Study On The Effects Of Gas Properties And Particle Size On Acoustic Propagation Characteristics

In industrial production,obtaining the parameters of the monitored objects timely and accurately is helpful to improve production efficiency and ensure production safety.Acoustic detection technology,as a non-contact measurement method,can adapt to harsh and opaque measurement environment and has attracted more and more attention in recent years.Among them,acoustic temperature measurement technology based on sound velocity measurement is the most representative and has been successfully applied to the combustion monitoring of power station boilers.Based on this background,this thesis aims to improve the measurement accuracy of acoustic temperature measurement technology and expand the application range of acoustic temperature measurement technology.First of all,based on the theory of acoustics,this thesis deduces the basic characteristics of sound propagation under ideal conditions,and systematically introduces the cross-correlation time-delay estimation algorithm of sound waves,and points out that the linear sweep signal is more suitable as the sound source signal in the measurement process by means of MATLAB noise simulation.In order to further reduce the measurement error of the acoustic temperature measurement technology,this thesis explores the change of the sound wave propagation velocity with temperature under different air humidity,different air pressure,and different smoke components through numerical calculations.The results show that the change of pressure and smoke composition has little effect on the acoustic velocity under the same conditions,while the influence of air humidity on the acoustic velocity increases with the increase of temperature.In addition,the theory of cutoff frequency was verified through simulation and experimental research,and the sound propagation characteristics in the pipeline were obtained.Finally,this thesis preliminary studies the sound propagation characteristics of particulate deposits.Through the relevant experiments performed in the deposits of different particle sizes,the propagation characteristics of acoustic signals at different frequencies were compared.Experimental results show that low-frequency sound waves can effectively reduce the sound scattering effect caused by particulate matter,and are suitable for measuring acoustic signals in particulate deposits.