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Rayleigh-Scattering-Based Measurement of 'trapped waves' in High-speed JetsRecently reported research by others identified a system of waves in the near-exit region of high-speed jets that are different from the well-known Kelvin-Helmholtz waves. In an experimental study, Rayleigh-scattering-based measurement of density fluctuations associated with these waves was used. Simultaneously, a microphone placed near the exit of the jet measured pressure fluctuations associated with the ‘trapped waves’. The pressure fluctuations were observed as a series of peaks in the spectra. Measurements were acquired in high subsonic and under-expanded screeching supersonic flows from a 1-inch diameter convergent nozzle in a free jet facility. The Rayleigh measurement volume was translated throughout the flow field while the microphone was held fixed just outside the flow near the nozzle exit. Even though the signal-to-noise ratio for the Rayleigh data was poor, cross-correlation of density fluctuations with the microphone signal provided some insight into the propagation characteristics of the trapped waves as well as the screech component.
Document ID
20205001488
Document Type
Conference Paper
Authors
Amy F. Fagan
(Glenn Research Center Cleveland, Ohio, United States)
Khairul B.M.Q. Zaman
(Glenn Research Center Cleveland, Ohio, United States)
Date Acquired
April 28, 2020
Subject Category
Aeronautics (General)
Meeting Information
26th AIAA/CEAS Aeroacoustics Conference at the AVIATION Forum(Virtual)
Funding Number(s)
WBS: 110076.02.03.04.40.02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Technical Review
Single Expert
Keywords
Rayleigh scattering
aeroacoustics
cross-correlation
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