Abstract
The capability to simultaneously acquire two orthogonal components of a Raman spectrum has been added to the Sandia Raman/Rayleigh/CO-LIF instrument for combustion measurements. This addition allows removing unpolarized fluorescence interference signal from Raman spectra, extending the applicability of the instrument to rich hydrocarbon flames. The optical set-up and the data analysis approach are described. The instrument is tested in challenging rich laminar and turbulent CH4/air flames, deemed inaccessible with the previous instrument. Experimental results show good agreement with laminar calculations performed with Chemkin. The approach also avoids the cumbersome calibration and correction procedures required for data collected with the previous version of the instrument in presence of mild fluorescence interference. The drawback is a drop in the instrument precision, in particular for CO2 and O-2 concentrations. Published by Elsevier Inc. on behalf of The Combustion Institute.