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In Situ Optical Techniques for Jet Engine Exhaust Hydrocarbon Detection
Final rept. Sep 1976-Oct 1977
ARO INC ARNOLD AFS TN
Pagination or Media Count:
An investigation was conducted to determine the feasibility of developing an in situ optical technique suitable for jet engine exhaust diagnostics of gaseous hydrocarbon concentrations. Two absorption spectroscopy techniques were investigated 1 high-resolution interferometric spectroscopy in the 12800-3250 cm region of the IR and 2 the absorption of the radiation of a modified He-Ne laser emitting in the IR. A candidate for use as a radiation source in a correlation spectrometer, a microwave-excited methane infrared source, was also evaluated. Another spectroscopic technique, the detection of CH visible emission, was also investigated. As a means of investigating the possible effects of mechanical probing on the chemical identify and hence the spectroscopic properties of the hydrocarbon constituents of exhaust gases, a simulation of the effects of probing on methane containing exhaust constituents was performed. A preliminary investigation of the gaseous hydrocarbon content of a combustor using in situ optical probing and online conventional gas analyzers as well as optical probing and laboratory gas analysis of samples drawn with an orifice-type emissions probe is also reported. It was concluded that the best approach to in situ gaseous hydrocarbon detection may be a multiple-pass, tuneable diode laser system.
APPROVED FOR PUBLIC RELEASE