Acoustic agglomeration is widely considered a potentially effective technology for application in artificial defogging and precipitation. A coupled three-dimensional Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) model was constructed to investigate the agglomeration performance of liquid droplets in the acoustic field. The acoustic field is calculated by solving the Linearized Navier-Stokes Equations (LNSEs) in the time domain, and the background flow is initially obtained using the Reynolds-averaged Navier-Stokes (RANS) equations with a k–ε turbulence model. The motion of the droplet aerosol follows Newton’s second law with fluid-particle and particle-particle interactions, including collision, agglomeration, and fragmentation. The agglomeration performance of liquid droplets under high-intensity acoustic waves was numerically investigated in terms of the effects of the acoustic properties as well as the droplet characteristics.

The numerical results show that it is necessary to consider droplet fragmentation in the process of acoustic agglomeration under the action of high-speed jet. The sprayed droplets are more likely to collide and condense than those without a breakup model, which has rarely been reported in previous studies. Acoustic frequency has a significant effect on agglomeration behavior, with optimal frequencies of about 225 Hz, 150 Hz, and 125 Hz corresponding to droplets with mode diameters of 15.97 μm, 25.85 μm, and 42.88 μm, respectively. However, despite the fact that most studies favoured large acoustic intensity for agglomeration performance, the agglomeration performance of aerosol particles is not always positively correlated with acoustic intensity, especially for large droplets. The optimal intensity of droplet with d_p = 42.88 μm is in the range of 120-130 dB, which is smaller than the maximum operation pressure of 150 dB used in this study. In addition, an effective approach to increase the agglomerate size is to extend the residence time that liquid droplets are exposed in the acoustic and flow field, especially because the typical acoustic intensity of actual operation is usually not that high.

声团聚被广泛认为是用于人工除雾和沉淀的潜在有效技术。建立了三维计算流体动力学和离散元耦合模型（CFD-DEM），以研究液滴在声场中的团聚性能。声场是由在时域中求解线性Navier-Stokes方程（LNSEs）来计算，并且最初使用雷诺平均纳维-斯托克斯（RANS）方程与所获得的背景流ķ - ε湍流模型。液滴气溶胶的运动遵循牛顿第二定律，该定律具有流体-颗粒和颗粒-颗粒相互作用，包括碰撞，团聚和破碎。从声学特性和液滴特性的影响出发，对高强度声波下液滴的团聚性能进行了数值研究。

数值结果表明，在高速射流作用下的声团聚过程中，有必要考虑液滴的破碎。与没有破裂模型的液滴相比，喷雾的液滴更容易碰撞和冷凝，这在以前的研究中很少报道。声频率对团聚行为有重要影响，最佳频率约为225 Hz，150 Hz和125 Hz，分别对应于模式直径为15.97μm，25.85μm和42.88μm的液滴。但是，尽管事实上大多数研究都倾向于使用较大的声强来提高结块性能，但气溶胶颗粒的结块性能并不总是与声强呈正相关，特别是对于大液滴而言。d的最佳液滴强度_p  = 42.88μm在120-130 dB的范围内，小于本研究中使用的最大工作压力150 dB。另外，增加附聚物尺寸的有效方法是延长液滴在声场和流场中暴露的停留时间，特别是因为实际操作中典型的声强通常不那么高。