PULSATING COMBUSTION CHARACTERISTICS OF A SPRAY FLAME IN A RIJKE-TUBEWITH 2 DIFFERENT ATOMIZERS

Pulsating spray combustion in a Rijke tube was characterized. A specia lly designed Y-type atomizer and a commercially available solid-cone a tomizer were used. Both were characterized in terms of spray Sauter me an diameter using a phase Doppler particle analyser. The operating reg ions for which acoustic oscillations were excited in the Rijke tube we re identified. These regions are characterized by atomizing air, fuel and combustion air flow rates, atomizer position in the tube, and spra y mean droplet diameters. With the Y-type atomizer, oscillations did n ot have a defined structure, and the pressure amplitudes varied withou t control. Pulsations were generated only in fuel-rich combustion. Wit h the solid-cone atomizer, operating regions for which acoustic oscill ations occurred in the combustor were also identified. In this case, p ulsations were generated at near-stoichiometric combustion. Sound pres sure amplitudes for the oscillating cases, though present, were much m ore difficult to control and of lower magnitude than in similar studie s related to the pulsating combustion of solid (coal, wood, agricultur al residue) and gaseous (propane, natural gas, acetylene) fuels in Rij ke combustors. (C) 1997 Elsevier Science Ltd.