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Gasdynamic enhancement of nonpremixed combustion

Marble, Frank E. (1994) Gasdynamic enhancement of nonpremixed combustion. Symposium (International) on Combustion, 25 (1). pp. 1-12. ISSN 0082-0784. doi:10.1016/S0082-0784(06)80621-1.

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To promote efficient performance of very high speed air-breathing propulsion systems, the combustor Mach number must be of the order of six for a flight Mach number of 18. Because of this high gas speed through the combustor, mixing rates of hydrogen fuel with air must be very rapid in order to allow a combustor of reasonable length. It is proposed to enhance the rate of mixing and combustion of hydrogen and air, and thereby reduce combustor length, through the introduction of streamwise vorticity generated by the interaction of a weak oblique shock wave with the density gradient between air and a cylindrical jet of hydrogen. Because of the high Mach number flow in the combustor, the oblique shock traverses the jet at a small angle with respect to the free stream direction, and the principle of slender body theory allows one conceptually to replace the three-dimensional steady flow with a two-dimensional unsteady flow. As a consequence, two-dimensional time-dependent computational studies and an extensive experimental shock tube investigation were employed to assess mixing rates for the steady flow in the combustor. The results indicated that under realistic conditions, adequate mixing could be accomplished within 1 ms, a rate that was technologically interesting. Encouraged by these experiments, a “practical” injector, utilizing shock-enhanced mixing, was designed for a combustor having a free stream Mach number of 6.0. A detailed aerodynamic and mixing investigation was carried out in the Mach 6 High Reynolds Number Tunnel at the NASA-Langley Research Center. The results confirmed both the details and the overall effectiveness of the shock-enhanced mixing concept.

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Additional Information:© 1994 Combustion Institute Published by Elsevier B.V. Publication History: Formerly known as Symposium on Combustion and Flame, and Explosion Phenomena; Continued as Proceedings of the Combustion Institute.
Group:Guggenheim Jet Propulsion Center
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Guggenheim Jet Propulsion Center372
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Record Number:CaltechAUTHORS:20101123-150925263
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Official Citation:Gasdynamic enhancement of nonpremixed combustion Source: Symposium, International, on Combustion [0082-0784] Marble yr:1994 vol:25 iss:1 pg:1-12
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21006
Deposited By: Ruth Sustaita
Deposited On:24 Nov 2010 18:52
Last Modified:09 Nov 2021 00:05

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