Ship hull form of the underwater area strongly influences the resistance of the ship. The major factor in ship resistance is skin friction resistance. Bulbous bows, polymer paint, water repellent paint （highly water-...Ship hull form of the underwater area strongly influences the resistance of the ship. The major factor in ship resistance is skin friction resistance. Bulbous bows, polymer paint, water repellent paint （highly water-repellent wall）, air injection, and specific roughness have been used by researchers as an attempt to obtain the resistance reduction and operation efficiency of ships. Micro-bubble injection is a promising technique for lowering frictional resistance. The injected air bubbles are supposed to somehow modify the energy inside the turbulent boundary layer and thereby lower the skin friction. The purpose of this study was to identify the effect of injected micro bubbles on a navy fast patrol boat （FPB） 57 m type model with the following main dimensions： L=2 450 ram, B=400 mm, and T=190 mm. The influence of the location of micro bubble injection and bubble velocity was also investigated. The ship model was pulled by an electric motor whose speed could be varied and adjusted. The ship model resistance was precisely measured by a load cell transducer. Comparison of ship resistance with and without micro-bubble injection was shown on a graph as a function of the drag coefficient and Froude number. It was shown that micro bubble injection behind the mid-ship is the best location to achieve the most effective drag reduction, and the drag reduction caused by the micro-bubbles can reach 6%-9%.展开更多
高速客船发动机作为高速客船的心脏,满负荷运行时间长,运行温度高,因此其对发动机油的性能要求非常高。针对高速客船发动机的工况特点和润滑需求,研制生产了CK-4 Plus 10W-40柴油机油,并在2台具有代表性的高速客船发动机上开展超过1000 ...高速客船发动机作为高速客船的心脏,满负荷运行时间长,运行温度高,因此其对发动机油的性能要求非常高。针对高速客船发动机的工况特点和润滑需求,研制生产了CK-4 Plus 10W-40柴油机油,并在2台具有代表性的高速客船发动机上开展超过1000 h的应用性能验证研究。定期采样跟踪分析、船上实时监控分析以及发动机拆解观察的结果表明:CK-4 Plus 10W-40柴油机油具有优异的综合性能,完全满足高速客船发动机长换油周期的润滑需求。基于CK-4 Plus 10W-40柴油机油优异的综合性能表现,某公司10余艘高速客轮已全面推广使用CK-4 Plus 10W-40柴油机油,取得了良好经济效益。展开更多
Since trim and sinkage are significant while vessels are advancing forward with high speed, the predicted vessel resistance based on restrained model theory or experiment may not be real resistance of vessels during v...Since trim and sinkage are significant while vessels are advancing forward with high speed, the predicted vessel resistance based on restrained model theory or experiment may not be real resistance of vessels during voyage. It is necessary to take the influence of hull gesture into account for oredicting the resistance of high-speed ship. In the present work the resistance problem of high speed ship is treated with the viscous flow theory, and the dynamic mesh technique is adopted to coincide with variation of hull gesture of high speed vessel on voyage. The simulation of the models of S60 ship and a trimaran moving in towing tank with high speed are conducted by using the above theory and technique. The corresponding numerical results are in good agreement with the experimental data. It indicates that the resistance prediction for high speed vessels should take hull gesture into consideration and the dynamic mesh method proposed here is effective in calculating the resistance of high speed vessels.展开更多
基金Supported by the Directorate for Research and Community Service,University of Indonesia(RUUI Research Laboratory 2010),Jakarta,Indonesia
文摘Ship hull form of the underwater area strongly influences the resistance of the ship. The major factor in ship resistance is skin friction resistance. Bulbous bows, polymer paint, water repellent paint （highly water-repellent wall）, air injection, and specific roughness have been used by researchers as an attempt to obtain the resistance reduction and operation efficiency of ships. Micro-bubble injection is a promising technique for lowering frictional resistance. The injected air bubbles are supposed to somehow modify the energy inside the turbulent boundary layer and thereby lower the skin friction. The purpose of this study was to identify the effect of injected micro bubbles on a navy fast patrol boat （FPB） 57 m type model with the following main dimensions： L=2 450 ram, B=400 mm, and T=190 mm. The influence of the location of micro bubble injection and bubble velocity was also investigated. The ship model was pulled by an electric motor whose speed could be varied and adjusted. The ship model resistance was precisely measured by a load cell transducer. Comparison of ship resistance with and without micro-bubble injection was shown on a graph as a function of the drag coefficient and Froude number. It was shown that micro bubble injection behind the mid-ship is the best location to achieve the most effective drag reduction, and the drag reduction caused by the micro-bubbles can reach 6%-9%.
文摘高速客船发动机作为高速客船的心脏,满负荷运行时间长,运行温度高,因此其对发动机油的性能要求非常高。针对高速客船发动机的工况特点和润滑需求,研制生产了CK-4 Plus 10W-40柴油机油,并在2台具有代表性的高速客船发动机上开展超过1000 h的应用性能验证研究。定期采样跟踪分析、船上实时监控分析以及发动机拆解观察的结果表明:CK-4 Plus 10W-40柴油机油具有优异的综合性能,完全满足高速客船发动机长换油周期的润滑需求。基于CK-4 Plus 10W-40柴油机油优异的综合性能表现,某公司10余艘高速客轮已全面推广使用CK-4 Plus 10W-40柴油机油,取得了良好经济效益。
文摘Since trim and sinkage are significant while vessels are advancing forward with high speed, the predicted vessel resistance based on restrained model theory or experiment may not be real resistance of vessels during voyage. It is necessary to take the influence of hull gesture into account for oredicting the resistance of high-speed ship. In the present work the resistance problem of high speed ship is treated with the viscous flow theory, and the dynamic mesh technique is adopted to coincide with variation of hull gesture of high speed vessel on voyage. The simulation of the models of S60 ship and a trimaran moving in towing tank with high speed are conducted by using the above theory and technique. The corresponding numerical results are in good agreement with the experimental data. It indicates that the resistance prediction for high speed vessels should take hull gesture into consideration and the dynamic mesh method proposed here is effective in calculating the resistance of high speed vessels.
