微型内燃机工况下C1-C4烷烃着火延迟数值模拟

摘要

The ignition delay time is a crucial parameter in the glow plug ignition of micro-internal combustion engine (MICE). The effects of important operating parameters, such as the fuel species (methane, ethane, propane and n-butane), the initial temperature (500 K ~ 1 000 K), the initial pressure (1 ~ 10 atm) and equivalence ratio (0.6 ~ 1.2), on the ignition delay times were carried out via numerical simulation with Chemkin-Pro software. In addition, the effects of the residual exhaust gas caused by halfway scavenging on the ignition delay times of n-butane/air mixtures were investigated. The result shows that n-butane is a suitable fuel for MICE with glow plug ignition because of its short ignition delay time. Meanwhile, the ignition delay time decreases with the increase of the initial temperature, pressure and equivalence ratio. Moreover, the residual exhaust gas causes an increase of the ignition delay time of n-butane/air mixtures, and components of the exhaust have separated influence on the ignition delay time due to their different thermal and the chemical kinetic effects.%燃料着火延迟时间对采用蓄热自着火方式的微型内燃机非常重要。利用Chemkin-Pro软件，分别对甲烷、乙烷、丙烷和正丁烷空气混合气在微型内燃机运行工况下进行着火延迟时间模拟计算，探究初始温度（500 K ~1000 K）、压力（1~10 atm）和当量比（0.6~1.2）对着火延迟时间的影响。同时分析了微型内燃机扫气不尽的尾气残留组分（N2、CO2和H2O）对正丁烷着火延迟时间的影响。结果表明：在四种燃料中，正丁烷的低温着火延迟特性最佳，是一种适合于采用蓄热自着火方式的微型内燃机燃料；初始温度、压力的提高和当量比的增大有利于燃料着火延迟时间的缩短；尾气残留使得燃料着火延迟时间变长，着火延迟特性变差，尾气各组分的热效应和基元反应对燃料着火延迟有着不同的影响机制。