We have developed our own in-house codes to answer the problematic of design of marine propellers. The first motivation was to develop our own propeller turbines for racing sailing boats.
VLM design code : written in Julia and based on various PhD Thesis about the optimisation of propellers with the Vortex Lattice Method, we have a very specific knowledge brick to manage the case of the hydrogeneration case : that is the optimization of propeller for energy harvesting versus its drag.
This tool and underlying theory is however versatile and can handle the more common propulsion case where the Thrust is specified and the Torque has to be minimized.
With changing the fluid parameters, we are able to design efficient propellers for other fields of application, for example for small-scale wind-turbine
Coupled cavitation / load design process : our workflow evaluates cavitation and blade constraints at each design iteration. This is very valuable for multi-parametric optimization process as it ensures that all the designs comply with same cavitation and load constraints and thus are comparable.
Multi-parametric optimization is useful to check the impact of all main parameters governing a propeller design :
– diameter
– number of blades
– rotation rate …etc.
3D geometry generation : based on a work to redefine the NACA sections into modern NURBS definitions, we are able to generate smooth and CAD-friendly shapes with good curvature continuity. This revealed mandatory to be able to alter the final shape ( e.g. to add fillets at the root ) in a robust way and allow automated CFD optimization.
CFD validation : we have developed a specific workflow with OpenFOAM solver to compute any propeller shape in open-water conditions. Some of our propellers have been tested in towing tanks allowing to check the accuracy of design and computations.
CFD optimization : we are able to run optimization sets on specific parameters to maximize the efficiency and account 3D flow effects
Global optimization : propellers are not intended to work alone and not always at the same operating point. That’s why we have developped skills to run global optimization processes. Including motor / generator efficiency map, or usage scenarii, we are able to design a propeller that will outperform globally on its use, not only for a specific case.