The correlation between acoustic streaming patterns and aerosol removal efficiencies in an acoustic aerosol removal system

Abstract

© 2016 Taylor & Francis Group, LLC. Recently, researchers proposed that a second-order effect, acoustic streaming, induced aerosol depositions as a noninvasive aerosol removal technique. However, the acoustic streaming patterns, which determined the deposition efficiencies, were merely observed but not investigated. This article studied this correlation by both experimental and numerical methods. By keeping the sound frequency and sound pressure level constant, the acoustic streaming field was varied by the dimensions of the air duct and ultrasonic radiating plate. The numerical model was validated by the experimental results on three accounts, acoustic streaming patterns, velocity vectors, and deposition trends. Two new parameters, acoustic deposition ratio and near wall vorticity magnitude, were introduced to measure and predict the correlation between variation of the acoustic fields and deposition efficiencies. It was found that the geometry that produced a high vorticity magnitude near the deposition surfaces provided the condition to induced high occurrence for aerosols depositions (up to 3.5 times the rate caused by nature deposition). The finding in this study provided a method to quantify acoustic streaming fields, and the correlation between such quantity and the related deposition performance. This provides a guideline for designing acoustic aerosol manipulation devices, which aims to cause deposit with a noninvasive method.