Influence of oscillations on NOx emissions from ducted flames

Concentrations of NOx were measured at the exit of round sudden-expansion combustors and quantify the effects of oscillations at equivalence ratios between stoichiometry and the lean limit. The maximum temperature was constrained by the adiabatic flame temperature at the higher equivalence ratios so that oscillations led to lower mean temperatures and concentrations of NOx. In contrast, the minimum temperature and concentrations were constrained by extinction close to the lean limit and oscillations led to increased concentrations.