A method to analyze the radiation characteristics of a liquid column resonance transducer based on fluid motion

Liquid column resonance (LCR) transducers have been widely used in deep-sea acoustic applications because of their fluid-filled structures. Until now, studies of pipe resonance have generally been based on the plane acoustic wave equation, but for a vibrating object, the velocity is the primary focus instead of the pressure. Thus, the motion equation of a pipe resonance mode can be deduced based on the Navier-Stokes (N-S) equations. In this work, the velocity of an LCR transducer is obtained using the finite element model, and the velocity distribution inside the liquid column is examined. In addition, the radiating surface of the LCR transducer is identified and a simplified model of the radiation that consists of concave pistons and ring sources is proposed and verified. The theory behind the high mechanical quality (Q) value of the LCR transducer is explained through the radiation of the LCR transducer and the low viscosity of the water. This is also verified through a finite element model and measurements. Due to the high mechanical Q value and the low frequency of the LCR transducer, such measurements should be carried out in open-field water and the pulse should be long enough to achieve a steady state.