Research On Ultrasonic Particle Size Measurement Method Based On Signal Recombination

In recent years,ultrasound has received special attention in the field of particle size detection due to its advantageous characteristics such as strong penetration,fast detection speed and easy implementation of online measurement.Among them,the ultrasonic attenuation method has become the mainstream measurement method in this field,but the method suffers from high cost and complex theoretical analysis and inversion algorithms.In contrast,the ultrasonic-sedimentation method recently proposed by some scholars provides a simple idea of sizing,but there are still some areas to be improved in the current research of this type of method,especially the measurement results of this type of method point to the average velocity of the particle population,and it is difficult to measure the velocity distribution of the particle population,in this research status,this paper tries to explore a method to directly measure the velocity distribution of different particles through a horizontal plane,so as to achieve the measurement of particle size distribution,which can better solve the above problem.The main work of this paper is as follows:1.Theoretical derivation and simulation study: This paper introduces a signal recombination method by taking the settling velocity of particles as the starting point: by recombining the ultrasonic pulse echo signals of a certain group at a determined depth in the measuring cup,it is found that the frequency of the recombined signal can characterize the velocity of particles,and then the particle size can be calculated.Simulation studies are carried out and the results show that the method based on signal recombination can achieve particle size measurement.2.Experiment and denoising: The ultrasonic echo signal sampling,signal reorganization and adaptive denoising experiments of the reorganized signal were conducted for two different particle size distributions of polymethyl methacrylate(PMMA)suspensions and with water as the control,respectively.3.Qualitative analysis: The experimental results were analyzed by wavelet time-frequency method,and it was confirmed that there was a high correlation between the particle size distribution and the frequency composition of the reconstituted signal,and it was possible to distinguish the experimental sample 1,sample 2 and clear water qualitatively.4.Quantitative analysis: The method of particle size distribution characterization was proposed and applied to the simulated samples for examination,and the results showed that it is feasible to use the method to characterize the particle size distribution of the particles,and finally the quantitative expression of the particle size distribution of the experimental samples,using the method showed that the measured value of the particle size distribution of sample 1has a small error relative to the reference value and good repeatability,and the repeatability errors of D10,D50,and D90 were all below 1.50%;the measured values of the particle size distribution of sample 2 had a slightly larger error relative to the reference value and the repeatability was average,and the repeatability errors of D10,D50,and D90 were all below 6.20%.