燃煤可吸入颗粒物在驻波声场中动力学特性的研究  

Study on the Dynamical Behavior of Inhalable Particle From Coal Combustion in a Standing Wave Field

作　　者：赵兵[1] 姚刚[1] 沈湘林[1] 

机构地区：[1]东南大学洁净煤发电及燃烧技术教育部重点实验室,江苏省南京市210096

出　　处：《中国电机工程学报》2007年第26期13-17,共5页Proceedings of the CSEE

基　　金：国家重点基础研究发展规划项目(2002CB211600)~~

摘　　要：为研究可吸入颗粒物PM2.5在声波场中的动力学特性,利用可视化技术建立研究颗粒物动力学特性的实验装置。采用电厂飞灰作为颗粒源,利用高速CCD摄像机动态地显微拍摄颗粒在水平声场中的运动轨迹,并结合数值方法理论模拟颗粒的运动轨迹。结果显示颗粒在驻波场的波节点处不振动、不飘移;波腹处只振动、不飘移;其余各点处的颗粒既振动、也向波节方向漂移,并与竖直方向的运动叠加,形成在声场中的运动轨迹。颗粒振动频率与声波频率相同,但因颗粒存在惯性,振动速度幅值小于声波速度幅值,且相位滞后。动力学特性的结果显示:振动使得颗粒在单位时间内扫过的面积大大增加,有利于颗粒间的碰撞团聚;漂移特性有利于颗粒间的碰撞和气流中颗粒的分离。Dynamic behaviors of inhalable particles PM2.5, emitted from a coal fired boiler in a horizontal standing wave acoustic field were studied experimentally by means of a visualization method based on a microscope and pulsed laser illumination. Trajectories and shapes of fine particle in a horizontal acoustic wave field were visualized and recorded by a high rate CCD camera. In the meantime, the moving behavior of fine particle was also studied by numerical method in an acoustic standing wave field. Results showed that the particles at the node of the standing wave do not vibrate and drift, the particles at the antinode only vibrate but do not drift and the particles at other positions both vibrate and drift towards the nodes. Fine particles are marked with the less velocity amplitude than the acoustic velocity amplitude and delaying phase of vibration because of their inertia, while the vibration frequency is the same as that of the acoustic wave. The dynamical behavior results in the promotion of acoustic agglomeration owing to sweeping area greatly increased by the acoustic wave. The drift behavior of particle in a sound field is beneficial to the collision between particles and the separation of particles from the air flowing.

关 键 词：可吸入颗粒物PM 2.5 驻波 振动 漂移 

分 类 号：X511[环境科学与工程—环境工程]