Accurate liquid level monitoring in zirconium alloy pipes remains challenging due to the limited sensitivity of conventional axisymmetric guided wave modes to the asymmetric mass loading induced by partial liquid filling. In this study, a nondestructive evaluation strategy exploiting the F(1,1) flexural mode is proposed, and the non-axisymmetric displacement field offers enhanced sensitivity to the presence of local liquid. Through dispersion analysis, the differences in the dispersive characteristics of the F(1,1) flexural mode between water-filled and empty zirconium alloy pipes are calculated and validated. By acquiring full-wavefield information on the outer pipe wall, we employ frequency–wavenumber analysis to identify the effectively excited F(1,1) flexural mode and to extract the wave velocity shift and signal attenuation features correlated with liquid level. Using excitation and receiving sensors placed on the outer pipe wall, the liquid level is identified through the changes in guided wave propagation caused by liquid loading. The results show that variations in liquid level induce a time delay and attenuation of the guided wave, and that the time-of-flight difference exhibits a highly linear relationship with liquid height. This method enables high-precision liquid level monitoring without intruding into the pipe interior, providing a feasible technical approach for industrial pipeline condition monitoring.

Haidong Wang, Weiyi Meng. Numerical Simulation of Liquid Level Detection in Zirconium Alloy Pipes through Flexural Mode of Ultrasonic Guided Waves. Academic Journal of Engineering and Technology Science (2026), Vol. 9, Issue 2: 81-86. https://doi.org/10.25236/AJETS.2026.090211.

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