Numerical calculations of erosion in an abrupt pipe contraction of different contraction ratios

Abstract

SUMMARYErosion predictions in a pipe with abrupt contraction of di erent contraction ratios for the special case of two-phase (liquid and solid) turbulent ow with low particle concentration are presented. A mathematical model based on the time-averaged governing equations of 2-D axi-symmetric turbulent ow is used for the calculations of the uid velocity ÿeld (continuous phase). The particle-tracking model of the solid particles is based on the solution of the governing equation of each particle motion taking into consideration the e ect of particle rebound behaviour. Models of erosion were used to predict the erosion rate in mg/g. The e ect of Reynolds number and ow direction with respect to the gravity was investigated for three contraction geometries considering water ow in a carbon steel pipe. The results show that the in uence of the contraction ratio on local erosion is very signiÿcant. However, this in uence becomes insigniÿcant when the average erosion rates over the sudden contraction area are considered. The results also indicate the signiÿcant in uence of inlet velocity variations. The in uence of buoyancy is signiÿcant for the cases of low velocity of the continuous ow. A threshold velocity below which erosion may be neglected was indicated.

Erosion prediction of liquid-particle two-phase flow in pipeline elbows via CFD–DEM coupling method

“…The literature [23,24] suggests that the drag force plays the major role in the force acting on the particles by the fluid, and thus, in this paper we just focus on the gravity and the drag force. The widely used Di Felice Drag Model [25] is applied to describe the interaction between fluid and particles.…”

Erosion and penetration rates of a pipe protruded in a sudden contraction

“…Habib et al [26] reported erosion predictions with abrupt contraction of different contraction ratios for the case of two-phase (liquid and solid) turbulent flow with low particle concentration. A mathematical model based on the time-averaged governing equations of 2D axi-symmetry turbulent flow was used for the calculations of the fluid velocity field.…”

“…Wallace et al [17] also showed that Saffman's lift force did not contribute much to the particle motion and thereby could be neglected in present calculations. Erosion in straight pipes and contractions were carried out by [14,17,[19][20][21][22][23][24][25][26][27]. A few studies are available where the object of the exercise has been to model erosion resulting from random perpendicular impacts of particles passing through a straight walled pipe or constricted section.…”

Numerical investigation of solid-liquid slurry flow through an upward-facing step

“…(1)), and so an explicit turbulent-dispersion force term makes no appearance in the momentum equation. In the present work only the stationary drag was included, since all other contributions are negligible for the kind of flow considered and were found not to contribute significantly to particle motion (as already reported by Habib et al, 2004). Therefore, the i-component of the generalized drag is given by:…”

“…They focused on the mean and fluctuating velocity distributions of the two phases and considered slurries with particle volumetric concentration below 0.05. Badr et al (2005Badr et al ( , 2008 and Habib et al (2004Habib et al ( , 2007 studied the flow of sand particles and water through sudden contractions in vertical pipes. They made use of an Eulerian-Lagrangian model under the hypothesis of one-way coupling between the phases, with the aim to predict the erosion of the system.…”