A NUMERICAL STUDY OF ACOUSTICAL FEATURES OF CORRUGATED PIPES WITH HIGH FLOW VELOCITES

Flow induced sound in corrugated pipes might result in severe structural vibrations and damages in many engineering applications. In existing literatures, the sounding characteristics at low flow Mach number has been extensively studied both experimentally and numerically. In the current paper, a three-dimensional numerical study is carried out to investigate the acoustical features of corrugated pipes with high flow speed. Results show that unlike the typical axisymmetric standing wave pattern in low Mach number cases, the acoustic field in the corrugated pipe shows axial asymmetric feature as higher order radial and azimuthal modes occur for high flow velocity conditions. The predicted whistling frequency shows a step-wise feature with flow velocity and a two-peak pattern in the frequency spectrum. The comparison between the predicted and experimentally measured whistling frequencies show that the full 3D simulation could capture the major step-wise trend of the whistling characteristics of the corrugated pipe. Some of the predicted peaks could coincide with either the primary or the secondary peaks in the experiment. However, current numerical simulations could not predict all the acoustic modes in the corrugated pipe with high flow velocities, which needs further investigations.