Propeller blade

Abstract

A propeller blade includes a body configured to extend radially from the hub of a propeller. The body can include a front surface, a back surface, a leading edge, and a trailing edge. The top of the body can form a tippet that generally transitions the front and back surfaces from extending in a generally radial direction to a generally axial direction. The tippet can reduce radial flow and force losses, redirect the radial flow in an axial direction, reduce the exit flow area of the propeller, and increase the inlet flow area of the propeller. The front surface of the blade can have a planar configuration that prevents or reduces the creation of low or negative pressure across the front surface of the blade and associated cavitation.

1 . A propeller blade, comprising:
 a front surface;   an opposing back surface;   a leading end;   a trailing end; and   an upper end that curves from the front surface toward the back surface;   wherein a radius of curvature of the upper end varies along a length of the upper end.   
     
     
         2 . The blade as recited in  claim 1 , wherein the radius of curvature of the upper end at the leading end is smaller than the radius of curvature of the upper end at the trailing end. 
     
     
         3 . The blade as recited in  claim 1 , wherein a height of the blade at the leading end is greater than a height of the blade at the trailing end. 
     
     
         4 . The blade as recited in  claim 1 , wherein the front surface is generally planar. 
     
     
         5 . The blade as recited in  claim 1 , wherein the leading end comprises an edge. 
     
     
         6 . The blade as recited in  claim 5 , wherein the trailing end comprises a surface. 
     
     
         7 . The blade as recited in  claim 1 , wherein a thickness of the upper end decreases as the upper end extends away from the front surface. 
     
     
         8 . The blade as recited in  claim 1 , wherein a thickness of the blade at the trailing end is larger than a thickness of the blade at the leading end. 
     
     
         9 . The blade as recited in  claim 1 , wherein a height of the blade at the leading end is smaller than a height of the blade at the trailing end. 
     
     
         10 . A propeller blade, comprising:
 a body having a front surface, an opposing back surface, a leading end, and a trailing end; and   a tippet curving from the body in a direction generally away from the front surface and toward the back surface;   wherein a radius of curvature of the tippet proximate the leading end is smaller than a radius of curvature of the tippet proximate the trailing end.   
     
     
         11 . The blade as recited in  claim 10 , wherein the front surface is generally planar. 
     
     
         12 . The blade as recited in  claim 11 , wherein a thickness of the blade at the trailing end is larger than a thickness of the blade at the leading end. 
     
     
         13 . The blade as recited in  claim 12 , wherein a distance the tippet extends away from the front surface proximate the leading end is less than a distance the tippet extends away from the front surface proximate the trailing end. 
     
     
         14 . The blade as recited in  claim 10 , wherein a height of the blade at the leading end is greater than a height of the blade at the trailing end. 
     
     
         15 . The blade as recited in  claim 10 , wherein a height of the blade at the leading end is smaller than a height of the blade at the trailing end. 
     
     
         16 . A propeller, comprising:
 a hub; and   a plurality of blades extending outward from the hub, each blade of the plurality of blades including:
 a front surface, 
 an opposing back surface, 
 a leading end, 
 a trailing end, and 
 an upper end that curves in a direction generally away from the front surface and toward the back surface; 
 wherein a radius of curvature of the upper end at the leading end is smaller than a radius of curvature of the upper end at the trailing end. 
   
     
     
         17 . The propeller as recited in  claim 16 , wherein an inlet flow area of the propeller is greater than an outlet flow area of the propeller. 
     
     
         18 . The propeller as recited in  claim 17 , wherein upon rotation of the propeller in a fluid, the plurality of blades draw fluid radially inward toward the hub from radially beyond an outermost radius of the plurality of blades. 
     
     
         19 . The propeller as recited in  claim 16 , wherein a height of each blade at the leading end is smaller than a height of each blade at the trailing end. 
     
     
         20 . The propeller as recited in  claim 16 , wherein each upper end of each blade extends at an angle relative to a cylinder concentric to an axis of rotation of the propeller.