ARA has many years of knowledge and experience in propeller design, testing, modelling, acoustics and analysis and is constantly developing new technology and applying it to provide customers with the best solution for their needs
The numerical simulation of a rotating propeller geometry entails a high computational cost. This is for two reasons: the mesh density increases considerably, over and above that of the airframe, when modelling propeller blades and the numerical simulation of rotating blades requires an unsteady calculation.
Nevertheless, not all studies require the same level of fidelity. The ARA Computational Aerodynamics Applied team offers a range of possibilities to model propellers according to the customer or application needs: from low-fidelity codes to different high-fidelity CFD advanced techniques used in the aerospace industry.
The well established ARA strip code allows a low-fidelity rapid prediction of isolated, axisymmetric, propeller performance at a very low computational cost. The strip analysis, well-established in the propeller industry, is a very powerful tool for early design stages and optimisation purposes when a significant number of alternatives need to be evaluated.
Actuator Disc Modelling
In many studies, the flow around the blades is not of primary interest and the slipstream can be considered as stationary. When this approximation can be made, the full propeller can be replaced by a stationary propeller model which is less computationally expensive. The Solar–TAU RANS toolset used at ARA has got implemented an actuator disk model that consists of a simple geometry (disk) that applies stationary forces to the fluid equivalent to the ones that a full propeller would apply.
The formulation of the model allows the propeller thrust and power to be influenced by free-stream incidence and installation effects.
For detailed high-fidelity propeller modelling, the ARA computational aerodynamics team have the capability, using the Solar–TAU RANS toolset, to perform an unsteady (URANS) numerical simulation of the full modelled rotating blades.
This level of modelling allows the detailed analysis of the propeller performance and time-dependent interaction effects of the propeller on the airframe and vice versa. The co-existing static airframe and rotating propeller meshes interface by means of the use of the overset unstructured grids method (Chimera).