Droplet dispersion characteristics of the hollow cone sprays in crossflow

The flows in a jet entering a crossflow are unsteady and the droplet movement is of vital importance for the two-phase mixing effect. In this paper, the hollow cone spray into the crossflow is investigated experimentally by using the PIV visualization system and the image-processing techniques. The experiments are carried out inside a rectangular duct (95 mm × 95 mm in cross-section) at the ambient temperature and pressure. Different nozzle injection angles and crossflow velocities are experimented on. The instantaneous droplet distributions and the velocity vector fields are obtained. Our results show that the flow field falls into three main domains and their effects on the movement and distribution of the droplet are varied. The coherent structure which breaks the stability of the upper counter-rotating vortex pair (CVP) structure is induced on the interface between the upper CVP and the mainstream zone. When the spray is against the crossflow the larger coherent structures are induced and impose greater influences on the mixing process. The turbulence intensity on the shear layer increases and the dispersion of the droplet is promoted. The experimental findings will benefit the understanding of the mixing mechanism of the hollow cone spray in the crossflow and the achievement of an optimum mixing.