Abstract
The micro-bubble generator with a venturi tube generates a large number of micro-bubbles by bubble breakup phenomena. The bubble breakup is caused by a shock with pressure recovery in the diverging region of the venturi. However, a profile of Mach numbers in the flow direction of the venturi has not been estimated experimentally. In the present study, the profiles are estimated by measurements of pressure and void fraction profiles in the flow direction. In the experimental results, Mach numbers are higher than 1 between the throat and the bubble breakup point, and the numbers are lower than 1 downstream of the breakup point. It is proposed that the shock is present at the bubble breakup point. In addition, the breakup from the top to the bottom of a bubble surface is observed. This results means that the shock with pressure recovery causes the bubble breakup.
