The influence of elliptical and circular orifices on the transverse jet characteristics at supersonic crossflow

Abstract

The using of an elliptical nozzle has been considered as a potential method for improving the air-fuel mixing and atomization quality. The present paper focuses on the transverse jet breakup behaviors and droplet size distribution for circular and elliptical orifices in supersonic crossflow on a pulse wind tunnel test platform, and the laser based pulsed laser background imaging method and high-speed spray particle size analyzer were adopted. The results show that the jet penetration depth of elliptical 4 (Aspect ratio of 4) orifice is always smaller than that of the circular orifice. Another interesting finding is that the difference of the jet penetration depth between the circular and elliptical 4 orifices decreases with the increase of injection pressure. Moreover, the jet surface wave number of the elliptical orifice is more than that of the circular jet, and the elliptical jet surface wave length is smaller than that of circular one. Additionally, the spray Sauter Mean Diameter (SMD) of elliptical 4 nozzle is 14.5% smaller than the circular spray at injection pressure of 5 MPa, and the elliptical 4 spray also has the smallest Dv50 and Dv90 among other orifices. Because elliptical 4 jet held larger windward surface area, which is helpful to increase the shear action of supersonic crossflow. Furthermore, the elliptical 4 spray produces the smallest droplet diameter at the largest volume fraction, and also the elliptical 4 spray has the smallest span of droplet diameter distribution than other orifices.