Abstract
A new technique for measuring liquid-level utilizing wedge wave is presented and demonstrated through FEM simulation and a corresponding experiment. The velocities of wedge waves in the air and the water, and the sensitivities for the measurement, are compared with the simulation and the results obtained in the experiments. Combining the simulation and the measurement theory, it is verified that the foundation framework for the methods is available. The liquid-level sensing is carried out using the aluminum waveguide with a 30° wedge in the water. The liquid-level is proportional to the traveling time of the mode 1 wedge wave. The standard deviations and the uncertainties of the measurement are 0.65 mm and 0.21 mm using interface echo, and 0.39 mm and 0.12 mm utilized by end echo, which are smaller than the industry standard of 1.5 mm. The measurement resolutions are 7.68 μm using the interface echo, which is the smallest among all the guided acoustic wave-based liquid-level sensing.
Highlights
In order to detect fluid capacity, a liquid-level measurement has been carried out in the several fields such as fuel tanks, water cisterns, and so on [1,2,3]
For the interface echo method, the slower the velocity of wedge wave wave in the air is, the better the sensitivity becomes as shown in Equation (3)
At the time of 2.1 μs, the mode 1 and 2 wedge waves are almost mixed near the front surface of the waveguide
Summary
In order to detect fluid capacity, a liquid-level measurement has been carried out in the several fields such as fuel tanks, water cisterns, and so on [1,2,3]. The ultrasonic type is the method that detects the liquid-level by elapsed time of ultrasound-utilizing, air-coupled ultrasound [15,16], the immersed-type ultrasonic sensor [17,18], and guided ultrasound [19,20,21,22]. Those are widely employed in many applications because of their simplicity of use and safety. The resolution and the accuracy of the method is investigated, and the feasibility of this method for actual use is verified
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