Pressure Wave Propagation with Bubble Breakup Phenomena in a Venturi Tube

Abstract

A micro-bubble generator with a venturi tube generates many micro-bubbles and pressure waves with bubble breakup phenomena. However, physical characteristics of the pressure wave in the venturi tube are not clarified. In the present study, a propagation speed and a pressure value of the pressure wave in the venturi tube were measured by an observation with a high speed video camera and a pressure transducer. In addition, an effect of void fraction on the pressure wave was investigated with the observation, the pressure measurement and a void fraction measurement with a constant electric current method. From these measurements, it was confirmed that the propagation speed decreased with an increase of the void fraction. Besides, the speed followed a sonic speed of a homogeneous model for gas-liquid two-phase flow. Therefore the pressure wave propagation was affected by the gas volume of bubbly flow.