Erosion damage caused by solid particles in multiphase flows can affect the operation and integrity of fluid transport pipeline systems. Amongst available approaches for predicting erosion, mechanistic models provide reliable predictions under various conditions with a low calculation requirement time. A novel mechanistic model for predicting erosion in multiphase flows has been developed which is based on the trajectory of representative particles and the characteristics of various upward vertical gas-liquid flow regimes. Computational fluid dynamics (CFD) models are used to construct a trajectory-based model in a three-dimensional domain of the elbow geometry which describes the flow around the particles. In addition to gas-sand and liquid sand flows, multiphase flow regimes such as bubbly flow, churn flow, annular flow, and mist flow are characterized and applied to the trajectory-based model. The validity of the proposed model is examined using a large number of experimental erosion data from previous studies and comparing with the available mechanistic models from the literature suggests that the new model can provide more accurate predictions for both gas-dominated flow and high liquid rate multiphase flow conditions.

Introduction and Background

Multiphase flows are commonly found in various industries including oil and gas and there are many applications where particle-induced erosion should be monitored. Over the years, many approaches have been developed and introduced to predict erosion including multiphase fluid and solid particle flows. These approaches include one-equation models, mechanistic models, computational methods, and machine learning algorithms. While the one-equation, empirical models only account for the bulk fluid velocity [1, 2], mechanistic models consider particle velocities using a simplified fluid velocity [3, 4] and computational methods utilize two or three-dimensional Computational Fluid Dynamics (CFD) flow results, along with the particle motion equation [5, 6]. Moreover, the one-equation, empirical models account for limited parameters and can be highly conservative in predicting the erosion rate especially for multiphase flows as they only account for fluid mixture velocity and density, and sometimes pipe diameter and particle size. On the other hand, computational models using CFD codes describe the process in more detail and are more consistent with the erosion data for a wide range of flow conditions. Mechanistic models aim at predicting erosion more accurately than the empirical one-equation models and provide predictions for many cases quickly and at a lower computational cost compared to CFD simulations. Specifically, transient multiphase flow CFD simulations require substantial computational resources.

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