Transmission of Acoustic Waves from a Solid Cylinder into a Liquid and Equivalent Acoustic Impedances

Abstract

We discuss the feasibility of the one-dimensional theory by which the transmission of acoustic waves from a solid cylinder into a liquid is analyzed with the acoustic impedance. For this purpose, experiments were performed on a cylinder made of Cu with a size of 1.98 mmϕ × 51.96 mmt. The frequency of acoustic waves was varied from 0.80 to 1.3 MHz. The characteristics of the Pochhammer mode in the solid cylinder are clarified by certain equivalent acoustic impedances. At low frequencies from 0.80 to 1.0 MHz, several definitions of the equivalent acoustic impedances work effectively. At intermediate frequencies near 1.1 MHz, the equivalent impedances available are those defined near the lateral surface of the cylinder. At high frequencies from 1.15 to 1.3 MHz, the experimental transmission rate of acoustic waves decreases considerably, and the adequate impedance is obtained using the energy flux and the axial component of the velocity field in the cylinder.