气泡在横流中的生长与脱离特性实验研究

为了系统研究气泡在横流中的运动学特性,利用水循环回路形成横流,采用高速数码摄像技术和图像处理方法对横流中气泡的演化过程进行描述。通过调节横流的平均流速和气体流量,获得了6种横流中的气泡形态,即单气泡、颈状泡、条带泡、泡囊、离散泡和雾状泡;解释了各类气泡形态的特征,对气泡尺寸及分布进行了统计,对气泡在横流中的发展过程进行了描述,发现气泡形态及气泡尺寸与横流速度密切相关,并受气体流量的影响,其中颈状泡和条带泡对横流流速的变化最为敏感。

Experimental Study on Characteristics of Bubble Growth and Detachment in Crossflow

The present study aims to investigate characteristics of bubbles in liquid crossflow.A circulation loop was used to produce the crossflow.Evolution of bubbles in the crossflow was described using high-speed photography and image processing techniques.The adjustment of the mean velocity of the crossflow and air injection flowrate led to six bubble patterns,namely single bubble,neck bubble,ligament bubble,bubble pocket,fragmented bubbles and atomized bubbles.Distinct features of the bubble patterns were explained.Bubble size and its distributions were statistically investigated.The development of bubble patterns in the crossflow was delineated.The results indicate that bubble pattern and bubble size depend significantly on the mean velocity of the crossflow.The contribution of the air-injection flowrate is non-negligible as well.In comparison,the patterns of neck bubble and ligament bubble are more sensitive to the variation of the mean velocity of the crossflow.