Measurement of Solid in Liquid Content Using Ultrasound Attenuation

A. Q. Chen1, S. Freear2, D. M. J. Cowell

Institute of Integrated Information Systems, School of Electronic and Electrical Engineering, Faculty of Engineering, University of Leeds, Leeds LS2 9JT, UK

Emails: {een4qac1, S.Freear2}@leeds.ac.uk

ABSTRACT

This paper focuses on the relationship between acoustic attenuation and solid content in a liquid carrier. Using such a relationship, two techniques were discussed to enable precise measurements for different concentrations of Kaolin in water. The first technique uses the fast-Fourier-transform (FFT) amplitude, while the second technique uses the attenuation coefficient’s gradient to discriminate the different concentrations.

In the past, others have used the ultrasound’s velocity and attenuation measurements to characterise the different concentrations of Kaolin in water, but many have focused only on FFT measurements. This hinders precise measurements as it relies heavily on the positional information where the centre frequency is defined. Hence, in this paper the above second technique was suggested. The measurements presented were collected using a pair of transducers placed invasively in a cell facing opposite each other (Figure 1). This is known as the Pitch-catch mode and it is commonly used in ultrasound measurements. Such a method provides a direct and the shortest path for the sound wave to travel from the transmitter to the receiver. This paper discusses the above techniques and gives the comparison of their performances by ultrasonic characterisation of Kaolin slurries.

Keywords attenuation measurement, ultrasound, solid content