Acoustic Characterization of Transmitted and Received Acoustic Properties of Air-Coupled Ultrasonic Transducers Based on Matching Layer of Organosilicon Hollow Glass Microsphere

Abstract

An air-coupled transducer was developed in this study, utilizing hollow glass microsphere-organosilicon composites as an acoustically matching layer, which demonstrated outstanding acoustic performance. Firstly, a comparison and analysis of the properties and advantages of different substrates was carried out to determine the potential application value of organosilicon substrates. Immediately after, the effect of hollow glass microspheres with different particle sizes and mass fractions on the acoustic properties of the matching layer was analyzed. It also evaluated the mechanical properties of the matching layer before and after optimization. The findings indicate that the optimized composite material attained a characteristic acoustic impedance of 1.04 MRayl and an acoustic attenuation of 0.43 dB/mm, displaying exceptional acoustic performance. After encapsulating the ultrasonic transducer using a 3D-printed shell, we analyzed and compared its emission and reception characteristics to the commercial transducer and found that its emission acoustic pressure amplitude and reception voltage amplitude were 34% and 26% higher, respectively. Finally, the transducer was installed onto a homemade ultrasonic flow meter for practical application verification, resulting in an accuracy rate of 97.4%.

Keywords: air-coupled transducer; composite; flowmeter; matching layer.

Figure 1

Transmission of ultrasonic transducer.

Figure 2

Ultrasonic transducer assembly.

Figure 3

Device for measuring emission performance. (a) Experimental equipment table object; (b) Schematic diagram of the experimental equipment table.

Figure 4

Device for measuring receiving performance. (a) Experimental equipment table object; (b) Schematic diagram of the experimental equipment table.

Figure 5

Differential Time Ultrasonic Flow Meter Schematic.

Figure 6

Ultrasonic transducer test system for practical applications.

Figure 7

Curing effects of the three substrates.

Figure 8

Matching layer samples of different mass fractions in kind.

Figure 9

Matching layer acoustic test results: (a) Density of different samples; (b) Solid sound velocity of different samples; (c) Characteristic acoustic impedance of different samples; (d) Attenuation coefficients of different samples.

Figure 10

SEM image of samples: (a) 100 μm scale and (b) 500 μm scale.

Figure 11

Transducer object. (a) Exterior of the transducer; (b) Interior of the transducer before encapsulation; (c) Object after Encapsulation.

Figure 12

Changes in mechanical behavior before and after optimization. (a) Homemade transducer impedance test; (b) Mechanical quality factor test of Homemade Transducers.

Figure 13

Test results for different excitation voltages. (a) Emission sound pressure results; (b) Electric-acoustic conversion efficiency results.

Figure 13

Test results for different excitation voltages. (a) Emission sound pressure results; (b) Electric-acoustic conversion efficiency results.

Figure 14

Emission sound pressure for different cycles of burst.

Figure 15

Emission sound pressure plots of K1-20 with different cycle count of burst: (a) cycle count of burst is 3; (b) cycle count of burst is 5; (c) cycle count of burst is 10; (d) cycle count of burst is 15.

Figure 16

Maximum transmission distance results.

Figure 17

Comparison test results of emission sound pressure.

Figure 18

Receiving performance test results at different distances.

Figure 19

Received waveforms at different distances for model K1-20: (a) 5 cm; (b) 10 cm; (c) 15 cm; (d) 20 cm.

Figure 20

Waveforms of the receiver transducer of a homemade ultrasonic flowmeter.

Figure 21

Gas Flow Measurement Results.