Abstract Methanol is a promising fuel to suppress knock for improving engine compression ratio. In this study, knock combustion was simulated in a downsized spark engine with different methanol-isooctane blends. The pressure and temperature evolution profiles of these mixtures during knocking were obtained and showed that knock here originated from the intensive interaction between pressure wave and the heat released from auto ignition, which leaded to some other hot-spots. While using 5% methanol, the intensity of chemical reactions was reduced sharply comparing with that of pure isooctane, which lowered the heat release rate and successfully reduced the intensity of knock. The reactions below temperature of 950 K gradually become slower with methanol content increasing to 10% and 15%. However, the accelerated reactions made fuel consumed faster once it exceeded this certain temperature limit, which leaded a slight increase in knock intensity. The outcome of this work is potentially useful for comprehending the knock process of methanol.

中文翻译：

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小型SI发动机甲醇-异辛烷混合物爆震燃烧数值分析

摘要 甲醇是一种很有前景的燃料，可以抑制爆震，提高发动机压缩比。在这项研究中，在具有不同甲醇-异辛烷混合物的小型火花发动机中模拟了爆震燃烧。获得这些混合物在爆震过程中的压力和温度演变曲线，表明这里的爆震源于压力波和自动点火释放的热量之间的强烈相互作用，这导致了一些其他热点。使用5%甲醇时，化学反应强度较纯异辛烷显着降低，降低了放热速率，成功降低了爆震强度。随着甲醇含量增加到 10% 和 15%，950 K 以下的反应逐渐变慢。然而，一旦超过此特定温度限制，加速反应会使燃料消耗更快，从而导致爆震强度略有增加。这项工作的结果可能有助于理解甲醇的爆震过程。