Combustion Oscillations, Extinction & Control
Abstract
The research has involved experiments with three main flow configurations and the development of a computational method. Most of the experiments were carried out in two sudden-expansion flows, one with a plane geometry which afforded complete optical assess and the other in an axisymmetric arrangement which was closer to engineering practice but with less comprehensive optical access. A combination of optical methods was used to explore these flows which gave rise to similar flammability limits. The oscillations observed with near-stoichiometric mixtures were examined but the new main finding related to near-limit mixtures where a process of local extinction due to strain rates gave rise to low-frequency oscillations which could couple with Helmholtz and acoustic frequencies. These oscillations are related to those which lead to dynamic problems in low NO(x) gas turbines. Experiments with opposed flows showed that extinction is related to the strain rates generated by impingement and that the relationship is more complex that considered here to fore. The calculation method showed that instabilities in plane sudden-expansion flows did not require consideration of time dependence and provides a vehicle for exploring different distributions of heat release rate, as found in the experiments.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2000
- Accession Number
- ADA378585
Entities
People
- J. H. Whitelaw