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中国物理学会期刊

基于神经网络和动力学模拟方法研究高温N2-O2态-态碰撞振动激发和解离过程

CSTR: 32037.14.aps.74.20250533

Vibrational excitation and dissociation processes in high-temperature N2-O2 state-to-state collisions based on neural network and dynamic simulation

CSTR: 32037.14.aps.74.20250533
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  • 散射截面和反应速率系数是阐明分子气体态-态碰撞传能机制的重要参数, 也是进行非平衡气体动力学建模的重要依据. 本文采用动力学模拟中的准经典轨迹方法(QCT)计算了90个不同初始振动态组合的N2(v) + O2(w)碰撞过程, 详细讨论了各个振动激发、解离反应通道的贡献和演变趋势. 研究发现: O2和N2在振动-振动能量交换(VV)通道的贡献比较接近, 振动-平动跃迁(VT)通道主要以O2为主; 总解离截面主要来自O2单解离通道, 交换解离其次, N2单解离和双解离通道的贡献相对较小. 基于QCT数据集, 训练了性能良好的神经网络模型(相关系数R值达到0.99), 可用于预测N2 + O2态-态碰撞的总解离截面. 和仅采用动力学模拟方法相比, 计算成本降低了约91.94%. 在5000—30000 K高温范围内, 给出了VV/VT速率系数的解析表达式.

     

    The scattering cross-sections and reaction rate coefficients are crucial parameters for elucidating the energy transfer mechanism of state-to-state collisions between molecular gases and also serve as a fundamental basis for modeling the non-equilibrium flow field. However, the database of kinetic processes related to nitrogen shock flows is still being developed. In this work, a detailed kinetic study of the N2 + O2 collision is carried out by combining the quasi-classical trajectory method (QCT) and neural network model (NN). Firstly, QCT is used to calculate 90 N2(v) + O2(w) processes with various initial vibrational states (v,w), and the contributions of all vibrational excitation and dissociation reaction channels are discussed. The following conclusions are drawn: 1) The contributions of the vibration-vibration (VV) energy exchange channel of O2 and N2 are similar, while the vibration-translational (VT) transition mainly occurs on O2; 2) The total dissociation cross-section primarily results from the O2 single-dissociation channel, followed by the exchange-dissociation channel, with relatively minor contributions from the N2 single- and double-dissociation channels. Then, based on the QCT dataset, a high-performance NN model (R-value of 0.99) is trained to predict the total dissociation cross-section caused by N2(v) + O2(w) collisions. Compared with the method that only uses QCT, the method that jointly uses OCT and NN model can achieve an approximately 91.94% reduction in computational cost. Finally, to facilitate use in kinetic modeling, Arrhenius-type fits for the VV/VT rate coefficients are provided over the temperature range of 5000–30000 K, and an exponential form related to the translational energy Et is used to fit the total dissociation cross-section.

     

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