ANALYSIS OF LASER-INDUCED-FLUORESCENCE CARBON-MONOXIDE MEASUREMENTS IN TURBULENT NONPREMIXED FLAMES

The influence of fluctuating concentrations and temperature on the las er-induced-fluorescence (LIF) measurement of CO inturbulent flames is described, under conditions in which the fluorescence and the temperat ure are measured independently. The analysis shows that correlations b etween CO concentration and temperature can bias the averaged mole fra ction extracted from LIF measurements. The magnitude of the bias can e xceed the order of the average CO mole fraction. Further, LIF measurem ents of CO concentrations in a turbulent, nonpremixed, natural gas fla me are described. The averaged CO mole fractions are derived from the fluorescence measurements by the use of flame temperatures independent ly measured by coherent anti-Stokes Raman spectroscopy. Analysis of th e fluctuations in measured temperature and fluorescence indicates that temperature and CO concentrations in flame regions with intensive mix ing are indeed correlated. In the flame regions where burnout of CO ha s ceased, the LIF measurements of the CO mole fraction correspond to t he probe measurements in exhaust. (C) 1995 Optical Society of America