Fiber-coupled multiple-line infrared emission measurements to determine temperature, CO2, and H2O

Abstract This paper presents the design of a custom fiber-based system designed to simultaneously monitor carbon dioxide and water column densities and line-of-sight averaged temperature. The system utilizes zirconium fluoride optical fibers to transmit infrared radiation (2– 5 μm ) from high-temperature combustion effluent. Bandpass filters are used to separate emission from different species and optically thick emission from carbon dioxide is used to determine temperature. The temperature and molecule specific spectral profiles of the radiating gases, as well as atmospheric absorption, dictates high-resolution modeling of system radiation. Using this information, band models have been created that relate the net emissivity for a particular bandpass filter to the temperature and column densities of the flow field. Initial testing has been done on a methane burner; the ability to follow fluctuations for each constituent has been demonstrated. The band models have been used to reduce the flame radiance data for each filter; column density and temperature results from several flame conditions are reported.