Design and construction of an acoustic horn for high power ultrasonic transducers

Typical high power transducers consist of a piezoelectric or magnetostrictive element of transduction and a solid acoustic horn that acts as a vibration amplifier. In order to obtain high power capacity, the acoustic horn needs to be optimized to match the active element. In this study, we did optimal design of an acoustic horn for a high power magnetostrictive transducer and constructed a sample prototype of the horn to verify the validity of the design. For the design, we derived the theoretical output power of a horn as a function of its dimensions, and determined the optimal dimensions to achieve the maximum power through finite element analyses with ANSYS®. The analytical method could quite quickly determine the horn length while the finite element method could refine the planar dimensions of the structure. The transducer had the resonant frequency of 19.3 kHz and had the maximum sound pressure level of 199 dB with an omni-directional radiation pattern in water. The analysis method developed in this study is so general that it can be applied to the design of acoustic horns for high power transducers of various operating frequencies and transduction materials.