However the whole sentence esp. in the descriptive text should be less technicla and more poetic I believe. I think the sentence should go like that:
wiatraczek na patyku obracający się przy wietrze or wiatraczek na patyku obracający się przy każdym podmuchu wiatru,i.e. a kind of a toy children esp. my grandson like.

pinwheel consists of a stick, on top of
which are a few curved plastic or paper
wheels pinned to the top of the stick.
It turns when one runs with it, because
of the created air current.
In Muret-Sanders I found:
pinwheel-1.Windmuehle (Kinderspielzeug)
As far as I know, we also called it:
Windrad--when I was a child.
2. Feuerrad (Feuerwerkskoerper)
3. techn. Stift(nokken)rad

Good luck,
Lis