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

Abstract 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 ν 2 (1623 cm −1 ) and ν 3 (1342 cm −1 ) of ethene are in close vicinity of the oxygen Raman transition at 1556 cm −1 , either the ν 2 or the ν 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 © 2003 John Wiley & Sons, Ltd.