Direct Simulations of Chemically Reacting Turbulent Mixing Layers

Direct Simulations of Chemically Reacting Turbulent Mixing Layers
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
Total Pages: 64
Release: 2018-11-03
Genre: Science
ISBN: 9781730760235

The results of direct numerical simulations of chemically reacting turbulent mixing layers are presented. This is an extension of earlier work to a more detailed study of previous three dimensional simulations of cold reacting flows plus the development, validation, and use of codes to simulate chemically reacting shear layers with heat release. Additional analysis of earlier simulations showed good agreement with self similarity theory and laboratory data. Simulations with a two dimensional code including the effects of heat release showed that the rate of chemical product formation, the thickness of the mixing layer, and the amount of mass entrained into the layer all decrease with increasing rates of heat release. Subsequent three dimensional simulations showed similar behavior, in agreement with laboratory observations. Baroclinic torques and thermal expansion in the mixing layer were found to produce changes in the flame vortex structure that act to diffuse the pairing vortices, resulting in a net reduction in vorticity. Previously unexplained anomalies observed in the mean velocity profiles of reacting jets and mixing layers were shown to result from vorticity generation by baroclinic torques. Metcalfe, Ralph W. and Mcmurtry, Patrick A. and Jou, Wen-Huei and Riley, James J. and Givi, Peyman Unspecified Center...

Direct Simulations of Chemically Reacting Turbulent Mixing Layers

Direct Simulations of Chemically Reacting Turbulent Mixing Layers
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
Total Pages: 64
Release: 2018-07-06
Genre:
ISBN: 9781722357658

The results of direct numerical simulations of chemically reacting turbulent mixing layers are presented. This is an extension of earlier work to a more detailed study of previous three dimensional simulations of cold reacting flows plus the development, validation, and use of codes to simulate chemically reacting shear layers with heat release. Additional analysis of earlier simulations showed good agreement with self similarity theory and laboratory data. Simulations with a two dimensional code including the effects of heat release showed that the rate of chemical product formation, the thickness of the mixing layer, and the amount of mass entrained into the layer all decrease with increasing rates of heat release. Subsequent three dimensional simulations showed similar behavior, in agreement with laboratory observations. Baroclinic torques and thermal expansion in the mixing layer were found to produce changes in the flame vortex structure that act to diffuse the pairing vortices, resulting in a net reduction in vorticity. Previously unexplained anomalies observed in the mean velocity profiles of reacting jets and mixing layers were shown to result from vorticity generation by baroclinic torques. Metcalfe, Ralph W. and Mcmurtry, Patrick A. and Jou, Wen-Huei and Riley, James J. and Givi, Peyman Unspecified Center...

Direct Numerical Simulation for Turbulent Reacting Flows

Direct Numerical Simulation for Turbulent Reacting Flows
Author: Thierry Baritaud
Publisher: Editions TECHNIP
Total Pages: 328
Release: 1996
Genre: Science
ISBN: 9782710806981

Contents: Description of accurate boundary conditions for the simulation of reactive flows. Parallel direct numerical simulation of turbulent reactive flow. Flame-wall interaction and heat flux modelling in turbulent channel flow. A numerical study of laminar flame wall interaction with detailed chemistry: wall temperature effects. Modeling and simulation of turbulent flame kernel evolution. Experimental and theoretical analysis of flame surface density modelling for premixed turbulent combustion. Gradient and counter-gradient transport in turbulent premixed flames. Direct numerical simulation of turbulent flames with complex chemical kinetics. Effects of curvature and unsteadiness in diffusion flames. Implications for turbulent diffusion combustion. Numerical simulations of autoignition in turbulent mixing flows. Stabilization processes of diffusion flames. References.

Modeling and Simulation of Turbulent Mixing and Reaction

Modeling and Simulation of Turbulent Mixing and Reaction
Author: Daniel Livescu
Publisher: Springer Nature
Total Pages: 273
Release: 2020-02-19
Genre: Technology & Engineering
ISBN: 9811526435

This book highlights recent research advances in the area of turbulent flows from both industry and academia for applications in the area of Aerospace and Mechanical engineering. Contributions include modeling, simulations and experiments meant for researchers, professionals and students in the area.

Chemical Reactions in Turbulent Mixing Flows

Chemical Reactions in Turbulent Mixing Flows
Author: Paul E. Dimotakis
Publisher:
Total Pages: 72
Release: 1998
Genre: Gas dynamics
ISBN:

This program focused on fundamental investigations of mixing, chemical-reaction, and combustion processes, in turbulent, subsonic, and supersonic free-shear flows. The program was comprised of an experimental effort; an analytical, modeling, and computational effort; and a diagnostics, instrumentation, and data-acquisition-development effort, with significant progress in each. With regard to gas-phase shear-layer mixing and combustion, effects of inflow/initial conditions, compressibility, and Reynolds number were experimentally investigated and, to a large extent, clarified. New measures to characterize level sets in turbulence were developed and successfully employed to characterize experimental data of liquid-phase turbulent-jet flows as well as three-dimensional direct-numerical-simulation data of Rayleigh-Taylor-instability flows. The computational effort has added to our understanding of the (H2+NO)/F2 chemical system employed in the shear-layer-mixing investigations as well as mixing in high-speed flows, along with further developments in Riemann-Invariant-Manifold gasdynamic simulation techniques and their application to unsteady detonation phenomena. On the diagnostic front, developments in digital imaging and Image Correlation Velocimetry have continued, and been used to investigate turbulent-jet mixing, the unsteady flow over an accelerating airfoil, to mitigate aliasing problems in the computer reconstruction of (2+1)-dimensional isosurface data, and in other applications.

Coarse Grained Simulation and Turbulent Mixing

Coarse Grained Simulation and Turbulent Mixing
Author: Fenando F. Grinstein
Publisher: Cambridge University Press
Total Pages: 481
Release: 2016-06-30
Genre: Science
ISBN: 1107137047

Reviews our current understanding of the subject. For graduate students and researchers in computational fluid dynamics and turbulence.

Turbulent Mixing in Nonreactive and Reactive Flows

Turbulent Mixing in Nonreactive and Reactive Flows
Author: S. Murthy
Publisher: Springer Science & Business Media
Total Pages: 469
Release: 2013-11-11
Genre: Science
ISBN: 1461587387

Turbulence, mixing and the mutual interaction of turbulence and chemistry continue to remain perplexing and impregnable in the fron tiers of fluid mechanics. The past ten years have brought enormous advances in computers and computational techniques on the one hand and in measurements and data processing on the other. The impact of such capabilities has led to a revolution both in the understanding of the structure of turbulence as well as in the predictive methods for application in technology. The early ideas on turbulence being an array of complicated phenomena and having some form of reasonably strong coherent struc ture have become well substantiated in recent experimental work. We are still at the very beginning of understanding all of the aspects of such coherence and of the possibilities of incorporating such structure into the analytical models for even those cases where the thin shear layer approximation may be valid. Nevertheless a distinguished body of "eddy chasers" has come into existence. The structure of mixing layers which has been studied for some years in terms of correlations and spectral analysis is also getting better understood. Both probability concepts such as intermittency and conditional sampling as well as the concept of large scale structure and the associated strain seem to indicate possibilities of distinguishing and synthesizing 'engulfment' and molecular mixing.