Slurry Flow Erosion In Centrifugal Pump CFD Simulation

Description

Slurry Flow Erosion In Centrifugal Pump CFD Simulation, ANSYS Fluent Tutorial

Description

Centrifugal pumps are a kind of rotating machinery used in hydropower, dredging, petroleum, mining, etc. Many centrifugal pumps are used for slurry pipeline transportation systems. One of the common problems for these pumps is erosion, which reduces hydraulic performance, increases the noise and vibration level, and sometimes causes the failure of the pumps.

The failure leads to the replacement of the defective and the shutting down of the whole transportation system. So, investigating erosion characteristics has always been a significant research topic in
pumping systems. The erosion predictions for centrifugal pumps still need to be improved in experimental and numerical approaches. Therefore, prediction methods that consider the flow mechanism inside the pump need to be improved to assist in reducing pump erosion.

We use ANSYS Fluent software to stimulate the slurry flow in the centrifugal pump. We perform this CFD project and investigate it by CFD analysis.

We designed a centrifugal pump in which the computational domain consists of rotating and stationary zones. The flow enters the pump through the stationary part entrance and then turns into the rotational zone. The rotating region of the pump rotates with a rotational speed equal to 1000 rpm. The fluid rotates as the blades rotate and then reaches the pump outlet.

First, we simulated water flow using the SST k-w turbulence model to see the flow behavior through a centrifugal pump, the range of pressure drop, the velocity contour, and the other results, such as streamlines, shown in the results.

Second, we simulated the slurry flow, including water as the base fluid and calcium carbonate as particles with 8% concentration, using a multiphase DPM model, which is applied to investigate two-phase flows with particle concentrations less than 10% numerically. In slurry flow, particles hit the blades and cause erosion, which is essential to investigate in this simulation.

We solved the slurry in steady and unsteady particle treatment. The unsteady simulation aims to show the particle path lines. Also, we obtained an animation of the fluid flow in the pump to understand better particle injection, flowing, and rotating in the domain.

Finally, we considered the steady solution to see the erosion on the blades. We used pure water simulation results as initial predictions for solving the model with DPM since accuracy takes more time in multiphase models.

We modeled the geometry of the project using Design Modeler software. Then we meshed the model with ANSYS Meshing software. The mesh model is polyhedral, and the number of cells equals 1,498,132.

Slurry Flow Erosion In Centrifugal Pump Methodology

In this problem, the DPM model solves the slurry flow via two-way interaction between the discrete phase and water. The particles are injected from the inlet surface as inert and in the rosin-rammler model.

Multiple Reference Frames (MRF) model has been applied for the rotation simulation. The diameter of particles is considered equal to 100 µm. The SST k-w turbulent modal is used for both water and slurry flow.

The different erosion models on blade walls in boundary setup are activated. These models are Generic, Finnie, McLaury, Oka, and DNV.

The High Order Time Relaxation and Wraped-Face Gradient Correction are activated to achieve better convergence.

Conclusion

This simulation mainly aims to see the erosion created by particles on the blades so you can see the erosion rate contours in the attached files. The results show that the blade edges’ erosion rate is higher than in other parts.

The pressure and velocity contours, velocity vectors, particle tracks, and path lines are also presented for the pure water, steady and unsteady DPM solution for the problem. Additionally, particle movement in the domain is shown via animation.

The contours show that the pressure increases radially; By increasing the pressure from the pump’s central part to the periphery. Also, due to the rotational motion of the blades in the central part, you can see the maximum speed in this part and the maximum value of the pressure difference or pressure gradient.