As a resource development model with both economic and ecological functions,the environmental friendliness of marine ranching products meets the environmental needs of consumers.However,the lack of technological innov...As a resource development model with both economic and ecological functions,the environmental friendliness of marine ranching products meets the environmental needs of consumers.However,the lack of technological innovation ability limits the development of marine ranching.Therefore,this research builds a marine ranching collaborative innovation system with multi-agent participation.Evolutionary game theory is used to analyze strategic choices of all parties and the conditions of system equilibrium,and numerical simulation is used to analyze the effect of relevant factors.This paper integrates the benefits from the improvement of environmental friendliness into the payoff matrix,and explains the significance of collaborative innovation to the development of marine ranching from the perspective of ecological environment.The results showed:the participation willingness of marine ranching enterprises is positively related to open innovation subject,while the participation willingness of the other two parties is negatively related to the government;The incentive effect of collaboration is negatively correlated with the government’s will,positively correlated with the other two parties;The incentive effect of government subsidies positively affects the willingness of the three parties to participate.Finally,suggestions are provided for each participant to maintain the strategic choice of marine ranching collaborative innovation system.展开更多
This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for...This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for membrane desalination devices to produce fresh water.A new exhaust-gas heat exchanger of fins and tube,with a reinforced heat transfer tube section,unequal spacing fins,a mixing zone between the fin groups and four routes tube bundle,was designed.Numerical simulations were also used to provide reference information for structural design.Experiments were carried out for exhaust gas waste heat recovery from a marine diesel engine in an engine test bench utilizing the heat exchanger.The experimental results show that the difference between heat absorption by water and heat reduction of exhaust gas is less than 6.5%.After the water flow rate was adjusted,the exhaust gas waste heat recovery efficiency was higher than 70%,and the exhaust-gas heat exchanger’s outlet water temperature was 55°C–85°C at different engine loads.This means that the heat recovery from the exhaust gas of a marine diesel engine meets the requirement to drive a membrane desalination device to produce fresh water for fishers working in small and medium-sized fishing vessels.展开更多
Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation.The emission factor for nitrogen...Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation.The emission factor for nitrogen oxides is lower than what is typically found for marine gasoil but does not reach the tier III limit.The emissions of particulate matter are significantly lower than for fuel oils and similar to what is found for LNG engines.The main part of the particles can be found in the ultrafine range with the peak being at around 18 nm.About 93%of the particles are evaporated and absorbed when using a thermodenuder,and thus a large majority of the particles are volatile.Methanol is a potential future marine fuel that will reduce emissions of air pollutants and can be made as a biofuel to meet emission targets for greenhouse gases.展开更多
This paper presents a simulator model of a marine diesel engine based on physical, semi-physical, mathematical and thermodynamic equations, which allows fast predictive simulations The whole engine system is divided i...This paper presents a simulator model of a marine diesel engine based on physical, semi-physical, mathematical and thermodynamic equations, which allows fast predictive simulations The whole engine system is divided into several functional blocks: cooling, lubrication, air, injection, combustion and emissions. The sub-models and dynamic characteristics of individual blocks are established according to engine working principles equations and experimental data collected from a marine diesel engine test bench for SIMB Company under the reference 6M26SRP1. The overall engine system dynamics is expressed as a set of simultaneous algebraic and differential equations using sub-blocks and S-Functions of Matlab/Simulink. The simulation of this model, implemented on Matlab/Simulink has been validated and can be used to obtain engine performance, pressure, temperature, efficiency, heat release, crank angle, fuel rate, emissions at different sub-blocks. The simulator will be used, in future work, to study the engine performance in faulty conditions, and can be used to assist marine engineers in fault diagnosis and estimation (FDI) as well as designers to predict the behavior of the cooling system, lubrication system, injection system, combustion, emissions, in order to optimize the dimensions of different components. This program is a platform for fault simulator, to investigate the impact on sub-blocks engine's output of changing values for faults parameters such as: faulty fuel injector, leaky cylinder, worn fuel pump, broken piston rings, a dirty turbocharger, dirty air filter, dirty air cooler, air leakage, water leakage, oil leakage and contamination, fouling of heat exchanger, pumps wear, failure of injectors (and many others).展开更多
Longitudinal vibration,torsional vibration and their coupled vibration are the main vibration modes of the crankshaft-sliding bearing system.However,these vibrations of the propeller-crankshaft-sliding bearing system ...Longitudinal vibration,torsional vibration and their coupled vibration are the main vibration modes of the crankshaft-sliding bearing system.However,these vibrations of the propeller-crankshaft-sliding bearing system generated by the fluid exciting force on the propeller are much more complex.Currently,the torsional and longitudinal vibrations have been studied separately while the research on their coupled vibration is few,and the influence of the propeller structure to dynamic characteristics of a crankshaft has not been studied yet.In order to describe the dynamic properties of a crankshaft accurately,a nonlinear dynamic model is proposed taking the effect of torsional-longitudinal coupling and the variable inertia of propeller,connecting rod and piston into account.Numerical simulation cases are carried out to calculate the response data of the system in time and frequency domains under the working speed and over-speed,respectively.Results of vibration analysis of the propeller and crankshaft system coupled in torsional and longitudinal direction indicate that the system dynamic behaviors are relatively complicated especially in the components of the frequency response.For example,the 4 times of an exciting frequency acting on the propeller by fluid appears at 130 r/min,while not yield at 105 r/min.While the possible abnormal vibration at over-speed just needs to be vigilant.So when designing the propeller shafting used in marine diesel engines,strength calculation and vibration analysis based only on linear model may cause great errors and the proposed research provides some references to design diesel engine propeller shafting used in large marines.展开更多
