ultrasonic waves in defining the corrosion degradation level of the corroded structural components of a ship. The study incorporates the fundamental antisymmetric Lamb mode, excited by piezoelectric transducers attached at the pre-selected points on stiffened panels, representing typical structural ship components. The specimens are exposed to accelerated marine corrosion degradation, the influence of the degree of degradation on the wave time of flight being analysed. The study indicates that guided waves are a promising approach for diagnosing corroded structural components. The signals characterised by a high signal-to-noise ratio have been captured, even for relatively long distances between the transducers. This proves that the proposed approach can be suitable for monitoring more extensive areas of ship structures by employing a single measurement.","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"76 - 84"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44159719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The installation error of an acoustic transceiver array is one of the important error sources in an ultra-short baseline (USBL) system. In a USBL system with a positioning accuracy of 0.5%, an installation error angle of 1° will lead to a positioning error of 1.7% times the slant distance. In this paper, a dual transponder-based installation angle error calibration method for USBL is proposed. First, the positioning errors induced by various installation angles are deduced and analysed using the linear measurement of seafloor targets. Then, an iterative algorithm is proposed that estimates the rolling alignment error, pitching alignment error, and heading alignment error, in that order. The simulation and experienced results show that, after three iterations, the estimates of the three alignment errors can converge quickly, all of the estimates converge to within 0.001° and the estimated values are very close to the true values. The horizontal positioning error caused by the installation error angle can be reduced by nearly 75%. The method has good effectiveness and robustness, and can greatly improve the positioning accuracy of the USBL system.
{"title":"An Installation Angle Error Calibration Method in an Ultra-Short Baseline System Based on a Dual Transponder","authors":"Baoheng Liu, Xiaochuan Zhang, Shuyang Jia, Sichen Zou, Deyan Tian, Lianglong Da","doi":"10.2478/pomr-2023-0028","DOIUrl":"https://doi.org/10.2478/pomr-2023-0028","url":null,"abstract":"Abstract The installation error of an acoustic transceiver array is one of the important error sources in an ultra-short baseline (USBL) system. In a USBL system with a positioning accuracy of 0.5%, an installation error angle of 1° will lead to a positioning error of 1.7% times the slant distance. In this paper, a dual transponder-based installation angle error calibration method for USBL is proposed. First, the positioning errors induced by various installation angles are deduced and analysed using the linear measurement of seafloor targets. Then, an iterative algorithm is proposed that estimates the rolling alignment error, pitching alignment error, and heading alignment error, in that order. The simulation and experienced results show that, after three iterations, the estimates of the three alignment errors can converge quickly, all of the estimates converge to within 0.001° and the estimated values are very close to the true values. The horizontal positioning error caused by the installation error angle can be reduced by nearly 75%. The method has good effectiveness and robustness, and can greatly improve the positioning accuracy of the USBL system.","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"121 - 129"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45490269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dominika Cuper-Przybylska, Van Nhanh Nguyen, Cao Dao Nam, J. Kowalski
Abstract The paper presents a 3D model of the processes taking place in the cylinder of a large 4-stroke marine engine. The model is based on CFD calculations performed on the moving mesh. The modelling range includes the full duty cycle (720° crankshaft position) and the complete geometry of the cylinder with inlet and exhaust ducts. The input data, boundary conditions and validation data were obtained by direct measurements on the real object. Fuel injection characteristics were obtained by Mie scattering measurements in a fixed-volume chamber. The modelling results have been validated in terms of the pressure characteristics of the engine’s cylinder within the entire range of its loads. The mean error did not exceed 1.42% for the maximum combustion pressure and 1.13% for the MIP (Mean Indicated Pressure). The model was also positively validated in terms of the O2 and NOx content of the exhaust gas. The mean error in this case was 1.2% for NOx fractions in the exhaust gas and 0.4% for O2 fractions. The complete model data has been made available in the research data repository on an open access basis.
