二冲程柴油机扫气过程数值模拟分析  

Numerical Simulation Analysis on Scavenging Processes of Two-Stroke Diesel Engine

作　　者：赵峰[1,2] 于洪亮[1,3] 段树林[1] ZHAO Feng;YU Hongliang;DUAN Shulin(Marine Engineering College,Dalian Maritime University,Liaoning Dalian 116026,China;Department of Marine Engineering, Jiangsu Maritime Institute,Nanjing 211170,China;Marine Engineering Institute,Jimei University,Fujian Xiamen 361021,China)

机构地区：[1]大连海事大学轮机工程学院,辽宁大连116026 [2]江苏海事职业技术学院轮机工程学院,南京211170 [3]集美大学轮机工程学院,福建厦门361021

出　　处：《船舶工程》2018年第11期61-65,共5页Ship Engineering

基　　金：江苏海院千帆新锐课题:船用柴油机三维教学模型的研发(XR1502);江苏海院重点课题:采用EGR技术降低船舶柴油机NOX排放的研究(2017KJZD-01)

摘　　要：建立6S50MC二冲程柴油机气缸直流扫气三维模型,利用三维流体动力学(CFD)仿真软件FIRE,研究扫气口设计参数对换气过程的影响,特别是对排气口开启初期废气倒流现象有了更精确的模拟和合理的解释。此外,对不同气口设计方案下的缸内残余废气浓度随曲轴转角的变化过程作了细致描述,并针对扫气口仰角变化对换气过程的影响作了进一步探讨。研究结果表明:二冲程柴油机排气阀开启时刻对扫气初期的废气倒流现象影响较大,且开启时刻越迟,废气倒流越明显;二冲程柴油机扫气口设计仰角越大,越利于初期扫气,但新旧气体混合也比较严重,对后期扫气不利。因此,对于额定转速较高的二冲程柴油机,由于扫气过程时面值较小,适合设计一定的仰角以增大初期扫气量;反之,取消扫气口仰角,则更有利于提高二冲程柴油机整个换气过程的换气质量。The article mainly describes the application of FIRE,the three-dimensional computational fluid dynamics (CFD)software,in the 6S50MC series large two-stroke diesel engine.The influence of intake design parameters on the scavenging process is studied,and especially have an accurate simulation and reasonable explanation on the phenomenon of exhaust gas back to scavenging box of the early period.Additionally,the article gives a detail description of the changing process of different air intake design of the cylinder under,the gas flow field and exhaust gas concentration with the crank angle.Further study has been done on the effect of the changes of the intake ports in elevation varying with the scavenging process.The results indicate that the exhaust valve opening moment of the two-stroke diesel engine has a great influence on the abnormal backward flow of exhaust gas in the early stage,and the later the opening moment is,the more obvious the reflux of exhaust gas is.The larger of the elevation angle of the scavenging port of the two-stroke diesel engine,the more favorable to the initial scavenging.However,the mixture of fresh and exhaust gases is also relatively serious, which is unfavorable to the later scavenging.Therefore,for a two-stroke diesel engine with a higher rated speed, the time-area value is small during scavenging,So it is suitable to design a certain elevation angle to increase the initial fresh gas.On the contrary,eliminating the scavenging port elevation angle is more conducive to improving the gas scavenging quality of the two-stroke diesel engine during the entire gas-change process.

关 键 词：船用柴油机 扫气过程 数值模拟 分析 

分 类 号：U664.121[交通运输工程—船舶及航道工程] TK42[交通运输工程—船舶与海洋工程]