Ventilation arrangement

1. A ventilation arrangement for a wind turbine, comprising:

an air inlet opening located in a nose cone of said wind turbine;

a manhole cover for covering a manhole of a rotor hub of said wind turbine, wherein the rotor hub is contained within the nose cone and spaced therefrom to form an internal space between an inner surface of the nose cone and an outer surface of the rotor hub, the manhole cover providing a vent opening for venting hot air from an internal space of said rotor hub into the internal space between the inner surface of the nose cone and the outer surface of the rotor hub; and

a piping establishing fluid communication between the internal space of the rotor hub and the air inlet opening.

2. The ventilation arrangement according to claim 1 , wherein the piping comprises a flexible piping which is supported by the manhole cover so that the manhole cover and the flexible piping can rotate with respect to each other.

3. The ventilation arrangement according to claim 1 , further comprising a shielding member located adjacent the air inlet opening, wherein the shielding member is configured to preventingress of water into the piping.

4. The ventilation arrangement according to claim 1 , further comprising an air filter disposed between the air inlet opening and the internal space of the rotor hub for filtering the cool air directed into the internal space of the rotor hub.

5. The ventilation arrangement according to claim 1 , wherein the vent opening is provided with shutters to preventingress of water into the internal space of the rotor hub.

6. The ventilation arrangement according to claim 1 , further comprising spacers configured to provide a space between the manhole cover and a wall of the rotor hub so that hot air can be vented from the inside of the rotor hub through said space.

7. The ventilation arrangement according to claim 1 , further comprising a branched piping located inside the rotor hub, wherein each branch of the piping leads from the piping toward an installation to be cooled.

8. The ventilation arrangement according to claim 1 , further comprising a fan mounted in front of an opening of the manhole cover, the fan being configured to exhaust hot air from the internal space of the rotor hub into the internal space between the inner surface of the nose cone and the outer surface of the rotor hub.

9. The ventilation arrangement according to claim 1 , further comprising a fan mounted in front of an opening of the manhole cover, the fan being configured to draw cool air from an exterior space of the rotor hub.

10. The ventilation arrangement according to claim 9 , further comprising a diverging nozzle disposed behind the fan to distribute cool air within said internal space of the rotor hub.

11. The ventilation arrangement according to claim 1 , further comprising a duct located behind the air inlet opening, the duct having a NACA profile to draw cool air from outside the nose cone, wherein the duct is connected to the piping.

12. The ventilation arrangement according to claim 1 , wherein the manhole cover is disposed in the internal space between the nose cone and the rotor hub.

13. The ventilation arrangement according to claim 12 , wherein the piping comprises a flexible piping and an elbow located inside of the nose cone and upstream of the flexible piping to preventingress of water into the flexible piping.

14. The ventilation arrangement according to claim 13 , further comprising a drain piping extending between the elbow and a rear end of the rotor hub facing a nacelle of the wind turbine.

15. The ventilation arrangement according to claim 12 , wherein the piping comprises a flexible piping which is supported by the manhole cover so that the manhole cover and the flexible piping can rotate with respect to each other.