{"title":"High Quality Multi-Zone and 3D CFD Model of Combustion in Marine Diesel Engine Cylinder","authors":"Dominika Cuper-Przybylska, Van Nhanh Nguyen, Cao Dao Nam, J. Kowalski","doi":"10.2478/pomr-2023-0021","DOIUrl":"https://doi.org/10.2478/pomr-2023-0021","url":null,"abstract":"Abstract The paper presents a 3D model of the processes taking place in the cylinder of a large 4-stroke marine engine. The model is based on CFD calculations performed on the moving mesh. The modelling range includes the full duty cycle (720° crankshaft position) and the complete geometry of the cylinder with inlet and exhaust ducts. The input data, boundary conditions and validation data were obtained by direct measurements on the real object. Fuel injection characteristics were obtained by Mie scattering measurements in a fixed-volume chamber. The modelling results have been validated in terms of the pressure characteristics of the engine’s cylinder within the entire range of its loads. The mean error did not exceed 1.42% for the maximum combustion pressure and 1.13% for the MIP (Mean Indicated Pressure). The model was also positively validated in terms of the O2 and NOx content of the exhaust gas. The mean error in this case was 1.2% for NOx fractions in the exhaust gas and 0.4% for O2 fractions. The complete model data has been made available in the research data repository on an open access basis.","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"61 - 67"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44762899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The current research is focused on the identification of cargo containers in a stack from their images in the infrared and visible spectra, in order to locate the container-origin of ignition within the cargo temperature control and fire safety system. The relevance of the topic is reinforced by the functional requirements for shipboard safety, which are embodied in Chapter II-2 of the Safety of Life at Sea (SOLAS) Convention, and demanded by the necessity of enhancing safety measures during cargo transportation by the world container fleet. The thermal imager’s field of view (FOV) and the coordinate dependencies between the object and its image have been studied and modelled, and an algorithm for fire detection has been defined within the scope of the current research in connection with the containers within the camera’s FOV. A corresponding verification has been carried out by means of simulation modelling using the Unity and C# programming language capabilities.
{"title":"Image Processing Method for Cargo Container Identification in a Stack Within the Cargo Temperature Control and Fire Safety System on Container Ships","authors":"V. Konon","doi":"10.2478/pomr-2023-0027","DOIUrl":"https://doi.org/10.2478/pomr-2023-0027","url":null,"abstract":"Abstract The current research is focused on the identification of cargo containers in a stack from their images in the infrared and visible spectra, in order to locate the container-origin of ignition within the cargo temperature control and fire safety system. The relevance of the topic is reinforced by the functional requirements for shipboard safety, which are embodied in Chapter II-2 of the Safety of Life at Sea (SOLAS) Convention, and demanded by the necessity of enhancing safety measures during cargo transportation by the world container fleet. The thermal imager’s field of view (FOV) and the coordinate dependencies between the object and its image have been studied and modelled, and an algorithm for fire detection has been defined within the scope of the current research in connection with the containers within the camera’s FOV. A corresponding verification has been carried out by means of simulation modelling using the Unity and C# programming language capabilities.","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"114 - 120"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43039401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Van Giao Nguyen, S. Rajamohan, K. Rudzki, Janusz Kozak, Prabhakar Sharma, Nguyen Dang Khoa Pham, Phuoc Quy Phong Nguyen, Phu Nguyen Xuan
Abstract In marine vessel operations, fuel costs are major operating costs which affect the overall profitability of the maritime transport industry. The effective enhancement of using ship fuel will increase ship operation efficiency. Since ship fuel consumption depends on different factors, such as weather, cruising condition, cargo load, and engine condition, it is difficult to assess the fuel consumption pattern for various types of ships. Most traditional statistical methods do not consider these factors when predicting marine vessel fuel consumption. With technological development, different statistical models have been developed for estimating fuel consumption patterns based on ship data. Artificial Neural Networks (ANN) are some of the most effective artificial methods for modelling and validating marine vessel fuel consumption. The application of ANN in maritime transport improves the accuracy of the regression models developed for analysing interactive relationships between various factors. The present review sheds light on consolidating the works carried out in predicting ship fuel consumption using ANN, with an emphasis on topics such as ANN structure, application and prediction algorithms. Future research directions are also proposed and the present review can be a benchmark for mathematical modelling of ship fuel consumption using ANN.
