Investigation into Thermal-Fluid interaction of ammonia turbulent swirling flames under various Non-Premixed burner conditions

Abstract

This study deals with flow and turbulence interaction of an ammonia flame in a non-premixed burner. Numerical investigations have been performed on the velocity field, thermal field and the turbulence parameters for various oxidizers. In order to validate the simulations and select the most favorable turbulence model, some modeling have first been performed under non-reacting conditions, and the predictions are compared with the measurements. Although the predicted results obtained by using all k-epsilon models are in acceptable consistency with the experimental values, the predictions acquired through RNG k-epsilon model have showed more consistent results with the experimental measurements since there are swirling flows in the flow-field. The further modeling results under the reacting conditions showed the main flow and the external recirculation regions occurred in the flow-field. However, a central recirculation zone was not observed for all cases studied. It is revealed that the predicted axial velocity values for ammonia-air combustion are higher than those of oxy-conditions in the reaction zone. The radial and the tangential velocity values are lower than axial velocity values for all cases. Besides, the tangential velocity component is much lower in case of the ammonia-oxy combustion. It was observed that high turbulence intensity values (about % 350 and % 290 for oxy- and air-combustion) occurred in the mixing zone due to mean velocity affecting velocity fluctuations. Moreover, a consistency between the temperature and the velocity profiles has been predicted in the main flow zone.