ノズルから離脱する気泡に及ぼす表面濡れ性の影響

抄録

Pouring air bubbles from nozzle is used for the industrial field such as promotion of the heat transfer and equalization of liquid components. Therefore, many studies on characteristic of the air bubbles were reported. Main parameters that affect bubble formation are air flow rate, nozzle diameter, physical properties of surrounding liquid and the most importantly wettability of nozzle surface that is gas-liquid interface. If this can be understood and controlled, we can use bubbles effectively according to the purpose of use it. In this study, we use super water repellent nozzle like over 120-degree to confirm experimentally about bubble frequency and detachment characteristics in order to clarify the wettability of the nozzle surface that has effect on bubble detachment. In detail, we measured a nozzle exit pressure in each flow rate using 4 kinds of nozzles. In addition, we photographed the state of bubble departure of nozzle with a high- speed camera. As a result, we could compare with not processed nozzle and water repellent nozzle. Moreover, we evaluated surface wettability focusing on contact angle changing as the bubble grows from the viewpoint of image processing.