Axial flow device

Abstract

An axial flow device includes a hub having an outer periphery and a plurality of blades each having a root portion, a tip portion and a body portion between the root portion and the tip portion and projecting outward from the outer periphery of the hub. Furthermore, the root portion has a first angle of attack, the tip portion has a second angle of attack, and the second angle of attack is greater than the first angle of attack. Specifically, each blade is integrally formed based on a continuous angle of attack variation from the root portion through the body portion to the tip portion.

What is claimed is: 
     
         1 . An axial flow device, comprising:
 a hub having an outer periphery; and   a plurality of blades, wherein each blade has a root portion, a tip portion and a body portion between the root portion and the tip portion and projects outward from the outer periphery of the hub, wherein the root portion has a first angle of attack and the tip portion has a second angle of attack, wherein the second angle of attack is greater than the first angle of attack, wherein the blade is integrally formed based on a continuous angle of attack variation from the root portion through the body portion to the tip portion.   
     
     
         2 . An axial flow device according to  claim 1 , wherein the continuous angle of attack variation is substantially in a range of 27 degrees to 55 degrees. 
     
     
         3 . An axial flow device according to  claim 1 , wherein the first angle of attack is substantially in a range of 27 degrees to 45 degrees. 
     
     
         4 . An axial flow device according to  claim 1 , wherein the second angle of attack is substantially in a range of 37 degrees to 55 degrees. 
     
     
         5 . An axial flow device according to  claim 1 , wherein the angle of attack uniformly varies from the root portion through the body portion to the tip portion. 
     
     
         6 . An axial flow device according to  claim 1 , wherein the varying rate of the angle of attack increases from the root portion through the body portion to the tip portion. 
     
     
         7 . An axial flow device according to  claim 1 , wherein the varying rate of the angle of attack decreases from the root portion through the body portion to the tip portion. 
     
     
         8 . An axial flow device according to  claim 1 , wherein each blade is forwardly skewed. 
     
     
         9 . An axial flow device according to  claim 1 , wherein each blade is backwardly skewed. 
     
     
         10 . An axial flow device according to  claim 1 , wherein each blade is backwardly skewed in the region adjacent to the root portion and forwardly skewed in the region adjacent to the tip portion. 
     
     
         11 . An axial flow device according to  claim 1 , wherein each blade is forwardly skewed in the region adjacent to the root portion and backwardly skewed in the region adjacent to the tip portion. 
     
     
         12 . An axial flow device according to  claim 1 , further comprising a frame, wherein the plurality of blades project outward radially from the outer periphery of the hub toward the frame.