EVALUATION OF ACOUSTIC FORCES ON A PARTICLE IN AEROSOL MEDIUM

Lee, S ; Richard Dimenna, R

关键词: ACOUSTICS;    AEROSOLS;    AGGLOMERATION;    AIR FLOW;    ELECTROSTATICS;    PARTICLE SIZE;    STANDING WAVES;    ULTRASONIC WAVES;    PARTICULATES;    FILTERS;   

DOI  :  10.2172/917513
RP-ID  :  WSRC-STI-2007-00512
PID  :  OSTI ID: 917513
Others  :  TRN: US200817%%619

学科分类：环境科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

The acoustic force exerted on a solid particle was evaluated to develop a fundamental understanding of the critical physical parameters or constraints affecting particle motion and capture in a collecting device. The application of an acoustic force to the collection of a range of submicron-to-micron particles in a highly turbulent airflow stream laden with solid particles was evaluated in the presence of other assisting and competing forces. This scoping estimate was based on the primary acoustic force acting directly on particles in a dilute aerosol system, neglecting secondary interparticle effects such as agglomeration of the sub-micron particles. A simplified analysis assuming a stable acoustic equilibrium with an infinite sound speed in the solid shows that for a solid-laden air flow in the presence of a standing wave, particles will move toward the nearest node. The results also show that the turbulent drag force on a 1-{micro}m particle resulting from eddy motion is dominant when compared with the electrostatic force or the ultrasonic acoustic force. At least 180 dB acoustic pressure level at 1 MHz is required for the acoustic force to be comparable to the electrostatic or turbulent drag forces in a high-speed air stream. It is noted that particle size and pressure amplitude are dominant parameters for the acoustic force. When acoustic pressure level becomes very large, the acoustic energy will heat up the surrounding air medium, which may cause air to expand. With an acoustic power of about 600 watts applied to a 2000-lpm air flow, the air temperature can increase by as much as 15 C at the exit of the collector.