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Pressure oscillations and acoustic-entropy interactions in ramjet combustion chambers

Humphrey, J. W. and Culick, F. E. C. (1987) Pressure oscillations and acoustic-entropy interactions in ramjet combustion chambers. AIAA Papers, AIAA-87-1872 . American Institute of Aeronautics and Astronautics .

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A one-dimensional analytical model is presented for calculating the longitudinal acoustic modes of idealized "dump-type" ramjet engines. The model contains the matching required to place an oscillating flame sheet in the interior of a combustion chamber with mean flow. The linear coupling of the acoustic and entropy waves at the inlet shock, flame sheet, and exit nozzle along with acoustic admittances at the inlet and exit are combined to determine the stability of the system as well as the acoustic modes. Since the acoustic and entropy waves travel at different velocities, the geometry is a critical factor in determining stability. Typical values of the admittances will produce damped solutions when the entropy is neglected, but, as the ratio of the entropy to acoustic fluctuations is increased, the coupling can either feed acoustic energy into or out of different modes independently. This transfer of energy has a destabilizing or stabilizing effect on the acoustic modes of the system depending upon the phase of the energy transfer.

Item Type:Report or Paper (Report)
Additional Information:© 1987 by J. W. Humphrey. Published by the American Institute of Aeronautics and Astronautics, Inc. We gratefully acknowledge that this work was supported by the Office of Naval Research through a graduate research fellowship and contract N00014-84-K-0434.
Group:Guggenheim Jet Propulsion Center, GALCIT
Funding AgencyGrant Number
Office of Naval ResearchN00014-84-K-0434
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Other Numbering System NameOther Numbering System ID
Guggenheim Jet Propulsion Center300
Series Name:AIAA Papers
Issue or Number:AIAA-87-1872
Record Number:CaltechAUTHORS:20101202-105114390
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Official Citation:Pressure oscillations and acoustic-entropy interactions in ramjet combustion chambers HUMPHREY, JOSEPH W., California Institute of Technology, Pasadena; CULICK, F. E. C., California Institute of Technology, Pasadena AIAA-1987-1872 SAE, ASME, and ASEE, Joint Propulsion Conference, 23rd, San Diego, CA, June 29-July 2, 1987.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21124
Deposited By: Ruth Sustaita
Deposited On:04 Dec 2010 00:19
Last Modified:03 Oct 2019 02:20

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