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Accession Number:
AD1013291
Title:
Critical Scales, Fundamental Structures and Inherent Instabilities of Turbulent Flames
Descriptive Note:
Technical Report,01 Apr 2012,31 Mar 2015
Corporate Author:
The Regents of the University of California San Diego United States
Report Date:
2015-06-01
Pagination or Media Count:
7.0
Abstract:
This research addressed a number of fundamental aspects of turbulent combustion. Regime diagrams were identified for both premixed and non-premixed turbulent flames. Characteristics of turbulent flames in the different regimes were investigated. To complement low-speed regimes, types of high-speed turbulent combustion were determined. Interactions of detonations with turbulent fields were clarified. The limits in which detonation thicknesses were small and large in comparison with the range of turbulence scales were both analyzed. It was shown that in both limits interactions of detonations with non-uniform fluid density fields had greater effects than interactions with non-uniform fluid velocity fields. High-speed turbulent combustion dynamics thereby was shown to behave very differently than low-speed turbulent-combustion dynamics. In addition, fuel-spray interactions in mixing layers were studied. By exhibiting fuel-dependent non-monotonic variations of mixture fraction in the two-phase flow fields, traditional approaches to subgrid-scale modeling of turbulent spray combustion were shown to be in need of revision. Useful directions for future research in the area were identified. In addition to these advances, chemistry of hydrogen combustion was improved. A wide range of hydrogen combustion problems was identified and solved. Especially noteworthy was the clarification of the third explosion limit for hydrogen. While previously diffusion of HO2 was believed to be of greatest importance for the third limit, it was shown that, instead diffusion of H2O2 was of greatest importance for this limit. The research finally resulted in a thorough understanding of hydrogen combustion, with the chemical kinetics now well defined. A complete summary of these results was prepared.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
