Theoretical Investigation of Propagation of Longitudinal Guided Waves in Cylindrical Pipe Filled with Quiescent or Flowing Fluid: A Foundational Experimental Investigation

Longitudinal ultrasonic guided waves propagation in fluid-filled cylindrical steel pipe is investigated numerically and experimentally. By using displacement and stress boundary conditions, dispersion equation for longitudinal guided waves in fluid-filled steel pipe with quiescent or flowing fluid is derived and numerical analyzed. According to numerical results, it is shown that optimized guided waves have potentials to measure flow rate of fluid filled in narrow cylindrical pipes. In experiments, the 4 PZT wafers adhered to one end of the outer surface of a steel pipe filled with and without water are used as the actuators and receivers simultaneously. According to received signals, experimental propagation velocities of longitudinal guided wave modes are obtained. Experimental results show a good agreement with theoretical predication. Foundational experimental results show that longitudinal ultrasonic guided waves can be used for flow rate measurement of fluid in narrow pipes.