Numerical modeling and simulation of compressible reacting turbulent shear layers
Burr, Ronald Frederick
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Permalink
https://hdl.handle.net/2142/21342
Description
Title
Numerical modeling and simulation of compressible reacting turbulent shear layers
Author(s)
Burr, Ronald Frederick
Issue Date
1991
Doctoral Committee Chair(s)
Dutton, J. Craig
Department of Study
Mechanical Science and Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Mechanical
Language
eng
Abstract
Numerical modeling and simulation of compressible reacting turbulent shear layers are considered. In the numerical modeling portion of this work, improved turbulent transport models for compressible shear layers are presented and validated with detailed experimental data. The new compressible models are one-equation and two-equation algebraic Reynolds stress models (ASMs), which account for variations in the anisotropy of the normal stresses through modification of the pressure-strain terms of the Reynolds stress transport equations. In contrast to previous models, the compressible ASMs correctly predict the experimentally observed increase in turbulence anisotropy with increasing compressibility, as well as the reduction in the normalized shear layer growth rate. The effects of compressibility on the transport and mixing of a passive scalar are also considered. Finally, reacting compressible turbulent shear layer modeling results are presented. An assumed probability density function (PDF) turbulent H$\sb2$-air combustion model is implemented and demonstrated using three forms of PDFs. For comparison, 9-species, 18-reaction finite-rate and equilibrium calculations are also presented. The importance of modeling unmixedness and its effect on chemical reaction and heat release are clearly illustrated. The above models are developed and validated in a new parabolized Navier-Stokes (PNS) code.
In the second major emphasis of the present research effort, numerical simulations of temporally evolving compressible and reacting shear layers are performed. The results are examined in terms of the steady-state shear layer modeling techniques. Results from the simulations are consistent with recent experimental data and further support the proposed compressibility modification to the pressure-strain modeling. It is shown that standard incompressible pressure-strain models overestimate the contribution of these terms under compressible conditions. Reacting shear layer results are also presented. Consistent with previous simulations, the basic shear layer structure is relatively unaffected by slow reaction, although the growth rate is reduced. In the slower reaction cases, the heat release takes place in a distributed fashion at the mixed vortex core and results in controlled expansion of the eddy. For faster reactions, a larger fraction of the reaction and heat release takes place in the strained interfaces between the fuel and oxidizer layers and increases the distortion of the vortex structure.
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