Aeroacoustical coupling and its structural effects on a PWR steam line. Part 2. Vibroacoustical analysis of pipe shell deformations

A pure tone phenomenon has been observed at 460 Hz in a PWR steam line. The acoustical energy has been identified to be generated in an open gate valve. The objective here is to understand the way of energy transfer from the fluid to the main pipe using two fully coupled methods. The first method consists in a modal analysis of the line using a fluid-structure finite elements model. The second one is based on the analysis of dispersion diagrams derived from the local equations of cylindrical shells filled with fluid. The way of energy transfer in transverse acoustical waves induced combined flexion-ovalisation deformations of the pipe is highlighted using both methods. The dispersion diagrams allow a fast and accurate analysis. The modal analysis using a finite elements model may complete the first one with quantitative data.