Patent Description:
Multipoint fuel injection systems would benefit from a simple, low cost fuel injector and manifold construction to permit a large number of injectors to be used. Traditional fuel injector and nozzle designs require complex manifolding that can impede air flow from a compressor to the combustor in a gas turbine engine. Advanced engines require thermal protection to prevent fuel from reaching a temperature where it can break down and grow internal carbon buildup. The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved systems and methods for combustion systems. This disclosure provides a solution for this need. <CIT> relates to heat shielding for internal fuel manifolds, <CIT> relates to fuel injectors for multipoint arrays, <CIT> relates to methods and apparatus for decreasing combustor emissions with spray bar assembly, <CIT> relates to a heat shield for a fuel manifold, and <CIT> relates to additive manufacturing structure for heat insulation cover.

A fuel injection system is defined in claim <NUM> and includes an outer support defining a fuel manifold and an inner support, with a feed arm extending radially between the inner support and the outer support. A plurality of outlet openings extending in an axial direction from the feed arm for feeding respective injection nozzles. The feed arm defines a plurality of fuel passages therethrough in fluid communication with the fuel manifold and outlet openings to supply fuel from the fuel manifold to the outlet openings. A heat shield extends from the outer support to the inner support and extends about the outer support and the feed arm to provide heat shielding to the fuel manifold and the fuel passages.

The feed arm and a portion of the heat shield adjacent to the feed arm follow a vaulted angle. The feed arm and the portion of the heat shield adjacent to the feed arm define at least one vaulted peak pointed in an axial direction opposite that of the outlet openings.

An insulative gap can be defined between the heat shield and both of the outer support and the feed arm. The heat shield can include openings therethrough for connection of injection nozzles to the outlet openings. The heat shield can be solely supported by flexure structures that connect the heat shield to the inner and outer supports. Each flexure structure can define a plurality of holes through the heat shield into the insulative gap. Each flexure structure can define a curved cross-sectional shape in radial cross-section. The fuel passages in the feed arm can define a plurality of vaulted chambers.

A multipoint fuel injection system is defined in claim <NUM> and includes a circumferentially extending outer support defining a fuel manifold, a circumferentially extending inner support, and a plurality of circumferentially spaced apart feed arms extending radially between the inner support and the outer support. A plurality of outlet openings extend in an axial direction from each feed arm for feeding respective injection nozzles. The feed arm defines a plurality of fuel passages therethrough in fluid communication with the fuel manifold and outlet openings to supply fuel from the fuel manifold to the outlet openings. A single heat shield extends from the outer support to the inner support and extends about the outer support and the feed arms to provide heat shielding to the fuel manifold and the fuel passages.

The outer support can define manifold passages in fluid communication with the fuel passages, wherein the manifold passages extend through the outer support in a circumferential direction. The manifold passages can have axially oriented vaulted surfaces. A radially inner portion of each feed arm can define weight reduction voids therein. Circumferential portions of the heat shield can extend circumferentially from feed arm portions of the heat shield.

A combustor dome can define a combustion space with an inner combustor wall and an outer combustor wall, wherein the combustor dome, inner combustor wall, and outer combustor wall are positioned to provide heat shielding to the inner and outer supports on a combustor side thereof.

A method of making a fuel injector system is defined in claim <NUM> and includes additively manufacturing a circumferentially extending outer support together with a circumferentially extending inner support, a feed arm extending radially between the inner support and the outer support, and a heat shield extending from the outer support to the inner support and extending about the outer support and the feed arm, wherein the heat shield is spaced apart from the feed arm with an insulative gap. Additively manufacturing includes building in an axial build direction beginning from downstream portions of the inner and outer supports.

Additively manufacturing includes forming the feed arm and a portion of the heat shield adjacent the feed arm by additively growing the feed arm and heat shield in the axial build direction, wherein the feed arm and portion of the heat shield adjacent to the feed arm are self-supporting as they are grown and are grown to define a vaulted angle relative to the axial build direction. Additively manufacturing can include forming vaulted weight reduction voids within the feed arm. Additively manufacturing can include forming vaulted fuel manifold passages in the outer support.

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an embodiment of a system in accordance with the disclosure is shown in <FIG> and is designated generally by reference character <NUM>. Other embodiments of systems in accordance with the disclosure, or aspects thereof, are provided in <FIG>, as will be described. The systems and methods described herein can be used to provide heat shielding, e.g. in internally manifolded multipoint fuel injection systems such as in gas turbine engines.