Optimization procedures are required to minimize the amount of fuel consumption and exhaust emissions from marine engines.This study discusses the procedures to optimize the performance of any marine engine implemente...Optimization procedures are required to minimize the amount of fuel consumption and exhaust emissions from marine engines.This study discusses the procedures to optimize the performance of any marine engine implemented in a 0D/1D numerical model in order to achieve lower values of exhaust emissions.From that point,an extension of previous simulation researches is presented to calculate the amount of SOx emissions from two marine diesel engines along their load diagrams based on the percentage of sulfur in the marine fuel used.The variations of SOx emissions are computed in g/k W·h and in parts per million(ppm)as functions of the optimized parameters:brake specific fuel consumption and the amount of air-fuel ratio respectively.Then,a surrogate model-based response surface methodology is used to generate polynomial equations to estimate the amount of SOx emissions as functions of engine speed and load.These developed non-dimensional equations can be further used directly to assess the value of SOx emissions for different percentages of sulfur of the selected or similar engines to be used in different marine applications.展开更多
In this study,a model is developed to simulate the dynamics of an internal combustion engine,and it is calibrated and validated against reliable experimental data,making it a tool that can effectively be adopted to co...In this study,a model is developed to simulate the dynamics of an internal combustion engine,and it is calibrated and validated against reliable experimental data,making it a tool that can effectively be adopted to conduct emission predictions.In this work,the Ricardo WAVE software is applied to the simulation of a particular marine diesel engine,a four-stroke engine used in the maritime field.Results from the bench tests are used for the calibration of the model.Finally,the calibration of the model and its validation with full-scale data measured at sea are presented.The prediction includes not only the classic engine operating parameters for a comparison with surveys but also an estimate of nitrogen oxide emissions,which are compared with similar results obtained with emission factors.The calibration of the model made it possible to obtain an overlap between the simulation results and real data with an average error of approximately 7%on power,torque,and consumption.The model provides encouraging results,suggesting further applications,such as in the study on transient conditions,coupling of the engine model with the ship model for a complete simulation of the operating conditions,and optimization studies on consumption and emissions.The availability of the emission data during the sea trial and validated simulation results are the strengths and novelties of this work.展开更多
Based on the ArcGIS geographic information system and the ORACLE database management system,this paper reports our studies on the technology of Marine Engineering Geological Exploration Information System(MEGEIS). By ...Based on the ArcGIS geographic information system and the ORACLE database management system,this paper reports our studies on the technology of Marine Engineering Geological Exploration Information System(MEGEIS). By analyzing system structure,designing function modules and discussing data management,this paper systematically proposes a framework of technol-ogy to integrate,manage,and analyze the seabed information comprehensively. Then,the technology is applied to the design and development of the Bohai Sea Oilfield Paradigm Area Information System. The system can not only meet the practical demands of marine resources exploration and exploitation in the Bohai Sea oilfield,but also serve as a preparatory work in theory and technology for the realization of the 'Digital Seabed'.展开更多
NIN has developed a new type of Ti alloy. It is suitable for structure pieces applied in hightemperature and high-pressure water/steam conditions. Its nominal composition is Ti-4Al-2V. In this paper, its microstructu...NIN has developed a new type of Ti alloy. It is suitable for structure pieces applied in hightemperature and high-pressure water/steam conditions. Its nominal composition is Ti-4Al-2V. In this paper, its microstructure, mechanical properties and corrosion resistance were studied in detail.展开更多
This paper deals with the coupling problem between the dynamic behaviors and the tribological behaviors of the piston-liner systems in multi-cylinder internal combustion engines. Firstly, based on the correction of so...This paper deals with the coupling problem between the dynamic behaviors and the tribological behaviors of the piston-liner systems in multi-cylinder internal combustion engines. Firstly, based on the correction of some errors in the equation of piston secondary motion, which have been employed by many authors for several years, a detailed mathematical model for the coupling problem between the dynamical and tribological behaviors in the piston-liner systems of multi-cylinder internal combustion engines is presented. Secondly, the lubrication and friction between the liner and piston in each cylinder is included applying the average flow model of the Reynolds equation. Thirdly, the vibration of each liner is computed through the finite element model of a four-cylinder engine block, by which not only the liner motions caused by the block vibration but also the local vibration and the local static deformation of each liner can be figured out and taken into account. Through theoretical analysis and computation, some conclusions can be drawn as: 1) Both the liner vibration and piston motion are different for different cylinder in a multi-cylinder internal combustion engine, and hence different piston-liner systems will have different tribological behaviors. 2) Different liners have coincident dynamic response on the whole, especially for the lower frequency components. However, differences still exist among the vibrations of different liners, and these differences are mainly owing to the higher frequency components. 3) The impacts of liner vibrations on the tribological behaviors in piston-liner systems are primarily ascribed to its higher frequency components.展开更多
