Rotary Equipment & Turbomachinery: Fan Stage Aerodynamic Performance, Axial Flow

Axial Flow Fan Stage (Rotor–Stator, MRF) — ANSYS Fluent CFD Simulation

An axial fan stage is a rotor–stator assembly that produces steady, directed airflow for industrial uses such as cooling freshly painted body parts. The two components share the work: the spinning rotor blades add energy to the air and induce swirl, and the stationary stator blades then straighten that swirling flow so it leaves the stage roughly normal to the outlet. This project uses ANSYS Fluent to model both the rotating and stationary zones of such a fan stage and evaluate its aerodynamic performance — a classic, transferable introduction to turbomachinery CFD.

The 3-D rotor–stator geometry is built in Design Modeler with separate rotating and stationary zones defined, then meshed in ANSYS Meshing with about 244,675 cells. To keep the computation efficient, a periodic boundary condition is used to model only a single slice of the fan rather than the full annulus — the standard way to cut the cost of a turbomachinery analysis without losing fidelity.

The rotation is handled with the Moving Reference Frame (MRF) method, which simulates the rotor spinning at 1800 rpm while the stator stays fixed — a steady-state approach to rotating machinery that avoids the expense of a fully transient moving mesh. Turbulence is modeled with the standard k-ε model across the rotating flow field.

At the end of the solution, you generate 2-D and 3-D contours of pressure and velocity, along with streamlines and velocity vectors that clearly reveal the swirl induced by the rotor and its correction by the stator. From the results you extract the key turbomachinery performance metrics: a rotor tip linear velocity of about 31 m/s, a Tip Speed Ratio (TSR) of 4, and an outlet airflow rate of 16.14 L/s. By the end of this project, you'll be able to build a rotor–stator geometry with distinct motion zones, apply periodic boundaries to model a representative slice, set up the MRF method for rotating machinery, and post-process the flow to compute the performance metrics that define fan and compressor behavior — a workflow that transfers directly to blowers, axial compressors, pumps, and ventilation fans.