A multipoint fuel injection system <NUM> includes a circumferentially extending outer support <NUM> defining a fuel manifold, a circumferentially extending inner support <NUM>, and a plurality of circumferentially spaced apart feed arms <NUM> extending radially between the inner support <NUM> and the outer support <NUM>. Only one feed arm <NUM> is visible in <FIG>, but in the view shown in <FIG>, the plurality of feed arms <NUM> is shown. A plurality of outlet openings <NUM> (labeled in <FIG>) extend in an axial direction A (identified in <FIG>) from each feed arm <NUM> for feeding respective injection nozzles <NUM>.

With reference now to <FIG>, a combustor dome <NUM> defines a combustion space <NUM> with an inner combustor wall <NUM> and an outer combustor wall <NUM>. The combustor dome <NUM>, inner combustor wall <NUM>, and outer combustor wall <NUM> are positioned to provide heat shielding to the inner and outer supports <NUM>, <NUM> on a combustor side thereof. An outer lock ring <NUM> is positioned radially outboard of the outer support <NUM> to mount the combustor dome <NUM>, the outer support <NUM>, and the outer combustor wall <NUM> together. An inner lock ring <NUM> is positioned radially inboard of the inner support <NUM> to mount the combustor dome <NUM>, the inner support <NUM>, and the inner combustor wall <NUM> together.

With reference again to <FIG>, the inner and outer lock rings <NUM>, <NUM> are mounted to an engine case that includes a compressor section <NUM> upstream of a combustor section <NUM> thereof that is upstream of a turbine section <NUM> thereof. Compressed air from the compressor section <NUM> enters the combustor section <NUM> through the compressor exit and diffusor <NUM>, passes through the injection nozzles <NUM> into the combustion space <NUM> as it is mixed with fuel, is combusted in the combustion space <NUM>, and the combustion products pass through the turbine vanes <NUM> into the turbine section <NUM> where the power is extracted from the combustion products.

With reference now to <FIG>, the feed arm <NUM> defines a plurality of fuel passages <NUM> therethrough in fluid communication with the fuel manifold in the outer support <NUM>, and in fluid communication with the outlet openings <NUM> to supply fuel from manifold passages <NUM> of the fuel manifold to the outlet openings <NUM>. The manifold passages <NUM> extend through the outer support <NUM> in a circumferential direction. Each of the fuel passages <NUM> includes a portion <NUM> that leads from the main portion of the feed arm <NUM> to the respective outlet <NUM>, as shown in <FIG> for two of the outlets <NUM>. The manifold passages <NUM> and the fuel passages <NUM> have vaulted surfaces that are all axially oriented upward in the same axial direction A.

With continued reference to <FIG>, a single heat shield <NUM> extends from the outer support <NUM> to the inner support <NUM> (shown in <FIG>). The heat shield <NUM> extends about the outer support <NUM> and the feed arms <NUM> to provide heat shielding to the fuel manifold passages <NUM> and the fuel passages <NUM>. This one heat shield <NUM> shields the outer support <NUM> and multiple feed arms <NUM>. A single contiguous insulative gap <NUM> is defined between the heat shield <NUM> (which is on the outside of the insulative gap <NUM>) and both of the outer support <NUM> and the feed arm <NUM> (which are on the inside of the insulative gap <NUM>), so there is nothing separating the portion of the insulative gap <NUM> shielding the outer support <NUM> from fluid communication with the portion of the insulative gap <NUM> shielding the feed arms <NUM>. For the portion of the gap <NUM> adjacent the feed arm <NUM> as shown in <FIG>, the gap is substantially constant all around the feed arm <NUM>. The heat shield <NUM> includes openings <NUM> (also labeled in <FIG> and <FIG>) therethrough for connection of injection nozzles <NUM> (labeled in <FIG> and <FIG>) to the outlet openings <NUM>. The heat shield can be solely supported by flexure structures <NUM> that connect the heat shield to the inner and outer supports <NUM>, <NUM>. The flexure structures <NUM> are separated from one another by holes <NUM>, which breathe outward from the insulation gap <NUM>. Given that the air in the insulation gap is stagnant, the holes <NUM> do not undermine the heat shielding, but do allow for pressure equalization of the gap <NUM>. Each flexure structure <NUM> can define a curved cross-sectional shape in radial cross-section as shown in <FIG>.

