态-态模型下的CO_(2)系统热非平衡过程数值研究  

Numerical study of thermal nonequilibrium process in CO_(2) system with state-to-state model

作　　者：段欣葵 曾明[1] 王辉[1] 王东方[1] DUAN Xinkui;ZENG Ming;WANG Hui;WANG Dongfang(College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,China)

机构地区：[1]国防科技大学空天科学学院,长沙410073

出　　处：《空气动力学学报》2024年第6期66-75,I0002,共11页Acta Aerodynamica Sinica

基　　金：国家自然科学基金(11927803)。

摘　　要：以火星大气条件下飞行器非平衡流场研究为背景,采用态-态模型对定容静止CO_(2)系统自30 km火星大气条件(181 K)瞬时升温后的热非平衡过程开展数值模拟。考虑CO_(2)分子的对称拉伸、弯曲和非对称拉伸三个振动模态共201个振动能级,微观过程包括:振动-平动(VT)能量交换过程引起的同一模态内部的和不同模态间的振动能级跃迁,振动-振动(VV)能量交换过程引起的同一模态内部振动能级跃迁。分析不同振动模态的能级分布演化特点,并考察对应微观过程细节探究内在原因,结果表明:VT过程起支配作用,对由初始低温突然升温后保持定温的气体非平衡过程,VV过程的贡献可以忽略;CO_(2)分子的弯曲振动模态具有最快的激发速率,平衡时也具有最高的粒子数占比,升温至2 000 K情况下,对称拉伸和非对称拉伸模态的松弛时间约为弯曲模态的2.2倍和46.1倍;更高温度下振动能级跃迁速率加大,升温至5 000 K情况达到平衡的平均松弛时间比2 000 K情况低了2个量级。With the background of research on nonequilibrium flow field outside Mars probe,the thermal nonequilibrium process after temperature increase of a stationary CO_(2) system from Martian atmospheric condition at an altitude of 30 km(181 K)is studied with state-to-state model.The system with initial condition of Martian atmosphere is heated suddenly to a high temperature and then is kept at constant temperature and volume.Three vibrational modes(symmetric stretching,bending and asymmetric stretching modes)and totally 201 vibrational energy levels are considered.The microscopic processes include:vibration-translation(VT)energy exchange processes that cause transitions between energy levels of the same or different modes,vibration-vibration(VV)energy exchange processes that cause transitions within the same mode.The time evolution of vibrational distribution for the three modes and the specifics of the corresponding microscopic processes are analyzed.The results show that:(1)VT processes are dominant,the contribution of VV processes can be ignored for such sudden increase and then constant temperature case.(2)Among the three vibrational modes,the bending mode has the fastest excitation rate and the largest equilibrium population.For the case of temperature rise to 2000 K,the relaxation time for the symmetric and asymmetric stretching modes is respectively about 2.2 times and 46.1 times of that for the bending mode.(3)As the transition rates increase with temperature,the average relaxation time for 5000 K case is lower than that for 2000 K by two orders of magnitude.

关 键 词：热非平衡 态-态模型 CO_(2) 数值模拟 振动能级分布 

分 类 号：V211.22[航空宇航科学与技术—航空宇航推进理论与工程]