Two-dimensional temperature determination in the exhaust region of a laminar flat-flame burner with linear Raman scattering.

For planar temperature measurements in combusting flows, the well-established laser Raman technique has been further developed to provide two-dimensional local resolution. After excitation with a frequency-doubled Nd:YAG laser, the anti-Stokes and the Stokes Raman signals of the vibrational Q branch of molecular N(2) were detected at 473.3 and 607.3 nm, respectively. From the ratio of the two images, two-dimensional temperature distributions have been obtained by application of an analytical function, which was determined from theoretically calculated Raman spectra. Time-averaged measurements have been performed in the exhaust region of an atmospheric-pressure laminar CH(4)/air flat-flame burner for different equivalence ratios. The accuracy and precision of the results are discussed in combination with the prospects for time-resolved single-pulse measurements.