| Autor: |
Robert W. Bilger, Kevin M. Lyons, Jonathan H. Frank, David F. Marran, Sten H. Strner, Marshall B. Long |
| Rok vydání: |
1994 |
| Předmět: |
|
| Zdroj: |
Symposium (International) on Combustion. 25:1159-1166 |
| ISSN: |
0082-0784 |
| DOI: |
10.1016/s0082-0784(06)80754-x |
| Popis: |
Three different experimental approaches for making instantaneous, two-dimensional (2D) measurementsof the mixture fraction in turbulent nonpremixed hydrocarbon flames are presented. The availability of spatial information on the mixture fraction provided by these techniques makes determination of the scalar dissipation feasible. Each of the techniques to be presented is based on simultaneously imaging fuel concentration and Rayleigh scattering. Measurement of the fuel concentration can be accomplished in a number of ways, including (1) Raman scattering from the fuel, (2) fluorescence from the fuel, or (3) fluorescence from a molecular tag added to the fuel. Preliminary results for experiments utilizing each of these approaches will be presented. In one experiment, joint Raman/Rayleigh measurements were performed in a turbulent methane flame.This approach worked quite well and was able to provide valuable mixture fraction statistics. However, the weak Raman signal required a tradeoff between signal/noise and spatial resolution. A second experiment involved imaging fuel fluorescence from an acetaldehyde flame. The acetaldehyde fluorescence/Rayleigh images obtained in this experiment were of high quality. On the fuel-rich side of the flame, however, the calculated mixture fraction shows a dip and plateau. These irregularities may be the result of fuel pyrolysis and could represent a limitation of this approach. A third method of mixture fraction measurement was to introduce acetone as a fuel tracer and image its fluorescence. Acetone fluorescence proved to be problematic when excited at a wavelength of 320 nm. Our measurements show indications of a temperature dependence of the fluorescence yield, making it difficult to interpret the signal. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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