大孔径高气速单孔气泡形成

在内径为190mm的鼓泡塔内，研究了空气-去离子水系统在大孔径高气速条件下的单孔气泡形成。考察了五个不同的孔径，分别为4、8、10、15及21mm，孔口气速范围为0.8~154.8m·s^-1。以CCD摄像记录气泡的形状及尺寸，根据气泡长径比的变化，得到气泡初始形态转变时的临界孔口气速：当孔口气速低于20m·s^-1时，孔口气泡近似于球形，长径比小于1.1；当孔口气速大于50m·s^-1时，气泡呈现椭球形,长径比大于1.5。并对气泡尺寸与孔径及孔口气速进行关联,所得关联式对孔径大于3mm、孔口气速在10~80m·s^-1范围内所形成的气泡尺寸预测效果较好。

Bubble formation from large submerged single orifice at high gas velocity

The formation of bubbles generated in a bubble column with 190 mm I.D.from large orifices at high gas velocity was studied for air-deionized water system.The experiments were made with orifice diameters varying from 4 mm to 21 mm and hole gas velocity in the range of 0.8—154.8 m·s^-1.The bubble shape and bubble size were recorded by CCD camera，critical hole gas velocity for bubble deformation was derived from the transition of aspect ratio of bubbles.The results showed that bubbles were spherical when hole gas velocity was lower than 20 m·s^-1.When hole gas velocity was higher than 50 m·s^-1，the shape of bubbles changed to elliptical.A correlation equation was established for bubble size as a function of hole gas velocity and orifice diameter，and the equation predicted the bubble size well for orifice diameter larger than 3 mm and hole gas velocity from 10 m·s^-1 to 80 m·s^-1 in air-deionized water system.