Study On Propagation Characteristics Of Ultrasonic Guided Waves In Fouling Pipeline Based On Finit Element Method

The fouling accumulation reduces the heat transfer capacity of the heat exchanger,increases the flow resistance of the medium,affect the safe operation of the equipment,caused huge economic losses,so it has been concerned by the scholars of heat transfer.Because of the uncertainty of the composition and morphology of the fouling,it brings great difficulties to the qualitative and quantitative detection.Ultrasonic guided wave method is a widely used nondestructive testing method,which has the advantages of high precision,high speed and low cost.It has a good application prospect in the field of fouling detection.As a consequence,a method based on ultrasonic guided wave is proposed,and the propagation characteristics of ultrasonic guided waves in the pipeline are analyzed.The research results lay the foundation for the realization of the measurement of the fouling thickness in pipes using the ultrasonic guided wave method.Firstly,the propagation characteristics of ultrasonic guided waves in the pipeline are analyzed theoretically,and the dispersion curves of guided waves in the pipeline are drawn by Matlab and according to the actual detection needs to select the mode suitable for detection.ANSYS finite element software was used to simulate the propagation of ultrasonic guided waves in clean pipeline and fouling pipeline.There are two questions were studied,one is the influence of the wave source(center frequency,period)to detect fouling pipeline,the other one is the amplitude relationships of different fouling thickness pipeline by the same source.The influence of fouling on ultrasonic guided waves propagated in the pipes,and center frequency and cycle which suitable for the detection of fouling pipes are obtained.After the sensitivity analysis of the L(0,3)mode guided wave,the L(0,3)mode guided wave is chosen as the best mode to detect the fouling pipeline.The experimental platform of ultrasonic guided wave pipeline fouling detection is designed and tested.The results are consistent with the numerical simulation results,and the guided wave modes and the optimal excitation frequencies obtained from the simulation can be directly applied to practical detection.