Patent Description:
Present gas turbine engines use liquid hydrocarbon fuels (LHF). LHF is provided through a fuel supply system and introduced into the combustor by liquid injectors. The fuel supply system and liquid injectors are designed for handling and efficient burning of the LHF. For instance, as liquid is much denser than the air (gas) it is to be mixed with, it is necessary for the liquid injectors to atomize the LHF into tiny droplets in order to facilitate more uniform burning. More recently it has been proposed to utilize hydrogen (H<NUM>) as a fuel.

<CIT> discloses a direct fuel injection system for injecting hydrogen fuel into a gas turbine combustor. The fuel injection system comprises a plurality of fuel injector blocks. Each fuel injector block includes one or more air admission ducts for receiving air from a diffuser and an air outlet for delivering air into a mixing zone for combustion with fuel. Each fuel injector block also includes a fuel admission duct or aperture having a fuel inlet for receiving fuel from a manifold, and a fuel outlet for delivering fuel into the mixing zone.

<CIT> discloses a combustor for a combustion turbine engine which incorporates a fuel and air premixer with locally varied structure of one or more of air ducts, fuel delivery passages, fuel and air mixing ducts, and/or fuel and air discharge ducts. The premixer is a monolithic, three-dimensional lattice structure of selectively oriented, asymmetrical- and serpentine-shaped metallic webs. The web structure defines locally varying passages which form the air ducts and passages.

The present invention relates to a gas turbine engine according to claim <NUM>.

Preferred embodiments of the gas turbine engine according to the invention are set out in the dependent claims.

In this disclosure, like reference numerals designate like elements where appropriate and reference numerals with the addition of one-hundred or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding elements.

The example gas turbine engine <NUM> is a turbofan that generally incorporates a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM>, and a turbine section <NUM>. The fan section <NUM> drives air along a bypass flow path B in a bypass duct defined within a nacelle <NUM>. The turbine engine <NUM> intakes air along a core flow path C into the compressor section <NUM> for compression and communication into the combustor section <NUM>. In the combustor section <NUM>, the compressed air or other combustion gas is mixed with fuel from a fuel system <NUM> and ignited by igniter <NUM> to generate an exhaust gas flow that expands through the turbine section <NUM> and is exhausted through exhaust nozzle <NUM>. Although depicted as a turbofan turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines, such as industrial gas turbine engines and propeller gas turbine engines where, rather than having the propulsor be an enclosed fan, the propulsor is an open propeller.

While present gas turbine engines use liquid hydrocarbon fuels (LHF), the engine <NUM> of the present disclosure is designed to use gaseous fuel, such as hydrogen, in the fuel system <NUM>. The hydrogen referenced in this disclosure is assumed to be in its gaseous phase. In this regard, the fuel system <NUM> may carry liquid cryogenic hydrogen or gaseous hydrogen, both of which are provided to the combustor section <NUM> as gaseous hydrogen. A challenge to using hydrogen is that because it is a gas, its handling and combustion properties differ from that of LHF. For instance, hydrogen does not require atomization like a liquid, and hydrogen has higher flammability and different flame characteristics than LHF. Accordingly, injector nozzles and combustors that are designed for hydrogen are needed. In these regards, the engine <NUM> includes a combustion system <NUM> that is configured for introducing the hydrogen fuel into the combustor section <NUM>.

<FIG> shows a sectioned view of the combustion system <NUM> taken along a radial plane that includes the engine axis A (superimposed). The combustion system <NUM> includes a combustion chamber <NUM> in the combustor section <NUM> for introducing hydrogen and combustion gas (e.g., air in the examples herein). The combustion chamber <NUM> is annularly disposed about the engine axis, i.e., chamber <NUM> is an annulus around the axis A. The combustion chamber <NUM> has first and second axial ends 40a/40b and radially inner and outer walls 40c/40d. Radially "inner" and "outer" as used herein indicate radial proximity to the engine axis A.

There is an injector ring <NUM> disposed about the engine axis A (e.g., co-axial with axis A) at the first axial end 40a that is connected to the fuel system <NUM> (hydrogen source) and the compressor section <NUM> for introducing a hydrogen and air mixture into the combustion chamber <NUM>. As also shown in <FIG>, the injector ring <NUM> includes an injector body <NUM> that defines a hydrogen manifold cavity <NUM> and hydrogen feed conduits <NUM> that extend off of the hydrogen manifold cavity <NUM> and open into a mixing region <NUM> at an axial end of the injector ring <NUM>. In the illustrated example, the hydrogen manifold cavity <NUM> includes an open-cell metallic foam <NUM>. For instance, the open-cell metallic foam <NUM> is formed of an alloy that has low susceptibility to hydrogen embrittlement, such as but not limited to, stainless steel or nickel alloy, and which is corrosion resistant and temperature resistant at the expected operating conditions. The foam <NUM> serves as a flame arrestor, allowing feed flow of hydrogen but facilitating the prevention of flame propagation back (flashback) through the injector ring <NUM>. In general, flashback is prevented when the gas injection speed is higher than the local flame propagation speed.

