CFD modelling of flow-induced vibration under multiphase flow regimes.

Asiegbu, Nkemjika Mirian

Abstract

Internal multiphase flow-induced vibration (MFIV) in pipe bends poses serious problems in oil and gas, nuclear and chemical flow systems. The problems include: high amplitude displacement of the pipe structure due to resonance; fatigue failure due to excessive cyclic stress, induced by fluctuating forces; and structural wear, due to the relative motion of the pipe and its support. Current industry guidelines are based on single phase flows, while the few existing MFIV models in literature are based on small scale laboratory experiments, which do not completely address the complexities in multiphase flows, or the differing multiphase flow mechanisms between small and large pipes. Therefore, numerical simulations of two-phase flow induced fluctuating forces, stresses, displacements and natural frequencies at 900 bends have been carried out, in order to investigate the characteristics of MFIV in pipes of 0.0525m, 0.1016m and 0.2032m internal diameters (I.D.). An integrated high-fidelity CFD and FEA-based numerical-analytical modelling framework was applied, to predict the defining characteristics of MFIV in the pipes. The CFD simulations of thirty-five cases of slug, cap bubbly and churn turbulent flow-induced fluctuations at the bends were carried out using the volume of fluid (VOF) model for the two-phase flows, and the

Citation

ASIEGBU, N.M. 2020. CFD modelling of flow-induced vibration under multiphase flow regimes. Robert Gordon University [online], PhD thesis. Available from: https://openair.rgu.ac.uk

• Thesis Type: Thesis
• Deposit Date: Jul 16, 2020
• Publicly Available Date: Jul 16, 2020
• Keywords: Multiphase flows; Vibration; Flow-induced vibration; Oil and gas engineering; Fluid mechanics
• Public URL: https://rgu-repository.worktribe.com/output/947884