Determination of temperatures and fuel/air ratios in an ethene-air flame by dual-pump CARS

The simultaneous determination of temperature and ethene, oxygen and nitrogen concentrations is demonstrated using the dual-pump coherent anti-Stokes Raman spectroscopy (CARS) technique. Temperature and relative N(2)/O(2) concentrations were calculated from contour fitting against theoretically calculated spectra, while relative N(2)/C(2)H(4) Concentrations were obtained from the integrated intensity ratio, calibrated in a heated gas cell. Detailed measurements were performed in a partially premixed ethene-air co-flowing jet flame established on a slot burner. As the two vibrational Raman modes nu(2) (1623 cm(-1)) and nu(3) (1342 cm(-1)) of ethene are in close vicinity of the oxygen Raman transition at 1556 cm(-1), either the nu(2) or the nu(3) transition can be excited together with O(2) using a single narrowband-broadband laser combination. Both possibilities are discussed. Additionally, nitrogen is probed for thermometry with the same broadband laser but another narrowband laser in a dual-pump CARS approach. Copyright (C) 2003 John Wiley Sons, Ltd.