Application of CARS to Simulated Practical Combustion Systems

Abstract

Results are presented of coherent anti-Stokes Raman spectroscopy (CARS) experiments performed in a combustor which produces a bluff-body-stabilized flame having recirculating flow characteristics similar to those in many practical combustion systems. These results were obtained from the following CARS measurements with gaseous propane used as the fuel: determination of temperature profiles in the flame based upon analysis of the scanned N2 spectra (time-averaged spectra), and the mapping of the concentration of N2 and O2 based upon the broadband integration of all Q-branch lines using a single laser pulse. Presented also are: 1) comparison of CARS temperature data and those from a thermocouple taken at the same locations in the combustor, 2) comparison of CARS concentration data for O2 and those obtained with a gas-sampling probe, and 3) comparison of temperature data obtained by single-pulse CARS and by the sodium line-reversal method. In addition, preliminary results obtained in experiments using the liquid fuels JP-4 and shale-oil-derived JP-8 are also reported. The results obtained to date indicate that with the CARS technique spatially and temporally resolved measurements of species concentration and temperature can be made in the reacting zone of large-scale combustors using gaseous or liquid fuel.