Fan shroud and/or fan blade assembly

Abstract

Briefly, embodiments of a fan for moving a volume of compressible fluid from an upstream side to a downstream side may comprise a vortex circulation channel formed within a shroud substantially surrounding the blades of the fan. As a portion of one or more blades of the fan moves within the vortex circulation channel, a vortex that is formed and confined within the channel may reduce formation of a vortex within the fan working area, thereby bringing about an increase in a volume of the compressible fluid capable of being moved by the fan. In an embodiment, a fin or other protrusion disposed on a tip portion of a blade may additionally increase flow of a compressible fluid through a fan. In an embodiment, use of a wraparound leading edge of a fan shroud may bring about further increases in volume of compressible fluid flow.

What is claimed is: 
     
         1 . A fan shroud at least partially surrounding one or more blades of a fan, the fan shroud comprising:
 a vortex circulation channel, formed within the fan shroud, sized to accept a tip portion of one or more blades of the fan during rotational motion of the one or more blades of the fan, the vortex circulation channel shaped to confine a vortex generated near the tip portion of the one or more blades of the fan during the rotational motion of the one or more blades of the fan.   
     
     
         2 . The fan shroud of  claim 1 , wherein the vortex circulation channel comprises at least one protruding edge disposed at an upstream direction relative to a plane of the rotational motion of the one or more blades of the fan. 
     
     
         3 . The fan shroud of  claim 1 , wherein the vortex circulation channel comprises at least one protruding edge disposed at a downstream direction from a plane of the rotational motion of the one or more blades of the fan. 
     
     
         4 . The fan shroud of  claim 1 , wherein the confined vortex of the vortex circulation channel operates to avoid impeding of the generated vortex into a working area defined by the shroud. 
     
     
         5 . The fan shroud of  claim 1 , wherein the confined vortex of the vortex circulation channel operates to substantially eliminate boundary layer separation in an upstream direction or in a downstream direction relative to a plane of the rotational motion of the one or more blades of the fan. 
     
     
         6 . The fan shroud of  claim 1 , wherein the one or more blades of the fan are capable of moving a volume of a compressible fluid from an upstream side to a downstream side relative to a plane of the rotational motion of the one or more blades of the fan. 
     
     
         7 . The fan shroud of  claim 1 , wherein the vortex circulation channel comprises an at least approximately semicircular profile in an upstream direction of a plane of the rotational motion of the fan. 
     
     
         8 . The fan shroud of  claim 7 , wherein the ratio between a radius of a blade of the fan to a curvature of a semicircular portion of the vortex circulation channel comprises a value of between 10.0:1.0 and 100.0:1.0. 
     
     
         9 . The fan shroud of  claim 1 , wherein the vortex circulation channel comprises an at least approximately semicircular profile in a downstream direction of a plane of the rotational motion of the fan. 
     
     
         10 . The fan shroud of  claim 1 , wherein the shroud comprises a wraparound forward edge, the wraparound forward comprising a radius of curvature of between about 2.0% and 5.0% of the radius of an area of an upstream side of the one or more blades of the fan. 
     
     
         11 . A fan shroud and blade assembly, comprising:
 one or more blades to move rotationally in a plane; and   a shroud, at least partially enclosing the one or more blades of the fan, the shroud comprising a vortex circulation channel formed on and sized to accept a tip portion of at least one of the one or more blades during rotational motion of the one or more blades of the fan, the vortex circulation channel to form a confined vortex at least partially in response to movement of the tip portion of the at least one of the one or more blades, and at least partially in response to a spacing between the tip portion of at least one of the one or more blades and the fan shroud.   
     
     
         12 . The fan shroud and blade assembly of  claim 11 , wherein the shroud operates to direct a flow of a compressible fluid through the one or more blades, and wherein the confined vortex is formed from the compressible fluid during the rotational motion of the one or more blades. 
     
     
         13 . The fan shroud and blade assembly of  claim 11 , wherein the vortex circulation channel additionally comprises at least one protruding edge disposed in an upstream direction relative to a plane of the rotational motion of the one or more blades. 
     
     
         14 . The fan shroud and blade assembly of  claim 13 , wherein the vortex circulation channel additionally comprises at least one protruding edge disposed in a downstream direction from the plane of rotational motion of the one or more blades. 
     
     
         15 . The fan shroud and blade assembly of  claim 11 , wherein the confined vortex of the vortex circulation channel operates to substantially eliminate boundary layer separation in an upstream direction or in a downstream direction, relative to the one or more blades, during rotational motion of the one or more blades. 
     
     
         16 . The fan shroud and blade assembly of  claim 11 , wherein at least a portion of the vortex circulation channel comprises an approximately semicircular profile having a radius of curvature of between 1/10 and 1/100 of the radius of the one or more blades. 
     
     
         17 . A system to move a volume of a compressible fluid, comprising:
 a shroud to substantially surround one or more blades of a fan; and   a vortex circulation channel formed within the shroud to accept a portion of at least one of the one or more blades of the fan during rotational motion of one or more blades of the fan, the vortex circulation channel to form a vortex to circulate a portion of the compressible fluid, the vortex to avoid interference with a working area defined by the shroud.   
     
     
         18 . The system of  claim 17 , wherein the vortex circulation channel is formed within the shroud and sized to accept a portion of all of the blades of the fan during rotational motion of the blades of the fan. 
     
     
         19 . The system of  claim 17 , wherein the vortex circulation channel comprises a first approximately semicircular-shaped region at an upstream side of the blades of the fan and a second semicircular-shaped region at a downstream side of the blades of the fan. 
     
     
         20 . The system of  claim 19 , wherein one or more of the first approximately semicircular-shaped region and the second semicircular-shaped region comprises a profile having a radius of curvature of between 1/10 and 1/100 of the at least one of the one or more blades of the fan.