Abstract To provide fundamental insights into the ignition enhancement of methanol (MeOH) by the addition of the more reactive dimethyl ether (DME), computational parametric studies were conducted in a one-dimensional counterflow fuel versus air mixing layer configuration with the incorporation of detailed chemistry and transport. Various computational analysis tools based on the computational singular perturbation (CSP) framework were employed for detailed identifications of complex chemical pathways. CSP tools were also used to develop a 43-species skeletal mechanism for efficient computation of ignition of methanol-DME blends at engine conditions. The overarching practical question was the extent to which the addition of DME improves the ignitability of the methanol. As a baseline analysis, the results of a uniform temperature condition at 850 K showed that the low temperature chemistry associated with the DME fuel was highly effective in promoting autoignition. The increase in the oxidizer side temperature was found to diminish the ignition enhancement by DME blending, as the overall reactivity increases and the dominant chemical pathways become shifted towards the high temperature reactions. Finally, the strain rate effect on the ignition delay time was found to be significant for the pure methanol case, and then the effect diminishes as the amount of DME addition increases. This behavior was explained by examining the spatial locations of the ignition kernels and the Damkohler number history for different strain rate conditions.

中文翻译：

---

通过在逆流混合层中添加二甲醚增强甲醇自燃的计算分析

摘要 为了通过添加更具反应性的二甲醚 (DME) 对甲醇 (MeOH) 的点火增强提供基本见解，在结合详细化学的一维逆流燃料与空气混合层配置中进行了计算参数研究。和运输。基于计算奇异扰动 (CSP) 框架的各种计算分析工具被用于详细识别复杂的化学途径。CSP 工具还用于开发 43 种骨架机制，以有效计算发动机条件下甲醇-二甲醚混合物的点火。首要的实际问题是添加二甲醚在多大程度上提高了甲醇的可燃性。作为基线分析，850 K 均匀温度条件的结果表明，与 DME 燃料相关的低温化学物质在促进自燃方面非常有效。发现氧化剂侧温度的增加会减少 DME 混合引起的点火增强，因为整体反应性增加并且主要化学途径转向高温反应。最后，发现对于纯甲醇情况，应变速率对点火延迟时间的影响是显着的，然后随着 DME 添加量的增加，这种影响减弱。这种行为是通过检查点火核的空间位置和不同应变率条件下的 Damkohler 数历史来解释的。