Human error,an important factor,may lead to serious results in various operational fields.The human factor plays a critical role in the risks and hazards of the maritime industry.A ship can achieve safe navigation whe...Human error,an important factor,may lead to serious results in various operational fields.The human factor plays a critical role in the risks and hazards of the maritime industry.A ship can achieve safe navigation when all operations in the engine room are conducted vigilantly.This paper presents a systematic evaluation of 20 failures in auxiliary systems of marine diesel engines that may be caused by human error.The Cognitive Reliability Error Analysis Method(CREAM)is used to determine the potentiality of human errors in the failures implied thanks to the answers of experts.Using this method,the probabilities of human error on failures were evaluated and the critical ones were emphasized.The measures to be taken for these results will make significant contributions not only to the seafarers but also to the ship owners.展开更多
The frequency stability of a marine power system is determined by the dynamic characteristic of the diesel engine speed regulation system in a marine power station. In order to reduce the effect of load disturbances a...The frequency stability of a marine power system is determined by the dynamic characteristic of the diesel engine speed regulation system in a marine power station. In order to reduce the effect of load disturbances and improve the dynamic precision of a diesel engine speed governor, a controller was designed for a diesel engine speed regulation system using H2 control theory. This transforms the specifications of the system into a standard H2 control problem. Firstly, the mathematical model of a diesel engine speed regulation system using an H2 speed governor is presented. To counter external disturbances and model uncertainty, the design of an H, speed governor rests on the problem of mixed sensitivity. Computer simulation verified that the H2 speed governor improves the dynamic precision of a system and the ability to adapt to load disturbances, thus enhancing the frequency stability of marine power systems.展开更多
In power production,gas turbines are commonly used components that generate high amount of energy depending on size and weight.They function as integral parts of helicopters,aircrafts,trains,ships,electrical generator...In power production,gas turbines are commonly used components that generate high amount of energy depending on size and weight.They function as integral parts of helicopters,aircrafts,trains,ships,electrical generators,and tanks.Notably,many researchers are focusing on the design,operation,and maintenance of gas turbines.The focal point of this paper is a DEMATEL approach based on fuzzy sets,with the attempt to use these fuzzy sets explicitly.Using this approach,the cause–effect diagram of gas turbine failures expressed in the literature is generated and aimed to create a perspective for operators.The results of the study show that,"connecting shaft has been broken between turbine and gear box"selected the most important cause factor and"sufficient pressure fuel does not come for fuel pump"is selected the most important effect factor,according to the experts.展开更多
Corpus Christi, Texas, is a growing urban area with a busy port and a petrochemical industrial base that is currently in compliance with the US Environmental Protection Agency’s (EPA) National Ambient Air Quality Sta...Corpus Christi, Texas, is a growing urban area with a busy port and a petrochemical industrial base that is currently in compliance with the US Environmental Protection Agency’s (EPA) National Ambient Air Quality Standards (NAAQS) for ozone. However, the Texas Commission on Environmental Quality (TCEQ) has classified this urban airshed as a near non-attainment area. A comprehensive annual air emission inventory based on marine engines activity was developed for the years of 2006-2009 for the Port of Corpus Christi, Texas using recent EPA approved methodology. A regional-scale photochemical model Comprehensive Air Modeling system with extensions (CAMx) was used to evaluate the impact of these emissions on the ground level ozone concentrations by zeroing out the emissions and employing Direct Decoupled Method (DDM) for sensitivity analysis to estimate the 8-hour ozone sensitivity coefficients due to NOx and VOC emissions from marine engines. The analysis has shown a localized increase of up to 7.8 ppb in the 8-hour ozone concentration very close to the port premises and a decrease of about 1.73 ppb further downwind. Ozone sensitivity analysis using DDM on the 8-hour ozone concentrations showed a higher sensitivity to NOx emissions. Thus, any NOx related controls of marine engines will benefit local urban and regional ozone levels.展开更多
According to the conductivity test results,it is found that oil conductivity increases with an increasing additive content,and the turbidity of engine oil is also augmented with an increasing additive content.After te...According to the conductivity test results,it is found that oil conductivity increases with an increasing additive content,and the turbidity of engine oil is also augmented with an increasing additive content.After testing the turbidity and stability of oils containing the typical conventional calcium sulfonate,the overbased calcium sulfonate and the mixture of the above two calcium sulfonates,the results show that at the same amount of additives used,the oil with a higher turbidity demonstrated a worse stability.A nonionic dispersant that was added into lube oils at a definite concentration could improve the detergent compatibility.For this reason,the sediment volume in three kinds of oils all decreased obviously,resulting in successful improvement of storage stability of marine engine oils.展开更多
