Modelling and analysis of vortex-induced vibrations for flexible cylinders conveying two-phase slug flows.

Meenakumari, Hareesh Narain Ravindran; Zanganeh, Hossein; Hossain, Mamdud

Abstract

Hydrocarbon flows in a marine riser may appear in multiple phases with varying flow patterns, among which, slug flows are known to exhibit complex flow characteristics due to fluctuations in multiphase mass, velocities, and pressure changes. This flow regime can therefore cause significant vibrations and cyclic stresses on the pipeline. The fatigue life of a marine riser can also be significantly reduced when subjected to external excitations due to vortex-induced vibrations (VIV). Bulk of the literatures concerning two-phase flow induced vibrations have largely focused on the use of a simplified linearized tensioned beam model. Fundamental understanding of the vibration phenomena in three-dimensional space and time considering geometric and hydrodynamic non-linearities is still lacking. In this study, a long flexible cylinder subjected to external excitations by vortex-induced vibrations (VIV) in combination with internal slug flow-induced vibrations (SIV) is investigated. A three-dimensional semi-empirical model is presented which comprises of nonlinear structural equations of coupled cross-flow, in-line and axial motions along with equations involving centrifugal force and Coriolis force capable of predicting vibrations due to hydrodynamic slug flow. The model describes variations in lift and drag coefficients using two coupled wake oscillator models and is capable of capturing mass variations in the slug-flow regime. A numerical space-time finite difference approach in conjunction with frequency domain and modal analysis is used for analysing the highly non-linear partial differential equations. The presented model is validated through comparisons with published experimental results pertaining to internal SIV and external VIV for horizontal and vertical pipes. Similar trends in modal participation and oscillation amplitudes were observed in the validation results, indicating that the model has quantitative similarities with published experimental results for both VIV and SIV.

Citation

MEENAKUMARI, H.N.R., ZANGANEH, H. and HOSSAIN, M. 2023. Modelling and analysis of vortex-induced vibrations for flexible cylinders conveying two-phase slug flows. In Qiu, H., Zhang, Y. and Iasiello, M. (eds.) Proceedings of the 9th World congress on Mechanical, chemical and material engineering. Orléans, ON, Canada: Avestia [online], paper no. ICMIE 138. Available from: https://doi.org/10.11159/icmie23.138

• Conference Name: 9th World congress on mechanical, chemical, and material engineering 2023 (MCM 2023)
• Conference Location: London, UK
• Start Date: Aug 6, 2023
• End Date: Aug 8, 2023
• Acceptance Date: May 26, 2023
• Online Publication Date: Aug 6, 2023
• Publication Date: Dec 31, 2023
• Deposit Date: Apr 5, 2024
• Publicly Available Date: Apr 5, 2024
• Publisher: Avestia
• Series ISSN: 2369-8136
• ISBN: 9781990800276
• DOI: https://doi.org/10.11159/icmie23.138
• Keywords: VIV; Flexible cylinder; Slug-flow; 3-D response
• Public URL: https://rgu-repository.worktribe.com/output/2284409
• Publisher URL: https://avestia.com/MCM2023_Proceedings/files/papers.html