Abstract

Second Harmonic Field of Nonuniformly Vibrating Transducer

O.A.Sapozhnikov, Yu.A.Pishchalnikov, V.A.Khokhlova, A.V.Morozov (Department of Acoustics, Faculty of Physics, Moscow State University, Moscow, Russia)

e-mail: oleg@acs366b.phys.msu.su

The accurate prediction of the second harmonic field of piezoceramic transducers operating at the high intensity level is important for many applications. The second harmonic field can be calculated if the normal velocity distribution (NVD) along a vibrating surface is known. However, up to now, there is no reliable method of the NVD measurement in liquids. The well-developed laser vibrometer method can be employed only when the transducer is in contact with vacuum or gas because of strong acousto-optic interaction in condense media. In the lack of exact knowing of NVD, the common approach is to assume a uniform distribution for acoustic field calculation. The novel recently developed method for accurate evaluation of the NVD along the vibrating surface of a piezoceramic transducer in liquid is presented here. The method includes the scan of acoustic wave amplitude and phase along the plane perpendicular to the beam axis at some distance from the source and theoretical back propagation of the field with the changed phase sign to the source using the Rayleigh integral. The second harmonic field then is simulated based on both the reconstructed NVD and the uniform distribution. The simulations are compared with the experimental measurements of the second harmonic field. [Work supported by CRDF, NIH-Fogarty, and RFBR].

Section : 10