The mechanism of micro-bubble generation in a two dimensional venturi tube

Abstract

Recently, the micro-bubble technologies are applied in a wide field, and grow to the field close to the human lives. Though many methods of micro-bubble generation have been proposed, pressure loss of a venturi tube is less than among others. The studies on micro-bubble generation with venturi tube have ever seen, but the generation mechanism of a micro-bubble is not fully evident. The purpose of this paper is to make the micro-bubble generation mechanism experimentally clear. In conclusion, by inspecting the images of high-speed camera, the water jet occurs on the trailing edge of a bubble when its leading edge arrives at the throat inlet and divides it into two parts in the throat section. Then, passing through the diffuser, outer shapes of the two parts become unstable and break down into micro-bubbles. It is clear that the mechanical conditions of this occurrence are based on the accelerations at a nozzle and a diffuser. Then, the generated bubble size is distributed around a peak of about 200µm.