Methanol as a fuel is gaining popularity due to its favorable properties and potential for sustainable production as bio- or electro-methanol. By operating according to the Spark-Ignited (SI) principle with a Three-Way Catalyst (TWC), low emissions can be achieved. The main phenomena limiting the efficiency of the SI engine when operating with stoichiometric mixtures are knock and, occasionally, pre-ignition. One method to suppress both knock and pre-ignition is water injection. This study explores the possibility of suppressing knock in-cycle using direct water injection for cycles with an elevated risk of knocking. The prediction was based on the observation that, at knock-limited operation, only cycles with the most advanced combustion phasing knock. Furthermore, at knock-limited loads, combustion predominantly consisted of a single combustion mode: deflagration. The results demonstrated partial knock suppression and allowed for a combustion phasing advancement of 1.5°at loads of 10 and 15 bar gross indicated mean effective pressure. The earliest practical point during the combustion cycle to confidently determine if knock will occur was when about 10%–20% of the fuel had been consumed. However, theoretically, in a best-case scenario, this could be as early as when 5% of the fuel was consumed. An experiment simulating pre-ignition also demonstrated the ability to detect such cycles and partially suppress the ensuing knock. A major limitation of the method is that the window between detecting a cycle with a high likelihood of knock and knock onset was less than 7°at 1000 rpm.

中文翻译：

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化学计量甲醇自燃和直接注水的循环中爆震抑制


甲醇作为燃料因其良好的特性和可持续生产生物或电甲醇的潜力而越来越受欢迎。通过根据火花点火 （SI） 原理使用三元催化剂 （TWC） 运行，可以实现低排放。在使用化学计量混合物运行时，限制 SI 发动机效率的主要现象是爆震，偶尔还会发生早燃。抑制爆震和早燃的一种方法是注水。本研究探讨了在敲击风险较高的循环中使用直接注水抑制爆震的可能性。该预测基于以下观察结果：在爆震限制操作中，只有具有最先进燃烧相位爆震的循环。此外，在爆震限制负载下，燃烧主要由单一燃烧模式组成：爆燃。结果表明，部分爆震抑制，并允许在 10 和 15 bar 总负载下燃烧相位前进 1.5°，指示平均有效压力。在燃烧循环中，要自信地确定是否会发生爆震，最早的实用时间点是当燃料消耗了大约 10%-20% 时。然而，从理论上讲，在最好的情况下，这可能最早在消耗 5% 的燃料时。模拟提前点火的实验也证明了检测此类循环并部分抑制随后的爆震的能力。该方法的一个主要局限性是，在 7 rpm 时，检测到极有可能爆震的循环和爆震开始之间的窗口小于 1000°。