Measurements of no rotational and vibrational temperatures behind a normal shock in hypervelocity flow via absorption spectroscopy

IF 2.3 3区工程技术 Q2 ENGINEERING, MECHANICAL

Experiments in Fluids Pub Date : 2024-07-12 DOI:10.1007/s00348-024-03841-w

Samuel E. Feltis, Zhili Zhang, Tyler S. Dean, Rodney D. W. Bowersox, Farhan Siddiqui, Mark Gragston

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Abstract

Tunable Diode Laser Absorption Spectroscopy (TDLAS) measurements of nitric oxide (NO) using a Quantum Cascade Laser (QCL) in the vicinity of 5.26 μm were conducted in a hypervelocity flow generated in the Texas A&M Hypervelocity Expansion Tunnel (HXT). The nascent NO was produced downstream of symmetric Mach reflections generated in Mach 8.5 flows with stagnation enthalpies from 6.9 to 11.1 MJ/kg. Path-averaged flow parameters of rotational and vibrational temperatures and NO concentration at a measurement rate of 30 kHz were obtained. By probing the R-branch of the fundamental absorption band in NO, thermal nonequilibrium and NO concentration levels in the post-shock region were measured. Measurements are compared to equilibrium calculations. NO equilibrium values during the 1 ms test period differ from the experimental rotational and vibrational measurements across the same time period. The experimental measurements of the rotational temperature show a consistent value around 3000 K larger than the recovered vibrational temperature across any run. The NO concentrations in all runs are near to the reported equilibrium value; often beginning higher than, and over time decaying to, the equilibrium concentration value of the specific tunnel run.

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通过吸收光谱测量超高速流中正常冲击后的无旋转和振动温度

在德克萨斯州A&M超高速膨胀隧道（HXT）产生的超高速气流中，使用量子级联激光器（QCL）在5.26微米附近对一氧化氮（NO）进行了可调二极管激光吸收光谱（TDLAS）测量。新生氮氧化物产生于马赫数为 8.5、停滞焓为 6.9 至 11.1 MJ/kg 的对称马赫反射流的下游。在 30 kHz 的测量速率下，获得了旋转和振动温度以及 NO 浓度的路径平均流动参数。通过探测 NO 基本吸收带的 R 支，测量了冲击后区域的热非平衡和 NO 浓度水平。测量结果与平衡计算结果进行了比较。1 毫秒测试期间的 NO 平衡值与同一期间的旋转和振动实验测量值不同。旋转温度的实验测量值显示，在任何一次运行中，旋转温度都比恢复的振动温度大 3000 K 左右。所有运行中的氮氧化物浓度都接近报告的平衡值；通常开始时高于特定隧道运行的平衡浓度值，并随着时间的推移逐渐降低到平衡浓度值。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Experiments in Fluids 工程技术-工程：机械

CiteScore

5.10

自引率

12.50%

发文量

157

审稿时长

3.8 months

期刊介绍： Experiments in Fluids examines the advancement, extension, and improvement of new techniques of flow measurement. The journal also publishes contributions that employ existing experimental techniques to gain an understanding of the underlying flow physics in the areas of turbulence, aerodynamics, hydrodynamics, convective heat transfer, combustion, turbomachinery, multi-phase flows, and chemical, biological and geological flows. In addition, readers will find papers that report on investigations combining experimental and analytical/numerical approaches.