Experimental Study of Ultrasonic Wave Propagation in a Long Waveguide Sensor for Fluid-Level Sensing

This work reports an ultrasonic long waveguide sensor for measuring the fluid level utilizing longitudinal L(0, 1), torsional T(0, 1), and flexural F(1, 1) wave modes. These wave modes were transmitted and received simultaneously using stainless-steel wire. A long waveguide (>12 m) covers a broader region of interest and is suitable in the process industry’s hostile environment applications, “fluid levels and temperature measurements.” In this work, we used fluids “diesel, water, and glycerin” for measuring fluid levels based on the sensor’s reflection factors from time domain and frequency domain signals. We examined the impact of wave mode attenuation effects for long waveguide sensor design while changing the waveguide lengths. Initially, we obtained the L(0, 1) and T(0, 1) modes reflections from the 12.6 m waveguide length when one end of the long waveguide was fixed with a shear transducer at 45° orientation. Subsequently, we want to study and identify all wave modes (especially F mode) travel distances. Hence, we would like to investigate the guided wave propagation characteristics (attenuation, ultrasonic velocity, and frequency of all wave modes) in the long waveguide while cutting systematically at intervals of 1 m, starting from its original length of the waveguide 12.6 m by analyzing the A-scan signals of various lengths of a single waveguide. This simple and cost-effective technique can monitor the high fluid depths and temperature in power plants, oil, and petrochemical industries while designing a long waveguide sensor with appropriate ultrasonic parameters.