AIRFOIL FOR A ROTARY MACHINE INCLUDING A PROPELLOR ASSEMBLY

1 . An airfoil comprising:

a proximal end;

a distal end opposite said proximal end;

a distal portion extending adjacent said distal end;

an edge extending between said proximal end and said distal end; and

a surface extending between said proximal end and said distal end, said edge and said surface defining a sweep and a cahedral through said distal portion.

2 . The airfoil in accordance with claim 1 , wherein said edge is at least one of a trailing edge and a leading edge.

3 . The airfoil in accordance with claim 2 , wherein a camber of said airfoil is adjusted in span and chord directions of said airfoil to reduce adverse effects of a high flow acceleration around said at least one of a trailing edge and a leading edge.

4 . The airfoil in accordance with claim 2 , wherein a twist of said airfoil is adjusted along a span of said airfoil to compensate for the aerodynamic loading due to the cahedral and the sweep.

5 . The airfoil in accordance with claim 1 , wherein the cahedral is a dihedral.

6 . The airfoil in accordance with claim 5 , wherein said edge and said surface define an anhedral in addition to the dihedral.

7 . The airfoil in accordance with claim 5 , wherein the sweep is a forward sweep.

8 . The airfoil in accordance with claim 1 , wherein the cahedral is a anhedral.

9 . The airfoil in accordance with claim 8 , wherein the sweep is an aft sweep.

10 . The airfoil in accordance with claim 1 , wherein said surface comprises a high-pressure surface, said airfoil further comprising a low-pressure surface opposite said high-pressure surface, said high-pressure surface and said low-pressure surface sloped throughout said distal portion to at least partly define the cahedral.

11 . The airfoil in accordance with claim 10 , further comprising a shift, each of said high-pressure surface and said low-pressure surface having a curved shape adjacent said shift.

12 . The airfoil in accordance with claim 1 , wherein said airfoil comprises at least one of the following: an outlet guide vane, a fan blade, a rotor blade, a stator vane, a ducted fan blade, an unducted fan blade, a strut, a wind turbine blade, a propeller, an impeller, a diffuser vane, a return channel vane, a marine propeller, and a pylon.

13 . A rotary machine comprising:

at least one rotatable member;

a casing extending at least partly circumferentially around said at least one rotatable element; and

a propeller assembly adjacent said casing and drivingly coupled to said at least one rotatable member, said propeller assembly comprising:

a hub;

at least one blade extending radially from said hub, said at least one blade comprising:

a proximal end adjacent said hub;

a distal end opposite said proximal end;

an intermediate portion extending between said proximal end and said distal end;

a distal portion extending between said intermediate portion and said distal end;

an edge extending between said proximal end and said distal end; and

a surface extending between said proximal end and said distal end, said edge and said surface defining a sweep and a cahedral through said distal portion and at least a portion of said intermediate portion.

14 . The rotary machine in accordance with claim 13 , wherein said at least one blade defines a low pressure side and a high pressure side, said surface extending on the low pressure side of said at least one blade such that the cahedral is a dihedral.

15 . The rotary machine in accordance with claim 13 , wherein said rotary machine comprises an unducted single fan turbine engine.

16 . The rotary machine in accordance with claim 13 , wherein said rotary machine comprises a turboprop engine.

17 . The rotary machine in accordance with claim 13 , wherein the cahedral is a dihedral.

18 . The rotary machine in accordance with claim 17 , wherein the dihedral extends on a suction side of said at least one blade and the sweep is an aft sweep.

19 . A method of operating a rotary machine including at least one rotatable member and a propeller assembly drivingly coupled to the at least one rotatable member, the propeller assembly including a hub and at least one blade extending radially from the hub, the method comprising:

rotating the at least one rotatable member such that the propeller assembly rotates;

contacting air with the at least one blade, the at least one blade including a leading edge, a surface, and a tip, the leading edge and the surface defining a sweep and a cahedral of the at least one blade; and

directing air along the leading edge and the surface defining the sweep and the cahedral such that a flow pattern is generated adjacent the tip, the cahedral and the sweep of the at least one blade configured to reduce noise generated by the flow pattern.

20 . The method in accordance with claim 19 , wherein contacting air comprises contacting air with a distal portion and an intermediate portion of the at least one blade, the dihedral extending through the distal portion and at least a portion of the intermediate portion.