Cooling fan with adjustable tip clearance

1. A cooling fan comprising:

a fan housing;

a conduit through said fan housing;

a plurality of blades rotatably disposed within said conduit, wherein each of said plurality of blades extends radially outward from a hub to a tip, wherein the radial gap between the tips of said blades and said conduit defines a tip clearance; and

a tip clearance reduction system operable to control the tip clearance,

wherein said tip clearance reduction system comprises a connector that allows said plurality of blades to be attached more than one position relative to said housing.

2. The cooling fan of claim 1 wherein said conduit further comprises a tapered section and a straight section.

3. The cooling fan of claim 2 wherein said plurality of blades is disposed within the tapered section and are axially translatable relative to said conduit.

4. The cooling fan of claim 1 further comprising:

a motor housing coupled to said fan housing; and

a motor coupled to said motor housing, wherein said motor rotatably supports said plurality of blades.

5. The cooling fan of claim 4 wherein said motor is at least partially disposed within a straight section of said conduit and is axially translatable relative to said fan housing.

6. The cooling fan of claim 1 wherein said tip clearance reduction system comprises an insert disposed between the tips of said blades and said conduit.

7. The cooling fan of claim 1 wherein said tip clearance reduction system comprises a recessed portion of said fan housing, wherein the tips of said blades are aligned with said recessed portion.

8. The cooling fan of claim 1 wherein said fan housing is mounted to a chassis supporting an electronic device.

9. A cooling fan comprising:

a fan housing;

a conduit through said fan housing;

a plurality of blades rotatably disposed within said conduit, wherein each of said plurality of blades extends radially outward from a hub to a tip, wherein the radial gap between the tips of said blades and said conduit defines a tip clearance;

a tip clearance reduction system operable to control the tip clearance;

a motor housing coupled to said fan housing;

a motor coupled to said motor housing, wherein said motor rotatably supports said plurality of blades; and

wherein said tip clearance reduction system comprises an alignment ring disposed between said motor housing and said motor.

10. A cooling fan comprising:

a fan housing;

a conduit through said fan housing;

a plurality of blades rotatably disposed within said conduit, wherein each of said plurality of blades extends radially outward from a hub to a tip, wherein the radial gap between the tips of said blades and said conduit defines a tip clearance; and

means for reducing the tip clearance,

wherein said fan housing is connected to a chassis supporting an electronic device.

11. The cooling fan claim 10 wherein said plurality of blades are disposed within a tapered section of said conduit and said means for adjusting the tip clearance comprises means for axially translating said plurality of blades relative to said fan housing.

12. The cooling fan of claim 11 further comprising a motor coupled to said fan housing and rotatably supporting said plurality of blades, wherein said means for reducing the tip clearance comprises means for axially translating said motor relative to said fan housing.

13. The cooling fan of claim 12 further comprising a motor housing coupled to said fan housing and supporting said motor, wherein said means for reducing the tip clearance comprises means for axially translating said motor housing relative to said fan housing.

14. The cooling fan of claim 10 wherein said means for reducing the tip clearance comprises means for connecting an insert between the tips of said blades and said fan housing.

15. A method for constructing a fan comprising:

rotatably disposing a plurality of blades within a conduit through a fan housing, wherein each of the plurality of blades extends radially outward from a hub to a tip, wherein the radial gap between the tips of the blades and the conduit defines a tip clearance;

utilizing a tip clearance reduction system to control the tip; and

connecting the fan housing to an electronic device chassis.

16. The method of claim 15 wherein utilizing the tip clearance reduction system comprises axially translating the plurality of blades within a tapered section of the conduit.

17. The method of claim 15 wherein utilizing the tip clearance reduction system comprises installing an insert that surrounds the plurality of blades.

18. The method of claim 15 wherein utilizing the tip clearance reduction system comprises installing an alignment ring.