<FIG> illustrates an axial view of a representative example arc section of the injector ring <NUM>. The injector ring <NUM> includes radially inner and outer annular band sections 42a/42b and a radially intermediate annular band section 42c between the radially inner and outer annular band sections 42a/42b. The hydrogen feed conduits <NUM> are within the intermediate annular band section 42c and are tangentially-sloped with respect to the engine axis A. The term "tangential slope" (or variation thereof) refers to an orientation that (a) forms an oblique angle with the engine axis A and (b) lies in a plane that is (i) non-intersecting with the engine axis A and (ii) is substantially tangent to the circumference at the radial location where the conduit <NUM> opens to the mixing region <NUM>. For instance, a tangential slope is in either a clockwise or counter-clockwise direction with respect to the engine axis A (looking aft). For a passage, the slope is taken with respect to the central axis of the passage at the plane of its exit. A "conduit" as used herein is defined by one or more structures that together convey a fluid from one point to another. For example, a conduit conveying fluid from point A to point B may include one of, or a combination of: a tube, an aperture defined through a part of an engine, a filter, a pump, and so on, depending on the application and context as would be understood by a person of ordinary skill in the art reading the present disclosure.

The radially inner and outer annular band sections 42a/42b include gas (air) feed conduits <NUM> that also open into the mixing region <NUM>. In general, the size (at the passage exits) of all of the hydrogen feed conduits <NUM> are equivalent, and the size (at the conduit exit) of all of the gas feed conduits <NUM> are equivalent, although the sizes may differ between the hydrogen feed conduits <NUM> and the gas feed conduits <NUM>. The gas feed conduits <NUM> are radially and tangentially sloped. The term "radial slope" (or variation thereof) refers to an orientation that has a radial angle component with respect to the engine axis A. For instance, a radial slope is either in a radially inwardly or outwardly direction with respect to the engine axis A (looking aft).

In the illustrated example, the gas feed conduits <NUM> in the radially inner annular band 42a are radially outwardly sloped, and the gas feed conduits <NUM> in the radially outer annular band are radially inwardly sloped. Additionally, the gas feed conduits <NUM> and the hydrogen feed conduits <NUM> are tangentially sloped in a common clockwise or common counter-clockwise direction (<FIG> is clockwise, as the figure view is axial looking forward).

The orientations of the feed conduits <NUM>/<NUM> facilitate good mixing of the hydrogen and air, as well as 3D circulation in the combustion chamber <NUM>. For instance, the tangential slopes of the feed conduits <NUM>/<NUM> swirl the flows of hydrogen and air about the engine axis A. The radial slope of the gas feed conduits <NUM> directs flow of air across the face of the intermediate annular band section 42c, thereby facilitating mixing with the hydrogen and directing the mixture downstream into the combustion chamber <NUM>.

The combustion chamber <NUM> may also include cooling jets <NUM> for introducing additional air for combustion and cooling the walls of the chamber <NUM>, as well as downstream dilution jets <NUM> for further controlling stability and radial flame profile. The dilution jets <NUM> may also be tangentially-sloped for further swirling effect. As an example, the dilution jets <NUM> are tangentially sloped in the opposite direction (clockwise or counter-clockwise) of the tangential slopes of the feed passages <NUM>/<NUM>. Such a configuration facilitates producing a counter-swirl to the bulk of the flow in the combustion chamber <NUM> from the injector ring <NUM>, for more rapid uniform circumferential mixing. For example, the injector ring <NUM> may introduce approximately <NUM>% to <NUM>% of the air for combustion into the combustion chamber <NUM>, and the remainder of the air may be provided by the cooling jets <NUM> and dilution holes <NUM>.

This combustion chamber <NUM> may also work for lean-burn combustion system. For example, approximately <NUM>% to <NUM>% of the combustion air can be introduced through the injector ring <NUM> into the combustion chamber <NUM>. The remainder of the air can be used for the combustor exit temperature profile trimming through dilution or profile trimming jets <NUM>.

<FIG> illustrates an example configuration of the combustion system <NUM> for fuel staging. For instance, the injector ring <NUM> is comprised of arc sections <NUM>/<NUM> that serve, respectively, as pilot sections and main sections. The sections <NUM>/<NUM> circumferentially alternate such that each of the pilot sections <NUM> is circumferentially between two of the main sections <NUM> and each of the main sections <NUM> is circumferentially between two of the pilot sections <NUM>. In these regards, the pilot sections <NUM> each have first arc length (L1) about the axis A, the main sections <NUM> each have a second arc length (L2) about the axis A, and the first arc length L1 is smaller than the second arc length L2. Such a configuration may also facilitate control of power output, widening of the flame stability envelope, and thermoacoustic stability.

The pilot sections <NUM> introduce a first percentage of the hydrogen and air mixture into the combustion chamber <NUM>, and the main sections <NUM> introduce a second percentage of the hydrogen and air mixture into the combustion chamber. In general, the pilot sections <NUM> are used for engine starting, flame stability, and power level controls. In these regards, the percentage of the hydrogen and air mixture provided by the pilot sections <NUM> versus the percentage provided by the main sections <NUM> may be adjusted based on engine performance. The stoichiometric ratios of the hydrogen and air in the mixtures provided by the sections <NUM>/<NUM> may also be adjusted for further control over engine performance. For example, an engine controller may control the percentage and ratios in accordance with a control schedule, such as a lookup table. The fuel system <NUM> may include valves, flow meters, and other known flow control devices that are configured to be operated by the controller in response to the control schedule to control flow of hydrogen and air.

