2138 超高速度カメラによるベンチュリ管内微細気泡発生機構の解明  [in Japanese] The Observation of Micro-bubble Generation in Venturi Tube by Ultra-high-speed Camera  [in Japanese]

Micro-bubble generation techniques are proposed in former investigations. In the present study one of the effective technique by using converging-diverging nozzle (venturi tube) is introduced. Rapid pressure recovery in the diverging nozzle induced bubble fission. The purpose of this study is to clarify the mechanism of the bubble fission in the venturi tube and elucidate the relation between the flow structure in the tube and the generated bubbles' diameter. The observation by an ultra-high-speed camera suggests that the bubble fission is caused by the strong shock-type pressure recovery in venturi tube. The region where the bubble fission occurred depends on the liquid phase flow rate and Sauter mean diameter became smaller with increase of the flow rate.