Mixing of hollow-cone water spray in a confined high-temperature gas crossflow

The mixing process of hollow-cone spray in a confined high temperature gas crossflow accompanied with evaporation is studied numerically. A fundamental insight into the mixing is obtained. The characteristics of the mixing flow field are investigated and the mixing under different conditions are quantitatively evaluated based on the cross-sectional temperature distribution using a newly proposed spatial uniformity index. It is shown that the temperature pattern of the mixing flow field depends primarily on the initial droplet distribution and the subsequence droplet dispersion dynamics. Several pairs of small vortices are generated near the wall due to the interaction between the crossflow and the droplet swarm. These vortices promote the evaporation of the entrained droplets and dissipate quickly due to the vapor convection. The influences of factors such as spray angles, axial injection angles, tangential injection angles and position of nozzle on the mixing are analyzed, showing that an optimum mixing can be achieved with appropriate spray angle.