Erosion in a 90 degree Knee, ANSYS Fluent CFD Simulation Training

Description

The present problem simulates the Erosion in a 90-degree Knee by ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

Fluid impurity is not a problem in a straight-ahead pipe. But when the fluid redirects, these impurities cannot redirect with the fluid. This causes local independence of solid particles from the fluid in pipelines, resulting in the impact of heterogeneous particles on the body of the fluid pipelines and erosion, consequently.

Unfortunately, in almost all industrial applications, the fluid is not pure, so the phenomenon of erosion causes problems in pipeline transport. Also, an issue that reinforces this event is the amount of flow turbulence. The more turbulent the flow, the greater the particle’s momentum flows.

The impacts on the transmission pipeline are more significant when the flow changes direction, resulting in more erosion. In addition to the turbulence of the flow, other factors such as particle size, particle flow rate redirection, the number of particle impacts to the surface, and the flow rate also influence the amount and profile of the erosion.

The other endpoint is that the place of erosion is usually where the flow redirects. This is precisely why fasteners and joints generally examine the erosion profile at the knees.

Erosion Methodology

The beginning of each simulation starts with designing the computational domain. Although the geometry is a knee joint, it must be divided into different sections to produce a structured mesh. Each segment has individually meshed so that the boundary layer settings are well implemented.

The 3-D geometry is designed by ANSYS Design Modeler software. The mesh is done by ANSYS Meshing software. The computational domain is divided into 4 parts, and a structured mesh is used for each segment. The benefits of a structured mesh include increased CFD simulation speed and accuracy.

This is especially important for issues such as checking the erosion profile because, in addition to the boundary layer, path lines and particle tracking should be well observed when moving along the knee section. The element number is 4,319,695.

Since the mesh was sufficiently fine-grained, the Enhanced-Wall-Treatment method was applied instead of Wall-Function for boundary layer estimation. One of the benefits of this method is the high accuracy of the results in boundaries. The Discrete Phase Model (DPM) is applied to simulate the solid particles that existed in the pipeline.

Erosion Conclusion

An important point to consider is that the length of the pipe must be long enough to develop the flow before reaching the knee joint. Otherwise, the particle density in the flow may produce unrealistic results. Velocity magnitudes of fluid and particles can easily be analyzed based on the related contours.

Also, the particle concentration and the most important result of this study, erosion contour, are presented for a comprehensive analysis of the erosion in pipeline bends.