Stability of moving combustion fronts in porous media
The stability of moving combustion fronts during underground combustion processes is analyzed. The behavior of small deformations in front configuration is studied using linear stability theory and relatively simple models of the combustion processes. In this way the main physical phenomena which influence stability can be clearly distinguished. For wet combustion processes, where both air and water are injected, front stability is affected not only by the ratio of the mobilities of fluids flowing ahead of and behind the front, but also by heat transport near the front and by expansion accompanying vaporization of water at the front. Even more interesting is a ''reverse mobility'' effect predicted by the analysis. Under some conditions at relatively high air to water injection ratios, fluid flow and the heat produced by combustion interact in such a way that normally ''favorable'' mobility ratios become unfavorable. That is, existence of a low mobility in the region of two-phase flow of air and water behind the front can actually promote front instability. For dry combustion the heat transport and reverse mobility effects on stability do not occur and the combustion fronts are typically neither highly stable nor highly unstable, i.e., the effective mobility ratio is near unity.
- OSTI ID:
- 7294990
- Report Number(s):
- CONF-761008-168
- Country of Publication:
- United States
- Language:
- English
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