Condition-based maintenance based on fault prediction has been widely concerned by the industry. Most of the contributions on fault prediction are based on various sensor data and mathematical models of the equipment....Condition-based maintenance based on fault prediction has been widely concerned by the industry. Most of the contributions on fault prediction are based on various sensor data and mathematical models of the equipment. The complexity of the model and data signal is the key factor affecting the practicability of the model. In addition, even for the same type and batch of equipment, the manufacturing process, operation environment and other factors also affect the model parameters. In this paper, a series event model is conducted to predict the fault of marine diesel engines. Numerical example illustrates that the proposed event model is feasible.展开更多
The existing marine diesel engine fault diagnosis methods mainly have the problems of model complexity, large amount of calculation, and unable to carry out real-time fault diagnosis of diesel engine. In this paper, a...The existing marine diesel engine fault diagnosis methods mainly have the problems of model complexity, large amount of calculation, and unable to carry out real-time fault diagnosis of diesel engine. In this paper, a simple and practical approach to detect faults of marine diesel engine is studied. According to a set of sensing data, the fitting equation of each parameter changing with the running state of diesel engine was fitted statistically. Then, the threshold range of each parameter changing with the running state of diesel engine was fitted. During fault diagnosis, the real-time parameters of the sensor in the current running state were calculated according to the real-time running data. If the parameters exceed the threshold range, it is abnormal operation. Because the sensor signal corresponds to the operation status of each specific component, the abnormal evaluation directly indicates the specific fault. Experimental results show that the method has a good practical effect.展开更多
This study aims to determine the awareness and opinions on Clean Air Act among marine engineering students at maritime university,specifically,John B.Lacson Foundation Maritime University-Molo,Iloilo City,Philippines....This study aims to determine the awareness and opinions on Clean Air Act among marine engineering students at maritime university,specifically,John B.Lacson Foundation Maritime University-Molo,Iloilo City,Philippines.The participants of this study were 30 marine engineering students of the maritime university,especially JBLFMU-Molo for school year 2014-2015.Participants of the study were enrolled at the College of Maritime Education,JBLFMU-Molo,Iloilo City,Philippines.The researchers employed quantitative research design.The respondents’comments,suggestions,observations,and remarks on the perceived awareness and opinions on Clean Air Act were captured in this study.After gathering the qualitative information,the researchers classified and categorized the write-ups of the respondents into different categories.The results reveal that the participants of the present study were aware of the Clean Air Act as an entire group and when classified according to different categories.Most of the participants said that Clean Air Act protects the environment,followed by the participants who said that Clean Air Act can prevent air pollution.Next,in rank,the participants who said“it is good because you can go everywhere to inhale fresh air,followed by participants who said Clean Air Act can reduce the things that can harm the ozone layer,the last participants said that they never heard of Clean Air Act.展开更多
With the emphasis on energy and environmental protection,energy-conservation and emission-reduction become vital issues for industrial development.Moreover,with the development of legislation on marine environment,the...With the emphasis on energy and environmental protection,energy-conservation and emission-reduction become vital issues for industrial development.Moreover,with the development of legislation on marine environment,the marine diesel engine has become focusing on energy saving and emission reduction for ships.For low-speed diesel engines under high load,waste heat from exhaust gas can be recovered by the compact and efficient gas turbine.In this paper,the matching design research between low speed diesel engine and gas turbine is carried out.To balance efficiency and compactness,the impeller was adjusted and generated by ANSYS BLADEGEN,based on 1D thermodynamic design.And the 1D calculation is similar to the ANSYS CFX simulation result:the total-static efficiency is 73.8%compared to 76.7%.Moreover,the flow separation happened at the impeller suction side and created vortex due to the high incidence angle.The off-design operating point simulation of the turbine shows though the pressure ratio increase will cause the efficiency to decline a little,the total shaft power rises.In sum,this paper worked out a power turbine suitable for a low-speed diesel engine according to the turbine character matching design and simulation,which provides foundation to the construction of a steady operation of waste heat recovery system for marine diesel engine.展开更多
The article describes an electronic database of selected marine piston combustion engines created for diagnostic purposes. The database was made for vessels of the biggest Polish shipowner. It is used for archiving an...The article describes an electronic database of selected marine piston combustion engines created for diagnostic purposes. The database was made for vessels of the biggest Polish shipowner. It is used for archiving and comparing measured parameters of diagnosed engines with model parameters. To facilitate the search for and use of required data, they have been collected and catalogued. For this purpose the database has been prepared by using a computer program included in the Microsoft Office suite. The database search relies on the details concerning the type of vessel. The fields displayed include such items as the year and place of construction, the parameters of the ship, flag, etc.. For each vessel special forms are available for main and auxiliary engines, enabling easy and quick check of the necessary parameters during operation of the engine. The database contains parameters of the main propulsion and auxiliary engines, as well as model characteristics to help determine the diagnostics, prognosis and genesis.展开更多
基金supported by the National Natural Science Foundation of China(Nos.71901199 and 72273135)the Frontier Science Research Support Program,Management College,OUC(No.MCQYZD2302)+3 种基金the China Postdoctoral Science Foundation Funded Project(No.2019M660170)the Postdoctoral Innovation Project of Shandong Province(No.201902019)the Special Program for Rural Revitalization Research of OUC(No.ZX2022002)the‘Youth Innovation Team Program’Team in Colleges and Universities of Shandong Province(No.2022RW011).
