Numerical calculation of particle movement in sound wave fields and experimental verification through high-speed photography

Inhalable particulate matter, especially PM2.5, is a main pollutant in China that is harmful to both human health and the atmosphere. The PM2.5 removal efficiency of traditional dust removal devices such as ESP is low, and pretreatment must be conducted before dust enters the dust remover. Acoustic agglomeration is a pretreatment technology that uses high-intensity sound waves to agglomerate and develop fine particles; this method improves the PM2.5 removal efficiency of traditional dust removal devices. In a sound wave field, fine particles are carried by a medium (air in this study) and vibrate at different amplitudes when they vary in size. Thus, relative movement is generated and subsequently, particles increasingly collide and agglomerate. In this study, the movements of differently sized particles in traveling and standing wave sound fields are calculated, including the velocities, displacements, and amplitudes. Re<1 in this study, and the viscous force in the Stokes region is chosen as the main force. High-speed photography is employed to observe particle movement in different sound wave fields. The vibration speed and amplitude determined by analyzing the tracks in the photos are consistent with the calculated results. The movement of fine particles in a sound field with different conditions must be studied to identify the mechanisms of acoustic agglomeration.