液中超音波パルスを用いたオリフィスからの単一気泡発生法(流体工学,流体機械)

概要

論文の詳細を見る
A new experimental method to generate single small gas bubbles from a submerged orifice using pulsed ultrasound wave in a liquid is presented. Pulsed ultrasound wave having frequency of 15 kHz and maximum pressure amplitude of about 10 kPa is irradiated to a bubble growing from an orifice. Single air bubbles ranging from about 0.05 to 0.2mm in radius are obtainable in silicone oil (kinematic viscosity: 1mm^2/s) using two orifices (0.02 and 0.04mm in diameter), and by varying the timing to apply the pulse. Bubble deformation and detaching process was visualized and analyzed using both high-speed photography and direct numerical simulation. Consequently, it is revealed that bubbles are forced to elongate upward due to the oscillatory flow of gas through an orifice with high velocity, and the elongation causes the bubble to detach from an orifice. The sizes of bubbles at detachment can be well estimated with a common spherical bubble formation model.
社団法人日本機械学会の論文
2006-05-25