Species measurements in a nitrogen-diluted, ethylene air diffusion flame using direct sampling mass spectrometry and tunable diode laser absorption spectroscopy

Tunable diode laser absorption spectroscopy combined with extractive sampling is used to quantify fuel and acetylene concentrations in a 32% ethylene-diluted, nitrogen diffusion flame. Additional major species concentrations are determined using quartz microprobe, direct-sampling mass spectrometry. Quantification of these mass spectra used a multilinear regression technique anchored by computed nitrogen concentration profiles in a simulation from Yale University. Because of the overlap in mass spectra features for ethylene, nitrogen, and carbon monoxide, both optical and mass spectrometric techniques are required to determine the suite of major species in this flame system. Good agreement is observed between these experimental measurements and numerical simulation of this flame system. Probe clogging in these sooting flames remains a challenge for all probe techniques and additional, non-intrusive optical diagnostics must be applied to characterize flame regions with substantial soot formation.