Influence of Turbulence Modelling Approach on Characteristics of Premixed Jet Flames Doped with Ammonia

This work investigates the influence of the turbulence model used on the modelling of flames with the addition of ammonia (10% by volume) to a fuel. A fuel-air nozzle with a fixed diameter of 25 mm was placed in an inner fused silica combustion chamber with a diameter of 75 mm. A fixed velocity of 40 m/s was assumed at the burner outlet nozzle. The EDC (Eddy Dissipation Concept) model was used to simulate the combustion process with the UCSanDiego mechanism. The lean premixed flames studied were characterized by high turbulence intensity. Transport processes are likely to be faster than chemical reactions for fuel nitrogen compounds, so the EDC time constants were modified to compensate for simplifications in the EDC model implementation (Ansys Fluent). The change in the turbulence model did not significantly affect the maximum values of the monitored parameters, but the final NO content in the flue gas increased from 2900 to 3070 ppm. In each of the above cases, a broadened preheating zone was observed, especially in the axial direction, due to the strong interaction between the flame and the wall.