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Simultaneous Laser Raman-rayleigh-lif Measurements and Numerical Modeling Results of a Lifted Turbulent H2/N2 Jet Flame in a Vitiated CoflowAn experiment and numerical investigation is presented of a lifted turbulent H2/N2 jet flame in a coflow of hot, vitiated gases. The vitiated coflow burner emulates the coupling of turbulent mixing and chemical kinetics exemplary of the reacting flow in the recirculation region of advanced combustors. It also simplifies numerical investigation of this coupled problem by removing the complexity of recirculating flow. Scalar measurements are reported for a lifted turbulent jet flame of H2/N2 (Re = 23,600, H/d = 10) in a coflow of hot combustion products from a lean H2/Air flame ((empty set) = 0.25, T = 1,045 K). The combination of Rayleigh scattering, Raman scattering, and laser-induced fluorescence is used to obtain simultaneous measurements of temperature and concentrations of the major species, OH, and NO. The data attest to the success of the experimental design in providing a uniform vitiated coflow throughout the entire test region. Two combustion models (PDF: joint scalar Probability Density Function and EDC: Eddy Dissipation Concept) are used in conjunction with various turbulence models to predict the lift-off height (H(sub PDF)/d = 7,H(sub EDC)/d = 8.5). Kalghatgi's classic phenomenological theory, which is based on scaling arguments, yields a reasonably accurate prediction (H(sub K)/d = 11.4) of the lift-off height for the present flame. The vitiated coflow admits the possibility of auto-ignition of mixed fluid, and the success of the present parabolic implementation of the PDF model in predicting a stable lifted flame is attributable to such ignition. The measurements indicate a thickened turbulent reaction zone at the flame base. Experimental results and numerical investigations support the plausibility of turbulent premixed flame propagation by small scale (on the order of the flame thickness) recirculation and mixing of hot products into reactants and subsequent rapid ignition of the mixture.
Document ID
20030014612
Acquisition Source
Glenn Research Center
Document Type
Contractor Report (CR)
Authors
Cabra, R. (California Univ. Berkeley, CA United States)
Chen, J. Y. (California Univ. Berkeley, CA United States)
Dibble, R. W. (California Univ. Berkeley, CA United States)
Myhrvold, T. (Norwegian Univ. of Science and Technology Trondheim, Norway)
Karpetis, A. N. (Sandia National Labs. Livermore, CA United States)
Barlow, R. S. (Sandia National Labs. Livermore, CA United States)
Date Acquired
September 7, 2013
Publication Date
December 1, 2002
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
NASA/CR-2002-212082
NAS 1.26:212082
E-13735
Report Number: NASA/CR-2002-212082
Report Number: NAS 1.26:212082
Report Number: E-13735
Meeting Information
Meeting: 29th International Symposium on Combustion
Location: Sapporo
Country: Japan
Start Date: July 21, 2002
End Date: July 26, 2002
Sponsors: Combustion Inst.
Funding Number(s)
CONTRACT_GRANT: NAG3-2103
PROJECT: RTOP 708-90-01
Distribution Limits
Public
Copyright
Public Use Permitted.

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