Energy distribution and radiation loading of a cylindrical source suspended within a nonconcentric fluid cylinder

摘要

Acoustic radiation from a cylindrical source undergoing angularly periodic and axially-dependent harmonic surface vibrations while eccentrically suspended within a fluid cylinder, which is submerged in an infinite fluid medium, is analyzed in an exact manner. This configuration, which is a realistic idealization of a cylindrical liquid-filled acoustic lens with focal point inside the lens when used as a sound projector, is of practical importance with applications in underwater and biomedical ultrasonics. The formulation utilizes the appropriate wave-field expansions along with the pertinent translational addition theorem to develop an infinite series solution. The analytical results are illustrated with a numerical example in which the basic acoustic quantities, such as the modal acoustic radiation impedance load on the source, on-axis pressure magnitude, radiated far-field pressure directivity patterns, and the radiation intensity distribution are evaluated for representative values of the parameters characterizing the system. Numerical results clearly illustrate that, in addition to source frequency and surface velocity distribution, its position (eccentricity) can be of great significance in sound radiation.