| Research Abstract |
Novel techniques to remove fine particles in liquid have been desired. As one of the technique, ultrasound irradiates fine solid particles in liquid or multiphase flows. The fine solid particles in liquid or in multiphase flows are aggregates to local places, and after that, the aggregated particles are removed. Several (not many) methods similar to this method have been reported in academic journals. However, the basic phenomenon of aggregating particles itself and particle behavior have not been clarified enough. Therefore, the purpose of this study is to observe the particle behavior when ultrasonic wave horizontally irradiates on fine particles and liquid in a rectangular vessel and to classify the particle behavior. Ultrasound frequencies of 22kHz frequency or 96kHz were used, output to acoustic transducer was N=3〜30W. Experiments were carried out using aluminum powder, aluminum particles with 30μm diameter, aluminum particles with 50 to 150μm diameter, four different size of acrylic particles with 12, 20, 30, and 50μm diameters. Irradiation direction of the ultrasound is denoted to z direction. Vertical direction is denoted to y direction. As the result, the followings are obtained
On the sound pressure profile, when ultrasound irradiated only liquid, i.e., single phase,
(1) It was confirmed that there was a sinusoidal sound pressure profile in the z-direction.
(2) Wavy sound pressure profile along y-direction was also obtained.
On the aggregation of the particle, when ultrasound irradiated the solid-liquid mixture, i.e., multiphase. It was found that four patterns of the particles behavior were observed as follows : (a) particle clump aggregation, (b) band aggregation, (c) point-like aggregation, and (d) no aggregation.
Furthermore, the basic phenomena of the particle aggregation and experimental results are discussed.
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