VERIFICATION OF CFD PREDICTION ACCURACY OF FLOW TURBULENCE INDUCED VIBRATION LOADINGS AROUND A PIPE BEND

摘要

Bends widely used in process piping systems can cause strong pressure fluctuations on pipe wall for a high-velocity flow, and hence, flow induced vibration (FIV) of piping occurs. Currently, the FIV assessment is made primarily based on the guideline published by Energy Institute. However, it is based on very conservative assumptions, and thus, results in excessive design of piping systems. The coupling analysis of CFD/FEA (Computational Fluid Dynamics/Finite Element Analysis) is expected to be a useful approach for more proper FIV assessment. The present study mainly aims at verifying CFD prediction accuracy of wall pressure fluctuations or FIV loadings around a pipe bend. In CFD benchmark study, large eddy simulations (LES) with dynamic Smagorinsky model (DSM) were performed for a 90° mitred bend used in the experiments in literature, under two different flow velocity conditions. The benchmark simulation results show that the power spectral density (PSD) of the LES-predicted wall pressure fluctuations at the sampling locations is near to the experimental results with moderate conservativeness desirable for engineering applications. Also, the LES-predicted peak frequencies are close to the experimental data. Therefore, it is suggested that the applied numerical approaches be applicable to predict the FIV loadings with moderately high accuracy for engineering applications.