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Published July 2010 | Published
Journal Article Open

NO and OH Spectroscopic Vibrational Temperature Measurements in a Post-Shock Relaxation Region


In this paper, spatial temperature profiles are examined in the nonequilibrium relaxation region behind a stationary shock wave in a hypervelocity air Mach 7.42 freestream. The normal shock wave is established through a Mach reflection from an opposing wedge arrangement in an expansion tube facility. Schlieren images confirm that the shock configuration is steady and the location is repeatable. Emission spectroscopy is used to identify dissociated species and to make vibrational temperature measurements using both the nitric oxide and the hydroxyl radical A-X band sequences. Temperature measurements are presented at selected locations behind the normal shock. LIFBASE is used as the simulation spectrum software for OH temperature-fitting; however, the need to access higher vibrational and rotational levels for NO leads to the use of an in-house developed algorithm. For NO, results demonstrate the contribution of higher vibrational and rotational levels to the spectra at the conditions of this study. Very good agreement is achieved between the experimentally measured NO vibrational temperatures and calculations performed using an existing state-resolved, three-dimensional forced-harmonic oscillator thermochemical model. The measured NO vibrational temperatures are significantly higher than the OH temperatures.

Additional Information

© 2010 by University of Illinois. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Received 6 July 2009; revision received 29 January 2010; accepted for publication 31 January 2010. This research was funded in part through the Air Force Office of Scientific Research/Multi-University Research Initiative Grant FA9550-04-1-0425 with John Schmisseur as Technical Monitor.

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