CARS Spectra from Lean and Stoichiometric CH(4)-N(2)O Flames
ARMY ARMAMENT RESEARCH AND DEVELOPMENT CENTER DOVER NJ LARGE CALIBER WEAPON SYSTEMS LAB
Pagination or Media Count:
Broadband CARS spectra were obtained from both the reaction zone and post-flame region of lean and stoichiometric CH4-N2O flames. To assess methods of obtaining concentration from broadband spectra, N2 CARS spectra were obtained from a series of air and argon AIRAR mixtures at room temperature. The concentration of N2 with good accuracy 6 was obtained both from fitting the shape of the broadband spectra and from the ratio of the resonant to nonresonant susceptibility. Both methods were utilized in interpreting flame spectra. CARS spectra of both N2 and N2O were obtained from the reaction zone of near 0.3 equivalence ratio fueloxidizer CH4-N2O flames. Spectra were obtained from room temperature to near the adiabatic flame temperature. Simultaneous observation of both N2 and N2O spectra allows determination of temperature and concentration of both species from the same point in the flame. The spectra demonstrated the high spatial resolution of CARS. In addition, N2 CARS spectra were obtained from the post-flame region of 0.3, 0.4, 0.5 and 1.0 CH4-N2O flames. The N2 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 calculation. The temperature and concentration profiles obtained from both N2 and N2O CARS spectra can be used to understand the elementary processes occurring in the CH4-N2O flames investigated.
- Atomic and Molecular Physics and Spectroscopy
- Combustion and Ignition