NDLI: Instability modes excited by natural screech tones in a supersonic rectangular jet

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Instability modes excited by natural screech tones in a supersonic rectangular jet

Content Provider	NASA Technical Reports Server (NTRS)
Author	Raman, Ganesh Rice, Edward J.
Copyright Year	1993
Description	The evolution of hydrodynamic instability modes self-excited by harmonically related natural screech tones was experimentally investigated. A convergent rectangular nozzle with an aspect ratio of 9.63 was used to produce a supersonic shock containing jet. Measurements in the flow-field were made using standard hot-film probes positioned only in the subsonic (outer) portions of the flow. The hydrodynamic instability mode observed in the shear layer at the screech frequency was observed to be antisymmetric (sinuous) about the smaller dimension of the jet, whereas its harmonic was observed to be symmetric (varicose). In addition, the near-field noise measurements indicated that the radiated screech tone noise was out of phase on either side of the small jet dimension whereas its harmonic was in phase over the same region. To our knowledge such an observation on the nature of the harmonic has thus far gone unreported and therefore is the focus of the present work. The hydrodynamic instability modes occurring at the screech frequency and its harmonic satisfied the conditions for resonance. Detailed measurements of the coherent wave evolution in the streamwise and spanwise directions indicated that strong spanwise variations were present beyond x/h = 8. Details of the screech noise radiated by the coherent instability modes are also presented in this paper.
File Size	9004749
Page Count	19
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_19940017801
Archival Resource Key	ark:/13960/t4rj9cf20
Language	English
Publisher Date	1993-12-01
Access Restriction	Open
Subject Keyword	Aerodynamics Aerodynamic Noise Noise Measurement Convergent Nozzles Sound Pressure Flow Stability Shear Layers Stagnation Pressure Flow Distribution Supersonic Jet Flow Resonance Aeroacoustics Hot-film Anemometers Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aircraft Aerospace Engineering Aerospace Aeronautic Space Science
Content Type	Text
Resource Type	Article

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