Transducer design for low-frequency circular close-packed array and its mutual radiation analysis

Conventional flextensional transducers possess advantages of low frequency, small dimension, and high power [K. D. Rolt, J. Acoust. Soc. Am. 87, 1340 (1990)]. The low-frequency circular array composed of flextensional transducers has a strong mutual radiation effect due to the large vibration amplitude of the radiation surface located inside the circular array and the close distance between array elements [Z. Y. He et al., AIP Conf. Proc. 1272, 345 (2010)]. Here, a single-sided radiation flextensional transducer (SSR FT) is designed for a low-frequency circular close-packed array to diminish the mutual radiation effect. On the basis of the vibration principle of SSR FT, effects of structural parameters on electroacoustic, vibration, and radiation performance are studied for the final design of the transducer. Subsequently, the mutual radiation effect of circular close-packed arrays composed of SSR FTs and their counterparts is qualitatively analyzed on the basis of resonant mass, equivalent circuit, and numerical simulations. Finally, fabricated and tested circular arrays lead to a conclusion that the circular array composed of SSR FTs has a weaker mutual radiation effect and smaller dimensions than its counterpart composed of class IV FTs [K. P. B. Moosad, G. Chandrashekar, M. J. Joseph, and R. John, Appl. Acoust. 72, 127-131 (2011)]. The results confirm that the circular close-packed array provides flexibility in the application of low-frequency and small-dimension underwater acoustic sources.