Characterization of Acoustic Beam Propagation Through High-Grade Stainless Steel Pipes for Improved Pulsed Ultrasound Velocimetry Measurements in Complex Industrial Fluids

The newly developed Flow-Viz rheometric system is capable of performing detailed non-invasive velocimetry measurements through industrial stainless steel pipes. However, in order to improve the current design for non-invasive measurements in industrial fluids, pulsed ultrasound sensors need to be acoustically characterized. In this paper, acoustic characterization tests were carried out, with the aim of measuring the ultrasound beam propagation through stainless steel (SS316L) pipes and into water. For these tests, a high-precision robotic XYZ-scanner and needle hydrophone setup was used. Several ultrasound sensor configurations were mounted onto stainless steel pipes, while using different coupling media between the transducer-to-wedge and sensor wedge-to-pipe boundaries. The ultrasound beam propagation after the wall interface was measured by using a planar measuring technique along the beam’s focal axis. By using this technique, the output for each test was a 2-D acoustic color map detailing the acoustic intensity of the ultrasound beam. Measured beam properties depicted critical parameters, such as the start distance of the focal zone, focal zone length, Doppler angle, and peak energy within the focal zone. Variations in the measured beam properties were highly dependent on the acoustic couplants used at the different interfaces within the sensor unit. Complete non-invasive Doppler ultrasound sensor technology was for the first time acoustically characterized through industrial grade stainless steel. This information will now be used to further optimize the non-invasive technology for advanced industrial applications.