Title: The effect of pipe bend on low-frequency longitudinal mode guided wave propagation

Author(s): WU Wenjun;WANG Yuemin;CHEN Le;GENG Haiquan

Affiliation(s): School of Energy and Power Engineering, Wuhan University of Technology, et al.

Abstract: The pipe bend significantly changes the propagation characteristics of guided wave,and makes the interpretation of the received signals difficult.Therefore,better understanding of guided wave propagating in bended pipe is essential for the inspection of pipeline comprising bends.First of all,the different features of dispersion curves derived with the semi-analytical finite element method for guided wave in bended pipes are summarized.Secondly,based on the dispersion curves for guided wave in bended pipes,experiments are performed to investigate the mode conversions of L(0,1) mode guided wave traveling through pipe bends.It is found that,except for the mode conversion from L(0,1) to F(1,1),the L(0,1) reflections of bends are also observed in some cases,which are proven to be the mode converted negative L(0,1)mode guided wave,and the negative L(0,1) mode guided wave becomes more obvious with the decrease of excitation frequency and bending radius.The findings of this paper will provide some insight for guided wave behavior in bended pipe,and generalize the application of guided wave inspection in practical pipelines.