SOUND TRANSMISSION THROUGH FLUID PIPING SYSTEMS.

Abstract : A new pipe-wall transducer has been designed and built which either suppresses spurious responses, or automatically compensates for them so as to be able to accurately measure acoustic energy in fluid filled pipes. This development is a necessary prerequisite to any study involving measurements in piping systems. Sound propagation in fluid filled piping systems could be completely understood if it were possible to set up a mathematical analog of the system. Correlation analysis was chosen as a tool with which to investigate sound propagation in an actual piping system, with a goal of determining the relative importance of vibrational energy in the fluid column and in the pipe walls (to be differentiated by the difference in their propagation velocities), and of determining the reflection coefficient and phase angle associated with discontinuities in the piping system. In order to gain an understanding of the correlator records we have calculated correlator output for a number of idealized situations in order to determine the importance of such variables as bandwidth, spectrum shape, dimension, and termination impedance. The calculations allow for a complex propagation constant in a given medium, but do not consider flanking paths.