SWIRLING FLOW AND BREAKUP CHARACTERISTICS AT HIGH REYNOLDS NUMBER IN A PRESSURE-SWIRL ATOMIZER FOR ARTIFICIAL SNOWMAKING

Abstract

The pressure-swirl atomizer is used to provide atomized droplets, which is the main atomization component of the snowmaker. The formation of snowflakes is significantly affected by the effective collision between droplets and ice nucleus produced by ice nucleus generator. Whether the collision position moves forward or lags behind, it will both cause deterioration of the snow quality. Therefore, the flow and breakup process, breakup length, and variation law of atomization are very crucial for regulating the snow quality. The fully developed swirling flow at high Reynolds number in the pressure-swirl atomizer for outdoor snowmakers were investigated based on VOF-LES approach, and its accuracy was verified by experimental results. It was found that the Kelvin-Helmholtz instability caused by the velocity difference at gas-liquid interface decisively leads to the liquid film fragmentation. The primary breakup occurs after 5.4 ~ 5.8 times orifice diameter. As the injection pressure increases from 0.6 MPa to 1.4 MPa, the breakup length reduces by 7.7%, the jet velocity increases by 66.7%. It is critical to adjust the effective collision position and enhance the convection, so as to improve the quality of snow.