二甲醚掺混对氨高温着火延迟期的影响  

Effects of Dimethyl Ether Addition on the High Temperature IgnitionDelays of Ammonia

作　　者：张齐英 姜雪 刘曦宇 张天琦 黄佐华[1] ZHANG Qiying;JIANG Xue;LIU Xiyu;ZHANG Tianqi;HUANG Zuohua(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学能源与动力工程学院,西安710049

出　　处：《西安交通大学学报》2023年第9期79-86,共8页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(51876164);航空航天结构力学及控制国家重点实验室开放课题资助项目(MCMS-E-0323K01)。

摘　　要：针对氨燃料化学反应活性低、直接在发动机上使用较难实现可靠着火及高效燃烧的问题,开展了添加高反应活性燃料二甲醚改善氨着火性能的实验及模拟研究。利用激波管实验装置获得了压力为1 MPa、温度在1 079~1 667 K范围内和当量比为1条件下氨/二甲醚燃料的着火延迟期的实验数据,揭示了添加二甲醚后的着火促进效果;利用实验数据评价了不同化学反应动力学模型对氨/二甲醚燃料着火延迟期的预测表现;基于Dai模型开展了化学反应动力学理论分析,明晰了掺混二甲醚对反应路径、着火敏感反应和自由基产率的影响机制。实验结果表明,高温下掺混二甲醚对氨着火延迟期有显著的非线性促进作用,实际应用中仅掺混少量即可达到着火调控效果。化学反应动力学分析结果表明:添加摩尔分数为5%的二甲醚对氨的化学反应路径影响较小,着火过程中两种燃料之间存在自由基的竞争;添加二甲醚在着火初期提高了OH自由基生成反应的产率,从而显著缩短了着火延迟期。该研究可为氨燃料发动机的着火调控和性能优化提供参考。Focusing on the problem that ammonia with low chemical reactivity has difficulty achieving reliable ignition and efficient combustion in engine applications,experimental and simulation studies were conducted in the paper to understand the effects of adding active additives,namely dimethyl ether(DME),on the ignition delay times of ammonia.Firstly,experimental measurements of stoichiometric ammonia/DME mixtures were conducted in a shock tube at temperatures of 1079—1667 K and with a pressure of 1 MPa to reveal that DME addition can shorten the ignition delay times.Secondly,predictions of the literature chemical kinetic models on the ignition delay times of ammonia/DME mixtures were verified against the experimental results.Thirdly,chemical kinetics analyses,including reaction pathway analysis,sensitivity analysis,and free-radical ROP analysis,were carried out to understand the influence of DME addition on the ignition delay times of ammonia using the Dai model.Experimental results indicate that the addition of DME remarkably promotes the ignition delay of ammonia nonlinearly at high temperatures,revealing that only a small amount of DME addition can reduce the ignition delay times in practical applications.Chemical kinetic analysis reveals that the addition of 5%DME has a limited effect on the reaction pathway of ammonia and the two fuels compete for free radicals during the ignition;DME addition can accelerate the production rate of the OH radical in the early stage of the ignition,thus significantly shortening the ignition delay times.The research can provide a reference for the ignition improvement and performance optimization of ammonia-fueled engines.

关 键 词：着火延迟期 氨 二甲醚 化学反应动力学 

分 类 号：TK40[动力工程及工程热物理—动力机械及工程]