EXPERIMENTAL INVESTIGATION OF OH* AND CH* CHEMILUMINESCENCE UNDER VARYING OPERATING CONDITIONS

In this study a measurement method is presented to determine the air excess ratio in two dimensions from the OH*/CH* chemiluminescence intensity ratio. For those measurements three bandpass filtered images of OH*, CH* and CO2* need to be taken simultaneously. The original image is tripled by three lenses. After distortion correction those three images can be used to calculate the OH*/CH* ratio. To validate the gained data, the focus lies on fundamental investigations with a spectrometer; done on two combustion processes: a premixed natural gas/air swirl-flame with a preheat temperature of 450K and a sequential combustion process where the second natural gas/vitiated air flame is investigated. Here the inlet temperature of the vitiated air in the second combUstion stage is 1,300K Beside preheat temperature, pressure is varied from one to three bar. Hence reference data is available for the range below and beyond the autoignition temperature of natural gas at various pressures. Thus the impact of a sequential combustion process on the OH*/CH* chemiluminescence intensity ratio is captured too.