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SPECTRAL OPTIMIZATION AND UNCERTAINTY QUANTIFICATION IN
COMBUSTION MODELING
by
David Allan Sheen
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(AEROSPACE ENGINEERING)
May 2011
Copyright 2011 David Allan Sheen
Object Description
| Title | Spectral optimization and uncertainty quantification in combustion modeling |
| Author | Sheen, David Allan |
| Author email | sheen@usc.edu; sheen.david@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Aerospace Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2010-12-07 |
| Date submitted | 2011 |
| Restricted until | Unrestricted |
| Date published | 2011-01-25 |
| Advisor (committee chair) | Wang, Hai |
| Advisor (committee member) |
Egolfopoulos, Fokion N. Ghanem, Roger G. Bickers, Eugene |
| Abstract | Reliable simulations of reacting flow systems require a well-characterized, detailed chemical model as a foundation. Accuracy of such a model can be assured, in principle, by a multi-parameter optimization against a set of experimental data. However, the inherent uncertainties in the rate evaluations and experimental data leave a model still characterized by some finite kinetic rate parameter space. Without a careful analysis of how this uncertainty space propagates into the model's predictions, those predictions can at best be trusted only qualitatively.; In this work, the Method of Uncertainty Minimization using Polynomial Chaos Expansions is proposed to quantify these uncertainties. In this method, the uncertainty in the rate parameters of the as-compiled model is quantified. Then, the model is subjected to a rigorous multi-parameter optimization, as well as a consistency-screening process. Lastly, the uncertainty of the optimized model is calculated using an inverse spectral optimization technique, and then propagated into a range of simulation conditions. An as-compiled, detailed H₂/CO/C₁-C₄ kinetic model is combined with a set of ethylene combustion data to serve as an example.; The idea that the hydrocarbon oxidation model should be understood and developed in a hierarchical fashion has been a major driving force in kinetics research for decades. How this hierarchical strategy works at a quantitative level, however, has never been addressed. In this work, we use ethylene and propane combustion as examples and explore the question of hierarchical model development quantitatively. The Method of Uncertainty Minimization using Polynomial Chaos Expansions is utilized to quantify the amount of information that a particular combustion experiment, and thereby each data set, contributes to the model. This knowledge is applied to explore the relationships among the combustion chemistry of hydrogen/carbon monoxide, ethylene, and larger alkanes.; Frequently, new data will become available, and it will be desirable to know the effect that inclusion of these data has on the optimized model. Two cases are considered here. In the first, a study of H₂/CO mass burning rates has recently been published, wherein the experimentally-obtained results could not be reconciled with any extant H₂/CO oxidation model. It is shown in that an optimized H₂/CO model can be developed that will reproduce the results of the new experimental measurements. In addition, the high precision of the new experiments provide a strong constraint on the reaction rate parameters of the chemistry model, manifested in a significant improvement in the precision of simulations.; In the second case, species time histories were measured during n-heptane oxidation behind reflected shock waves. The highly precise nature of these measurements is expected to impose critical constraints on chemical kinetic models of hydrocarbon combustion. The results show that while an as-compiled, prior reaction model of n-alkane combustion can be accurate in its prediction of the detailed species profiles, the kinetic parameter uncertainty in the model remains to be too large to obtain a precise prediction of the data. Constraining the prior model against the species time histories within the measurement uncertainties led to notable improvements in the precision of model predictions against the species data as well as the global combustion properties considered. Lastly, we show that while the capability of the multispecies measurement presents a step-change in our precise knowledge of the chemical processes in hydrocarbon combustion, accurate data of global combustion properties are still necessary to predict fuel combustion. |
| Keyword | kinetic modeling; optimization; uncertainty quantification |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m3626 |
| Rights | Sheen, David Allan |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Sheen-4250 |
| Archival file | uscthesesreloadpub_Volume26/etd-Sheen-4250.pdf |
Description
| Title | Page 1 |
| Full text | SPECTRAL OPTIMIZATION AND UNCERTAINTY QUANTIFICATION IN COMBUSTION MODELING by David Allan Sheen A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (AEROSPACE ENGINEERING) May 2011 Copyright 2011 David Allan Sheen |
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