Study on acoustic waveguides and reflectors for use in ultrasonic two-phase flow measurement

Detection of bubbles or particles in a dominant liquid two-phase flow inside pipes or vessels is important in research and industries. The ultrasonic pulse-echo method, known from NDT, allows one to clamp piezoceramic probes outside of the pipe or vessel to be investigated. For some real processes, ultrasonic probes must also be insulated against higher temperatures and aggressive medias. This is possible by mounting a waveguide between the probe and two-phase flow. To concentrate the echo waves on the waveguide, the backwall surface of the vessel or tube must be considered as a reflector concentrating ultrasonic waves. A spherical concave reflector was found out to generate intense backwall echoes on the probe.