Impact of Wedge Parameters on Ultrasonic Lamb Wave Liquid-Level Sensor

Abstract

The ultrasonic Lamb wave detection principle can realize the noncontact measurement of liquid level in closed containers. When designing an ultrasonic Lamb wave sensor, it is vital to thoroughly study and select the optimal wedge size at the front of the sensor. In this paper, firstly, we select the best working mode of Lamb waves according to their propagation dispersion curve in aluminum alloy, and we obtain the best angle of wedge through experiments. Secondly, we study the impact of the size of the wedge block on the results, and we obtain the selection method of wedge block parameters. The evaluations show that, when the frequency–thickness product is 3 MHz·mm, the Lamb waves work in the A1 mode, and the experimental effect is the best. At this time, the incident angle of the ultrasonic wave is 27.39°. The wedge thickness should be designed to avoid the near-field area of the ultrasonic field, and we should choose the length as odd multiples of 1/4 wavelength. The rules obtained from the experiment can effectively select the best working mode for ultrasonic Lamb waves, while also providing a basis for the design of the wedge block size in a Lamb wave sensor.

Ultrasonic guided waves interaction with cracks in the front glass of thin-film solar photovoltaic module

“…The non-visible modes are either non-existent or considerably less dominant relative to the appearing modes, which can be related to the perpendicular angle of incidence of the emission signal. Changing the angle of incidence by placing the transducers in an oblique orientation will shift the dominance of and generate the invisible modes in the present experiments [33,35,36]. However, our work stayed as close as possible to real applications in which normal incidence is expected.…”

A non-reference detection method of the external ultrasonic liquid level switch using the PZT

“…Gao et al [16] built a non-contact, fixed-point, liquid level monitoring system based on the ultrasonic impedance method, and studied the relationship between the length of the near-field area and the ultrasonic echo energy. Xue et al [17] studied the internal wedge parameters of the Ultrasonic Lamb Wave Liquid-Level sensor, it is indicated that the most suitable working mode as 𝐴 when 𝑓 = 3 MHz•mm and the corresponding ultrasonic incident angle is 27.39•, The wedge thickness should be as odd multiples of 1/4 wavelength. Zhao [18] provided an air-coupled ultrasonic Lamb wave liquid level detection method based on empirical mode decomposition and deep belief network for a steel oil tank of 5 mm thickness.…”