马有福，王硕，陆鹏，朱奎，马浩.排气参数对水下排气柴油机防倒灌的影响[J].内燃机工程,2020,41(6):95-100.
排气参数对水下排气柴油机防倒灌的影响
Effects of Exhaust Parameter on Prevention of Water Backflow Intrusion in Diesels Exhausting Underwater
DOI：10.13949/j.cnki.nrjgc.2020.06.012
关键词:船用柴油机  水下排气  水倒灌  气液逆流极限
Key Words:marine diesel engine  exhausting underwater  water backflow  counter current flow limitation
基金项目:—
作者单位
马有福，王硕，陆鹏，朱奎，马浩 1.上海理工大学 能源与动力工程学院 上海市动力工程多相流动与传热重点实验室，上海 200093； 2.中国船舶集团有限公司第七一一研究所，上海 200090 
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摘要:通过数值模拟方法研究了船用柴油机排气温度与排气背压变化对水平布置排气管内气液两相逆流特性的影响。结果表明：在相同排气量下，排气温度升高会使水倒流减弱，降低水倒灌发生风险；排气背压增大会使水倒流增强，即增大水倒灌发生风险。除排气速度外，排气的密度、黏度等物性参数也对水下排气管内水倒灌的发生具有重要影响。因此在柴油机排气系统设计中，需考虑排气参数波动对防倒灌的影响；在基于Wallis数的防倒灌设计准则中，需进一步考虑排气黏度对气液逆流极限完全携带点的影响。
Abstract:In order to prevent marine diesel engine from a damage caused by the water pouring back into the diesel from the exhaust pipe, a numerical simulation study was performed on effects of fluctuations in exhaust temperature and exhaust back pressure on the counter current flow limitation in horizontal exhaust pipes. The result indicates that, under the condition of the same exhaust mass flow rate, the increase in exhaust temperature can weaken water backflow in exhaust pipes while the increase in exhaust back pressure can enhance water backflow. In other words, an increased exhaust back pressure can increase the risk of water intrusion accident while an increased exhaust temperature can not. Meanwhile, the result reveales that, in addition to the gas velocity, the properties of exhaust gas, such as the density and viscosity, have a significant influence on the occurrence of water backflow in exhaust pipes. Therefore, it is suggested to consider the effect of exhaust parameter fluctuation on the prevention of water backflow intrusion in the design of exhaust system, and to consider the effect of gas viscosity on the zero liquid penetration point into the prediction model which is often based on a Wallis number that does not include the viscosity of gas.
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