Enhancing the ultrasonic waveguide sensor's fluid level sensitivity using through-transmission and pulse-echo...

Area of Science:

• Materials Science
• Mechanical Engineering
• Sensor Technology

Background:

• Accurate fluid level monitoring is crucial in various industries.
• Traditional sensors face limitations in hostile or inaccessible environments.
• Ultrasonic waveguide techniques offer potential for non-invasive level sensing.

Purpose of the Study:

• To develop and evaluate a U-shaped ultrasonic waveguide sensor for fluid level measurement.
• To compare the performance of U-shaped waveguides with straight waveguides.
• To explore the simultaneous use of multiple wave modes for enhanced sensing capabilities.

Main Methods:

• Utilized Finite Element Method (FEM) for simulating wave propagation in U-shaped waveguides immersed in different fluids.
• Employed through-transmission (TT) and pulse-echo (PE) techniques with a single shear transducer.
• Developed a level sensor based on amplitude drop and time-of-flight changes in TT and PE signals.
• Investigated sensor sensitivity using first and second pass signals (TT1, PE1, TT2, PE2) across various fluid levels and types.
• Compared U-shaped (TT) and straight (PE) waveguides, analyzing signal attenuation and dead-end reflections.

Main Results:

• The U-shaped waveguide sensor achieved an average error of 3.5% in level sensing, outperforming straight waveguides (5.6% average error).
• The U-shaped design minimizes dead-end reflections, allowing for greater fluid depth measurements by focusing on wave leakage.
• Simultaneous sensing using three wave modes [L(0,1), T(0,1), and F(1,1)] was demonstrated.
• Signal attenuation analysis identified differences between straight and U-shaped sensors related to surface interaction and dead-end regions.

Conclusions:

• The U-shaped ultrasonic waveguide sensor offers a more accurate and reliable method for fluid level measurement compared to straight waveguides.
• The sensor's design effectively mitigates reflection issues, enhancing its capability for deep fluid level monitoring.
• This technology is suitable for continuous fluid level monitoring in demanding industrial settings, including power plants and the oil/petrochemical sectors.