Elucidation of behavior of the multiphase flow including the fine particle under coexistence of flow and ultrasonic radiation

人们需要新的技术来去除液体中的细颗粒。超声波是一种对液体或多相流中的固体微粒进行照射的技术。在液体或多相流中，细小的固体颗粒在局部地方聚集，然后聚集的颗粒被去除。在学术期刊上已经报道了几种（不是很多）类似的方法。然而，粒子聚集的基本现象本身和粒子行为还没有得到足够的阐明。因此，本研究的目的是观察超声波水平照射矩形容器中细颗粒和液体时的颗粒行为，并对颗粒行为进行分类。超声频率为22kHz或96kHz，输出到声换能器的功率为N=3 ~ 30W。实验采用铝粉、直径为30μm的铝颗粒、直径为50 ~ 150μm的铝颗粒以及直径为12、20、30、50μm的四种不同尺寸的丙烯酸颗粒进行。超声波的照射方向表示为z方向。垂直方向表示为y方向。结果表明，当超声仅照射液体即单相时，声压分布如下：(1)确认了z方向存在正弦声压分布。(2) y方向波浪形声压分布图。对颗粒的聚集，当超声照射固液混合物，即多相。结果发现，颗粒的行为有四种模式：(a)颗粒团簇聚集，(b)带状聚集，(c)点状聚集，(d)无聚集。此外，还讨论了粒子聚集的基本现象和实验结果。

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 obtainedOn 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.