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Mechanisms of Coupled Vibrational Relaxation and Dissociation in Carbon Dioxide
The Journal of Physical Chemistry A ( IF 2.9 ) Pub Date : 2018-05-21 00:00:00 , DOI: 10.1021/acs.jpca.8b03266
Iole Armenise 1 , Elena Kustova 2
Affiliation  

A complete vibrational state-specific kinetic scheme describing dissociating carbon dioxide mixtures is proposed. CO2 symmetric, bending and asymmetric vibrations and dissociation-recombination are strongly coupled through intermode vibrational energy transfers. Comparative study of state-resolved rate coefficients is carried out; the effect of different transitions may vary considerably with temperature. A nonequilibrium 1-D boundary layer flow typical to hypersonic planetary entry is studied in the state-to-state approach. To assess the sensitivity of fluid-dynamic variables and heat transfer to various vibrational transitions and chemical reactions, corresponding processes are successively included to the kinetic scheme. It is shown that vibrational–translational (VT) transitions in the symmetric and asymmetric modes do not alter the flow and can be neglected whereas the VT2 exchange in the bending mode is the main channel of vibrational relaxation. Intermode vibrational exchanges affect the flow implicitly, through energy redistribution enhancing VT relaxation; the dominating role belongs to near-resonant transitions between symmetric and bending modes as well as between CO molecules and CO2 asymmetric mode. Strong coupling between VT2 relaxation and chemical reactions is emphasized. While vibrational distributions and average vibrational energy show strong dependence on the kinetic scheme, the heat flux is more sensitive to chemical reactions.

中文翻译:

二氧化碳中振动松弛和离解的耦合机理

提出了描述离解二氧化碳混合物的完整的特定于振动状态的动力学方案。一氧化碳2对称振动,弯曲振动和非对称振动以及解离复合通过模间振动能量传递紧密耦合。进行了国家解析率系数的比较研究;不同转变的影响可能随温度而有很大变化。在状态对状态方法中,研究了高超声速行星进入典型的非平衡一维边界层流。为了评估流体动力学变量和热传递对各种振动转变和化学反应的敏感性,将相应的过程相继包括到动力学方案中。结果表明,在对称和非对称模式下的振动-平移(VT)过渡不会改变流量,可以忽略不计,而VT 2弯曲模式下的交换是振动松弛的主要渠道。模间振动交换通过能量重新分布来增强VT松弛,从而隐含地影响流动。主要作用是对称和弯曲模式之间以及CO分子和CO 2不对称模式之间的近共振跃迁。强调了VT 2弛豫与化学反应之间的强耦合。虽然振动分布和平均振动能量强烈依赖于动力学方案,但热通量对化学反应更敏感。
更新日期:2018-05-21
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