Discussion Of Cavitation In FDAS Design

Abstract

The Flexural Disc Assembled System is a promising transducer for the acoustic antagonizing device with low frequency and high power in limited size. The flexural disc Arranged axially and by exploiting the acoustic interaction between the benders, we can easily reduce the resonant frequency and improve the bandwidth. In our research, we find the receiving signal always distort which caused by cavitation at high power transmission. Introduction The transmitting capability of transducer is restricted by cavitation during high power transmission. The cavitation is defined as when the pressure inside the liquid is decreasing, the formation, growth and vanish of the liquid bubble or steam inside the liquid or at the liquid-solid interface. According to the dynamics concept, the cavitation can be catalogued into four different types and are shifting cavitation, fixed cavitation, vortex cavitation and oscillation cavitation respectively. Oscillation cavitation means a series of continuous high amplitude and high frequency pressure pulse which cause the growth or vanish of the bubble and steam. This series of pressure pulse is formed by the pressure wave where latent at the liquid and vibrate along the normal position. The pressure pulse can either squeeze or stretch the liquid, the cavitation phenomenon is observed as the pressure inside the liquid is less than the gasification pressure of the fluid. Cavitation Character In FDAS The underwater transducer generally produce diffusion wave. The transducer will induce cavitation since the power is increasing and it leads to the transducer can’t transmit more power into water. It means the motion of fluid cannot follow with the motion of the transducer as the motion of the transducer is opposite toward fluid, and will cause the large stretch force at the liquid-solid interface. The cavitation will be emerged when the power of transducer is large enough to cause the liquid pressure placed at the liquid–solid interface is less than the gasification pressure.