Combustor including a heat shield for a turbine engine
A combustor of a turbine engine combusts fuel and air. The combustor includes a dome and a heat shield fastened to the dome. The heat shield is unconstrained relative to dome, to permit relative thermal expansion and contraction in a radial direction. A heat shield inner portion is generally annular in shape, is arranged about a dome eyelet longitudinal centerline axis, is smaller in diameter than a dome inner portion, and is assembled inside of the dome inner portion. A plurality of pinned assemblies fastens the heat shield to dome. Each pinned assembly includes a fastener with a pin end, the pin end assembled in a clearance fit into a hole in the heat shield inner portion. The fastener is fixed to the dome inner portion, the pin end sliding in the hole in the heat shield during relative thermal expansion and contraction between the dome and the heat shield.
1. A combustor of a turbine engine, the combustor comprising:
a fuel nozzle-mixer assembly disposed at a forward end of the combustor for receiving and mixing fuel and air, and injecting the fuel and the air into a combustion chamber for combustion;
at least one dome defining a longitudinal centerline axis, the at least one dome comprising a dome inner portion that is generally annular in shape, arranged about the longitudinal centerline axis and a generally planar dome face portion;
at least one heat shield fastened to the at least one dome, unconstrained relative to the at least one dome, to permit relative thermal expansion and contraction in a radial direction with respect to the longitudinal centerline axis, a heat shield of the at least one heat shield comprising:
a heat shield inner portion that is (i) generally annular in shape, (ii) arranged about the longitudinal centerline axis, (iii) smaller in diameter than the dome inner portion, and (iv) assembled inside of the dome inner portion; and
a heat shield face portion, thermally protecting the dome face portion from heat from the combustion;
a plurality of pinned assemblies arrayed circumferentially about the longitudinal centerline axis, and fastening the at least one heat shield to the at least one dome, the plurality of pinned assemblies comprising a fastener with a pin end that is assembled in a clearance fit into a hole in the heat shield inner portion, the fastener fixed to the dome inner portion, the pin end sliding in the hole during relative thermal expansion and contraction between the at least one dome and the at least one heat shield; and
a seal arranged circumferentially about the longitudinal centerline axis, forward of the plurality of pinned assemblies, between the dome inner portion and the heat shield inner portion, for maintaining concentricity of the heat shield inner portion relative to the dome inner portion.
2. The combustor of claim 1 , wherein the dome inner portion comprises a groove, and the seal is installed in the groove.
3. The combustor of claim 1 , wherein the fastener is fixed to the at least one dome by fastener threads and corresponding dome threads.
4. The combustor of claim 1 , wherein the heat shield is assembled to the at least one dome without melting and subsequent solidification of material.
5. The combustor of claim 1 , wherein the seal is a brush seal comprising a brush seal housing and a brush, the brush contacting the heat shield inner portion, and the brush having a plurality of strand-like members.
6. The combustor of claim 5 , wherein, the brush is made of a metal, a polymer, a plastic, or a composite.
7. The combustor of claim 1 , wherein the seal is a C-seal.
8. The combustor of claim 7 , wherein the C-seal comprises an opening facing forward.
9. The combustor of claim 1 , further comprising a bushing fixed in the hole, permitting relative motion between the pin end and the bushing.
10. The combustor of claim 9 , wherein the bushing is press fit into the hole, threaded into the hole, or joined to the hole with an adhesive.
11. The combustor of claim 1 , wherein the seal is a piston seal comprising an inner ring and an outer ring, the inner ring contacting the heat shield inner portion and the outer ring contacting the dome inner portion.
12. The combustor of claim 11 , wherein the inner ring, the outer ring, or both the inner ring and the outer ring are made of a cobalt alloy.
13. The combustor of claim 11 , wherein the inner ring, the outer ring, or both the inner ring and the outer ring are chrome plated.
14. The combustor of claim 1 , wherein the seal is a first seal, the at least one dome defines a cavity, and the combustor further comprises:
a second seal disposed between the at least one dome and the heat shield; and
a cooling air flow gap, defined by the first seal, the second seal, the at least one dome, and the heat shield,
wherein the cavity is at a relative high pressure, the combustion chamber is at a relative low pressure, and the cooling air flow gap is at a relative intermediate pressure less than that of the cavity, but greater than that of the combustion chamber.
15. The combustor of claim 14 , wherein the first seal limits the compressed air flowing from the cavity to the cooling air flow gap, maintaining the relative high pressure in the cavity and the relative intermediate pressure in the cooling air flow gap.
16. The combustor of claim 15 , wherein the second seal limits the compressed air flowing from the cooling air flow gap to the combustion chamber, maintaining the relative intermediate pressure in the cooling air flow gap and the relative low pressure in the combustion chamber.
17. A turbine engine comprising:
a compressor section that provides a compressed air flow;
a fuel system that provides a fuel supply;
a combustor located downstream of the compressor section, the combustor receiving the compressed air flow and the fuel supply, for combusting the compressed air flow and the fuel supply to generate combustion gases, the combustor comprising:
a fuel nozzle-mixer assembly disposed at a forward end of the combustor for receiving and mixing fuel and air, and injecting the fuel and the air into a combustion chamber for combustion;
at least one dome defining a longitudinal centerline axis, the at least one dome comprising a dome inner portion that is generally annular in shape, arranged about the longitudinal centerline axis, and a generally planar dome face portion; and
at least one heat shield fastened to the at least one dome, unconstrained relative to the at least one dome, to permit relative thermal expansion and contraction in a radial direction with respect to the longitudinal centerline axis, a heat shield of the at least one heat shield comprising:
a heat shield inner portion that is (i) generally annular in shape, (ii) arranged about the longitudinal centerline axis, (iii) smaller in diameter than the dome inner portion, and (iv) assembled inside of the dome inner portion; and
a heat shield face portion, thermally protecting the dome face portion from heat from the combustion;
a plurality of pinned assemblies arrayed circumferentially about the longitudinal centerline axis, and fastening the at least one heat shield to the at least one dome, the plurality of pinned assemblies comprising a fastener with a pin end that is assembled in a clearance fit into a hole in the heat shield inner portion, the fastener fixed to the dome inner portion, the pin end sliding in the hole during relative thermal expansion and contraction between the at least one dome and the at least one heat shield;
a seal arranged circumferentially about the longitudinal centerline axis, forward of the plurality of pinned assemblies, between the dome inner portion and the heat shield inner portion, for maintaining concentricity of the heat shield inner portion relative to the dome inner portion; and
a turbine section located downstream of the combustor, the turbine section comprising a turbine that is caused to rotate by the combustion gases.
18. The turbine engine of claim 17 , wherein the seal is a first seal, the at least one dome defines a cavity, and the combustor further comprises:
a second seal disposed between the at least one dome and the heat shield; and
a cooling air flow gap, defined by the seal, the second seal, the at least one dome and the heat shield, wherein the cavity is at a relative high pressure, the combustion chamber is at a relative low pressure, and the cooling air flow gap is at a relative intermediate pressure less than that of the cavity, but greater than that of the combustion chamber.
19. The turbine engine of claim 18 , wherein the first seal limits the compressed air flowing from the cavity to the cooling air flow gap, maintaining the relative high pressure in the cavity and the relative intermediate pressure in the cooling air flow gap.
20. The turbine engine of claim 19 , wherein the second seal limits the compressed air flowing from the cooling air flow gap to the combustion chamber, maintaining the relative intermediate pressure in the cooling air flow gap and the relative low pressure in the combustion chamber.