声波夹带法测量可吸入颗粒物粒径的误差和范围

Error and Range in Measurement of Inhalable Particle Sizes by Acoustic Entrainment Method

基于同时考虑Stokes力和非稳定力的水平驻波声场中的颗粒动力学模型,通过数值模拟计算研究声波夹带法测量粒径的误差和范围.结果表明:对于特定粒径的颗粒,存在一个使测量误差为0的最佳测试声场频率,低于该频率,粒径测量值偏大,高于该频率,粒径测量值偏小;随着颗粒密度的增加,测量误差迅速减小,最终测量误差接近0;随着声波频率的增加,测量范围的上限和下限均下降,粒径测量范围减小;随着声强的增加,测量范围上限增大,下限则保持不变,粒径测量范围增大.

Based on the dynamic model for particles subjected to both the Strokes force and unsteady force in a horizontal standing wave acoustic field, the error and range in measurement of particle sizes by acous- tic entrainment method were numerically studied. Results show that for a specified size of particles, there exists an optimal acoustic frequency corresponding to zero error of particle size measurement; when the a- coustic frequency is lower or higher than the optimal one, the measured value would be accordingly larger or smaller than the true value. As the particle density increases, the measurement error decreases rapidly, and finally the error approaches to zero. Both the upper limit and lower limit of the measurement range re- duce with the increase of acoustic frequency, resulting in decreased range of particle size measurement. As the acoustic intensity increases, the upper limit of the measurement range increases but the lower limit keeps constant, thus the measurement range increases.