{"title":"Using Artificial Neural Networks for Predicting Ship Fuel Consumption","authors":"Van Giao Nguyen, S. Rajamohan, K. Rudzki, Janusz Kozak, Prabhakar Sharma, Nguyen Dang Khoa Pham, Phuoc Quy Phong Nguyen, Phu Nguyen Xuan","doi":"10.2478/pomr-2023-0020","DOIUrl":"https://doi.org/10.2478/pomr-2023-0020","url":null,"abstract":"Abstract In marine vessel operations, fuel costs are major operating costs which affect the overall profitability of the maritime transport industry. The effective enhancement of using ship fuel will increase ship operation efficiency. Since ship fuel consumption depends on different factors, such as weather, cruising condition, cargo load, and engine condition, it is difficult to assess the fuel consumption pattern for various types of ships. Most traditional statistical methods do not consider these factors when predicting marine vessel fuel consumption. With technological development, different statistical models have been developed for estimating fuel consumption patterns based on ship data. Artificial Neural Networks (ANN) are some of the most effective artificial methods for modelling and validating marine vessel fuel consumption. The application of ANN in maritime transport improves the accuracy of the regression models developed for analysing interactive relationships between various factors. The present review sheds light on consolidating the works carried out in predicting ship fuel consumption using ANN, with an emphasis on topics such as ANN structure, application and prediction algorithms. Future research directions are also proposed and the present review can be a benchmark for mathematical modelling of ship fuel consumption using ANN.","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"39 - 60"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43078329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This article characterises the methodology for the endoscopic testing of a laboratory diesel engine used for testing marine fuels. The ‘Shadow’ measurement method used in the XLG3 type EVEREST digital endoscope, for quantitative and qualitative identification of detected surface defects, was approximated. Representative endoscopic images of the elements limiting the working space of the research engine are demonstrated, having been recorded during the usable quality testing of newly produced, low-sulphur marine fuels, so-called ‘modified fuels’. The main purpose of the endoscopic examinations was the final verification of the tested fuel’s suitability for feeding full-size marine engines.
{"title":"Health Monitoring of a Compression Ignition Engine Fed with Different Low-Sulphur Marine Fuels by Endoscopic Image Processing and Analysis","authors":"Z. Korczewski","doi":"10.2478/pomr-2023-0024","DOIUrl":"https://doi.org/10.2478/pomr-2023-0024","url":null,"abstract":"Abstract This article characterises the methodology for the endoscopic testing of a laboratory diesel engine used for testing marine fuels. The ‘Shadow’ measurement method used in the XLG3 type EVEREST digital endoscope, for quantitative and qualitative identification of detected surface defects, was approximated. Representative endoscopic images of the elements limiting the working space of the research engine are demonstrated, having been recorded during the usable quality testing of newly produced, low-sulphur marine fuels, so-called ‘modified fuels’. The main purpose of the endoscopic examinations was the final verification of the tested fuel’s suitability for feeding full-size marine engines.","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"85 - 94"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41685260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The rigidity in bending of a flexible link (is an important characteristic that should be considered during regular service conditions. The tension and bending with torsion of wire ropes are also significant factors. This study proposed a method to calculate the vectors of the generalised forces of bending of flexible links. One of the causes of torsional stresses in the power plant of underwater tethered systems is the interaction with ship equipment, such as spiral winding on the winch drum, friction on the flanges of the pulleys or winch drums, and bends on various blocks and rolls that cause torsion. The source of torsional stresses in the FL may also be related to manufacturing, storage, transportation, and its placement on the ship’s winch drums. Torsion can lead to a decrease in the tensile strength due to load redistribution between power elements, or even a violation of their structure. In some cases, torsion significantly affects the movement of the underwater tethered system as a whole. The development of a mathematical model to describe the marine tethered systems dynamics, taking into account the effect of torsion, is important and relevant. The mathematical model of the marine tethered systems dynamics was improved and solved by accounting for the generalised forces of the torsion rigidity of the flexible link, using an algorithm and computer program. The influence of the bending and torsional rigidity of the FL on its deflection and tensile strength were considered based on the example of two problems. The developed program’s working window image shows the simulated parameters and the initial position of the flexible link. The results show that torsion has almost no effect on the shape of the a flexible link’s deflection in the X0Z plane, but leads to a deviation from the X0Z plane when calculating the static deflection of the flexible link. When the carrier vessel is stationary and the submersible vehicle has no restrictions on movement and has positive buoyancy, torsion leads to a three-dimensional change in the shape of the flexible link both in the X0Z plane and in the X0Y plane. The tension force of the flexible link along its length is distributed unevenly, and the torsion of the flexible link can lead to significant changes in its shape, the trajectory of towed objects, and the forces acting on the elements of the marine tethered systems
