CFD modelling of pipe erosion under multiphase flow regimes.

Ogunsesan, Oluwademilade Adekunle

Abstract

Pipe erosion due to sand transport can have an adverse effect on the production efficiency of pipe-lines and other related flow systems. Proper knowledge of the flow characteristics, particle behaviour and geometric effects is very important in the accurate prediction of erosion rates and location. This study focuses on predicting erosion under complex multiphase flow conditions with emphasis on double bend geometries. The Eulerian Multifluid-VOF coupled with the Lagrangian Discrete Phase Model (DPM) has been employed to account for the flow and particle behaviour, RNG k - e model for the effects of turbulence and erosion rate was calculated using the Oka et al. model. A pseudo-single phase model was also evaluated in order to reduce the simulation resources to predict erosion in elbows mounted in series. Results from both modelling techniques were compared. Results show that phase distribution plays a vital role in estimating erosion in complex multiphase flows. The presence of a separation distance results in a change in phase distribution before the first and second elbows, and an increase in the separation distance aides the flow development towards the second elbow. The presence of the second bend has a significant influence on the erosion rate of the first bend compared to a single bend geometry. Furthermore, Elbow 2 is subjected to more erosion than Elbow 1 in churn flow, while Elbow 1 is more erosive in slug flow. The reverse of these were predicted with the pseudo single-phase approach for both flow conditions. Although the pseudo approach reduces computational time, it ignores vital flow features and predicts erosion rates higher than the Eulerian Multifluid-VOF approach in both elbows and flow condition. And, irrespective of modelling technique, the best double bend operating conditions predicted for both flow conditions are the same.

Citation

OGUNSESAN, O.A. 2020. CFD modelling of pipe erosion under multiphase flow regimes. Robert Gordon University [online], PhD thesis. Available from: https://openair.rgu.ac.uk

• Thesis Type: Thesis
• Deposit Date: Jul 22, 2020
• Publicly Available Date: Jul 22, 2020
• Keywords: Erosion; Pipes; Single-phase flows; Multi-phase flows; Pipe bends; Pipe elbows
• Public URL: https://rgu-repository.worktribe.com/output/950864
• Award Date: Feb 29, 2020