Time-Resolved On-Axis Spectroscopic Stagnation Temperature Measurements in Shock Tunnel Flows
Volume 3, Issue 2, December 2019, Pages: 6-11
Received: Sep. 25, 2019;
Accepted: Oct. 11, 2019;
Published: Dec. 2, 2019
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Hartmut Borchert, French-German Research Institute of Saint-Louis, Saint-Louis Cedex, France
Stefan Brieschenk, French-German Research Institute of Saint-Louis, Saint-Louis Cedex, France
Berthold Sauerwein, French-German Research Institute of Saint-Louis, Saint-Louis Cedex, France
This paper demonstrates time-resolved stagnation temperature measurements in a shock tunnel at a frequency of 25 kHz using emission spectroscopy in air and nitrogen test conditions. The two most important parameters for determining the flow conditions generated in a shock tunnel experiment are the stagnation pressure and temperature of the flow just upstream of the supersonic nozzle. While the pressure can be measured using a wall-mounted transducer with relative ease, the measurement of the temperature requires a optical technique such as time resolved emission spectroscopy. Knowledge of the transient stagnation temperature behavior is critical to all subsequent expansion tube flow processes. The driver gas emission spectrum data at the post-shock condition shows continuum and atomic line radiation. The continuum radiation can be described by a black body radiator with the individual spectra showing sufficient continuum information for accurately fitting Planck functions. Atomic line radiation was excluded by skipping those data from the measured spectra. The fitting routine shows clear differences in determined temperatures including and neglecting atomic line radiation. These measurements allow for the exact determination of the shock tunnel flow conditions in combination with pressure transducer data. The flow condition used in the experiment corresponds to a nominal Mach-10 condition at an altitude of 65 km, however, the technique is not limited to this condition and can be used for a large range of flow conditions.
Time-Resolved On-Axis Spectroscopic Stagnation Temperature Measurements in Shock Tunnel Flows, Engineering Physics.
Vol. 3, No. 2,
2019, pp. 6-11.
Copyright © 2019 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/
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