Contactless Liquid Height and Property Estimation Using Surface Acoustic Waves

Hani Alhazmi,Rasim Guldiken

doi:10.3390/acoustics2020021

Hani Alhazmi, Rasim Guldiken

Open Access

https://doi.org/10.3390/acoustics2020021

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Abstract

The propagation of surface acoustic waves over a solid plate is highly influenced by the presence of liquid media on the surface. At the solid–liquid interface, a leaky Rayleigh wave radiates energy into the liquid, causing a signification attenuation of the surface acoustic wave amplitude. In this study, we take advantage of this spurious wave mode to predict the characteristics of the media, including the volume or height. In this study, the surface acoustic waves were generated on a thick 1018 steel surface via a 5 MHz transducer coupled through an angle beam wedge. A 3D-printed container was inserted on the propagation path. The pulse-echo time-domain responses of the signal were recorded at five different volumes (0, 400, 600, 1000, and 1800 µL). With the aid of parametric CAD analysis, both the position and distance of the entire traveling wave in the liquid layer were modeled and verified with experimental studies. The results indicated that the average drop in the reflected wave amplitude due to liquid loading is −62.5% compared to the empty container, with a percentage of error within 10% for all cases. The localized-time frequency components of the reflected wave were obtained via a Short-Time Fourier Transform technique. Up to 10% reduction (500 KHz) in the central frequency was observed due to the liquid volume increasing. The method discussed herein could be useful for many applications, where some of the liquid’s parameters or the ultrasonic wave behavior in the liquid need to be assessed.

Highlights

Surface acoustic waves (SAWs) have been widely utilized to detect surface defects in many structural health monitoring applications
When the surface acoustic wave (SAW) arrives at the first point of contact between the liquid and sWolhidensuthrfeascue,rfsaocme eaceonuesrtgiyc wraadviaet(eSsAinWto) lairqruividesdautethtoe tfhirestdpiffoeinretnocfecionntthaectabceotuwsteiecnimthpeeldiqaunicde abnedtwseoelnidtshuertfwacoe,msoemdiea.enTehregyacroaudsiatitcesiminpteodlaiqnuciedsdtruoengtolythdeepdeifnfderseonncethine tdheenascitoyuastnicd ivmeploecditayncoef btheetwmeeedniuthme,twwhoemreedthiae.dTehnesiatcyoiussmticucimh pheigdhaenrciensstroolindgslythdaenpiennldiqsuoindst.he density and velocity of the medium, where the density is much higher in solids than in liquids
With the aid of the fact that when a SAW interacts with a liquid as it is traveling along the solid surface, some of its energy is transmitted through the liquid and some energy is reflected, the liquid height can be accurately estimated via analyzing the time domain response of the received signal

Summary

Introduction

Surface acoustic waves (SAWs) have been widely utilized to detect surface defects in many structural health monitoring applications. The propagation of surface waves along the solid–liquid interface, where the liquid velocity is higher than the shear velocity in the solid, was investigated theoretically and experimentally by Padilla for the existence of a surface wave at a plastic–liquid interface [9]. The first goal is to investigate the effect of liquid loading on the propagating SAWs over a solid surface and how the reflected wave from a defect changes due to the existence of liquid media in the propagation path. The second aim is to investigate the capability of measuring the liquid level that is present on the specimen’s surface via SAWs. Understanding how a liquid influences the SAW signal is essential when the SAWs are utilized in a structural health-monitoring application. It is vital to estimate the liquid properties if the height and surface parameters are known

Methodology

Estimating Liquid Height

Findings

Conclusions