Waveguide Transducer for Generation and Reception of High-Frequency Narrow-Beam Ultrasonic Wave

A new type of waveguide transducer with a bidirectional-tapering structure is proposed to generate and receive high-frequency narrow-beam ultrasonic waves, which can effectively improve the defect detection resolution of high-temperature critical components in specific direction. The waveguide unit is composed of an excitation region with a tapering structure, a uniform-thickness strip region, and an incident region with a broadening structure. The tapering structure will contribute to generating the high-frequency quasi-fundamental shear horizontal (SH
$0^{\ast }$
) wave, and the uniform-thickness strip region is conducive to transmitting SH
$0^{\ast }$
wave nondispersively, while the broadening structure can conduce to the incidence of the high-frequency narrow-beam ultrasonic wave. The critical criteria for SH
$0^{\ast }$
wave propagation with nondispersive waveform and high signal-to-noise ratio in the bidirectional-tapering waveguide are established using simulation and experiments. Moreover, the heat dissipation performance and beam radiation of the bidirectional-tapering waveguide are verified. The results show that the proposed bidirectional-tapering waveguide transducer can generate pure high-frequency narrow-beam ultrasonic wave in the high-temperature specimen.