Plasma-assisted deflagration to detonation transition in a microchannel with fast-frame imaging and hybrid fs/ps coherent anti-Stokes Raman scattering measurements
Plasma-assisted deflagration to detonation transition in a microchannel with fast-frame imaging and hybrid fs/ps coherent anti-Stokes Raman scattering measurements
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DOI：
10.1016/j.proci.2022.08.133
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发表时间：
2023-01
影响因子：
3.4
通讯作者：
Madeline Vorenkamp;S. Steinmetz;Timothy Y. Chen;Xingqian Mao;A. Starikovskiy;C. Kliewer;Y. Ju
中科院分区：
文献类型：
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作者：
Madeline Vorenkamp;S. Steinmetz;Timothy Y. Chen;Xingqian Mao;A. Starikovskiy;C. Kliewer;Y. Ju
本研究考察了纳秒介质阻挡放电（ns-DBD）等离子体在微通道中对燃料稀薄（Φ = 0.7）、二甲醚（DME）、氧气（O2）和氩气（Ar）预混料进行爆燃到爆轰过渡（DDT）实验时的动力学增强。非平衡等离子体产生活性物质和自由基，以及由于高能电子、离子、电子和振动激发而使混合物快速和缓慢加热以促进着火。通过高速成像和一维、双光束、飞秒/皮秒、相干反斯托克斯拉曼散射（CARS），研究了等离子体放电对预混料和由此产生的爆燃到爆轰过渡（DDT）开始时间和距离的影响。利用高速摄像机跟踪火焰锋面位置和速度的时间历程，识别滴滴涕的动力学和开始。结果表明，等离子体放电对滴滴涕的发生时间和距离具有非线性影响。结果表明，点火前少量的等离子体放电脉冲与无ns放电预激励相比，DDT的起始时间和起始距离分别缩短了60%和40%。结果还表明，增加等离子体放电脉冲数，DDT的起效时间和起效距离分别延长224%和94%。二甲醚的爆燃波速时程及燃烧气体窒息条件下的点火时间标度分析表明，二甲醚可能在燃烧气体和滴滴涕等压窒息条件下低温点火。等离子体诱导的低温氧化反应混合物是通过在放电过程中通过fs/ps CARS测量的co2 / o2比率来评估的。CARS的测量也证实了气体通过放电产生的可忽略的振动和旋转加热。本实验证明了非平衡等离子体能够改变二甲醚/氧/氩预混料的化学性质，从而控制DDT在先进推进发动机中的应用。
This study examines kinetic enhancement by nanosecond dielectric barrier discharge (ns-DBD) plasma on fuel-lean, Φ = 0.7, dimethyl ether (DME), oxygen (O2), and argon (Ar) premixture during deflagration to detonation transition (DDT) experiments in a microchannel. Nonequilibrium plasma produces active species and radicals as well as fast and slow heating of a mixture to promote ignition due to energetic electrons, ions, and electronic and vibrational excitations. Experiments are conducted to examine the influence of the plasma discharge on the premixture and on the resultant deflagration to detonation transition (DDT) onset time and distance through the use of high-speed imaging and one-dimensional, two-beam, femtosecond/picosecond, coherent anti-Stokes Raman scattering (CARS). A high-speed camera is used to trace the time histories of flame front position and velocity and to identify the dynamics and onset of DDT. The results show that plasma discharge can nonlinearly affect the onset time and distance of DDT. It is shown that a small number of plasma discharge pulses prior to ignition result in reduced DDT onset time and distance by 60% and 40%, respectively, when compared to the results without pre-excitation by ns discharges. The results also show that an increase of number of the plasma discharge pulses results in an extended DDT onset time and distance of 224% and 94%, respectively. Time history of the deflagration wave speed of DME and the analysis of ignition timescale under the choking condition of the burned gas of the deflagration wave suggest low temperature ignition may play a role for DME near the isobaric choking condition of the burned gas and the DDT. Plasma-induced low temperature oxidation of the reactive mixture is assessed via the CO2to O2ratio as measured through fs/ps CARS during the gas excitation in discharges. CARS measurements also confirm negligible vibrational and rotational heating of the gas by discharge. The present experiments demonstrate the ability of nonequilibrium plasma to alter the chemistry of DME/O2/Ar premixtures in order to control DDT for applications in advanced propulsion engines.