FSI: Centrifugal Pump, Mesh Motion

Centrifugal Pump with Fluid-Structure Interaction (FSI) — ANSYS Fluent CFD Simulation Training

This project simulates the fluid flow and structural dynamics within a centrifugal pump using ANSYS Fluent, with the full case analyzed through CFD post-processing.

The 3D geometry was created in Design Modeler and represents a centrifugal pump, with several blades arranged in the central zone. The fluid enters from the outside of the pump and, after rotating around the blades, exits axially from the center. The model was meshed in ANSYS Meshing, for a total of more than 3,649,835 cells.

Methodology

Pumps are industrial machines that move fluid from one place to another through mechanical action. They fall into two main categories — dynamic and positive-displacement pumps — and centrifugal pumps are among the most common dynamic types. A centrifugal pump raises the fluid pressure from inlet to outlet, driving the flow; the force that creates this pressure comes from an electric motor that rotates the impeller. The fluid enters at the center of the impeller and exits at the edge of the blades, so the centrifugal force increases its velocity and kinetic energy.

The model consists of three main parts: the central blades, defined as a solid body, and the casing around the pump, defined as the fluid passage, with a distinct central zone defined for the fluid so that the rotational motion of the blades can be applied to it. This central fluid zone uses the moving-reference-frame (frame motion) method at a rotational speed of 1500 rpm, meaning the fluid rotates around the blades at this speed. Water enters radially through the inlet port at 140 m/s and exits axially at the center of the pump at a relative pressure of 0 Pa.

The SST k-omega model solves the turbulent flow equations, chosen for its accuracy in predicting flow patterns both near and far from the walls. To capture the interaction between the fluid flow and the structural response of the pump components, a Fluid-Structure Interaction (FSI) model is employed. This allows the deformation of the pump blades under fluid loading to be captured, giving a realistic depiction of the fluid–structure coupling.

Results

The contours show that the pressure increases radially, rising from the central part of the pump toward the periphery. Because of the rotational motion in the central region, the maximum velocity appears there, along with the largest pressure difference (pressure gradient). Integrating the FSI model into the simulation provides critical insight into the structural dynamics of the impeller blades, contributing to a more robust understanding of the pump's operational efficiency and its potential failure points under dynamic loading.