文摘As a resource development model with both economic and ecological functions,the environmental friendliness of marine ranching products meets the environmental needs of consumers.However,the lack of technological innovation ability limits the development of marine ranching.Therefore,this research builds a marine ranching collaborative innovation system with multi-agent participation.Evolutionary game theory is used to analyze strategic choices of all parties and the conditions of system equilibrium,and numerical simulation is used to analyze the effect of relevant factors.This paper integrates the benefits from the improvement of environmental friendliness into the payoff matrix,and explains the significance of collaborative innovation to the development of marine ranching from the perspective of ecological environment.The results showed:the participation willingness of marine ranching enterprises is positively related to open innovation subject,while the participation willingness of the other two parties is negatively related to the government;The incentive effect of collaboration is negatively correlated with the government’s will,positively correlated with the other two parties;The incentive effect of government subsidies positively affects the willingness of the three parties to participate.Finally,suggestions are provided for each participant to maintain the strategic choice of marine ranching collaborative innovation system.
基金supported by the National Key Research and Development Program of China[Grant No.2017YFE0116100]the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China[Grant No.KYCX20_2821].
文摘This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for membrane desalination devices to produce fresh water.A new exhaust-gas heat exchanger of fins and tube,with a reinforced heat transfer tube section,unequal spacing fins,a mixing zone between the fin groups and four routes tube bundle,was designed.Numerical simulations were also used to provide reference information for structural design.Experiments were carried out for exhaust gas waste heat recovery from a marine diesel engine in an engine test bench utilizing the heat exchanger.The experimental results show that the difference between heat absorption by water and heat reduction of exhaust gas is less than 6.5%.After the water flow rate was adjusted,the exhaust gas waste heat recovery efficiency was higher than 70%,and the exhaust-gas heat exchanger’s outlet water temperature was 55°C–85°C at different engine loads.This means that the heat recovery from the exhaust gas of a marine diesel engine meets the requirement to drive a membrane desalination device to produce fresh water for fishers working in small and medium-sized fishing vessels.
文摘Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation.The emission factor for nitrogen oxides is lower than what is typically found for marine gasoil but does not reach the tier III limit.The emissions of particulate matter are significantly lower than for fuel oils and similar to what is found for LNG engines.The main part of the particles can be found in the ultrafine range with the peak being at around 18 nm.About 93%of the particles are evaporated and absorbed when using a thermodenuder,and thus a large majority of the particles are volatile.Methanol is a potential future marine fuel that will reduce emissions of air pollutants and can be made as a biofuel to meet emission targets for greenhouse gases.
文摘This paper presents a simulator model of a marine diesel engine based on physical, semi-physical, mathematical and thermodynamic equations, which allows fast predictive simulations The whole engine system is divided into several functional blocks: cooling, lubrication, air, injection, combustion and emissions. The sub-models and dynamic characteristics of individual blocks are established according to engine working principles equations and experimental data collected from a marine diesel engine test bench for SIMB Company under the reference 6M26SRP1. The overall engine system dynamics is expressed as a set of simultaneous algebraic and differential equations using sub-blocks and S-Functions of Matlab/Simulink. The simulation of this model, implemented on Matlab/Simulink has been validated and can be used to obtain engine performance, pressure, temperature, efficiency, heat release, crank angle, fuel rate, emissions at different sub-blocks. The simulator will be used, in future work, to study the engine performance in faulty conditions, and can be used to assist marine engineers in fault diagnosis and estimation (FDI) as well as designers to predict the behavior of the cooling system, lubrication system, injection system, combustion, emissions, in order to optimize the dimensions of different components. This program is a platform for fault simulator, to investigate the impact on sub-blocks engine's output of changing values for faults parameters such as: faulty fuel injector, leaky cylinder, worn fuel pump, broken piston rings, a dirty turbocharger, dirty air filter, dirty air cooler, air leakage, water leakage, oil leakage and contamination, fouling of heat exchanger, pumps wear, failure of injectors (and many others).