With reference now to <FIG>, the feed arm <NUM> and a portion <NUM> of the heat shield <NUM> adjacent to the feed arm <NUM> follow a vaulted angle θ on either side of a single peak <NUM>. A radially inner portion <NUM> of each feed arm <NUM> defines weight reduction voids <NUM> therein, which can have the same vaulted flow cross-section as shown in <FIG> for the fuel passages <NUM>. The fuel passages <NUM> and voids in the feed arm define respective vaulted chambers (the cross-sections for which are shown in <FIG>). Each respective fuel passage <NUM> is separated from fluid communication with its respective void <NUM> by a respective wall <NUM>, which is provided in each fuel passage <NUM> just downstream of where the branch <NUM> (labeled in <FIG>) diverts towards the respective outlet <NUM>. Each of the voids <NUM> vents through a respective opening <NUM> on the inner surface of the inner support <NUM>. Circumferential portions <NUM> of the heat shield <NUM> extend circumferentially from feed arm portions <NUM> of the heat shield.

The vaulting of the fuel passages <NUM> and voids <NUM>, the manifold passages <NUM>, the holes <NUM>, and the feed arm <NUM> and feed arm portion <NUM> of the heat shield <NUM> in the same axial direction A facilitate additively manufacturing. The circumferentially extending outer support <NUM> together with the circumferentially extending inner support <NUM> and the feed arm <NUM> and heat shield <NUM> can be grown or printed as a single build starting from the downstream portions of the inner and outer supports <NUM>, <NUM> (or the bottom as oriented in <FIG>), and building upward using a build direction aligned with the axial direction A. The vaulting angle θ can be the same or different for the various vaulted surfaces, as long as no vaulted surfaces have a vaulting angle θ that exceeds the maximum of the additive manufacturing process being used. This allows forming the feed arm <NUM> and a portion <NUM> of the heat shield <NUM> adjacent the feed arm <NUM> by additively growing the feed arm <NUM> and heat shield <NUM> while the feed arm <NUM> and portion <NUM> of the heat shield <NUM> adjacent to the feed arm <NUM> are self-supporting as they are grown. This reduces or eliminates the amount of support structure that must be additively manufactured into the build.

With reference now to <FIG>, the feed arm <NUM> described above has a single peak <NUM>, labeled in <FIG>, however it is contemplated that any suitable number of peaks can be included. Feed arm <NUM> is vaulted along a profile in the axial direction A that includes two peaks <NUM>, with a valley <NUM> therebetween (e.g., an "M" shape), where the peaks <NUM> extend in the opposite direction from the outlet openings <NUM>. While not depicted in <FIG>, those skilled in the art will readily appreciate that a heat shield conforming to the profile of the feed arm <NUM> can be included, similar to the heat shield <NUM> described above. The numerals <NUM>, <NUM>, <NUM>, and <NUM> in <FIG> indicate respective fuel channels through the manifold of the outer support <NUM>, feed arm <NUM>, and outlets <NUM>, respectively. Those skilled in the art will readily appreciate that feed arms <NUM> and <NUM> can be aerodynamically contoured to help shape flow from the compressor section <NUM> into the combustor section <NUM> (as labeled in <FIG>).

Claim 1:
A fuel injection system comprising:
an outer support (<NUM>) defining a fuel manifold;
an inner support (<NUM>), with a feed arm (<NUM>) extending radially between the inner support and the outer support;
a plurality of outlet openings (<NUM>) extending in an axial direction from the feed arm (<NUM>) for feeding respective injection nozzles, wherein the feed arm defines a plurality of fuel passages therethrough in fluid communication with the fuel manifold and outlet openings to supply fuel from the fuel manifold to the outlet openings; and characterized in that the fuel injection system further comprises:
a heat shield (<NUM>) extending from the outer support to the inner support and extending about the outer support and the feed arm to provide heat shielding to the fuel manifold and the fuel passages; and
wherein the feed arm (<NUM>) and a portion of the heat shield (<NUM>) adjacent to the feed arm (<NUM>) follow a vaulted angle on either side of a peak, and the feed arm (<NUM>) and the portion of the heat shield (<NUM>) adjacent to the feed arm define at least one vaulted peak pointed in an axial direction opposite that of the outlet openings (<NUM>).