Centrifugal Pump: 3-D

Description

This project uses ANSYS Fluent 2024 R2 to simulate a 3D centrifugal pump using the mesh motion (moving mesh) approach, a core application of the moving mesh module for capturing transient rotor-stator interaction. Unlike the steady MRF (Multiple Reference Frame) method used in a related pump study, this approach directly resolves the unsteady interaction between the rotating impeller and stationary casing, providing a more accurate representation of transient flow behavior and energy transfer from the impeller to the fluid.

Methodology

The geometry is built in SpaceClaim and DesignModeler, consisting of a rotating impeller zone and a stationary casing/volute zone connected through a non-conformal interface that allows relative rotation. The domain is meshed in ANSYS Meshing with approximately 2 million tetrahedral elements, resolving the casing, inlet, and impeller regions. The simulation uses a pressure-based, transient solver with the k-omega SST turbulence model, chosen for its robustness with rotating machinery and near-wall flow. Water is modeled as incompressible, the impeller rotates at 1500 RPM with mesh motion enabled, the inlet is set as a velocity inlet at 140 m/s, the outlet as a pressure outlet, and the Coupled algorithm is used for pressure-velocity coupling to aid convergence in transient conditions.

Conclusion

Pressure contours show a clear rise from the impeller eye to the casing outlet, confirming energy transfer from the rotating blades to the fluid, with high pressure near the impeller exit and low pressure at the inlet, consistent with expected pump behavior. The mesh motion approach captures unsteady pressure fluctuations and localized vortices within the casing, along with directional flow development and secondary circulation that a steady MRF approach cannot resolve. These results validate mesh motion as an effective method for studying unsteady centrifugal pump behavior and confirm the pump's ability to accelerate the fluid and build pressure head.