一次风管道内超声波传播特性研究

Study on ultrasonic propagation characteristics in primary air pipeline

本文基于超声波在两相介质中传播的Coupled-phase模型,考虑颗粒粒径分布、颗粒复散射以及颗粒间的相互作用等因素对模型进行修正,建立了电站锅炉一次风管道内气固两相介质中的声衰减系数和声速预测的计算公式,得到一次风管道气力输送系统中超声波衰减系数和声速预测与超声波频率、颗粒体积分数、两相密度以及颗粒粒径分布等因素的关系。结果表明:对于一般的电站锅炉,一次风管道超声波频率的增大、颗粒粒径的增大或颗粒体积分数的增大均会导致超声波衰减增大,而空气密度的增大会导致超声波衰减的减小;当这些参数发生变化时,影响超声波衰减的各因素的主导地位也会发生变化;当颗粒体积分数小于0.05%时,随着颗粒体积分数的增加,声速大致呈线性减小趋势。

Based on the coupled-phase model describing the propagation of ultrasonic waves in two-phase medium,considering the particle size distribution,particle scattering and interaction between particles,the model was modified.The modified model of the gas-solid two-phase in the power plant boiler primary air pipeline was established.The relationship between the acoustic attenuation coefficient and the sound speed prediction in primary air pipeline was obtained by considering the ultrasonic frequency,particle concentration,two-phase density and particle size distribution.The results show that,for the general primary air pipeline,an increase in the ultrasonic frequency or the particle size or the particle concentration will result in an increase in attenuation,and an increase in the density of the air will result in a decrease in attenuation.When the above parameters change,the dominance of various attenuation mechanisms affecting ultrasonic attenuation also changes.For the particle volume concentration within 0.05%,the sound speed decreases linearly with increasing of the particle concentration.