Multicomponent Comparison of Optical and Mass Spectrometric Diagnostics in Low-Pressure Flames.

摘要

A new generation flat flame burner system for characterization of one-dimensional premixed laminar flames has been developed to study the detailed flame chemistry relevant to gaseous flames of burning propellants. This instrument incorporates several spectral techniques in one apparatus so that various diagnostic techniques can be quantitatively compared and the usable detection range (both in terms of spatial resolution and species detection) expanded. Features include molecular beam sampling with triple quadrupole mass spectrometric detection (MB/MS), laser-induced fluorescence (LIF), resonance-enhanced multiphoton ionization (REMPI), and temperature analysis by thermocouple and LIF. The intercomparison of different diagnostic techniques was accomplished on a stoichiometric 20 Torr C2H4/O2/Ar flame. Profiles for O, H, and OH were obtained. Temperature profiles were taken of the unperturbed as well as perturbed (quartz sampler present) flames. As expected, the quartz sampler acted as a heat sink (approximately 200 K lower in the highest temperature flame regions). In general, the comparison between the different diagnostic techniques, is fair. Possible reasons for the minor discrepancies observed are discussed and include diffusion and thermal effects for the mass spectrometric technique as well as photochemical and stimulated emission effects for the laser diagnostics.