CMC stepped combustor liner

1. A combustor liner, comprising:

a first portion extending in a substantially axial direction;

a second portion extending in the substantially axial direction, the first portion axially forward of the second portion;

a step connecting the first portion and the second portion, the step arranged at an angle to the second portion that is less than 90° such that the step slants axially forward from the second portion to the first portion, the step having a step height defined as a distance between the first portion and the second portion, wherein and the first portion, second portion, and step are formed as a unitary ceramic component, wherein the step joins to the first portion at a first fillet and joins to the second portion at a second fillet, the first and second fillets arranged on surfaces of the combustor liner configured to face into a combustion chamber;

a first slot extending through the step, and wherein a ratio of a height of the first slot to the step height is greater than 0.66; and

a second slot extending through the step, and wherein a ratio of a width of the first and second slots to a distance between the first and second slots is greater than 0.5.

2. The combustor liner as recited in claim 1 , wherein a ratio of a radius of the second fillet to the step height is between 0.3 and 0.5.

3. The combustor liner as recited in claim 1 , wherein the slot extends substantially tangentially to the second portion.

4. The combustor liner as recited in claim 1 , wherein the slot has a diffuser portion.

5. The combustor liner as recited in claim 1 , wherein at least one hole extends through the second portion.

6. The combustor liner as recited in claim 1 , wherein a third portion is joined to the second portion at a second step.

7. The combustor liner as recited in claim 1 , wherein the first portion has a first length, the second portion has a second length, and the step has a step length, and wherein the first length and the second length are at least twice the step length.

8. The combustor liner as recited in claim 1 , wherein the slot includes an outlet, the outlet including a perimeter with at least one curve.

9. A combustor assembly, comprising:

a combustion chamber having a combustion chamber length between a bulkhead and an outlet;

a liner arranged within the combustion chamber, the liner including:

a first portion and a second portion extending in a substantially axial direction, the first portion axially forward of the second portion, and

a step connecting the first portion and the second portion, the step arranged at an angle to the second portion that is less than 90° such that the step slants axially forward from the second portion to the first portion;

wherein the step joins to the first portion at a first fillet and joins to the second portion at a second fillet, the first and second fillets arranged on surfaces of the liner facing into the combustion chamber;

wherein the first portion, second portion, and step are formed as a unitary ceramic component that extends at least 50% of the combustion chamber length; and

wherein a step height is defined between the first portion and the second portion and a ratio of a radius of the second fillet to the step height is between 0.3 and 0.5.

10. The combustor assembly of claim 9 , wherein the liner is a full hoop panel extending circumferentially about the combustion chamber.

11. The combustor assembly of claim 9 , wherein the liner comprises a plurality of liner panel segments arranged circumferentially about the combustion chamber.

12. The combustor assembly of claim 9 , wherein the liner is arranged within a metallic outer shell.

13. The combustor assembly of claim 12 , wherein the outer shell has a shell step arranged radially outward and axially upstream of the step.

14. The combustor assembly of claim 9 , wherein a slot extends through the step.

15. The combustor assembly of claim 14 , wherein a ratio of a height of the slot to a height of the step is greater than 0.66.

16. A gas turbine engine, comprising:

a combustor section having a plurality of combustor assemblies arranged circumferentially about an engine axis;

at least one of the combustor assemblies having a liner panel arranged within a combustion chamber, the liner panel including:

a first portion and a second portion extending in a substantially axial direction, the first portion axially forward of the second portion, and

a step connecting the first portion and the second portion, the step arranged at an angle to the second portion that is less than 90° such that the step slants axially forward from the second portion to the first portion, the step joining to the first portion at a first fillet and joining to the second portion at a second fillet, the first and second fillets arranged on surfaces of the liner panel facing into the combustion chamber;

wherein a step height is defined between the first portion and the second portion, and a ratio of a radius of the second fillet to the step height is between 0.3 and 0.5; and

wherein the liner panel is a ceramic matrix composite material.

17. The gas turbine engine of claim 16 , wherein a slot extends through the step, and wherein a ratio of a height of the slot to the step height is greater than 0.66.

18. The gas turbine engine of claim 16 , wherein the combustion chamber has an axial length between a bulkhead and an outlet, and the liner panel is formed as a unitary component that extends at least 50% of the combustion chamber length.