Pitting a CFD-Optimized Toroidal Propeller Against a Conventional One

What happened

This also contains wilder designs like toroidal propellers that even after more than a hundred years are still mostly just being evaluated. Recently [Neuronautics] took a shot at figuring out whether toroidal propellers even make sense .

In order to do this, first an efficiency baseline was established using a conventional and highly optimized propeller. This left figuring out an optimized shape for the toroidal propeller to pit against it.

While you can absolutely brute-force the seventeen shape parameters being considered here and test them in CFD, this would take insanely long. The hack here is to use multiple reference frame (MRF) to drastically speed up the selection process, though even then it still took two months.