The need to mitigate downtime in<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">marine vessels arising </span><span style="...The need to mitigate downtime in<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">marine vessels arising </span><span style="font-family:Verdana;">from propulsion system failures has led ship operating companies to devote enormous resources for</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">research based solutions. This paper applied duration models to determine</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">failure probabilities of shaft and gearbox systems in service boats. Using dockyard’s event history data on boat</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">repairs and maintenance, we applied Kaplan Meier hazard and survival curves to analyse</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">probability of failure</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">of shaft and gearbox</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">systems in supply, crew and tug boats. We found that average time to shaft and gearbox failure was 8.33, 5.23 and 5.21 months for tug, supply and crew boats respectively. The hazard plots however, showed that supply boats had higher probability of failure than crew boats and then tug boats in that order. Further analysis using Cox regression model showed that </span><span style="font-family:Verdana;">t</span><span style="font-family:Verdana;">he boats’ shaft and gearbox system failures were significantly affected by level of lubrication oil, stress corrosion cracking and impacts on the propul</span><span style="font-family:Verdana;">sion system’s components. The paper proposes that</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">design of maintenan</span><span style="font-family:;" "=""><span style="font-family:Verdana;">ce </span><span style="font-family:Verdana;">schedules for service boats should take the following into consideration: </span><span style="font-family:Verdana;">1)</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">estimated survival limits or failure times of propulsion system’s shaft and gearboxes</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> 2) significant risk factors that affect failure mode of</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">the propulsion system components.</span>展开更多
This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing th...This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing the IASFD,a propulsion shafting test rig for the longitudinal vibration control is built.Longitudinal vibration control experiments of the propulsion shafting are carried out under different magnitude and frequency of the excitation force.The results show that both IASFD elastic support and IASFD elastic damping support have excellent vibration attenuation characteristics,and can effectively suppress the longitudinal vibration of the shaft system in a wide frequency range.However,IASFD elastic damping support has a more significant vibration reduction effect than the other supports,and increasing the damping of the system has obvious effect on reducing the shafting vibration.For an excitation force of 45 N,the maximum reduction of the vibration amplitude is 89.16%.Also,the vibration generated by the resonance phenomenon is also significantly reduced.展开更多
In order to study hydrodynamic performance of a propeller in the free surface, the numerical simulation and open-water experiments are carried out with varying shaft depths of propeller. The influences of shaft depths...In order to study hydrodynamic performance of a propeller in the free surface, the numerical simulation and open-water experiments are carried out with varying shaft depths of propeller. The influences of shaft depths of a propeller on thrust and torque coefficient in calm water are mainly studied. Meanwhile, this paper also studies the propeller air-ingestion under special working conditions by experiment and theoretical calculation method, and compares the calculation results and experimental results. The results prove that the theoretical calculation model used in this paper can imitate the propeller air-ingestion successfully. The successful phenomenon simulation provides an essential theoretical basis to understand the physical essence of the propeller air-ingestion.展开更多
文摘The need to mitigate downtime in<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">marine vessels arising </span><span style="font-family:Verdana;">from propulsion system failures has led ship operating companies to devote enormous resources for</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">research based solutions. This paper applied duration models to determine</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">failure probabilities of shaft and gearbox systems in service boats. Using dockyard’s event history data on boat</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">repairs and maintenance, we applied Kaplan Meier hazard and survival curves to analyse</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">probability of failure</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">of shaft and gearbox</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">systems in supply, crew and tug boats. We found that average time to shaft and gearbox failure was 8.33, 5.23 and 5.21 months for tug, supply and crew boats respectively. The hazard plots however, showed that supply boats had higher probability of failure than crew boats and then tug boats in that order. Further analysis using Cox regression model showed that </span><span style="font-family:Verdana;">t</span><span style="font-family:Verdana;">he boats’ shaft and gearbox system failures were significantly affected by level of lubrication oil, stress corrosion cracking and impacts on the propul</span><span style="font-family:Verdana;">sion system’s components. The paper proposes that</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">design of maintenan</span><span style="font-family:;" "=""><span style="font-family:Verdana;">ce </span><span style="font-family:Verdana;">schedules for service boats should take the following into consideration: </span><span style="font-family:Verdana;">1)</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">estimated survival limits or failure times of propulsion system’s shaft and gearboxes</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> 2) significant risk factors that affect failure mode of</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">the propulsion system components.</span>
基金Supported by the National Science and Technology Major Project(No.2017-Ⅳ-0010-0047)Key Laboratory Fund for Ship Vibration and Noise(No.614220406020717)+1 种基金China Postdoctoral Science Foundation Funded Project(No.2020M670113)the Fundamental Research Funds for the Central Universities(No.JD2003)。
文摘This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing the IASFD,a propulsion shafting test rig for the longitudinal vibration control is built.Longitudinal vibration control experiments of the propulsion shafting are carried out under different magnitude and frequency of the excitation force.The results show that both IASFD elastic support and IASFD elastic damping support have excellent vibration attenuation characteristics,and can effectively suppress the longitudinal vibration of the shaft system in a wide frequency range.However,IASFD elastic damping support has a more significant vibration reduction effect than the other supports,and increasing the damping of the system has obvious effect on reducing the shafting vibration.For an excitation force of 45 N,the maximum reduction of the vibration amplitude is 89.16%.Also,the vibration generated by the resonance phenomenon is also significantly reduced.
基金financially supported by the National Natural Science Foundation of China(Grant No.41176074)the Fundamental Research Funds for the Central Universities(Grant No.HEUCFT1001)the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20102304120026)
文摘In order to study hydrodynamic performance of a propeller in the free surface, the numerical simulation and open-water experiments are carried out with varying shaft depths of propeller. The influences of shaft depths of a propeller on thrust and torque coefficient in calm water are mainly studied. Meanwhile, this paper also studies the propeller air-ingestion under special working conditions by experiment and theoretical calculation method, and compares the calculation results and experimental results. The results prove that the theoretical calculation model used in this paper can imitate the propeller air-ingestion successfully. The successful phenomenon simulation provides an essential theoretical basis to understand the physical essence of the propeller air-ingestion.