Investigation of liquid fuel combustion in a cross-flow burner

Abstract

A rotary swirl burner was employed for liquid fuel spray combustion in a cross-flow stream of air. The effect of fuel spray orientation on mixing dynamics with the swirled air was investigated for different nozzle angles, including -45°, 0°, and 45°, respectively, with a variable portion of the air (from 0 to 100 per cent) allowed to flow aligned with the spray without swirl. The effect of swirl on CO and NO x emissions was found to be dominated by the competitive influences of improved mixing and increased kinetic rates. For cross injector alignment with air, NO x emissions were reduced by increasing the co-current air flowdue to the improved premixing effect, while for inclined alignment its emissions exhibited a reduction by supplying enough air to the spray lee side. High swirl intensity (swirl number up to 12) and co-current/cross-flow combination produce a reduction in the unburned hydrocarbons. The enhancement in flame radiation output with swirl was pronounced by an increase to 1.9 times the output without swirl. Inserting a porous medium at the burner exit, increased the enhancement to 4.18 times and promoted droplet evaporation. Enlarging the re-circulation zone beneath the fuel injector to a certain extent improved mixing and combustion efficiency.