Effects of NOx addition on autoignition and detonation development in DME/air under engine-relevant conditions
Effects of NOx addition on autoignition and detonation development in DME/air under engine-relevant conditions
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在发动机相关条件下添加 NOx 对 DME/空气中自燃和爆炸发展的影响
DOI：
10.1016/j.proci.2018.06.063
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发表时间：
2019
影响因子：
3.4
通讯作者：
Chen Zheng
中科院分区：
文献类型：
--
作者：
Dai Peng;Chen Zheng
废气再循环（EGR）技术可以用于内燃机，以减少氮氧化物的排放，提高燃油经济性。同时，由于EGR中的NOx具有促进点火的作用，也会对尾气自燃和发动机爆震产生影响。在发动机相关条件下，研究了NOx添加对二甲醚(DME)/空气混合物自燃和爆轰发展的影响。同时进行了低温和高温化学的数值模拟。首先，评估和解释了NOx添加对负温度系数（NTC）机制的动力学影响。研究发现，NOx的加入主要通过提高OH的产量来促进低温和高温点火阶段。然后研究了不同NO添加量的NTC体系中局部NO积累和冷点诱导的自生反应锋传播。首次识别了包括局部NO积聚引起的爆轰在内的超声速自燃模式。这表明氮氧化物在废气中的局部积累可能导致EGR发动机的超爆震。引入声速与平均反应前传播速度之比的新参数来识别不同自燃模式下的状态。与以往研究中使用的传统对应参数相比，该新参数更为合适，因为它产生的爆轰发展曲线呈c形，几乎不受初始条件的影响。本研究的结果可能为使用EGR技术的发动机的爆震机制提供基本的见解。
Exhaust gas recirculation (EGR) technology can be used in internal combustion engines to reduce NOx emission and improve fuel economy. However, it also affects the end-gas autoignition and engine knock since NOx in EGR can promote ignition. In this study, effects of NOx addition on autoignition and detonation development in dimethyl ether (DME)/air mixture under engine-relevant conditions are investigated. Numerical simulation considering both low-temperature and high-temperature chemistry is conducted. First the kinetic effects of NOx addition on the negative temperature coefficient (NTC) regime are assessed and interpreted. It is found that NOx addition greatly promotes both low-temperature and high-temperature ignition stages mainly through increasing OH production. Then the autoignitive reaction front propagation induced by either local NO accumulation or a cold spot within NTC regime with different amounts of NO addition is investigated. For the first time, supersonic autoignition modes including detonation induced by local NO accumulations are identified. This indicates that local accumulation of NOx in end gas might induce super-knock in engines with EGR. A new parameter quantifying the ratio of sound speed to average reaction front propagation speed is introduced to identify the regimes for different autoignition modes. Compared to the traditional counterpart parameter used in previous studies, this new parameter is more suitable since it yields a detonation development regime in a C-shaped curve which is almost unaffected by the initial conditions. The results in this study may provide fundamental insights into knocking mechanism in engines using EGR technology.
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影响因子：
4.4
作者：
Burke, Ultan;Somers, Kieran P.;Curran, Henry J.
通讯作者：
Curran, Henry J.
DOI：
10.1016/j.proci.2016.07.054
发表时间：
2017
期刊：
--
影响因子：
--
作者：
Khanh Cung;A. Moiz;Xiucheng Zhu;Seong-Young Lee
通讯作者：
Khanh Cung;A. Moiz;Xiucheng Zhu;Seong-Young Lee
影响因子：
4.4
作者：
L. Bates;D. Bradley;Günter Paczko;N. Peters
通讯作者：
L. Bates;D. Bradley;Günter Paczko;N. Peters
影响因子：
4.4
作者：
H. El-Asrag;Y. Ju
通讯作者：
H. El-Asrag;Y. Ju
影响因子：
30.5
作者：
Richard L Gregory
通讯作者：
Richard L Gregory