Ventilation assembly for wind turbine rotor hub

1. A ventilation assembly for a wind turbine rotor hub, comprising:

a frame fixedly mountable to the wind turbine rotor hub, the frame including at least one opening; and

a cover for the at least one opening, the cover mounted to the frame to be freely rotatable with respect to the frame, wherein the cover has at least one ventilation opening to allow the ingress and egress of air and has a shielding member for shielding the at least one ventilation opening against ingress of liquid running down the wind turbine rotor hub.

2. The ventilation assembly according to claim 1 , wherein the shielding member is formed as a jalousie.

3. The ventilation assembly according to claim 1 , wherein the shielding member comprises at least one shroud.

4. The ventilation assembly according to claim 1 , wherein the cover further comprises a weight located off-axis of a rotational axis of the cover.

5. The ventilation assembly according to claim 1 , wherein the frame and the cover are mounted to each other by a shaft-to-collar connection, wherein the shaft is freely rotatable with respect to the collar.

6. The ventilation assembly according to claim 1 , wherein the frame comprises a groove surrounding the cover.

7. The ventilation assembly according to claim 1 , wherein the frame comprises a screen surrounding the cover.

8. The ventilation assembly according to claim 1 , further comprising a fan mounted to the frame to be freely rotatable with respect to the frame.

9. The ventilation assembly according to claim 8 , wherein the fan is mounted to a shaft of the cover.

10. The ventilation assembly according to claim 8 , wherein the cover is mounted to a shaft of the fan.

11. The ventilation assembly according to claim 1 , wherein an axis of rotation of the cover is aligned with an axis of rotation of the wind turbine rotor hub.

12. The ventilation assembly according to claim 1 , wherein the frame is mounted to a front side of the wind turbine rotor hub.

13. A passive ventilator for a wind turbine rotor hub, comprising:

a frame mountable to the wind turbine rotor hub, frame including at least one opening; and

a fan mounted to the frame by a shaft-to-collar connection, a rotational axis of the fan substantially axially aligned with a rotational axis of the wind turbine rotor hub, and the fan freely rotatable with respect to the frame.

14. The passive ventilator according to claim 13 , wherein the shaft is freely rotatable with respect to the collar.

15. The passive ventilator according to claim 13 , wherein a center of mass of the fan is located at a radial distance from an axis of rotation of the fan.

16. The passive ventilator according to claim 13 , wherein the frame is mounted inside the wind turbine rotor hub.

17. The passive ventilator according to claim 13 , further comprising a cover for the at least one opening, the cover mounted to the frame to be freely rotatable with respect to the frame, wherein the cover has at least one ventilation opening to allow ingress and egress of air and has a shielding member for shielding the at least one ventilation opening against ingress of liquid running down the wind turbine rotor hub.

18. The passive ventilator in accordance with claim 17 , wherein the cover further comprises a weight located off-axis of a rotational axis of the cover, the weight configured to substantially maintain a horizontal stability of the cover during rotation of the wind turbine rotor hub.

19. The passive ventilator in accordance with claim 17 , wherein the cover is configured to substantially prevent ingress of water during wind turbine rotor hub operation.