Airfoil having internally cooled wall with liner and shell

1. An airfoil comprising:

an airfoil section having an airfoil wall surrounding a cavity, the airfoil wall including first wall section comprised of a monolithic ceramic shell, a second wall section comprised of a ceramic matrix composite (CMC) liner bonded along an interface to an interior side of the monolithic ceramic shell, and a ceramic barrier coating bonded to an exterior side of the monolithic ceramic shell; and

the airfoil wall including at least one of: inter-section cooling channels extending along the interface and being bounded by the monolithic ceramic shell and the CMC liner or intra-section cooling channels extending within the CMC liner.

2. The airfoil as recited in claim 1 , wherein the monolithic ceramic shell has a first thermal conductivity and the CMC liner has a second thermal conductivity that is lower than the first thermal conductivity.

3. The airfoil as recited in claim 1 , wherein the monolithic ceramic shell is selected from the group consisting of SiC, Si3N4, Al2O3, SiAlON, nitrogen-bonded SIC, and AlN, and the CMC liner is SiC fiber/SiC matrix.

4. The airfoil as recited in claim 1 , wherein the airfoil wall includes the inter-section cooling channels.

5. The airfoil as recited in claim 4 , wherein the inter-section cooling channels are in a serpentine arrangement.

6. The airfoil as recited in claim 4 , wherein the inter-section cooling channels include flow guides and heat transfer enhancements.

7. The airfoil as recited in claim 4 , wherein the monolithic shell is comprised of first and second panels bonded along the interface with the CMC liner, the first and second panels meet at a joint, and the inter-section cooling channels open to an exit channel in the joint.

8. The airfoil as recited in claim 1 , wherein the airfoil wall includes the intra-section cooling channels.

9. The airfoil as recited in claim 8 , wherein the CMC liner includes first and second spaced-apart face layers, fibrous ligaments connecting the first and second spaced-apart face layers, and the intra-section cooling channels extend between the fibrous ligaments.

10. The airfoil as recited in claim 9 , wherein the fibrous ligaments form a pattern.

11. The airfoil as recited in claim 9 , wherein the intra-section cooling channels have a trapezoidal cross-section.

12. The airfoil as recited in claim 9 , wherein the monolithic shell is comprised of first and second panels bonded along the interface with the CMC liner, the first and second panels meet at a joint, and the intra-section cooling channels open to an exit channel in the joint.

13. An airfoil comprising:

an airfoil section having an airfoil wall surrounding a cavity, the airfoil wall including first wall section comprised of a monolithic ceramic shell, a second wall section comprised of a ceramic matrix composite (CMC) liner bonded along an interface to an interior side of the monolithic ceramic shell, and a ceramic barrier coating bonded to an exterior side of the monolithic ceramic shell, wherein the monolithic ceramic shell has a first thermal conductivity and the CMC liner has a second thermal conductivity that is lower than the first thermal conductivity; and

cooling channels extending along the interface and being bounded by the monolithic ceramic shell and the CMC liner.

14. The airfoil as recited in claim 13 , wherein the monolithic shell is comprised of first and second panels bonded along the interface with the CMC liner, the first and second panels meet at a joint, and the cooling channels open to an exit channel in the joint.

15. The airfoil as recited in claim 14 , wherein the monolithic ceramic shell is selected from the group consisting of SiC, Si3N4, Al2O3, SiAlON, nitrogen-bonded SIC, and AlN, and the CMC liner is SiC fiber/SiC matrix.

16. A gas turbine engine comprising:

a compressor section;

a combustor in fluid communication with the compressor section; and

a turbine section in fluid communication with the combustor,

the turbine section having an airfoil that includes

an airfoil section having an airfoil wall surrounding a cavity, the airfoil wall including first wall section comprised of a monolithic ceramic shell, a second wall section comprised of a ceramic matrix composite (CMC) liner bonded along an interface to an interior side of the monolithic ceramic shell, and a ceramic barrier coating bonded to an exterior side of the monolithic ceramic shell, and

the airfoil wall including at least one of: inter-section cooling channels extending along the interface and being bounded by the monolithic ceramic shell and the CMC liner or intra-section cooling channels extending within the CMC liner.

17. The gas turbine engine as recited in claim 16 , wherein the monolithic ceramic shell has a first thermal conductivity and the CMC liner has a second thermal conductivity that is lower than the first thermal conductivity.

18. The gas turbine engine as recited in claim 17 , wherein the airfoil wall includes the inter-section cooling channels, the monolithic shell is comprised of first and second panels bonded along the interface with the CMC liner, the first and second panels meet at a joint, and the inter-section channels open to an exit channel in the joint.

19. The gas turbine engine as recited in claim 17 , wherein the airfoil wall includes the intra-section cooling channels, the CMC liner includes first and second spaced-apart face layers and fibrous ligaments connecting the first and second spaced-apart face layers, the intra-section channels extend between the fibrous ligaments, the monolithic shell is comprised of first and second panels bonded along the interface with the CMC liner, the first and second panels meet at a joint, and the intra-section channels open to an exit channel in the joint.