点火正时和 EGR 对甲醇发动机爆震特性影响研究  

Effects of Ignition Timing and EGR on Methanol Engine Knocking Performance

作　　者：丁明峰[1] 洪伟[1] 解方喜[1] 钟兵[1] 刘伟 

机构地区：[1] 吉林大学 汽车仿真与控制国家重点实验室 [2] 福特汽车工程研究 南京 有限公司

出　　处：《汽车技术》2014年第8期50-55,共6页Automobile Technology

基　　金：国家高技术研究发展计划“863”资助项目(2012AA111702);国家自然科学基金资助项目(51276080)、(51206059)

摘　　要：以一台改装的点火式甲醇发动机为研究对象,通过控制进气压力保证每循环油量为定值,并且按过量空气系数为1进行燃烧,应用CFD软件Fire在易发生爆震的低速大负荷工况分别研究点火正时、EGR率和EGR温度对该发动机爆震指数的影响。结果表明:推迟点火正时可以使压力波动出现在缸压的下降段,有效改善爆震;随EGR率增加,初始爆震指数变化并不明显,之后爆震指数迅速下降;随EGR温度的降低,爆震指数也随之减小;上述3种方式中使用冷EGR降低爆震对缸压的影响最小。A modified spark ignition methanol engine is adopted as research object, and by controlling the inlet pressure to ensure that the fuel injection quantity is fixed value each cycle and combust with the excess air coefficient of 1. Selecting the low speed and high load condition in which knocking easily occur, to investigate the effect of ignition timing, EGR ratio and EGR temperature on knocking index by the CFD software FIRE. The results indicate that delaying the ignition timing can keep the pressure fluctuations appear in the decline period of cylinder pressure, which effectively improve knocking; with the increase of EGR ratio, the initial knocking index change is not obvious, afterwards, knocking index falls rapidly; whereas with the decrease of EGR temperature, the knocking index declines accordingly; among the above three methods, cold EGR has the minimal impact to the cylinder pressure.

关 键 词：甲醇发动机 爆震 点火正时 

分 类 号：U464.114[机械工程—车辆工程]