基金Supported by Shanghai Municipal Commission of Economy and Informatization of China(Grant Nos.201001007,2013000016)
文摘Longitudinal vibration,torsional vibration and their coupled vibration are the main vibration modes of the crankshaft-sliding bearing system.However,these vibrations of the propeller-crankshaft-sliding bearing system generated by the fluid exciting force on the propeller are much more complex.Currently,the torsional and longitudinal vibrations have been studied separately while the research on their coupled vibration is few,and the influence of the propeller structure to dynamic characteristics of a crankshaft has not been studied yet.In order to describe the dynamic properties of a crankshaft accurately,a nonlinear dynamic model is proposed taking the effect of torsional-longitudinal coupling and the variable inertia of propeller,connecting rod and piston into account.Numerical simulation cases are carried out to calculate the response data of the system in time and frequency domains under the working speed and over-speed,respectively.Results of vibration analysis of the propeller and crankshaft system coupled in torsional and longitudinal direction indicate that the system dynamic behaviors are relatively complicated especially in the components of the frequency response.For example,the 4 times of an exciting frequency acting on the propeller by fluid appears at 130 r/min,while not yield at 105 r/min.While the possible abnormal vibration at over-speed just needs to be vigilant.So when designing the propeller shafting used in marine diesel engines,strength calculation and vibration analysis based only on linear model may cause great errors and the proposed research provides some references to design diesel engine propeller shafting used in large marines.
基金performed within the Strategic Research Plan of the Centre for Marine Technology and Ocean Engineering(CENTEC)financed by Portuguese Foundation for Science and Technology(Fundacao para a Ciência e Tecnologia(FCT)),under contract UID/Multi/00134/2013-LISBOA-01-0145-FEDER-007629。
文摘Optimization procedures are required to minimize the amount of fuel consumption and exhaust emissions from marine engines.This study discusses the procedures to optimize the performance of any marine engine implemented in a 0D/1D numerical model in order to achieve lower values of exhaust emissions.From that point,an extension of previous simulation researches is presented to calculate the amount of SOx emissions from two marine diesel engines along their load diagrams based on the percentage of sulfur in the marine fuel used.The variations of SOx emissions are computed in g/k W·h and in parts per million(ppm)as functions of the optimized parameters:brake specific fuel consumption and the amount of air-fuel ratio respectively.Then,a surrogate model-based response surface methodology is used to generate polynomial equations to estimate the amount of SOx emissions as functions of engine speed and load.These developed non-dimensional equations can be further used directly to assess the value of SOx emissions for different percentages of sulfur of the selected or similar engines to be used in different marine applications.
基金Open access funding provided by Universita degli Studi di Napoli Federico II within the CRUI-CARE Agreement.
文摘In this study,a model is developed to simulate the dynamics of an internal combustion engine,and it is calibrated and validated against reliable experimental data,making it a tool that can effectively be adopted to conduct emission predictions.In this work,the Ricardo WAVE software is applied to the simulation of a particular marine diesel engine,a four-stroke engine used in the maritime field.Results from the bench tests are used for the calibration of the model.Finally,the calibration of the model and its validation with full-scale data measured at sea are presented.The prediction includes not only the classic engine operating parameters for a comparison with surveys but also an estimate of nitrogen oxide emissions,which are compared with similar results obtained with emission factors.The calibration of the model made it possible to obtain an overlap between the simulation results and real data with an average error of approximately 7%on power,torque,and consumption.The model provides encouraging results,suggesting further applications,such as in the study on transient conditions,coupling of the engine model with the ship model for a complete simulation of the operating conditions,and optimization studies on consumption and emissions.The availability of the emission data during the sea trial and validated simulation results are the strengths and novelties of this work.
文摘Based on the ArcGIS geographic information system and the ORACLE database management system,this paper reports our studies on the technology of Marine Engineering Geological Exploration Information System(MEGEIS). By analyzing system structure,designing function modules and discussing data management,this paper systematically proposes a framework of technol-ogy to integrate,manage,and analyze the seabed information comprehensively. Then,the technology is applied to the design and development of the Bohai Sea Oilfield Paradigm Area Information System. The system can not only meet the practical demands of marine resources exploration and exploitation in the Bohai Sea oilfield,but also serve as a preparatory work in theory and technology for the realization of the 'Digital Seabed'.
