Hollow airfoil with catenary profiles
A method of forming a gas turbine engine according to an example of the present disclosure includes, among other things, attaching a first skin to a main body to enclose at least one internal channel, the first skin and the main body cooperating to define pressure and suction sides of an airfoil, holding the first skin and the main body between first and second dies, and pressurizing the at least one internal channel such that walls of the first skin and the main body move outwardly toward surface contours of the first and second dies. A gas turbine engine component is also disclosed.
1. A method of forming a gas turbine engine component comprising:
attaching a first skin to a main body to enclose at least one internal channel, the first skin and the main body cooperating to define pressure and suction sides of an airfoil;
holding the first skin and the main body between first and second dies; and
pressurizing the at least one internal channel such that walls of the first skin and the main body move outwardly toward surface contours of the first and second dies; and
wherein the pressurizing step includes causing the first skin and the main body to complement respective ones of the surface contours, each of the surface contours including a plurality of pockets between a plurality of ridges.
2. The method as recited in claim 1 , wherein the airfoil is a fan blade.
3. The method as recited in claim 1 , wherein the at least one internal channel is a plurality of internal channels, and further comprising forming the plurality of internal channels in the main body.
4. The method as recited in claim 3 , wherein the walls of the first skin have a substantially constant thickness along the plurality of internal channels subsequent to the attaching step.
5. The method as recited in claim 4 , further comprising removing material from the walls along exterior surfaces of the pressure and suction sides.
6. The method as recited in claim 5 , wherein the first skin and main body comprise titanium.
7. The method as recited in claim 6 , wherein internal surfaces along the walls bounding the plurality of internal channels have a catenary profile.
8. The method as recited in claim 7 , wherein:
the at least one internal channel is a plurality of internal channels spaced apart by a plurality of ribs; and
the first and second dies are dimensioned such that during the holding step but prior to the pressurizing step the plurality of ridges of the first die abut against the first skin and the plurality of ridges of the second die abut against the main body at respective contact points, all of the plurality of pockets are spaced apart from the first skin and the main body, and each of the ribs is situated between a respective pair of the contact points.
9. The method as recited in claim 1 , wherein the attaching step includes brazing, diffusion bonding or welding the first skin to the main body.
10. The method as recited in claim 1 , wherein the pressurizing step includes communicating heat from the first and second dies to the first skin and the main body.
11. The method as recited in claim 10 , wherein the attaching step includes trapping an inert gas in the at least one internal channel.
12. The method as recited in claim 11 , wherein the inert gas comprises argon.
13. The method as recited in claim 10 , wherein the attaching step includes brazing, diffusion bonding or welding the first skin to the main body.
14. The method as recited in claim 1 , wherein the holding step includes the plurality of ridges abutting against the walls.
15. A method of forming an airfoil for a gas turbine engine comprising:
providing an airfoil section extending between a leading edge and a trailing edge in a chordwise direction and extending between a tip and a root section in a spanwise direction, the airfoil section defining a suction side and a pressure side separated in a thickness direction, and the airfoil section including one or more ribs defining a plurality of internal channels;
deforming walls of the airfoil section, including pressurizing the plurality of internal channels such that the walls move outwardly to define a plurality of bulged portions; and
removing material from the plurality of bulged portions along external surfaces of the pressure and suction sides.
16. The method as recited in claim 15 , wherein the walls of the airfoil section corresponding to the plurality of bulged portions have a substantially constant thickness along the plurality of internal channels subsequent to the deforming step.
17. The method as recited in claim 15 , wherein the removing step includes establishing a continuous surface contour along each of the respective pressure and suction sides that extends from the leading edge to the trailing edge.
18. The method as recited in claim 15 , wherein the airfoil section includes a first skin and a main body that cooperate to define the pressure and suction sides, and further comprising:
attaching the first skin to the main body to enclose the plurality of internal channels, including trapping an inert gas in the plurality of internal channel.
19. The method as recited in claim 18 , wherein the deforming step includes heating the inert gas to cause the walls to complement surface contours defined by first and second dies, the surface contours including a plurality of pockets.
20. The method as recited in claim 19 , further comprising:
holding the walls of the airfoil section between the first and second dies;
wherein the removing step includes establishing a continuous surface contour along each of the respective pressure and suction sides from the leading edge to the trailing edge;
wherein the surface contours includes a plurality of ridges between the plurality of pockets, the pockets dimensioned to receive respective ones of the bulges during the deforming step;
wherein the first and second dies are dimensioned such that during the holding step but prior to the deforming step the plurality of ridges of the first and second dies abut against the walls of the airfoil section at respective contact points, all of the plurality of pockets are spaced apart from the walls of the airfoil section, and each of the one or more ribs is situated between a respective pair of the contact points; and
wherein internal surfaces along the walls bounding the plurality of internal channels have a catenary profile.
21. The method as recited in claim 15 , wherein the walls defining the plurality of internal channels have a thickness that tapers in the chordwise direction between adjacent pairs of the ribs for at least a majority of a distance between the adjacent pairs of the ribs subsequent to the removal step.