The acoustic radiation characteristics of free-flooded ring transducers made of PZT4 and PMN-PT materials are calculated and compared. First, the theoretical formulae for free-flooded ring transducers are studied. The resonant frequencies of a transducer made of PZT4 and PMN PT materials are calculated. Then, the transmitting voltage responses of the free-flooded ring transducers are calculated using the finite element method. Finally, the acoustic radiation characteristics of the free-flooded ring transducers are calculated using the boundary element method. The calculated results show that the resonant frequencies of the free-flooded ring transducer made of PMN -PT are greatly reduced compared with those made of PZT4 with the same size. The transmitting voltage response of the transducer made of PMN-PT is much higher than that of the transducer made of PZT4. The calculated 3-dB beamwidth of the acoustic radiated far-field directivity of the free-flooded ring transducer made of PZT4 at the resonant frequency 1900 Hz is 63.6° and that of the transducer made of PMN-PT at the resonant frequency 1000 Hz is 64.6°. The comparison results show that the freepflooded ring transducer made of PMN PT material has many advantages over that made of PZT4. The PMNPT is a promising material for improving the performance of free-flooded ring transducers.
