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针对目前一些船舶在恶劣海况下遇到的加速问题,以及通过转速禁区时间过长的问题,从螺旋桨匹配和主机内部设计两方面进行原因分析。围绕转速禁区功率裕度,结合相关案例,从轻螺旋桨裕度、转速禁区及MAN主机输出扭矩能力等方面入手,提出改进措施。 相似文献
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The airside heat transfer and friction characteristics of seven interrupted fin-and-tube heat exchangers with hydrophilic coating under dehumidifying conditions are experimented. The effects of number of tube rows, fin pitch and inlet relative humidity on airside performance are analyzed. The test results show that the influence of fin pitch on the friction characteristic under dehumidifying conditions is similar to that under dry surface, and the friction factors decrease slightly with the increase of number of tube rows. The heat transfer performance decreases as fin pitch and number of tube rows increases. The heat transfer performance and the friction characteristic are independent of inlet relative humidity. Based on the test results, heat transfer and friction correlations in terms of the Colburn j factor and Fanning f factor, are proposed to describe the airside performance of the interrupted fin geometry with hydrophilic coating under dehumidifying conditions. The correlation of the Colburn j factor gives a mean deviation of 9.7%, while the correlation of the Fanning f factor shows a mean deviation of 7.3%. 相似文献
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本文将陀螺效应应用到船舶推进轴系的回旋振动计算中,在轴系回旋振动几何模型的基础上建立有、无陀螺效应的计算模型,并给出轴系回旋振动时的临界转速。文章选取5艘已设计完成的船舶推进轴系为实例,采用两种计算模型分析各自的回旋振动临界转速。结果表明,陀螺效应提高了船舶推进轴系回旋振动的临界转速,为设计过程中精确确定轴系的转速禁区给出了依据。 相似文献
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在那个黄沙蔽日、千里戈壁的黑非洲,在干旱盛行、烈日灼身的西撒哈拉沙漠,变化多端的天气里隐蔽着巨毒的蝮蛇、会喷血与变身的蜥蜴、还有爱吐口水的单峰骆驼,那是沙漠响马时有出没的地方,政府叛军以此为据点,土著聚集的村庄还曾流行过神秘的传染病——这条从欧洲、北非延伸而来的行车线,被商旅视为畏途,是真正意义上的生命禁区。 相似文献
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禁区之王,英文称“goal poacher”形容在足球场上出没于无形,却总能够在最正确的时刻出现在最正确的地点,完成最致命一击的球员。这类属于前锋的球员.他们有着出色的带球速度,也有令人眼花缭乱的假动作.并且.他们在禁区里有着超强的预判断能力以及精准的射门技术,化腐朽为神奇是他们最好的代名词。 相似文献
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