Water Level Sensing in a Steel Vessel Using A0 and Quasi-Scholte Waves

Peng Guo,Hongyuan Li,Kaili Zhang,Bo Deng,Zhenhua Tian,Xiang Lan,Hong Xu

doi:10.1155/2017/2596291

Peng Guo, Hongyuan Li + Show 5 more

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https://doi.org/10.1155/2017/2596291

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Abstract

This paper presents a water level sensing method using guided waves of A0 and quasi-Scholte modes. Theoretical, numerical, and experimental studies are performed to investigate the properties of both the A0 and quasi-Scholte modes. The comparative study of dispersion curves reveals that the plate with one side in water supports a quasi-Scholte mode besides Lamb modes. In addition, group velocities of A0 and quasi-Scholte modes are different. It is also found that the low-frequency A0 mode propagating in a free plate can convert to the quasi-Scholte mode when the plate has one side in water. Based on the velocity difference and mode conversion, a water level sensing method is developed. For the proof of concept, a laboratory experiment using a pitch-catch configuration with two piezoelectric transducers is designed for sensing water level in a steel vessel. The experimental results show that the travelling time between the two transducers linearly increases with the increase of water level and agree well with the theoretical predictions.

Highlights

In power plants, monitoring the water levels in core facilities, such as the boiler steam drum, condensers, and cooling pipes, is critical for the safety and economical operation of power plants
This paper presents a water level sensing method by using the A0 and quasi-Scholte modes
The water level sensing method adopts a pitch-catch sensing configuration with a pair of piezoelectric transducers (PZTs) transducers bonded on a steel vessel

Summary

Introduction

In power plants, monitoring the water levels in core facilities, such as the boiler steam drum, condensers, and cooling pipes, is critical for the safety and economical operation of power plants. There is a need to develop nondestructive technologies for high-precision, high-reliability, real-time monitoring of water levels in steel vessels. When a solid waveguide is immersed in water, the traction-free boundary condition changes and the wave propagation in the solid will change . Worlton [5] extended the Lamb theory by using experimental observations and derived the dispersion curves for aluminum and zirconium plates. Bingham et al [6] used ultrasonic guided waves to identify the mass loading on ship hulls. Pistone et al [10] performed experimental studies using a pulsed laser for structural health monitoring of immersed aluminum plates. Baron and Naili [12] studied the fluid-loaded anisotropic and homogeneous plane waveguide with two different fluids on each side using an analytical approach. Yu and Tian [13] used a scanning laser Doppler vibrometer for measuring quasi-

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