侵入式光纤照相法测量气泡尺寸分布

An Immerged Fibre-optic Photoimaging Method for Measurement of Bubble Size

基于光纤内窥镜技术构建了以光纤内窥镜、图像采集系统和照明系统组成的侵入式照相装置,测量了由微气泡发生器和两种不同孔径的膜管产生的气泡的尺寸分布,并与取样照相法进行了比较.结果表明,3种气泡生成装置产生的气泡直径在50～2000μm;对50～200μm气泡两种方法的测量结果相差不大,200～2000μm的微气泡取样照相法测量值比侵入式照相法高,可能是因为取样时大气泡易发生聚并和破碎.侵入式照相法能较准确测量较宽的气泡尺寸,适用于在线测量气液体系中分布较宽的气泡尺寸动态分布,也可用于其他测量方法及数值模拟方法的验证.

An immerged photoimaging system was developed to measure bubble size distribution, which mainly consisted of a fibre-optic endoscope, an image acquisition system and a light source. Bubbles generated by a microbubble generator and two ceramic microporous tubes with different pore-sizes were measured using this system, and the results were compared with those by the conventional sampling photoimaging method. The bubble sizes generated by the three generators ranged from 50 to 2 000 μm. The difference between the two methods was not obvious when the bubble diameter was smaller than 200 μm. However, it became significant when the bubble diameter was larger than 200 μm. This is probably because smaller bubbles are relatively more stable, and bigger bubbles are easy to coalesce, leading to measurement errors in the sampling course. The results suggest that this new method is capable of measuring a wide range of bubble sizes reliably, and can be used for in-situ measurement of bubble size in gas-liquid systems, verification of other methods and numerical simulation.