Microbubble is a part of advanced water treatment technologies, and there are several ways for microbubble generation. A strategy using Venturi (convergent-divergent) nozzle with air-suction holes has advantage of energy and time saving compared with the others. Here, we used 3D printer to make the various nozzle geometries in order to understand two-phase flow in the Venturi nozzle and air-breaking mechanism. It was evaluated the effects of convergent and divergent angles independently on air-suction rate and pressure drop, and the two-phase flow (air bubbles and liquid water) were observed. The convergent angle strongly affect the air-suction rate corresponding with increase of pressure drop. Meanwhile, as the divergent angle increased, it became dominant the minor loss by sudden enlargement of flow area, so that the air-suction rate and pressure drop showed decreased.

ABSTRACT
1. 서 론
2. 실 험
3. 이상유동 압력강하 및 겉보기속도
4. 실험결과 및 토의
5. 결 론
References

• 이창훈(Dept. of Mechnical Engineering, Incheon National University) | Chang-Hoon Lee
• 김지민(Dept. of Technology Education, Korea National University of Education) | Ji-Min Kim Corresponding Author