Ultrasonic Signal Characteristics in the Presence of Highly Reflecting Solid/Liquid Interfaces

D. M. J. Cowell and S. Freear

Institute of Integrated Information Systems (I3S), School of Electronic and Electrical Engineering, Faculty of Engineering, University of Leeds, Leeds, LS2 9JT, United Kingdom

Email: d.m.j.cowell@leeds.ac.uk

ABSTRACT

The ability to make non-invasive measurements is a highly desirable tool in the industrial process world. Using ultrasonics it is possible to make such measurements even through stainless steel vessel walls, although the technique is non-trivial. The acoustic impedance mismatch present between many industrial vessels and their contents makes non-invasive measurements extremely challenging.

When an ultrasound pulse is injected into a vessel wall the power is spread in time as many echoes occur. These echoes have a periodic, exponentially decaying form. This paper aims to explain the origin of these echoes and their characteristics through the use of basic ultrasonic wave expressions understandable by both readers with and without experience with ultrasound. Explanations and simulations demonstrating the challenges associated with non-invasive ultrasound are presented illustrating the effect of the vessel wall material.

Keywords Non-invasive, through wall, ultrasound, industrial measurement