{"title":"Mathematical Model of Flexible Link Dynamics in Marine Tethered Systems Considering Torsion and its Influence on Tension Force","authors":"Konstantin Trunin","doi":"10.2478/pomr-2023-0032","DOIUrl":"https://doi.org/10.2478/pomr-2023-0032","url":null,"abstract":"Abstract The rigidity in bending of a flexible link (is an important characteristic that should be considered during regular service conditions. The tension and bending with torsion of wire ropes are also significant factors. This study proposed a method to calculate the vectors of the generalised forces of bending of flexible links. One of the causes of torsional stresses in the power plant of underwater tethered systems is the interaction with ship equipment, such as spiral winding on the winch drum, friction on the flanges of the pulleys or winch drums, and bends on various blocks and rolls that cause torsion. The source of torsional stresses in the FL may also be related to manufacturing, storage, transportation, and its placement on the ship’s winch drums. Torsion can lead to a decrease in the tensile strength due to load redistribution between power elements, or even a violation of their structure. In some cases, torsion significantly affects the movement of the underwater tethered system as a whole. The development of a mathematical model to describe the marine tethered systems dynamics, taking into account the effect of torsion, is important and relevant. The mathematical model of the marine tethered systems dynamics was improved and solved by accounting for the generalised forces of the torsion rigidity of the flexible link, using an algorithm and computer program. The influence of the bending and torsional rigidity of the FL on its deflection and tensile strength were considered based on the example of two problems. The developed program’s working window image shows the simulated parameters and the initial position of the flexible link. The results show that torsion has almost no effect on the shape of the a flexible link’s deflection in the X0Z plane, but leads to a deviation from the X0Z plane when calculating the static deflection of the flexible link. When the carrier vessel is stationary and the submersible vehicle has no restrictions on movement and has positive buoyancy, torsion leads to a three-dimensional change in the shape of the flexible link both in the X0Z plane and in the X0Y plane. The tension force of the flexible link along its length is distributed unevenly, and the torsion of the flexible link can lead to significant changes in its shape, the trajectory of towed objects, and the forces acting on the elements of the marine tethered systems","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"188 - 196"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45214277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This paper utilised computational fluid dynamics (CFD) technology to calculate the resistance of a novel high-speed quadramaran in calm water using the Navier‒Stokes (N‒S) equation, analysed the total resistance, frictional resistance, and residual resistance characteristics of this novel high-speed quadramaran at different length Froude numbers, and compared them with the results of a conventional high-speed catamaran with the same displacement. The results showed that the total resistance of the quadramaran had a significant hump at the Froude number of 0.6, due to the complexity of the wave interference among the four demihulls, and the hump value was about 1.6 times that of the catamaran. Above the hump speed, the total resistance of the quadramaran decreased with the increase of the Froude number, until reaching the Froude number of 1.06, when the curve became flat, and it showed a maximum resistance reduction of 40% at the Froude number of 1.66 compared with the catamaran, where the total resistance curve was steep. The frictional resistance of the quadramaran increased gradually with the growth of the Froude number, which was basically consistent with the change trend of the catamaran. The residual resistance of the quadramaran first rose and then reduced with the rising Froude number, the curve showed a large hump due to the adverse wave interference, and the hump value was about 1.7 times that of the catamaran. Above the Froude number of 1.06, as the wave interference changed from adverse to favourable, the quadramaran had lower residual resistance than the catamaran. The bow and stern demihulls of the quadramaran were also analysed for their resistance characteristics. The total resistance of the bow demihulls increased gradually with the increase of the Froude number, the curve had a small hump at the Froude number of 0.7, and above the hump speed, the curve was steep. The total resistance of the stern demihulls first increased and then decreased with the growth of the Froude number, the hump value at the Froude number of 0.85 was significant and was about 2 times that of the bow demihulls, and the curve became flat above the Froude number of 1.51.
