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Dynamic Measurement of Temperature, Velocity, and Density in Hot Jets Using Rayleigh ScatteringA molecular Rayleigh scattering technique is utilized to measure gas temperature, velocity, and density in unseeded gas flows at sampling rates up to 10 kHz, providing fluctuation information up to 5 kHz based on the Nyquist theorem. A high-power continuous-wave laser beam is focused at a point in an air flow field and Rayleigh scattered light is collected and fiber-optically transmitted to a Fabry-Perot interferometer for spectral analysis. Photomultiplier tubes operated in the photon counting mode allow high-frequency sampling of the total signal level and the circular interference pattern to provide dynamic density, temperature, and velocity measurements. Mean and root mean square velocity, temperature, and density, as well as power spectral density calculations, are presented for measurements in a hydrogen-combustor heated jet facility with a 50.8-mm diameter nozzle at NASA John H. Glenn Research Center at Lewis Field. The Rayleigh measurements are compared with particle image velocimetry data and computational fluid dynamics predictions. This technique is aimed at aeronautics research related to identifying noise sources in free jets, as well as applications in supersonic and hypersonic flows where measurement of flow properties, including mass flux, is required in the presence of shocks and ionization occurrence.
Document ID
Document Type
Reprint (Version printed in journal)
Mielke, Amy F.
(NASA Glenn Research Center Cleveland, OH, United States)
Elam, Kristie A.
(Jacobs Sverdrup Technology, Inc. Cleveland, OH, United States)
Date Acquired
August 25, 2013
Publication Date
July 5, 2009
Publication Information
Publication: Experiments in Fluids
Volume: 47
Issue: 5-Apr
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
Meeting Information
14th International Symposium on Applications of Laser Techniques to Fluid Mechanics(Lisbon)
Funding Number(s)
WBS: WBS 561581.
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