DEMONSTRATION OF TEMPERATURE AND OH MOLE FRACTION DIAGNOSTIC IN SiH_4/H_2/O_2/Ar FLAMES USING NARROW-LINE UV OH ABSORPTION SPECTROSCOPY

摘要

Results of an experimental study of the application of frequency-modulated UV laser absorption spec-troscopy to silica (SiO_2) particle-forming flames (SiH_4/H_2/O_2/Ar) are presented. An argon-ion pumped ring-dye laser system in the rapid wavelength scanning configuration was used to obtain multiple line shape profiles of the R_1(7) and R_1(11) transitions in the A~2Σ~+ ← X~2Π_i (0,0) band of the OH spectrum (ν_o = 32,625.547 and 32,625.072 cm~(-1), respectively). Temperature and OH mole fraction were determined by a best fit of a convolved Voigt absorption profile to the data. Measurements were made in the multiphase regions of silane/hydrogen/oxygen/argon flames, verifying the applicability of the diagnostic approach to combustion synthesis systems. Absorption measurements were taken over a range of particle environments found at increasing heights above the burner surface (5―20 mm) and equivalence ratios (Φ = 1.0 and 1.2). The experimental data were compared with thermocouple measurements, equilibrium, and one-dimensional modeling simulations. The results of the study successfully demonstrate OH UV absorption spec-troscopy as a highly sensitive and accurate (uncertainties less than +- 10% in the current work) diagnostic approach for in situ measurements of temperature and OH mole fractions in combustion synthesis flames.