The ablating species from the thermal protection systems upon atmospheric entry interact with the atomic/molecular gas species in the shock layer and form new products that affect total radiation. In this work, the ablation of carbon was experimentally studied by resistively preheating graphite strips to representative reentry wall temperatures and exposing them to hypervelocity Earth-entry flow conditions generated in the X2 expansion tube facility at The University of Queensland, Australia. The graphite strips were mounted on a compression wedge and preheated to wall temperatures ranging from 1000 to 3000 K. The flowfield and interaction processes were optically diagnosed using a high frame-rate video camera, two-dimensional filtered imaging, and ultraviolet emission spectroscopy. The distribution of cyanogen (CN) violet band emission was investigated at different slices in the flowfield. Experimentally recorded CN emissions were compared with the spectra simulated using Specair to estimate CN number densities and transrotational and vibro-electronic temperatures at various spatial locations with a two-temperature model. The ablating flowfield was also compared with no-ablation cases by using an unheated steel strip instead of heated graphite. The results in the expansion region are possible indications of non-Boltzmann population distribution in CN energy levels.

进入大气后，热保护系统中的烧蚀物质与冲击层中的原子/分子气体物质相互作用，形成影响总辐射的新产品。在这项工作中，通过电阻性将石墨条预热至代表折返壁的温度，并将其暴露于澳大利亚昆士兰大学X2膨胀管设施产生的超高速地球进入流动条件下，对碳的消融进行了实验研究。将石墨条安装在压缩楔上，并预热至1000至3000 K的壁温。使用高帧频摄像机，二维过滤成像和紫外线发射光谱对流场和相互作用过程进行光学诊断。研究了流场中不同层的氰化（CN）紫带发射分布。将实验记录的CN排放量与使用Specair模拟的光谱进行比较，以使用双温度模型估算CN在不同空间位置的CN密度，横向旋转和振动电子温度。还通过使用未加热的钢带代替加热的石墨，将消融流场与不消融情况进行了比较。扩展区域中的结果可能是非能级CN能量水平的玻尔兹曼分布的指示。将实验记录的CN排放量与使用Specair模拟的光谱进行比较，以使用双温度模型估算CN在不同空间位置的CN密度，横向旋转和振动电子温度。还通过使用未加热的钢带代替加热的石墨，将消融流场与不消融情况进行了比较。扩展区域中的结果可能是CN能级中非玻尔兹曼种群分布的指示。将实验记录的CN排放量与使用Specair模拟的光谱进行比较，以使用双温度模型估算CN在不同空间位置的CN密度，横向旋转和振动电子温度。还通过使用未加热的钢带代替加热的石墨，将消融流场与不消融情况进行了比较。扩展区域中的结果可能是非能级CN能量水平的玻尔兹曼分布的指示。