{"title":"Numerical Analysis of Resistance Characteristics of a Novel High-Speed Quadramaran","authors":"Xin Liu, Jinglei Yang, Defeng Wu, Liang Hou, Xiaowen Li, Qian Wan","doi":"10.2478/pomr-2023-0018","DOIUrl":"https://doi.org/10.2478/pomr-2023-0018","url":null,"abstract":"Abstract This paper utilised computational fluid dynamics (CFD) technology to calculate the resistance of a novel high-speed quadramaran in calm water using the Navier‒Stokes (N‒S) equation, analysed the total resistance, frictional resistance, and residual resistance characteristics of this novel high-speed quadramaran at different length Froude numbers, and compared them with the results of a conventional high-speed catamaran with the same displacement. The results showed that the total resistance of the quadramaran had a significant hump at the Froude number of 0.6, due to the complexity of the wave interference among the four demihulls, and the hump value was about 1.6 times that of the catamaran. Above the hump speed, the total resistance of the quadramaran decreased with the increase of the Froude number, until reaching the Froude number of 1.06, when the curve became flat, and it showed a maximum resistance reduction of 40% at the Froude number of 1.66 compared with the catamaran, where the total resistance curve was steep. The frictional resistance of the quadramaran increased gradually with the growth of the Froude number, which was basically consistent with the change trend of the catamaran. The residual resistance of the quadramaran first rose and then reduced with the rising Froude number, the curve showed a large hump due to the adverse wave interference, and the hump value was about 1.7 times that of the catamaran. Above the Froude number of 1.06, as the wave interference changed from adverse to favourable, the quadramaran had lower residual resistance than the catamaran. The bow and stern demihulls of the quadramaran were also analysed for their resistance characteristics. The total resistance of the bow demihulls increased gradually with the increase of the Froude number, the curve had a small hump at the Froude number of 0.7, and above the hump speed, the curve was steep. The total resistance of the stern demihulls first increased and then decreased with the growth of the Froude number, the hump value at the Froude number of 0.85 was significant and was about 2 times that of the bow demihulls, and the curve became flat above the Froude number of 1.51.","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"11 - 27"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47918733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This article presents the analysis of a damping fluid deficiency in a torsional vibration viscous damper. The problem is analysed both qualitatively and quantitatively. Experimental results are presented, showing what happens to the damper in a situation where the design of the housing is inadequate and the inertia forces prevent the formation of an oil film. In addition, the article deals with the problem of the proper design of the oil channel and the dimensions required to enable the damper to operate reliably. The results of the article may be useful to the constructors of torsional vibration viscous dampers for marine engines.
{"title":"Behaviour of a Torsional Vibration Viscous Damper in the Event of a Damper Fluid Shortage","authors":"A. Chmielowiec, Adam Michajłyszyn, W. Homik","doi":"10.2478/pomr-2023-0026","DOIUrl":"https://doi.org/10.2478/pomr-2023-0026","url":null,"abstract":"Abstract This article presents the analysis of a damping fluid deficiency in a torsional vibration viscous damper. The problem is analysed both qualitatively and quantitatively. Experimental results are presented, showing what happens to the damper in a situation where the design of the housing is inadequate and the inertia forces prevent the formation of an oil film. In addition, the article deals with the problem of the proper design of the oil channel and the dimensions required to enable the damper to operate reliably. The results of the article may be useful to the constructors of torsional vibration viscous dampers for marine engines.","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"105 - 113"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44211166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This paper deals with the wave-induced cyclic response of a porous seabed (by means of oscillating parameters: pore-fluid pressure, soil displacement components, effective normal stress and shear stress components) due to a surface sinusoidal water-wave propagating over a seabed of infinite thickness. The main existing analytical solutions to the governing problem are critically discussed, pointing out their meaningful errors and doubtful items. A phase-lag phenomena is particularly studied as an immanent part of any complex-valued analytical solutions having a cyclic nature.
{"title":"Comments on Existing Analytical Solutions to the Wave-Induced Cyclic Response of a Porous Seabed of Infinite Thickness","authors":"W. Magda","doi":"10.2478/pomr-2023-0033","DOIUrl":"https://doi.org/10.2478/pomr-2023-0033","url":null,"abstract":"Abstract This paper deals with the wave-induced cyclic response of a porous seabed (by means of oscillating parameters: pore-fluid pressure, soil displacement components, effective normal stress and shear stress components) due to a surface sinusoidal water-wave propagating over a seabed of infinite thickness. The main existing analytical solutions to the governing problem are critically discussed, pointing out their meaningful errors and doubtful items. A phase-lag phenomena is particularly studied as an immanent part of any complex-valued analytical solutions having a cyclic nature.","PeriodicalId":49681,"journal":{"name":"Polish Maritime Research","volume":"30 1","pages":"197 - 206"},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46179628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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