Systematic Errors in Ultrasonic Propagation Parameter Measurements. Part 2. Effects of Guided Cylindrical Modes

摘要

It was shown in Part 1 (AD-437 995) of this series of reports that appreciable errors in sound speed and sound absorption determinations may be attributed to a neglect in applying appropriate corrections to those situations closely approximating free-field conditions (finite size, plane-parallel source). In the present report it is shown that appreciable errors in the measurement of sound speed and sound absorption for guided mode propagation may be attributed to neglect in applying corrections that may be required because of the selection of geometric parameters or the method of measurement. This report contains graphs of pressure and phase, relative to planewave values and averaged over a plane-parallel receiver of size equal to the source size, for acoustic energy propagation down a right-circular liquid cylinder with lateral boundary condition appropriate to one of the following: absolutely rigid walls, infinitely flexible walls, liquid walls, or elastic solid walls. The latter boundary condition, which is considered to be that more appropriate to the situation of a liquid contained within a thick-walled metal tube, is shown to result in maximum anomalies in sound speed determinations when the transducer completely closes one end of the tube. (Author)