SPRAY CHARACTERISTICS OF A NEW AIR-ASSISTED ATOMIZER

The spray characteristics of a new air-assisted atomizer was investigated experimentally.Annular and central swirling air jets smash the fuel jet and make it spray.The radial distributions of the mean and fluctuating velocities of the air flow and drops,the drop size and the concentration were measured at several axial stations with 2D PDA.Two atomizers with different mixing chamber were tested to investigate the effect of the central swirling air jet on the spray structure.The radial distributions of the mean velocity show that a lower axial velocity region and a solid rotation body exist at the center of the spray.The radial profile of drop volume flux peaks drifts off the centerline,indicating a hollow cone spray.The results show that high turbulence occurs at the central region and the region where the central swirling jet intersects the annular jet.The radial position of maximum mean axial velocity moves outwards with increasing strength of swirling.The atomization performance of the atomizer with lower swirling strength is better than that of the atomizer with higher swirling strength near the atomizer exit,but downstream the both atomizers possess same atomization performance.