Development of high-speed spectrometer system with high spatial and wavelength resolution and the application to flame diagnostics

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The purpose of the previous study was to investigate the local flamefiont structure and its chemistry by the spatial and temporal behavior of excited radicals, flame stoichiometry, heat release and chemical reaction process. Spatially, temporally, and spectrally resolved chemiluminescence measurements of electronically excited radicals in a flame such as OH^*, CH^*, and C_2^* was carried out to observe the time evolution of chemical reactions in fluid flows. Firstly, we developed an optical measurement technique using specially designed Cassegrain Optics minimized of spherical aberration to detect emissions locally in flames and highspeed (1 MHz) spectrum detectors with gratings. The Cassegrain Optics was coupled with a single core fiber optic so that the light detected with good spatial resolution was guided to spectrometers. Obtained timeseries signals of omission intensities were analyzed statistically as well as instantaneously.Distributions of local flame temperabe and chemilumine … More scence of OH^*, CH^* and C_2^* radicals were simultaneously measured in laminar diffusion flames and laminar premixed flames. The tempffature measurement is based on the Rayliegh scatering method. The Cassegrain optics was used-to measure the chemiluminescence and Rayleigh scattering with high spatial resolution. Relationships between the local flame temperature and chemiluminescence intensities were examined.Temperature measurement method using C_2 band emission intensity ratio is applied to the measurement of timeresolved local temperature in premixed flames. First of all, the relationship between temperature and each peaks of C_2 emission intensity is calculated by using quantum physical theory. We try to know te relationship between local temperature in flame and emission intensity ratio of C_2 chemiluminescence by using experimental method. The temperature obtained from emission intensity ratio is the vibrational temperature of C_2 in the local region of flame. The C_2 vibrational temperature has the possibility to be higher than the temperature in thermal equilibrium state. The temperature measured by thermocouples is used as the temperature in thermal equilibrium state in the present study. The objectives in the present study are to measure local chemiluminescence of premixed laminar flames of propane or methane and air with the Cassegrain optical system and spectroscope unit and to investigate the relationship between temperature measured by thermocouples and C_2 band emission intensity ratio as precise as possible. By changing the temperature in premixed laminar propane/air flames by the difference of the equivalence ratio, the relationship between temperature measured by thermocouples and C_2 band emission intensity ratio can be considered to be a linear fimction. By changing the temperature by diluting with N2, those relationships become linear as well. These measurement methods are applied to premixed methane/air vibrated flames. The Cassegrain optical system and the spectroscope unit are used to measure local chemiluminescence in local region of vibrated premixed flame. The measured chemiluminescence intensity parts with enough strong emission intensity are chosen by numerical processing and the parts show the similar relationships with thermal temperature measured by thermocouples as observed in premixed laminar flames. Less