This disclosure may be further understood in view of the following examples. A gas turbine engine <NUM> according to an example of the present disclosure includes an annular combustion chamber <NUM> disposed about an axis A, first and second axial ends 40a/40b, and radially inner and outer walls 40c/40d, and an injector ring <NUM> disposed about the axis A at the first axial end 40a for introducing a hydrogen and gas mixture into the combustion chamber <NUM>.

In a further example of the foregoing example, the injector ring <NUM> includes a hydrogen manifold cavity <NUM> and hydrogen feed conduits <NUM> that extend off of the hydrogen manifold cavity <NUM> and open into a mixing region <NUM> at an axial end of the injector ring <NUM>.

In a further example of any of the foregoing examples, the hydrogen manifold cavity <NUM> includes an open-cell metallic foam <NUM>.

In a further example of any of the foregoing examples, the injector ring <NUM> includes radially inner and outer annular band sections 42a/42b, a radially intermediate annular band section 42c between the radially inner annular band section 42a and the radially outer annular band section 42b, and the hydrogen feed conduits <NUM> are within the intermediate annular band section 42c.

In a further example of any of the foregoing examples, the hydrogen feed conduits <NUM> are tangentially-sloped.

In a further example of any of the foregoing examples, the radially inner and outer annular band sections 42a/42b include gas feed conduits <NUM> that open into the mixing region <NUM>.

In a further example of any of the foregoing examples, the gas feed passages <NUM> are radially and tangentially sloped.

In a further example of any of the foregoing examples, the gas feed passages <NUM> in the radially inner annular band section 42a are radially outwardly sloped, and the gas feed passages <NUM> in the radially outer annular band section 42b are radially inwardly sloped.

In a further example of any of the foregoing examples, the gas feed passages <NUM> and the hydrogen feed passages <NUM> are tangentially sloped in a common clockwise or common counter-clockwise direction.

In a further example of any of the foregoing examples, the injector ring <NUM> includes pilot injector arc sections <NUM> for introducing a first percentage of the hydrogen and gas mixture into the combustion chamber <NUM> and main injector arc segments <NUM> for introducing a second percentage of the hydrogen and gas mixture into the combustion chamber <NUM>.

In a further example of any of the foregoing examples, the pilot injector arc segments <NUM> and the main injector arc segments <NUM> circumferentially alternate such that each of the pilot injector arc segments <NUM> is circumferentially between two of the main injector arc segments <NUM> and each of the main injector arc segments <NUM> is circumferentially between two of the pilot injector arc segments <NUM>.

An example gas turbine engine according to an example of the present disclosure includes a combustor section <NUM> that has a combustion chamber <NUM> disposed about an axis A, first and second axial ends 40a/40b, and radially inner and outer walls 40c/40d, hydrogen source <NUM>, and an injector ring <NUM> disposed about the axis A at the first axial end 40a and configured to introduce a hydrogen and gas mixture into the combustion chamber <NUM>. The injector ring <NUM> includes a hydrogen manifold cavity <NUM> and hydrogen feed passages <NUM> that extend off of the hydrogen manifold cavity <NUM> and open into a mixing region <NUM> at an axial end of the injector ring <NUM>, an open-cell metallic foam <NUM> disposed in the hydrogen manifold cavity <NUM>, radially inner and outer annular band sections 42a/42b, a radially intermediate annular band section 42c between the radially inner annular band section 42a and the radially outer annular band section 42b, the hydrogen feed passages <NUM> being within the intermediate annular band section 42c, and gas feed passages <NUM> in the radially inner and outer annular band sections 42a/42b that open into the mixing region <NUM>.

Claim 1:
A gas turbine engine (<NUM>) comprising:
an annular combustion chamber (<NUM>) disposed about an axis (A) and having first and second axial ends (40a, 40b) and radially inner and outer walls (40c, 40d); and
an injector ring (<NUM>) disposed about the axis (A) at the first axial end (40a) for introducing a hydrogen and gas mixture into the combustion chamber (<NUM>), the injector ring including a hydrogen manifold cavity (<NUM>) and hydrogen feed conduits (<NUM>) that extend off of the hydrogen manifold cavity (<NUM>) and open into a mixing region (<NUM>);
wherein the hydrogen manifold cavity (<NUM>) includes an open-cell metallic foam (<NUM>);
wherein the injector ring (<NUM>) includes radially inner and outer annular band sections (42a, 42b), a radially intermediate annular band section (42c) between the radially inner annular band section (42a) and the radially outer annular band section (42b), and the hydrogen feed conduits (<NUM>) are within the intermediate annular band section (42c); and
wherein the radially inner and outer annular band sections (42a, 42b) include gas feed conduits (<NUM>) that open into the mixing region (<NUM>).