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The structure of a chemically reacting plane mixing layer

Published online by Cambridge University Press:  21 April 2006

S. M. Masutani  and
C. T. Bowman
S. M. Masutani
Affiliation:
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA Present address: Hitachi Research Laboratory, Ibaraki-ken, Japan.
C. T. Bowman
Affiliation:
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
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Abstract

Experiments were performed to examine the structure of a chemically reacting, gas-phase, two-stream plane mixing layer. Temporally and spatially resolved measurements of streamwise velocity and of the concentrations of a reactant and product species and a conserved scalar were recorded across the mixing layer at streamwise locations between Redelta; = 730–2520. Non-reacting flow experiments were conducted to establish the entrainment and mixing characteristics of the layer. Reacting flow experiments were performed using dilute concentrations of the reactants, NO and O3, to ensure that the flow field remained isothermal. The probability density functions (p.d.f.s) and associated statistical quantities of the conserved and reactive scalars are compared with results from previous analytical and experimental studies. The data suggest, in concert with the Broadwell-Breidenthal model, that fluid in the mixing layer exists in three states: tongues of unmixed free-stream fluid which, on occasion, stretch across the layer; finite-thickness interfacial diffusion zones of mixed fluid which border the parcels of unmixed fluid; and regions comprising fluid of nearly homogeneous composition. The data also confirm previously reported asymmetry in entrainment rates from the two feed streams and show the important role of molecular diffusion in the mixing process. A fast-chemistry assumption, applied to predict reactive-species concentrations from the measured conserved-scalar p.d.f.s, overestimates the extent of reaction, indicating the importance of finite-rate chemistry for the present conditions. A Damköhler number, based on large-scale mixing times, is shown to be useful in determining the applicability of a fast-chemistry analysis to reacting mixing layers.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 172 , November 1986 , pp. 93 - 126
Copyright
© 1991 Cambridge University Press

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References

Alber, I. E. & Batt R. G.1976 Diffusion-limited chemical reactions in a turbulent shear layer. AIAA J. 14, 70.Google Scholar
Bates S. C.1977 Luminescent visualization of molecular and turbulent transport in a plane shear layer. MIT Gas Turbine Lab. Rep. 134.Google Scholar
Batt R. G.1977 Turbulent mixing of passive and chemically reacting species in a low-speed layer. J. Fluid Mech. 82, 53.Google Scholar
Bilger R. W.1980 Turbulent flows with non-premixed reactants. In Turbulent Reacting Flows, p. 65. Springer.
Breidenthal R. E.1981 Structure in turbulent mixing layers and wakes using a chemical reaction. J. Fluid Mech. 109, 1.Google Scholar
Broadwell, J. E. & Breidenthal R. E.1982 A simple model of mixing and chemical reaction in a turbulent shear layer. J. Fluid Mech. 125, 397.Google Scholar
Browand, F. K. & Latigo B. O.1979 Growth of the two-dimensional mixing layer from a turbulent and non-turbulent boundary layer. Phys. Fluids 22, 1011.Google Scholar
Brown, G. L. & Roshko A.1974 On density effects and large structure in turbulent mixing layers. J. Fluid Mech. 64, 775.Google Scholar
Coles D.1981 Prospects for useful research on coherent structure in turbulent shear flow. Proc. Indian Acad. Sci. 4, 111.Google Scholar
Corcos, G. M. & Sherman F. S.1976 Vorticity concentration and the dynamics of unstable free shear layers. J. Fluid Mech. 73, 241.Google Scholar
Dimotakis P. E.1984 Entrainment into a fully developed two-dimensional shear layer. AIAA Paper No. 84–0368.Google Scholar
Driscoll J. F., Schefer, R. W. & Dibble R. W.1982 Mass fluxes ‘u’ and ‘v’ measured in a turbulent non-premixed flame. Proc. 19th Symp. on Combustion, p. 477, The Combustion Institute.
Givi P.1984 Turbulent reacting flows. Ph.D. thesis, Carnegie-Mellon University.
Jimenez J., Martinez-Val, R. & Rebollo M.1979 The spectrum of large-scale structures in a mixing layer. Proc. 2nd Symp. on Turbulent Shear Flows, Imperial College.
Kollmann, W. & Janicka J.1982 The probability density function of a passive scalar in turbulent shear flows. Phys. Fluids 25, 1755.Google Scholar
Konrad J. H.1976 An experimental investigation of mixing in two-dimensional turbulent shear flows with applications to diffusion-limited chemical reactions. Project SQUID Tech. Rep. CIT-8-PU.Google Scholar
Koochesfahani M. M.1984 Experiments on turbulent mixing and chemical reactions in a liquid mixing layer. Ph.D. thesis, California Institute of Technology.
Koochesfahani, M. M. & Dimotakis P. E.1984 Laser induced fluorescence measurements of concentration in a plane mixing layer. AIAA Paper No. 84–0198.Google Scholar
Kychakoff G., Howe, R. D. & Hanson R. K.1984 Quantitative flow visualization technique for measurements in combustion gases. Appl. Opt. 23, 704.Google Scholar
Lasheras J. C., Cho, J. E. & Maxworthy T.1986 On the origin and evolution of streamwise vortical structures in a plane, free shear layer. J. Fluid Mech. 172, 231–258.Google Scholar
Masutani S. M.1985 An experimental investigation of mixing and chemical reaction in a plane mixing layer. Ph.D. thesis, Stanford University.
Masutani, S. M. & Bowman C. T.1982 A fiberoptic absorption probe for measurement of a conserved scalar in nonpremixed turbulent reacting flow. Western States Section Combustion Institute Meeting, October 1982, Paper 82–62.Google Scholar
Mungal M. G.1983 Experiments on mixing and combustion with low heat release in a turbulent shear flow. Ph.D. thesis, California Institute of Technology.
Pope S. B.1981 Calculation of a turbulent mixing layer involving the NO + O3 reaction. In S. V. Sherikar & R. Chevray, Proc. 3rd Symp. on Turbulent Shear Flows, University of California.
Roshko A.1976 Structure of turbulent shear flows: a new look. AIAA J. 14, 1349.Google Scholar
Shea J. R.1977 A chemical reaction in a turbulent jet. J. Fluid Mech. 81, 317.Google Scholar
Sherikar, S. V. & Chevray R.1981 A chemically reacting plane mixing layer. Proc. 3rd Symp. on Turbulent Shear Flows, University of California.
Wallace A. K.1981 Experimental investigation of the effects of chemical heat release in the reacting turbulent plane shear layer. Ph.D. thesis, University of Adelaide.
Williams F. A.1985 Combustion Theory. Benjamin/Cummings.
Winant, C. D. & Browand F. K.1974 Vortex pairing: the mechanism of turbulent mixing layer growth at moderate Reynolds number. J. Fluid Mech. 63, 237.Google Scholar