Molecular beam sampling-mass spectrometer study of H2−O2−NO flames

Abstract

Nitric Oxide has been added to low pressure H2−O2−Ar flames and its concentration profile through the flame has been measured by molecular beam sampling/mass spectrometry. The stoichiometry of the flames ranged from =.88 to 1.74 and temperature and major species profiles were measured in each flame. The NO concentration decreased rapidly from its initial value (8000 or 4000 ppm) by about 25–35% in the first 10 mm for all flames. In the lean flames the NO concentration increased in the post flame gases to approximately the initial values. In the rich flames, the NO decreased another 12–20% in the post flame gases. N2 profiles obtained in the same flames show a rapid increase early in the flame and then a decrease in the lean flames and a near steady behavior in the rich flames. This behavior is unusual in that it implies that N2 must be involved in rapid reversible reactions in the H2−O2 flames. The chemical kinetics considerations of these results are discussed.