甲醇—异辛烷/正庚烷混合燃料滞燃期特性的数值研究  

Numerical Study on Ignition Delay Period of Methanol-isooctane/n-heptane Blended Fuel

作　　者：王刚[1] 廖世勇[1] 刘训标[1] 

机构地区：[1]重庆通信学院电力工程系,重庆400035

出　　处：《车用发动机》2009年第4期7-15,共9页Vehicle Engine

基　　金：国家自然科学基金资助项目(50706058);重庆市自然科学基金资助项目(CSTC;2008BB6147)

摘　　要：基于甲醇、异辛烷和正庚烷的详细化学动力学机理,对甲醇、异辛烷、正庚烷及其构成的混合燃料的滞燃期进行了计算研究。研究表明:温度对滞燃期的影响最大,异辛烷和正庚烷燃烧有着明显的负温度系数现象,而甲醇燃烧则没有这一特征;对于甲醇—异辛烷/正庚烷混合燃料,当初始温度小于1000 K时,混合燃料滞燃期随甲醇含量的增加而延长,当初始温度大于1000 K时,混合燃料滞燃期随甲醇含量的增加而缩短;随着混合燃料中甲醇含量的增加,燃料滞燃期的负温度系数特性明显减弱,当甲醇摩尔分数大于85%时,混合燃料滞燃期的负温度系数现象消失;压力对滞燃期的影响也比较明显,在不同的初始温度下,压力对异辛烷和正庚烷滞燃期的影响程度不同;当量比对甲醇、异辛烷和正庚烷的影响特性不同,甲醇的滞燃期随当量比的增加而缩短,当初始温度小于1200 K时,异辛烷和正庚烷的滞燃期随当量比的增加而缩短,当初始温度大于1200 K时,其滞燃期随当量比的增加而延长。根据滞燃期的计算值,对滞燃期公式进行了改进,提出了可以准确计算异辛烷和正庚烷不同当量比燃烧时的滞燃期公式和可以计算甲醇、异辛烷、正庚烷混合燃料滞燃期的经验公式。The ignition delay periods of methanol, isooctane, n-heptane and their blended fuel were studied based on their detailed chemical kinetic mechanism. The results show that the initial temperature has the greatest influence on the ignition delay period. The combustion of isooctane and n-heptane has the negative temperature coefficient （NTC） characteristic, but that of methanol does not. For the methanol-isooctane/n-heptane blended fuel, with the increase of methanol fraction, the ignition delay period is prolonged when the initial temperature is lower than 1 000 K, but is shortened when higher than 1 000 K. Meanwhile, the negative temperature coefficient characteristic is weakened with the increase of methanol fraction and vanishes when the mole fraction of methanol is larger than 85%. The pressure also has great influence on the ignition delay period, and the influences of pressure on the ignition delay period of isooctane and n-heptane are different at different initial temperatures. Besides, the equivalence ratio has different influences on the ignition delay periods of methanol, isooctane and n-heptane. With the increase of equivalence ratio, the ignition delay period of methanol decreases, while that of n-heptane is shortened when the initial temperature is lower than 1 200 K, but is prolonged when higher than 1200 K. According to the calculated value of ignition delay period, the model of ignition delay period is improved. Finally, the formulas of calculating the ignition delay periods of isooctane and n-heptane at different equivalence ratios and methanol, isooctane and n-heptane blended fuel are put forward.

关 键 词：甲醇 异辛烷 正庚烷 混合燃料 滞燃期 数值计算 

分 类 号：TK407.9[动力工程及工程热物理—动力机械及工程]