旋回を伴う流れの速度場・圧力場と気泡の微粒化(解析・予測・制御流体機器・船舶・航空機,一般講演)

概要

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In the present study a micro-bubble generator based on the Coanda effect induced by the swirling flow is investigated numerically. A brief description of the principle of the micro-bubble generation is explained in the following. First, a swirling flow is generated by an impeller. Then a strong sink occurs at the exit of the casing, and a jet occurs around the exit channel, where the jet is reflected along the face of the casing by the Coanda effect. The instability of the vortex core of swirling flow causes the spiral-type vortex breakdown. The air column at the center of the swirling flow breaks by strong shear and pressure fluctuations of the vortex breakdown. The purpose of the present study is to reveal the mechanism of gas- breakup in the micro-bubble generator. The shapes of this device is simplified so as to facilitate numerical calculations, but the essence of their structure is still hold. The Navier-Stokes equation is solved by the velocity and pressure method. The relationship among the swirling flow, the Coanda effect, and the vortex breakdown phenomenon is qualitatively discussed by these calculations. In addition, the characteristics of the swirling flow in the pump. i.e., velocity and pressure fields is discussed.
2009-09-02