Free radicals augmentation, and large eddy probability-density simulation for high-speed turbulent combusting jets.

Persistent Link:
http://hdl.handle.net/10150/187211
Title:
Free radicals augmentation, and large eddy probability-density simulation for high-speed turbulent combusting jets.
Author:
Yang, Yongsheng.
Issue Date:
1995
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Theoretical and experimental investigations aimed at altering "nature-prescribed" hydrocarbon combustion are described; the basic intention is to anchor combustion zones in supersonic streams. The well-known free-radicals augmented combustion is studied, but with a novel innovation of donor injection, rather than free-radicals themselves. Standard methane/air combustion is explored in an open jet geometry in the turbulent regime. A new flammability criterion is established in the light of the Kolmogorov microscale mixing. The diagnostics are non-intrusive through infrared thermograms and acoustic emissions. Fifty percent extension of the lean flammability limit is experimentally demonstrated. Unambiguous differences in acoustic power spectra indicate a great increase of the reaction rate. Possible reductions of pollutants observed from thermochemical calculations are further confirmed by infrared imaging processing. Numerical simulations of high-speed turbulent combustion are studied. A new method: Large Eddy Probability-density Simulation (LEPS), has been proposed based on both the large eddy simulation and the probability density function method. In this approach, a mixed finite-spectral method is employed to solve for the velocity field, while the probability density function method is used to solve for the energy and species equations. In the PDF solver, a modified composition joint PDF equation is derived, in which the mean velocity field from the κ-ε model in the traditional PDF equation is replaced by the resolved velocity field from the LES so that the large-scale effect is explicitly represented. The solution algorithms are discussed in full detail. This new method is highly perspective in simulating turbulent reacting flows because both advantages of the LES and PDF approach have been taken, whereas both disadvantages have been offset! Initial simulation results are presented. Future work is outlined.
Type:
text; Dissertation-Reproduction (electronic)
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Aerospace and Mechanical Engineering; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Ramohalli, Kumar

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleFree radicals augmentation, and large eddy probability-density simulation for high-speed turbulent combusting jets.en_US
dc.creatorYang, Yongsheng.en_US
dc.contributor.authorYang, Yongsheng.en_US
dc.date.issued1995en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractTheoretical and experimental investigations aimed at altering "nature-prescribed" hydrocarbon combustion are described; the basic intention is to anchor combustion zones in supersonic streams. The well-known free-radicals augmented combustion is studied, but with a novel innovation of donor injection, rather than free-radicals themselves. Standard methane/air combustion is explored in an open jet geometry in the turbulent regime. A new flammability criterion is established in the light of the Kolmogorov microscale mixing. The diagnostics are non-intrusive through infrared thermograms and acoustic emissions. Fifty percent extension of the lean flammability limit is experimentally demonstrated. Unambiguous differences in acoustic power spectra indicate a great increase of the reaction rate. Possible reductions of pollutants observed from thermochemical calculations are further confirmed by infrared imaging processing. Numerical simulations of high-speed turbulent combustion are studied. A new method: Large Eddy Probability-density Simulation (LEPS), has been proposed based on both the large eddy simulation and the probability density function method. In this approach, a mixed finite-spectral method is employed to solve for the velocity field, while the probability density function method is used to solve for the energy and species equations. In the PDF solver, a modified composition joint PDF equation is derived, in which the mean velocity field from the κ-ε model in the traditional PDF equation is replaced by the resolved velocity field from the LES so that the large-scale effect is explicitly represented. The solution algorithms are discussed in full detail. This new method is highly perspective in simulating turbulent reacting flows because both advantages of the LES and PDF approach have been taken, whereas both disadvantages have been offset! Initial simulation results are presented. Future work is outlined.en_US
dc.description.noteDigitization note: p.179 unavailable for rescan.-
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAerospace and Mechanical Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairRamohalli, Kumaren_US
dc.contributor.committeememberPeterson, Thomasen_US
dc.contributor.committeememberChan, Choliken_US
dc.identifier.proquest9603358en_US
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