基于VOF方法的弹簧喷嘴雾化数值模拟研究

Numerical simulation of spring-nozzle atomization using the volume-of-fluid method

弹簧喷嘴在除氧器中广泛应用,其雾化质量显著地影响着传热传质速率。采用欧拉VOF方法追踪气液两相交界面的动力学特性,研究喷嘴出口处液膜破裂和液滴的形成过程。结果表明,射流一开始呈连续的液膜,液膜开始破碎位置在垂直位移约20 cm左右,破碎后液滴的粒径和破碎时液膜厚度很接近。液膜在气体剪切力和表面张力的作用下,液膜表面首先产生褶皱,继而产生一些不规则分布的孔洞,然后孔洞的数量和尺寸不断增加,最后导致液膜撕裂,产生小液柱或液滴。

Spring nozzles are widely used in deaerators and their atomization quality significantly affects the heat and mass transfer rate.The spray issued from a spring nozzle was studied numerically with an adapted volume of fluid method combined with a continuous surface force model to capture the gas-liquid interface dynamics.The analysis in this paper focused on the formation of a water film and the generation of droplets near the spring nozzle outlet.The numerical simulation results showed that the continuous water film is broken up into droplets at the location of about 20 cm from the nozzle exit vertically.The initial droplet diameter is very close to the film thickness at the beginning of the breaking.Under the effects of gas shear force and surface tension,the film surface first wrinkles and then gives rise to some irregularly distributing holes.The number and size of the holes increase continuously,which finally leads to liquid film tearing and produces liquid column and droplets.