Parallel strip waveguide for ultrasonic flow measurement in harsh environments

Area of Science:

• Materials Science
• Acoustics
• Fluid Dynamics

Background:

• Wetted ultrasonic transit time flow meters use piezoelectric transducers.
• Hostile environments like extreme temperatures can damage transducer materials and adhesives, limiting applications.
• Existing designs face challenges in durability and performance under harsh conditions.

Purpose of the Study:

• To investigate a new flow meter design incorporating a thermal buffer waveguide.
• To analyze the impact of waveguide geometry on guided wave propagation.
• To assess the effects of thermal gradients on sound speed and dispersion in strip waveguides.

Main Methods:

• Designed a flow meter with an integrated thermal buffer waveguide of five parallel stainless steel strips.
• Studied the propagation characteristics of guided waves in thin strips with finite widths.
• Examined the influence of thermal gradients on acoustic properties of the waveguide.

Main Results:

• The finite width of the strips significantly affects guided wave propagation, deviating from ideal Lamb-like waves.
• Thermal gradients alter the average sound speed and dispersion characteristics of the strip waveguides.
• The study identified that waveguide geometry influences pulse frequency content and shape.

Conclusions:

• The proposed thermal buffer waveguide offers enhanced thermal protection for transducers.
• Understanding wave propagation in finite-width strips is crucial for accurate ultrasonic flow measurement.
• Suggested modifications to waveguide geometry can optimize signal transmission for improved flow meter performance.