Moving Mesh (Mesh Motion): Aircraft Propeller

This project analyses the thrust and lift generated by a rotating propeller and its effect on an aircraft fuselage using ANSYS Fluent, with the Mesh Motion (moving mesh) technique as the central theme. A propeller converts the rotational power of an engine into thrust: its twisted blades act like small rotating wings, producing an aerodynamic force that can be resolved into a component along the aircraft axis (the propulsive thrust) and a component in the plane of the blades (the torque). Reproducing this behaviour in CFD requires the propeller region to physically rotate within the simulation, and the moving-mesh approach is what makes that possible — it is the core of the methodology.

The aircraft and propeller geometry was designed in SolidWorks and imported into ANSYS Meshing for grid generation and boundary naming. The mesh was first built with tetrahedral elements and then converted to a polyhedral mesh within Fluent, which yields fewer cells and higher quality: the element count is 3,812,519 for the tetrahedral mesh and 692,023 for the polyhedral mesh.

The model is divided into two zones, rotational and stationary, which is the defining structure of a mesh-motion simulation. A cylindrical rotating domain sized at 1.12 propeller diameters surrounds the impeller and is meshed more finely, reflecting the greater importance of the blade region to the results. This rotating domain sits inside the fixed outer zone, and the two are connected through an interface that transfers flow quantities between them. The Mesh Motion method makes the rotating domain physically spin about the impeller axis, directly capturing the propeller's rotation, and a transient solver is used to resolve the resulting time-dependent flow.

To scale the simulation correctly, the advance ratio is used as the governing similarity parameter. With an impeller diameter of 0.0532 m and a rotational speed of 1800 rpm (30 rad/s), an advance ratio of J = 1.225 corresponds to a flow velocity of 2 m/s. These conditions provide a consistent basis for simulating the propeller across different scales by holding the advance ratio fixed.

The results yield the drag and lift on the fuselage together with the thrust and torque on the propeller, presented in the accompanying diagrams, along with contours, vectors and flow lines that reveal the flow physics around the aircraft and blades. The study shows that, by respecting the advance ratio for each propeller, working points can be defined through the relationship between flow velocity and rotational speed. For a fully rigorous match, additional criteria are needed — in particular the Reynolds number based on both the impeller speed and the flow velocity — and a valid scaled simulation requires that the computed Reynolds number exceed the critical value for that propeller. On that basis the model can represent real propeller operating points. As a study in moving-mesh modelling, the project demonstrates how splitting the domain into rotating and stationary zones joined by an interface, combined with a transient solver, captures the genuine rotation of a propeller and the thrust, torque and aerodynamic loads it produces.