Experimental Study to Monitor the Rising and Falling of Fluid Level Using Ultrasonic Waveguide Techniques

This paper presents a study on ultrasonic-guided wave sensor to monitor the rising and falling of fluid levels using straight and bent (U) waveguide configurations. The fundamental longitudinal L(0,1) wave mode is transmitted and received through an aluminum waveguide using a shear transducer with a 0° orientation to the waveguide axis. Using the pulse-echo (PE) and through-transmission (TT) approaches, we have developed sensors for the U-bent and straight waveguides. However, using a U-bent waveguide, PE and TT signals are generated concurrently by utilizing a single shear transducer. In process industries, monitoring fluid levels and material characteristics using waveguide techniques plays a significant role, especially in hostile environments. The level measurement concept measures the attenuations and wave velocity of the received reflected signal from the dead end of the straight waveguide. Similarly, we have used the guided wave signals’ attenuation and change in velocity from the bent portion (no dead end) of a bent waveguide to monitor the fluid level. The liquid level monitoring experiment was conducted with different fluids (petrol, water, and glycerin). In this experimental study, we have compared and investigated the sensitivity of straight and U-bent waveguide sensors while rising (R) and falling (F) the fluid level. Both methods are simple techniques that can be made easily with a single transducer for the transduction and reception of ultrasonic waves in the waveguides. The straight and U-bent waveguide methods can be used for monitoring fluid levels in harsh conditions and unreachable areas of interest.