Dual-Pump Coherent Anti-Stokes Raman Scattering Thermometry in Heavily Sooting Flames

摘要: We investigate the utility of dual-pump coherent anti-Stokes Raman scattering N 2 for probing rich acetylene- and ethylene-fueled flames with soot volume fractions upwards ppm, which is well in excess recent reports sooting flame measurements approach. A substantial level interference coherent-Raman spectra observed when (3-branch signature positioned spectral regions that have been reported to be interference-free are removed from peaks C Swan system chief obstacle thermometry flames. This attributed processes laser-produced C2 olefinic hydrocarbons, exhibit frequencies resonant pump-2/Stokes frequency difference. second source also discussed, a significant nonresonant pedestal added signal, presumably as result laser-induced breakdown presence only highest loadings probed here. Two "spectrally quiet" signal near 483 496 nm identified, temperature profiles an array heavily acetylene-fueled nonpremixed premixed ethylene/air provided using Q-branch nm. The results show viable thermometer at least high albeit more restrictions on position than previously thought.