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Effect of Heating on Turbulent Density Fluctuations and Noise Generation From High Speed JetsHeated jets in a wide range of temperature ratios (TR), and acoustic Mach numbers (Ma) were investigated experimentally using far field microphones and a molecular Rayleigh scattering technique. The latter provided density fluctuations measurements. Two sets of operating conditions were considered: (1) TR was varied between 0.84 and 2.7 while Ma was fixed at 0.9; (2) Ma was varied between 0.6 and 1.48, while TR was fixed at 2.27. The implementation of the molecular Rayleigh scattering technique required dust removal and usage of a hydrogen combustor to avoid soot particles. Time averaged density measurements in the first set of data showed differences in the peripheral density shear layers between the unheated and heated jets. The nozzle exit shear layer showed increased turbulence level with increased plume temperature. Nevertheless, further downstream the density fluctuations spectra are found to be nearly identical for all Mach number and temperature ratio conditions. To determine noise sources a correlation study between plume density fluctuations and far field sound pressure fluctuations was conducted. For all jets the core region beyond the end of the potential flow was found to be the strongest noise source. Except for an isothermal jet, the correlations did not differ significantly with increasing temperature ratio. The isothermal jet created little density fluctuations. Although the far field noise from this jet did not show any exceptional trend, the flow-sound correlations were very low. This indicated that the density fluctuations only acted as a "tracer parameter" for the noise sources.
Document ID
Document Type
Conference Paper
Panda, Jayanta
(Ohio Aerospace Inst. Brook Park, OH, United States)
Seasholtz, Richard G.
(NASA Glenn Research Center Cleveland, OH, United States)
Elam, Kristie A.
(Akima Corp. Fairview Park, OH, United States)
Mielke, Amy F.
(NASA Glenn Research Center Cleveland, OH, United States)
Eck, Dennis G.
(QSS Group, Inc. Cleveland, OH, United States)
Date Acquired
August 21, 2013
Publication Date
June 1, 2004
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
AIAA Paper 2004-3016
Meeting Information
Confederation of European Aerospace Societies(Manchester)
Funding Number(s)
WBS: WBS 714-09-24
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