An Experimental Examination of the Relationship between Chemiluminescent Light Emissions and Heat-release Rate Under Non-Adiabatic Conditions
VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF MECHANICAL ENGINEERING
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Combustion instability research has matured over the last decade and with it the need for more detailed diagnostics has increased. One main gap in the diagnostics is the ability to obtain a reliable quantitative measure of unsteady heat-release rate. In an effort to move in this direction using chemiluminescence as the measured quantity, this paper examines the formation of chemiluminescence light in premixed flames under non-adiabatic conditions. The main chemiluminescence emitters considered in the study are OH and CH. Experimental results for two types of burners are reported, a laminar Bunsen burner with co-flow and a ceramic honeycomb flat flame burner. The study shows that although the chemiluminescence observed in the two burners behaves very differently with respect to changes in experimental variables, the variation can be fully understood. OH chemiluminescence is found to be a good indicator of heat-release in both burners, whereas CH chemiluminescence is shown to be insensitive to some changes in heat- release rate. Based on the experimental results, the notion that chemiluminescence yield behaves linearly with flow rate cannot be universally supported. The non-linear variation observed is shown to correspond to an equally non- linear variation of heat-release with flow-rate. The results of the study thus have important ramifications for the interpretation of chemiluminescence measurements in dynamic combustion environments.
- Radiation and Nuclear Chemistry
- Combustion and Ignition