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Technical Memorandum

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National Aeronautics and Space Administration

Lewis Research Center

Cleveland, Ohio 44135– 3191

National Aeronautics and Space Administration

Washington, DC 20546–0001

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June 1983

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This publication is available from the NASA Center for AeroSpace Information, (301) 621–0390.

Experiments in Dilution Jet Mixing

J.D. Holdeman, R. Srinivasan, and A. Berenfeld

Gas turbine combustors; Jet mixing; Dilution zone; Jets-in-crossflow

This paper presents experimental results which extend previous studies, on the mixing of a single row of jets with an

isothermal mainstream in a straight duct, to include flow and geometric variations typical of combustion chambers in

gas turbine engines. The principal conclusions reached from these experiments were: (1) at constant momentum ratio,

variations in density ratio have only a second-order effect on the profiles; (2) a first-order approximation to the mixing

of jets with a variable temperature mainstream can be obtained by superimposing the jets-in-an isothermal-crossflow and

mainstream profiles; (3) flow area convergence, especially injection-wall convergence, significantly improves the

mixing; (4) for opposed rows of jets, with the orifice centerlines in-line, the optimum ratio of orifice spacing to duct

height is 1/2 of the optimum value for single side injection at the same momentum ratio; and (5) for opposed rows of

jets, with the orifice centerlines staggered, the optimum ratio of orifice spacing to duct height is twice the optimum value

for single side injection at the same momentum ratio.

J.D. Holdeman, NASA Lewis Research Center; R. Srinivasan and A. Berenfeld, The Garrett Turbine Engine Co.,

Phoenix, Arizona 85010. Prepared for the Nineteenth Joint Propulsion Conference cosponsored by the AIAA, SAE, and

ASME, Seattle, Washington, June 2–29, 1983.

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