DROPLET CHARACTERISTICS OF A JET IN CROSSFLOW INSIDE THE PRIMARY BREAKUP ZONE: EFFECTS OF NOZZLE SHAPE AND SIZE

The advances in technology demand more accurate methods of spray formation for combustion purposes. One of the most common techniques to produce fine droplets is the jet in crossflow method. There are many parameters such as nozzle geometry, working fluid properties, and ambient conditions that affect spray characteristics. The main concern in the present research is to investigate the impact of nozzle shape and its dimensions on the size distribution of droplets in the primary zone. Accordingly, circular and rectangular geometries with different sizes are considered to examine shape effect. The shadowgraph method, with a pulsed LED illumination technique, is employed to capture high-resolution images. The gas Weber number and momentum ratio varied within 9−19 and 50−110, respectively. The results indicated that the droplet morphology is almost independent of nozzle geometry. On the other hand, the circular nozzle produced droplets with a smaller size in Sauter mean diameter (SMD) compared to the rectangular one. The rectangular coflow orifice had the worst function among the others. Furthermore, the orifice size had a noticeable influence on the droplet size. Nozzles with smaller dimensions provided droplets with a smaller size in SMD. Regardless of the nozzle shape, the SMD was reduced with both gas and liquid Weber numbers.