Spiral Sound Wave Transducer Based on the Longitudinal Vibration

Abstract

A spiral sound wave transducer comprised of longitudinal vibrating elements has been proposed. This transducer was made from eight uniform radial distributed longitudinal vibrating elements, which could effectively generate low frequency underwater acoustic spiral waves. We discuss the production theory of spiral sound waves, which could be synthesized by two orthogonal acoustic dipoles with a phase difference of 90 degrees. The excitation voltage distribution of the transducer for emitting a spiral sound wave and the measurement method for the transducer is given. Three-dimensional finite element modeling (FEM)of the transducer was established for simulating the vibration modes and the acoustic characteristics of the transducers. Further, we fabricated a spiral sound wave transducer based on our design and simulations. It was found that the resonance frequency of the transducer was 10.8 kHz and that the transmitting voltage resonance was 140.5 dB. The underwater sound field measurements demonstrate that our designed transducer based on the longitudinal elements could successfully generate spiral sound waves.

Recent Advances in the Synthesis of Difluorinated Architectures from Trifluoromethyl Groups

“…In 2020, Lu (Scheme 28) [45] and Wang (Scheme 29) [46] separately described a reductive de-fluorinative coupling reaction with trifluoromethyl alkenes employing epoxides as the electrophilic coupling partner. With the aid of Zn as the reductant, a broad array of functionalized gem-difluoroalkene-containing alcohol compounds were synthesized via sequential ring-opening radical addition and β-F elimination.…”

In Lab Demonstration of an Underwater Acoustic Spiral Source

“…Later, a reference source was included in the same package (BTech BT-SW1..6) [12], and was employed in the work of the spiral wavefront sonar [13] and in the work of the UUV spiral wavefront navigation [6]. In 2018, Lu et al developed a Phased-Spiral source using 8 longitudinal vibrating elements that vibrate due to multiple piezoelectric ceramic hollow cylinders [14]. One year later, the same authors developed a more simple Phased-Spiral source using a group of 3 omnidirectional spherical transducers [15].…”

In-Lab Demonstration of an Underwater Acoustic Spiral Source

“…The absolute angle error was less than 23° and 3° before and after the calibration, respectively. Thus, the prototype in question, at 30 kHz, had the worst performance before the calibration compared to the maximum absolute angle errors of 4°, 20°, 10°, and 21° in [ 18 , 25 , 26 , 27 ], respectively. On the other hand, it performed better after the calibration, at all tested frequencies, compared to the state-of-the-art work [ 25 ] with the maximum absolute angle error of 10°.…”

“…Later, a reference source was included in the same package (BTech BT-SW1..6) [ 24 ] and was employed in the work of the spiral wavefront sonar [ 25 ] and in the work of the UUV spiral wavefront navigation [ 18 ]. In 2018, Lu et al developed a Phased-Spiral source using eight longitudinal vibrating elements, which vibrated due to multiple piezoelectric ceramic hollow cylinders [ 26 ]. One year later, the same authors developed a simpler Phased-Spiral source using a group of three omnidirectional spherical transducers [ 27 ].…”