Optimized Stairmand Cyclone Separator

This is a Stairmand type cyclone separator with optimized geometry for better separation efficiency and reduced airflow resistance. It is inspired by the following study:
https://aaqr.org/articles/aaqr-13-04-oa-0129.pdf

Inlet and outlets have an outer diameter of 10 mm. Particle outlet has an inner diameter of 4 mm. For different diameter (D) values you can simply scale the model in your slicer by using the factor
F = D/10 (mm),
in which D is your required diameter in millimeters.
Note that the model is designed with its current overall dimensions in mind. Large scale factors will result in overly thick walls at some point.

There are 5 different clean air outlet configurations provided, 4 for every 90 deg in the horizontal plane and 1 in the upward direction. Note that STL files are upside down for printing purposes mentioned later below.

Ensure the following for the separator to work:
- higher air pressure at the inlet than at the clean air outlet
- particle outlet is pointing down