Control of Spray Flame Characteristics Using High Shear in a Double Concentric Swirl Burner

Abstract

The effect of high shear on the spray flame characteristic has been examined. The shear has been provided with the help of swirl angles in inner and outer swirlers (65° in inner swirler and 30° in outer swirler). Laser diagnostic tools like Particle Image Velocimetry (PIV) and Phase Doppler Particle Analyzer (PDPA) are used to obtain an exhaustive set of data related to droplet size, velocity, number density, vorticity in the flow and strain rate in the axial direction. A double concentric swirl burner and a commercially available air-assist nozzle have been used in this study. The burner allowed independent control of swirl and combustion airflow in the inner and outer annulus of the burner. Results have been obtained for a swirl combination of 65° in inner swirler and 30° in outer swirler (mentioned as 65°/30° in the rest of paper) and are compared with the swirl combination 50°/30°, data taken earlier by the authors (1). The distribution of air is also varied as it was done previously. The results provide a thorough understanding of the effect of giving high shear to the combustion air on the droplet size and distribution, which in turn controls the flame characteristic and stability (1).