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Rotational Raman-Based Temperature Measurements in a High-Velocity Turbulent JetSpontaneous rotational Raman scattering spectroscopy is used to acquire the first ever high quality, spatially-resolved measurements of the mean and root mean square (rms) temperature fluctuations in turbulent, high-velocity heated jets. Raman spectra in air were obtained across a matrix of radial and axial locations downstream from a 50 mm diameter nozzle operating from subsonic to supersonic conditions over a wide range of temperatures and Mach numbers, in accordance with the Tanna matrix frequently used in jet noise studies. These data were acquired in the hostile, high noise (115 dB) environment of a large scale open air test facility at NASA Glenn Research Center (GRC). Temperature estimates were determined by performing nonlinear least squares fitting of the single shot spectra to the theoretical rotational Stokes spectra of N2 and O2, using a custom in-house code developed specifically for this investigation. The laser employed in this study was a high energy, long-pulsed, frequency doubled Nd:YAG laser. One thousand single-shot spectra were acquired at each spatial coordinate. Mean temperature and rms temperature variations were calculated at each measurement location. Excellent agreement between the averaged and single-shot temperatures was observed with an accuracy better than 2.5 percent for temperature, and rms variations in temperature between +/-2.2 percent at 296 K and +/-4.5 percent at 850 K. The results of this and planned follow-on studies will support NASA GRC's development of physics-based jet noise prediction, turbulence modeling and aeroacoustic source modeling codes.
Document ID
20170006884
Acquisition Source
Glenn Research Center
Document Type
Other - Data Set
Authors
Randy J Locke
(Vantage Partners, LLC NASA Glenn Research Center)
Mark P Wernet
(Glenn Research Center Cleveland, Ohio, United States)
Robert C Anderson
(Glenn Research Center Cleveland, Ohio, United States)
Date Acquired
July 20, 2017
Publication Date
June 1, 2017
Subject Category
Aeronautics (General)
Report/Patent Number
MSFC-E-DAA-TN40888
NASA/TM-2017-219504/SUPPL
E-19366
Funding Number(s)
WBS: WBS 109492.02.03.02.20.01
CONTRACT_GRANT: NNC12BA01B
Distribution Limits
Public
Copyright
Public Use Permitted.
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