Torsional acoustic waveguide sensor for temperature and liquid level

In the present work a novel intrusive torsional acoustic waveguide sensor for temperature (T) and liquid level (H), which are critical measurands in process control systems, is developed. This sensor essentially consists of a metallic waveguide of varying cross section in which torsional acoustic waves are excited and received by a single piezoelectric transducer. The changes in the time of flight of the excited torsional acoustic waves in the waveguide are shown to directly relate to temperature and liquid level in the probed media. Experimental measurements showed that the flight time increases with temperature up to 1000degK while the resolution for liquid level was about 0.3 mm which is significantly less than industry standards of 1.5 mm.