He Dong, Hong Qizhen, Pirani Fernando, Li Renjie, Li Fei, Sun Quanhua, Si Ting, Luo Xisheng
Deep Space Exploration Laboratory/Department of Modern Mechanics, University of Science and Technology of China, Hefei 230026, People's Republic of China.
State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
J Chem Phys. 2024 Jun 14;160(22). doi: 10.1063/5.0212823.
Experimental and numerical studies were performed on the vibrational energy relaxation in shock-heated CO/N2/Ar mixtures. A laser absorption technique was applied to the time-dependent rovibrational temperature time-history measurements. The vibrational relaxation data of reflected-shock-heated CO were summarized at 1720-3230 K. In shock-tube experiments, the rotational temperature of CO quickly reached equilibrium, whereas a relaxation process was found in the time-dependent vibrational temperature. For the mixture with 1.0% CO and 10.0% N2, the vibrational excitation caused a decrease in the macroscopic thermodynamic temperature of the test gas. In the simulations, the state-to-state (StS) approach was employed, where the vibrational energy levels of CO and N2 are treated as pseudo-species. The vibrational state-specific inelastic rate coefficients of N2-Ar collisions were calculated using the mixed quantum-classical method based on a newly developed three-dimensional potential energy surface. The StS predictions agreed well with the measurements, whereas deviations were found between the Schwartz-Slawsky-Herzfeld formula predictions and the measurements. The Millikan-White vibrational relaxation data of the N2-Ar system were found to have the most significant impact on the model predictions via sensitivity analysis. The vibrational relaxation data of the N2-Ar system were then modified according to the experimental data and StS results, providing an indirect way to optimize the vibrational relaxation data of a specific system. Moreover, the vibrational distribution functions of CO and N2 and the effects of the vibration-vibration-translation energy transfer path on the thermal nonequilibrium behaviors were highlighted.
对冲击加热的CO/N2/Ar混合物中的振动能量弛豫进行了实验和数值研究。采用激光吸收技术对随时间变化的转动振动温度时间历程进行测量。总结了在1720 - 3230 K下反射激波加热CO的振动弛豫数据。在激波管实验中，CO的转动温度迅速达到平衡，而在随时间变化的振动温度中发现了弛豫过程。对于含有1.0% CO和10.0% N2的混合物，振动激发导致测试气体的宏观热力学温度降低。在模拟中，采用了态到态（StS）方法，其中将CO和N2的振动能级视为准物种。基于新开发的三维势能面，采用混合量子-经典方法计算了N2 - Ar碰撞的特定振动态非弹性速率系数。StS预测与测量结果吻合良好，而施瓦茨-斯拉斯基-赫茨菲尔德公式预测与测量结果之间存在偏差。通过敏感性分析发现，N2 - Ar系统的米利肯-怀特振动弛豫数据对模型预测影响最大。然后根据实验数据和StS结果对N2 - Ar系统的振动弛豫数据进行修正，为优化特定系统的振动弛豫数据提供了一种间接方法。此外，还突出了CO和N2的振动分布函数以及振动-振动-平动能量转移路径对热非平衡行为的影响。
