CARS spectra from lean and stoichiometric CH4N2O flames

✍ Scribed by L.E. Harris

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 871 KB
• Volume: 53
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(83)90010-x

✦ Synopsis

Broadband CARS spectra were obtained from both the reaction zone and postflame regions of lean and stoichiometric CH4/N20 flames. To assess methods of obtaining concentration from broadband spectra, N 2 CARS spectra were obtained from a series of air/Ar mixtures at room temperature. The concentration of N 2 was obtained with good accuracy (6%) both from fitting the shape of the broadband spectra and from the ratio of the resonant susceptibility to the nonresonant susceptibility. Both methods were utilized in interpreting flame spectra.

CARS spectra of both N 2 and N20 were obtained from the reaction zone of 0.3 equivalence ratio CHJN20 flames. Spectra were obtained from room temperature to near the adiabatic flame temperature. Simultaneous observation of both N 2 and N 20 spectra allowed determination of temperature and concentrations of both species from the same point in the flame. The spectra demonstrated the high spatial resolution of CARS.

In addition, N 2 CARS spectra were obtained from the postflame region of ¢ = 0.3, 0.4, 0.5, and 1.0 CH4/N20 flames. The N 2 spectra were used to obtain concentration and temperature profiles by a least squares fit to model calculations. The temperatures obtained varied with reactant flow rates. However, at appropriate flow rates, the concentrations and temperatures obtained close to the burner surface were in accord with thermochemical calculations.

The temperature and concentration profiles obtained from both N 2 and N20 CARS spectra can be used to help understand the elementary processes occurring in the CH 4/N 20 flames investigated.