文摘NIN has developed a new type of Ti alloy. It is suitable for structure pieces applied in hightemperature and high-pressure water/steam conditions. Its nominal composition is Ti-4Al-2V. In this paper, its microstructure, mechanical properties and corrosion resistance were studied in detail.
基金the Major Program(Grant No.59990470) of National Natural Science Foundation of Chinathe General Program(Grant No.50175088) of National Natural Science Foundation of China.
文摘This paper deals with the coupling problem between the dynamic behaviors and the tribological behaviors of the piston-liner systems in multi-cylinder internal combustion engines. Firstly, based on the correction of some errors in the equation of piston secondary motion, which have been employed by many authors for several years, a detailed mathematical model for the coupling problem between the dynamical and tribological behaviors in the piston-liner systems of multi-cylinder internal combustion engines is presented. Secondly, the lubrication and friction between the liner and piston in each cylinder is included applying the average flow model of the Reynolds equation. Thirdly, the vibration of each liner is computed through the finite element model of a four-cylinder engine block, by which not only the liner motions caused by the block vibration but also the local vibration and the local static deformation of each liner can be figured out and taken into account. Through theoretical analysis and computation, some conclusions can be drawn as: 1) Both the liner vibration and piston motion are different for different cylinder in a multi-cylinder internal combustion engine, and hence different piston-liner systems will have different tribological behaviors. 2) Different liners have coincident dynamic response on the whole, especially for the lower frequency components. However, differences still exist among the vibrations of different liners, and these differences are mainly owing to the higher frequency components. 3) The impacts of liner vibrations on the tribological behaviors in piston-liner systems are primarily ascribed to its higher frequency components.
文摘Human error,an important factor,may lead to serious results in various operational fields.The human factor plays a critical role in the risks and hazards of the maritime industry.A ship can achieve safe navigation when all operations in the engine room are conducted vigilantly.This paper presents a systematic evaluation of 20 failures in auxiliary systems of marine diesel engines that may be caused by human error.The Cognitive Reliability Error Analysis Method(CREAM)is used to determine the potentiality of human errors in the failures implied thanks to the answers of experts.Using this method,the probabilities of human error on failures were evaluated and the critical ones were emphasized.The measures to be taken for these results will make significant contributions not only to the seafarers but also to the ship owners.
基金Supported by the National Natural Science Foundation of China under Grant No.60774072Heilongjiang Province Natural Science Foundation under Grant No.F01-24Harbin Engineering University Basic Research Foundation under Grant No. HEUFP05014.
文摘The frequency stability of a marine power system is determined by the dynamic characteristic of the diesel engine speed regulation system in a marine power station. In order to reduce the effect of load disturbances and improve the dynamic precision of a diesel engine speed governor, a controller was designed for a diesel engine speed regulation system using H2 control theory. This transforms the specifications of the system into a standard H2 control problem. Firstly, the mathematical model of a diesel engine speed regulation system using an H2 speed governor is presented. To counter external disturbances and model uncertainty, the design of an H, speed governor rests on the problem of mixed sensitivity. Computer simulation verified that the H2 speed governor improves the dynamic precision of a system and the ability to adapt to load disturbances, thus enhancing the frequency stability of marine power systems.
文摘In power production,gas turbines are commonly used components that generate high amount of energy depending on size and weight.They function as integral parts of helicopters,aircrafts,trains,ships,electrical generators,and tanks.Notably,many researchers are focusing on the design,operation,and maintenance of gas turbines.The focal point of this paper is a DEMATEL approach based on fuzzy sets,with the attempt to use these fuzzy sets explicitly.Using this approach,the cause–effect diagram of gas turbine failures expressed in the literature is generated and aimed to create a perspective for operators.The results of the study show that,"connecting shaft has been broken between turbine and gear box"selected the most important cause factor and"sufficient pressure fuel does not come for fuel pump"is selected the most important effect factor,according to the experts.
文摘Corpus Christi, Texas, is a growing urban area with a busy port and a petrochemical industrial base that is currently in compliance with the US Environmental Protection Agency’s (EPA) National Ambient Air Quality Standards (NAAQS) for ozone. However, the Texas Commission on Environmental Quality (TCEQ) has classified this urban airshed as a near non-attainment area. A comprehensive annual air emission inventory based on marine engines activity was developed for the years of 2006-2009 for the Port of Corpus Christi, Texas using recent EPA approved methodology. A regional-scale photochemical model Comprehensive Air Modeling system with extensions (CAMx) was used to evaluate the impact of these emissions on the ground level ozone concentrations by zeroing out the emissions and employing Direct Decoupled Method (DDM) for sensitivity analysis to estimate the 8-hour ozone sensitivity coefficients due to NOx and VOC emissions from marine engines. The analysis has shown a localized increase of up to 7.8 ppb in the 8-hour ozone concentration very close to the port premises and a decrease of about 1.73 ppb further downwind. Ozone sensitivity analysis using DDM on the 8-hour ozone concentrations showed a higher sensitivity to NOx emissions. Thus, any NOx related controls of marine engines will benefit local urban and regional ozone levels.
