Reconfigurable Reflector Based Ultrasonic Waveguide for Temperature Measurement

An ultrasonic reconfigurable reflector technique was introduced in the waveguide sensor to monitor the temperature of the pipe surface. Researchers used mostly cylindrical wire waveguides to measure fluid level, rheology, and temperature. However, the strip waveguides have flat surfaces that can show a better coupling effect with ultrasonic (transducer) sources. Also, the strip sensor can lie/lay easily on the measurement region and have more surface contact. This sensor development considered the S₀ wave mode in the thin strip as a pulse-echo approach using a single transducer at 0° orientation with the waveguide axis. We considered echogenic features (clamp-reflectors) to develop the distributed temperature sensors in the ultrasonic strip waveguide. Here, the reflector types “screw & clamp” were introduced to obtain the desired strength of amplitudes from each reflector which can be helpful in the signal’s peak tracking. We compress the waveguide at appropriate locations using a screw-clamp setup to obtain a suitable ultrasonic reflection without removing the material (notch reflector). We obtained change in time of flight (δTOF) between consequent reflectors at various temperatures and compared it with the co-located conventional thermocouple for calibrating the waveguide sensor. Then, we used the calibrated single-strip waveguide with a reconfigurable reflector to measure temperatures at multiple locations on the pipe surface. We performed multiple experimental trials to check for the sensors’ repeatability. The single-strip waveguide sensor developed comprises non-destructive reflectors that are easy to use, reconfigurable, durable, and cost-effective. Measuring the in-situ properties of any structure at various locations could be highly feasible.