Fluid Structure Coupling Simulation on Flow-Induced Vibration in Tee Junction Pipes

Flow-Induced Vibration (FIV) caused by turbulent flow inside a pipe could lead to fatigue failure through shell mode vibration. Our previous study investigated the excitation source of the FIV for tee junctions experimentally to understand the FIV mechanism and to obtain Power Spectral Density (PSD) profiles of pressure fluctuations. Unsteady Computational Fluid Dynamics (CFD) simulations with a Large Eddy Simulation (LES) model were also performed to understand the turbulent structure for the tee junctions. As a result, the experiment shows the PSD profiles of pressure fluctuations have a dominant frequency component around Strouhal number 0.16, and the simulation results were well matched with the results of the experiment. The simulated flow field showed that the relatively large vortex shed from the branch pipe impinged periodically on the bottom of the main pipe with a frequency of Strouhal number 0.16, and the large vortex was dissipated downstream. These vortex behaviors would be the main mechanism generating the FIV excitation source. This study reports the simulation results of the vibration response by the fluid-structure coupling simulation with a one-way coupling method, which uses the unsteady pressure fluctuations obtained by CFD simulations. The simulated vibration response shows good agreement with the experiment.