聚焦型微通道内气泡生成特性数值模拟

Numerical Simulation of Bubble Generation Characteristics in Flow-focusing Microchannel

微气泡因具有比表面积小和稳定性好等特点被广泛应用于污水处理和矿物浮选等领域。为了高效获得稳定的微气泡,利用COMSOL软件研究了聚焦型微通道中气、液相流速、表面张力、液相黏度和壁面润湿性对气泡生成的影响。结果表明:当气相流速增加时,气相克服表面张力的能力增强,气泡的脱离尺寸和频率增大,脱离时间减小;液相流速增加时作用在微气泡上的惯性力和剪切力增大,气泡脱离时间和脱离尺寸均减小;表面张力增大时气泡脱离时间和脱离尺寸增大,脱离频率减小;液相黏度增大时,作用于气泡的黏性力随之增大,气泡的脱离时间和脱离直径均随之减小,脱离频率增大;接触角从40°增大到180°,气泡的脱离尺寸和脱离时间整体先增大后减小,脱离频率先减小后增大。

Microbubbles are widely used in sewage treatment and mineral flotation due to their small specific surface area and good stability.In order to obtain stable microbubbles efficiently,the effects of gas and liquid flow velocity,surface tension,liquid viscosity and wall wettability on bubble generation in focused microchannels were studied by COMSOL software.The results show that with the increase of flow velocity of gas phase,the ability of the gas phase to overcome the surface tension increases,the detachment size and frequency of bubbles increase,and the detachment time decreases.With the increase of flow velocity of liquid phase,the inertial force and shear force on microbubbles increase,and the detachment time and detachment size of bubbles decrease.With the increase of the surface tension,the detachment time and detachment size of bubbles increase,and the detachment frequency decreases.With the increase of liquid viscosity,the viscous force on microbubbles increases,the detachment time and detachment size of bubbles decrease,and the detachment frequency increases.When the contact angle increased from 40°to 180°,the detachment size and detachment time of bubbles increase initially and decrease afterwards,and the detachment frequency decreases initially and increases afterwards.