Hi Grünherz,
>Supercharger intake fan.

Actually, the fan-looking device is the "Dralldrossel" ("spin throttle") used to avoid throttling losses below full throttle height.
Though it looks like it could, it didn't rotate. It merely added a spin in the direction of the supercharger rotation to the intake airstream while restricting the air flow to the engine.
The spin meant the supercharger had to do less work, so the intake air was heated less during compression, making for a more efficient throttle.
Regards,
Henning (HoHun)