液固两相介质多频超声粒径分布测量

液固两相流动广泛存在于工业过程中,其粒径分布信息在线测量对生产优化与控制十分重要。超声法作为无扰动式多相流动参数测量方法,其衰减特性与固相颗粒粒径、体积分数等密切相关,可用于实现粒径分布在线测量。本文搭建液固两相介质超声衰减实验装置,装置采用石英砂作为固相颗粒,自来水为液相,利用线性调频超声信号激励研究液固两相介质的超声衰减特性。实验结果表明,随着激励频率和固相体积分数的升高,超声衰减系数逐渐增加,采用Twomey及遗传算法等对液固两相介质粒径分布进行反演,测试结果与马尔文激光粒度分析仪的粒径分布结果相比,相关系数为0.918。

Particle size distribution measurement of liquid-solid two-phase mediumwith multi-frequency ultrasound

Liquid-solid two-phase flow widely exists in industrial process and the online measurement of particle size distribution isimportant to the production optimization and control. As an undisturbed multiphase flow parameter measurement method, ultrasonicmethod''s attenuation characteristics are closely related to the particle size and volume fraction of solid particles, and can be used tomeasure the particle size distribution online. Experimental devices for ultrasonic attenuation of liquid-solid two-phase medium wereestablished. In the experiments silica sand is used as the solid particles and tap water is used as liquid phase. Chirp ultrasonic signal isused to excite and study the ultrasound attenuation characteristics of the liquid-solid two-phase medium. The experiment results show thatwith the increasing of the excitation frequency and solid volume fraction, the ultrasonic attenuation coefficient rises gradually. Twomeyalgorithm and genetic algorithm are used to inverse the particle size distribution of liquid-solid two-phase medium, the measurementresults are compared with those of Malvern laser particle size analyzer, and the correlation coefficient is 0. 918.