气固两相流介质中声衰减测量方法研究

通过声波衰减谱反推气固两相流状态，是气固两相流声学监测研究的一种重要方法。在假设声能量的相对衰减量与声波传播距离成正比的前提下，推导出声压级随传播距离变化的表达式。设计搭建了测试两相流下声衰减的实验台，根据声压级随传播距离变化的关系，推导出实验计算气固两相流声衰减系数的表达式。实验条件下的噪声主要为风机的漩涡噪声和旋转噪声，以及机械噪声和气流的气动噪声。分析不同噪声的特点，提出了通过A计权网络和小波滤波相结合的滤除噪声的方法。

A study of acoustical attenuation measurement in gas-solid two-phase flow

Deducing the state of gas-solid two-phase flow from acoustic attenuation spectrum is an important approach to acoustic monitor and study of gas-solid two-phase flow. The expression of sound pressure level associated with propagation distance is deduced by assuming that the relative attenuation amount of sound energy is proportional to sound propagation distance. The experimental apparatus for measuring acoustic attenuation in gas-solid two-phase flow is established. According to the expression of sound pressure level, the expression for calculating acoustic attenuation index of gas-solid two-phase flow is also obtained. The background noise in experiments is mainly the noise caused by fans＇ vortex and rotation, as well as the mechanical noise and aerodynamic noise. The characteristics of different noise are analyzed, and the method of eliminating noise is proposed, by using A-weighting network and wavelet filtering to- gether.