Effects of jet characteristics on NO formation in a jet-stabilized combustor

A three-dimensional numerical study is performed to investigate the effects of jet characteristics on the spray combustion and NO emission in a jet stabilized combustor. Three different jet Reynolds numbers, 13,904, 20,332, and 32,516 are considered for stabilizer jets which correspond to jet diameters of 6.4, 8.0 and 9.6 mm respectively. In the present study, the jet injection direction is varied between −20 and + 20° for each jet Reynolds number. The liquid phase is described using a Lagrangian formulation while an Eulerian approach is employed for the gas phase. The realizable k-ε model and presumed probability density function are applied to model turbulent flow and chemical reaction respectively. The radiation is modeled using the discrete ordinate method while the NO concentration is predicted through employing the thermal Zeldovich mechanism. The numerical models are validated against the available numerical results and experimental data. The present results indicate that the extension of the recirculation zone, before the stabilizer jets, has a significant impact on the combustion characteristics. The results show that the NO emission is very sensitive to the jet injection direction at high jet Reynolds number. The investigation of stabilizer jet direction reveals that the low values of NO emission are obtained through injecting air toward downstream. It is found the jet with 8.0 mm diameter and +20° injection direction has the lowest NO emission.