同轴式微通道壁面润湿性对微细气泡生成特性的影响规律

微细气泡的生成时间和大小对污水处理的效率具有重要影响。为探究微通道壁面润湿性对微细气泡生成特性的影响，采用两相流水平集的方法模拟研究不同接触角下微细气泡的生成过程。以接触角为主变量，液体流量、气体压强和气体类型为次变量，探究次变量对微细气泡生成时间和脱离体积的影响。设计并制造了同轴式微流控芯片，开展微细气泡生成特性的试验。结果表明接触角在0-180°递增时，微细气泡的生成时间总体呈下降趋势，脱离体积先增加后减小，其中90°接触角为生成时间的分界点和脱离体积的峰值点。此外，三个次变量中液体流量的变化对微细气泡生成特性的影响尤为显著，液体流量越大，其生成时间和脱离体积越小。实测值与仿真值的偏差在正负百分之十以内，验证了微通道壁面润湿性对微细气泡生成特性的影响规律。

Influence of wall wettability of coaxial microchannel on microbubble generation characteristics

The generation time and size of microbubbles have an important influence on the efficiency of sewage treatment. In order to investigate the influence of surface wettability of microchannel on microbubble generation features, two-phase fluid flow level set was adopted to simulate microbubble generation process at different contact angles. Contact angle was taken as the master variable, liquid flow rate, gas pressure and gas type as sub-variables, and the effects of sub-variables on microbubble generation time and detached bubble volume were investigated. A coaxial microfluidic chip was designed and fabricated, and experiments were carried out on the features of microbubble generation. The results show that the microbubble generation time decreases with increasing contact angle from 0° to 180°, and the detached bubble volume first increases and then decreases. The contact angle of 90° is the demarcation point of microbubble generation time and the peak point of detached bubble volume. In addition, among the three sub-variables, the change of liquid flow rate has a significant effect on the generation features of microbubbles. The larger the liquid flow rate, the smaller the generation time and detached bubble volume. The deviation between measured values and simulated values is ±10%, which verifies the effect of wettability on microbubble generation features.