Experimental investigation on detonation dynamics through a reactivity sink
Experimental investigation on detonation dynamics through a reactivity sink
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DOI：
10.1016/j.combustflame.2018.05.017
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发表时间：
2018-10
影响因子：
4.4
通讯作者：
Stéphane Boulal;P. Vidal;R. Zitoun;Takuya Matsumoto;A. Matsuo
中科院分区：
文献类型：
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作者：
Stéphane Boulal;P. Vidal;R. Zitoun;Takuya Matsumoto;A. Matsuo
本文报道了在初始温度和压力分别为290 K和20 kPa时，由化学计量丙烷-氧、氧和乙烷产生的非均匀混合物中爆轰动力学行为的实验研究。组成梯度平行于爆轰传播方向，等效比（ER）先从贫值减小，然后增大到富值。组成分布的特征与内质网汇的深度有关。梯度在50 × 50-mm2平方截面和665-mm总长度的腔室中产生。在预抽真空室中，混合组分按照密度递减的顺序分别通过室顶部的多孔板注入，以保证室的平面填充。然后利用光学氧传感器精确地控制非均匀分布作为时间的函数。Chapman-Jouguet （CJ）爆震通过3.6米长的驱动管在燃烧室底端传输。利用快速压力传感器、烟熏板和纹影图像以及高速摄像机来表征爆轰前缘的纵向速度、细胞结构和传输、失效和重新起爆机制。最浅的ER汇产生CJ爆轰的超临界传输模式，其速度和多细胞结构不断适应局部成分。最深的下沉导致亚临界行为，其特征是当内燃降低时激波火焰不耦合导致突然爆轰失效，而当内燃再次增加时没有爆轰重新起爆。中间下沉深度产生的临界行为是由膨胀的燃烧核和反射的横向马赫波产生的，然后是由SWACER回溯机制产生的。先前研究中使用的失效准则的详细描述可以很好地预测激波-火焰解耦的条件。
This article reports on an experimental investigation into dynamical behaviours of detonation in non-uniform mixtures, generated from stoichiometric propane–oxygen, oxygen and ethane, with initial temperature and pressure 290 K and 20 kPa, respectively. Composition gradients are parallel to the direction of detonation propagation, with an equivalence ratio (ER) that first decreases from lean values and then increases to rich ones. Composition distributions are characterized according to the depth of the ER sink. Gradients are generated in a 50 × 50-mm2-square cross-section and a 665-mm total length chamber. The mixture components are injected separately in the pre-evacuated chamber in their order of decreasing density through porous plates at the chamber top-end to ensure planar filling of the chamber. Non-uniform distributions are then precisely controlled as a function of time by means of optical oxygen sensors. A Chapman–Jouguet (CJ) detonation is transmitted at the chamber bottom-end from a 3.6-m-long driver tube. Fast pressure transducers, sooted plates and Schlieren visualizations coupled with high-speed cameras are used to characterize the longitudinal velocity, cellular structure and transmission, failure and re-initiation mechanisms of the detonation front. Shallowest ER sinks produce the supercritical transmission mode of the CJ detonation with continuous adaptation of velocity and multicellular structure to local composition. Deepest sinks lead to the subcritical behaviour characterized by sudden detonation failure from shock-flame decoupling when ER decreases, and without detonation re-initiation when ER increases again. Intermediate sink depths generate critical behaviour with detonation re-initiat ion at chamber walls from expanding combustion kernels and reflected transverse Mach waves and then from SWACER retro-active mechanism. An elaboration of the failure criterion used in a previous study is found to well predict conditions for shock-flame decoupling.