Prediction of Coincidence Frequencies for a Thin-Walled, Fluid-Filled Pipe

Abstract : This technical note outlines the role of piping-based noise generation and transmission in naval applications. It describes the nature of turbulence and how it generates acoustic energy. Coincidence between higher order acoustic modes and resonant structural modes is defined and its role in determining the efficiency of generating pipe wall vibrations by internal pressure fluctuations is discussed. The inertia effect of contained liquids is discussed. Coincidence data are presented for a 100 mm NB schedule 40 steel pipe, and the implications for naval applications discussed.