A fast response method for detection of ignition and extinction of liquid spray
flames has been improved. Also, a method of determining fuel-to-air ratios and
temperatures of pre-mixed, gaseous flames has been developed. Both methods utilize
chemiluminescent signals from an OH system centered at 309 nm and a CH system
centered at 431 nm. The ignition and extinction method was improved by replacing an
optical system composed of lenses and a monochromator by a system composed of a
fiber optic cable and band pass interference filters. The use of a solid-state photodiode
instead of a photomultiplier tube was investigated. Transient histories of the OH and CH
signals were recorded by performing light-off ignition and intermittent ignition flame
tests. These signal histories were compared to histories obtained using the original
apparatus. The fuel-to-air ratio and temperature detection method was investigated by
recording the spectra of laminar, pre-mixed methane flames of known stoichiometry with
a lens, monochromator, and photomultiplier tube set-up and measuring the flame
temperatures with a high-temperature Pt-10%Rh thermocouple. Various combinations of
signal characteristics were found to be functions of fuel-to-air ratio and temperature.
Optimum signals for monitoring with a detector were determined. Recommendations for
future work in this area are discussed.
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