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Title: Ultraviolet Laser Absorption Imaging of High-Speed Flows in a Shock Tube
Observation of high-speed reactive flows using laser-absorption-based imaging techniques is of interest for its potential to quantitatively reveal both gas-dynamic and thermochemical processes. In the current study, an ultraviolet (UV) laser-absorption imaging method based on nitric oxide (NO) is demonstrated to capture transient flows in a shock tube. A tunable laser was used to generate a continuous-wave UV beam at 226.1019 nm to coincide with a strong NO absorption feature. The UV beam was expanded to a 20-mm diameter and routed through the shock tube to image the flow adjacent to the end wall. Time-resolved imaging was realized using a Lambert HiCATT high-speed UV intensifier coupled to a Phantom v2012 high-speed camera. Static absorbance measurements of 1.97% NO/Ar mixtures were first performed to validate the proposed imaging concept, showing good agreement with values predicted by a spectroscopic model. UV laser-absorption images of incident and reflected shock waves captured at 90 kHz temporal resolution are then reported. Translational temperature profiles across the incident and reflected shocks calculated from absorbance images show reasonable agreement with calculated values. After the passage of the reflected shock wave, the flow near the end wall was monitored to probe the development of the end-wall thermal boundary layer. Thermometry measurements across the thermal boundary layer show good agreement with analytical solutions. This study demonstrates the potential of UV laser-absorption imaging in high-speed flow fields, to be applied to more complex applications in the future.  more » « less
Award ID(s):
1940865
NSF-PAR ID:
10311613
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
AIAA SCITECH 2022 Forum
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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