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Nonequilibrium Supersonic Freestream Studied Using Coherent Anti-Stokes Raman SpectroscopyMeasurements were conducted at the University of Virginia Supersonic Combustion Facility of the flow in a constant-area duct downstream of a Mach 2 nozzle. The airflow was heated to approximately 1200 K in the facility heater upstream of the nozzle. Dual-pump coherent anti-Stokes Raman spectroscopy was used to measure the rotational and vibrational temperatures of N2 and O2 at two planes in the duct. The expectation was that the vibrational temperature would be in equilibrium, because most scramjet facilities are vitiated air facilities and are in vibrational equilibrium. However, with a flow of clean air, the vibrational temperature of N2 along a streamline remains approximately constant between the measurement plane and the facility heater, the vibrational temperature of O2 in the duct is about 1000 K, and the rotational temperature is consistent with the isentropic flow. The measurements of N2 vibrational temperature enabled cross-stream nonuniformities in the temperature exiting the facility heater to be documented. The measurements are in agreement with computational fluid dynamics models employing separate lumped vibrational and translational/rotational temperatures. Measurements and computations are also reported for a few percent steam addition to the air. The effect of the steam is to bring the flow to thermal equilibrium, also in agreement with the computational fluid dynamics.




Document ID
20160009064
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Cutler, Andrew D. (George Washington Univ. Newport News, VA, United States)
Cantu, Luca M. (George Washington Univ. Newport News, VA, United States)
Gallo, Emanuela C. A. (George Washington Univ. Newport News, VA, United States)
Baurle, Rob (NASA Langley Research Center Hampton, VA, United States)
Danehy, Paul M. (NASA Langley Research Center Hampton, VA, United States)
Rockwell, Robert (Virginia Univ. Charlottesville, VA, United States)
Goyne, Christopher (Virginia Univ. Charlottesville, VA, United States)
McDaniel, Jim (Virginia Univ. Charlottesville, VA, United States)
Date Acquired
July 15, 2016
Publication Date
September 1, 2015
Publication Information
Publication: AIAA Journal
Volume: 53
Issue: 9
ISSN: 0001-1452
Subject Category
Instrumentation and Photography
Report/Patent Number
NF1676L-19231
Funding Number(s)
WBS: WBS 475122.02.07.09
Distribution Limits
Public
Copyright
Other