The developments in combustion technology has to be catered to in parallel by the development in the instrumentation employed in collection of combustion data, to get a better picture of the complex processes involved. In this regard, the flame temperature and equivalence ratio are the most important parameters that has to be studied to infer the combustion efficiency and emissions from combustion. Combustion reactions in flames give rise to the formation of various intermediate radicals, some of which are chemiluminescent by nature. The relative intensity of optical emissions from chemiluminescent radicals such as OH*(the asterisk is used as a notation for electronically excited states), CH* and C2* can be used for flame thermometry and spatial analysis of flame structure in hydrocarbon flames. The C2* radical and CH* radical is emphasized upon in this study for the analysis of laminar premixed hydrocarbon flames. Spatial distribution of these radicals is mapped from their chemiluminescence signals and recorded across various zones of the flame using a fiber optic bundle to capture incoming photons, a Czerny-Turner spectrometer encompassing a diffraction grating for optical dispersion and a CCD detector to record the spectrum. Local flame spectra recorded in the reaction zone of methane/air flames are known to exhibit strong emission signals from OH*, CH* and C2* radicals. The peak intensity ratios of these radicals in the reaction zone are functions of local equivalence ratio. To sum up, spectral intensity measurements of such chemiluminescent radicals serve as tools for analyzing the local flame stoichiometry and for the measurement of local flame temperature.
In this thesis work, an experimental set-up is proposed to capture the spectral signals of a premixed, laminar, methane-air Bunsen flame at various spatial locations across the geometry of the flame. Using the emission spectra of this flame, the flame characteristics like relative intermediate radical species concentration, the spatial distribution of radicals, the flame equivalence ratio, the rotational and vibrational flame temperature and their degree of agreement with the adiabatic flame temperature are studied. It has been found that a definite relationship exists between the spectral signals emitted by these chemiluminescent radicals and the flame parameters such as equivalence ratio and adiabatic flame temperature.