Particulate aggregation through a modulated annular one-dimensional acoustic field at resonant frequencies

Abstract

The visualization and analysis of a novel acoustic-particulate system is the objective of this study. The system is composed of rice-husk fired smoke particulates (36.7nm–840μm) and one annular resonant circular-tube waveguide contrarily coupled with two sound sources. The collective interaction behavior process of smoke particulates in an inhomogeneous acoustic field is displayed during an experiment and a simulation. The result shows that the aggregation and fragmentation of particles under a change in resonant frequencies and sound pressure amplitude is extremely complex. This complex process consists of dynamically tuning the particle characteristics to attain stripes shaped like thin-films/umbrellas and clusters with volume-change/fragmentation. The balanced modulation of the acoustic radiation force and secondary radiation force to alter the particle characteristics (size and stack density) is verified to be the control mechanism of the particle system. The intermediate variable of the process control is the acoustic contrast factor (Ф) related to the physical characteristics of the growing particulates. The value plus-minus alternation of Ф results in different particulate processes. This study can enhance the application of aerodynamic acoustic-particulate-fluid systems for environment protection, energy fuel conversion, and industrial production.