The Ugrinsky rotor was developed by the Russian engineer K.A.Ugrinsky in 1946. https://vawt.ro/2016/09/08/ugrinsky/ (Romanian). It may be used in a Vertical Axis Wind Turbine, VAWT. The rotor looks like a variation of the Savonius rotor, and it is said to be a little more efficient. The rotor vanes, or buckets may be straight, or "twisted" in a spiral. The rotor may also be 3D printed.

https://www.youtube.com/watch?v=tCETDwUQrqk&t=27s
https://www.youtube.com/watch?v=0rPtwoAb5oY

Cross section dimensions:
https://www.kleinwindanlagen.de/Forum/cf3/topic.php?t=6125

The patent version seems to have retractable portions.
https://patents.google.com/patent/RU2246634C2/en

There are STL files for several versions on thingiverse.

https://mdpi-res.com/d_attachment/energies/energies-15-02478/article_deploy/energies-15-02478.pdf?version=1648462064

This model: ( https://www.thingiverse.com/thing:2238394 )
Blade thickness 1.5 mm
Radius at blade center 60.0 mm
Outer diameter 121.5 mm
cBucket center distance 36.0 mm
cBucket radius r = 0.4*60 = 24.0 mm
RBucket center distance b = 0.8*60 = 48.0 mm
RBucket radius 60.0 mm
For helical version:
One 60 degree section height = 70.0 mm
Six stacked sections = 360 degres.
Curve centerline cross section is scalable.
This file shows only the cross section, not a complete model.

- Brian

A few minor changes were made to outer edges of blades.

Created helix, times 4, extending down 70 mm, for a section. (60 degrees)
Six sections would reach 360 degrees.
For blade cross section profile, did a two_rail_sweep to two helices. Repeated for other blade.

To Do: two interlocking pins and sockets, axis, top, bottom.

- Brian

ps Earlier, script ImportSTL was used to import the thingiverse .stl.
The 59,000plus triangles mostly imported, with some lost.
The very large file produced a moderately good looking rotor section, enough to check and get distances and angles.
Then deleted the .stl import. Too Big...

UgrinskyCrossSection03.3dm is a Left Handed helix spiral.
Turbine deflects wind downward? Lift force occurs? Less efficient than RH?

Could mirror cross section?
Instead, will redo as RH spiral.

- Brian

This is really interesting Brian,

Thank you

James Elliott

The cross section has similarities to the famous yin-yang symbol!

Thanks for sharing this Interesting info!

The .step models at mcmaster quickly open in MoI, and can be saved as .3dm files.
I plan to use one of these bold models to boolean difference a solid block model, to make internal threads.

https://www.mcmaster.com/screws/system-of-measurement~metric/metric-18-8-stainless-steel-button-head-hex-drive-screws/

Also, there is a more efficient radius setting for the rotor.
The smaller radius blade diameter is 0.35 * Diameter of rotor.
The larger radius blade radius is still = L = 1.0 * R = 1.0 * D/2. Depending on the ratio of rotor tip speed to incident wind speed, the 1.0 factor could be 1.3.
So I am re-doing the model...

https://www.witpress.com/Secure/elibrary/papers/ESUS21/ESUS21011FU1.pdf
This paper was with non-spiral rotor.
I have not seen any data for a helical rotor.

- Brian

Some notes on Helical Wind Turbines, this might provide some useful input to the discussion:
https://windcycle.energy/helical-wind-turbine/
best regards
O.

Thank you for the link, Ken.
- Brian