Pulsating combustion characteristics of a spray flame in a Rijke tube with two different atomizers

Pulsating spray combustion in a Rijke tube was characterized. A specially designed Y-type atomizer and a commercially available solid-cone atomizer were used. Both were characterized in terms of spray Sauter mean diameter using a phase Doppler particle analyser. The operating regions for which acoustic oscillations were excited in the Rijke tube were identified. These regions are characterized by atomizing air, fuel and combustion air flow rates, atomizer position in the tube, and spray mean droplet diameters. With the Y-type atomizer, oscillations did not have a defined structure, and the pressure amplitudes varied without control. Pulsations were generated only in fuel-rich combustion. With the solid-cone atomizer, operating regions for which acoustic oscillations occurred in the combustor were also identified. In this case, pulsations were generated at near-stoichiometric combustion. Sound pressure amplitudes for the oscillating cases, though present, were much more difficult to control and of lower magnitude than in similar studies related to the pulsating combustion of solid (coal, wood, agricultural residue) and gaseous (propane, natural gas, acetylene) fuels in Rijke combustors. (C) 1997 Elsevier Science Ltd.