基于超声声速的气力输送颗粒体积分数测量

Measuring Particle Volume Fraction of Pneumatic Conveying Based on Ultrasonic Velocity

气力输送过程中,颗粒相体积分数、颗粒速度和颗粒粒径等参数的在线测量对过程监测具有重要的意义。基于由Harker和Temple共同提出的两相流理论模型(H&T模型),对气力输送过程中的颗粒相体积分数、颗粒粒径和超声频率对超声声速的影响进行研究,通过数值模拟建立了超声声速与颗粒相体积分数的变化关系。模拟结果表明,与颗粒相体积分数对声速的影响相比,在一定的范围内,颗粒粒径变化和超声频率变化对声速的影响可以忽略不计。随着颗粒体积分数的增大,声速逐渐减小。以玻璃微珠和空气组成的气力输送作为研究对象,进行了试验测量。试验结果表明,该声速计算模型的计算结果与实际测量结果相近。该方法可以为实际生产中颗粒相体积分数的测量提供一种行之有效的途径。

In the process of pneumatic conveying,on-line measurement of particle volume fraction,particle velocity and particle size is of great significance to process monitoring.Based on the two-phase flow theory model(H&T model)proposed by Harker and Temple,the effects of particle volume fraction,particle size and ultrasonic frequency on ultrasonic velocity in pneumatic conveying process are studied.The relationship between ultrasonic velocity and particle volume fraction is established by numerical simulation.The simulation results show that,compared with the effect of particle volume fraction on sound velocity,the influence of particle size change and ultrasonic frequency change on sound velocity can be neglected in a certain range.The sound velocity decreases with the increase of particle volume fraction.The pneumatic conveying system consisting of glass beads and air is tested.The experimental results show that the calculation results of the model are close to the actual measurement results.This method can provide an effective means for measuring the volume fraction of particle phase in actual production.