文摘According to the conductivity test results,it is found that oil conductivity increases with an increasing additive content,and the turbidity of engine oil is also augmented with an increasing additive content.After testing the turbidity and stability of oils containing the typical conventional calcium sulfonate,the overbased calcium sulfonate and the mixture of the above two calcium sulfonates,the results show that at the same amount of additives used,the oil with a higher turbidity demonstrated a worse stability.A nonionic dispersant that was added into lube oils at a definite concentration could improve the detergent compatibility.For this reason,the sediment volume in three kinds of oils all decreased obviously,resulting in successful improvement of storage stability of marine engine oils.
文摘Condition-based maintenance based on fault prediction has been widely concerned by the industry. Most of the contributions on fault prediction are based on various sensor data and mathematical models of the equipment. The complexity of the model and data signal is the key factor affecting the practicability of the model. In addition, even for the same type and batch of equipment, the manufacturing process, operation environment and other factors also affect the model parameters. In this paper, a series event model is conducted to predict the fault of marine diesel engines. Numerical example illustrates that the proposed event model is feasible.
文摘The existing marine diesel engine fault diagnosis methods mainly have the problems of model complexity, large amount of calculation, and unable to carry out real-time fault diagnosis of diesel engine. In this paper, a simple and practical approach to detect faults of marine diesel engine is studied. According to a set of sensing data, the fitting equation of each parameter changing with the running state of diesel engine was fitted statistically. Then, the threshold range of each parameter changing with the running state of diesel engine was fitted. During fault diagnosis, the real-time parameters of the sensor in the current running state were calculated according to the real-time running data. If the parameters exceed the threshold range, it is abnormal operation. Because the sensor signal corresponds to the operation status of each specific component, the abnormal evaluation directly indicates the specific fault. Experimental results show that the method has a good practical effect.
文摘This study aims to determine the awareness and opinions on Clean Air Act among marine engineering students at maritime university,specifically,John B.Lacson Foundation Maritime University-Molo,Iloilo City,Philippines.The participants of this study were 30 marine engineering students of the maritime university,especially JBLFMU-Molo for school year 2014-2015.Participants of the study were enrolled at the College of Maritime Education,JBLFMU-Molo,Iloilo City,Philippines.The researchers employed quantitative research design.The respondents’comments,suggestions,observations,and remarks on the perceived awareness and opinions on Clean Air Act were captured in this study.After gathering the qualitative information,the researchers classified and categorized the write-ups of the respondents into different categories.The results reveal that the participants of the present study were aware of the Clean Air Act as an entire group and when classified according to different categories.Most of the participants said that Clean Air Act protects the environment,followed by the participants who said that Clean Air Act can prevent air pollution.Next,in rank,the participants who said“it is good because you can go everywhere to inhale fresh air,followed by participants who said Clean Air Act can reduce the things that can harm the ozone layer,the last participants said that they never heard of Clean Air Act.
文摘With the emphasis on energy and environmental protection,energy-conservation and emission-reduction become vital issues for industrial development.Moreover,with the development of legislation on marine environment,the marine diesel engine has become focusing on energy saving and emission reduction for ships.For low-speed diesel engines under high load,waste heat from exhaust gas can be recovered by the compact and efficient gas turbine.In this paper,the matching design research between low speed diesel engine and gas turbine is carried out.To balance efficiency and compactness,the impeller was adjusted and generated by ANSYS BLADEGEN,based on 1D thermodynamic design.And the 1D calculation is similar to the ANSYS CFX simulation result:the total-static efficiency is 73.8%compared to 76.7%.Moreover,the flow separation happened at the impeller suction side and created vortex due to the high incidence angle.The off-design operating point simulation of the turbine shows though the pressure ratio increase will cause the efficiency to decline a little,the total shaft power rises.In sum,this paper worked out a power turbine suitable for a low-speed diesel engine according to the turbine character matching design and simulation,which provides foundation to the construction of a steady operation of waste heat recovery system for marine diesel engine.
文摘The article describes an electronic database of selected marine piston combustion engines created for diagnostic purposes. The database was made for vessels of the biggest Polish shipowner. It is used for archiving and comparing measured parameters of diagnosed engines with model parameters. To facilitate the search for and use of required data, they have been collected and catalogued. For this purpose the database has been prepared by using a computer program included in the Microsoft Office suite. The database search relies on the details concerning the type of vessel. The fields displayed include such items as the year and place of construction, the parameters of the ship, flag, etc.. For each vessel special forms are available for main and auxiliary engines, enabling easy and quick check of the necessary parameters during operation of the engine. The database contains parameters of the main propulsion and auxiliary engines, as well as model characteristics to help determine the diagnostics, prognosis and genesis.