Determination of the receiving range of sound field measurements in cavitating media

Sound field measurements are widely used for the quantitative description of cavitation processes. For practical purposes it is important to know how local a sound field measurement information is, and therefore a technique is presented which allows the determination of the receiving range of such a measurement. The sound field is detected by two calibrated, similar hydrophones, mounted face to face in the cavitation cloud. The distance between the hydrophones is varied and the correlation between the two time-dependent signals is analyzed in the frequency domain defining a local parameter. The dependence of this parameter on the distance between the hydrophones describes the receiving range of a sound field measurement by means of a characteristic distance. The technique was applied to two different cavitation applications, and effective distances in the range 1–3 mm were obtained. It is shown that the spatial resolution of a sound field measurement in a cavitation field is determined by the hydrophone size and does not depend on the cavitation conditions if at least a medium cavitation activity is provided.