A numerical study on effects of swirl and primary aeration of fuel jet on pollutant emissions in a swirl burner

Abstract

This paper presents numerical results on the effects of partial premixing on pollutant emissions, viz., NOx and CO in a 42 mm diameter swirl burner, which is capable of generating high swirl intensity. The swirl number is quantified based on the geometrical swirl number for swirler unit employed in the burner. The simulation is carried out for swirl intensity S = 1.23 and a fuel flow rate of VF =1.0 m3/h. The partially aerated fuel is injected in the axial mode into a swirl airflow of Vs = 30 m3/h which amounts to stoichiometric air needed for the fuel jet. The percentage primary aeration %PA of the central fuel jet is varied from zero to 30%. The effects of primary aeration on pollutant emission levels NOx and CO are discussed. The results show that with increase in primary aeration, the NOx emission level decreases to a minimum at PA = 30%. However, the CO level becomes minimum at PA = 20%. The data gathered suggest that NOx and CO emissions can be optimally controlled by adjusting primary aeration level.