文丘里式微气泡发生器气泡碎化数值研究

Numerical simulation of bubble breaking behaviour in Venturi microbubble generator

以文丘里式微气泡发生器为研究对象,利用Fluent软件对文丘里式微气泡发生器内的流动过程进行数值模拟,得出气泡碎化原理。模拟结果表明,喉管处高速液体对气相形成黏性剪切作用,将气泡初步碎化;在扩张段,气相扩散现象明显,是气泡发生碎化的主要区域,扩张段的逆压梯度和涡旋促进了气相的扩散与气泡的再次破碎;在液相流量为1.5 L/min、气含率为5%的条件下,可产生粒径集中分布在100~150μm范围内的微气泡。

Using Venturi microbubble generator as research object,the mechanism of bubble fragmentation was studied by numerical simulation of flow process in the Venturi microbubble generator with Fluent software.The simulation results show that,at the throat of the generator,bubbles are initially fragmented by viscous shearing effect of the high-speed liquid on the gas phase.In the expansion section,the phenomenon of gas diffusion is obvious,and it is the main area where bubbles are fragmented,since the reverse pressure gradient and vortex in the expansion section promote the diffusion of gas and the re-fragmentation of the bubbles.When the liquid flow is 1.5 L/min and the gas holdup is 5%,the particle size of the generated microbubbles is concentrated in the range of 100-150μm.