Patent Description:
Dual circuit fuel injectors are currently used in gas turbine engine combustors. The primary circuit is useful at very low flow rates (e.g., during ignition) to add fuel the primary zone. As the fuel flow rate increases, the secondary circuit activates, which can have a larger flow capacity used to fuel more areas of the combustor. However, at intermediate flow conditions, the secondary fuel velocity may be too low to allow the fuel to reach certain zones within the combustor which may cause less than optimal combustion efficiencies or instabilities in the flow.

There is always a need in the art for improvements to fuel nozzles in the aerospace industry. This disclosure provides a solution for this need. <CIT> relates to an oil pre-mixer pre-evaporation combustion chamber head structure and discloses a nozzle according to the preamble of claim <NUM>.

In accordance with the invention, a nozzle for a fuel injector includes, a nozzle body defining a central axis from a nozzle inlet to a nozzle outlet. A first fuel circuit is defined in the nozzle body configured to issue a first fuel flow from a first outlet orifice into a combustor. A second fuel circuit is defined in the nozzle body radially outward from the first fuel circuit configured to issue a second fuel flow from a second outlet orifice at a prefilmer surface of the nozzle body. A third fuel circuit is defined in the nozzle body radially outward from the second fuel circuit configured to issue a third fuel flow from a third outlet orifice at the prefilmer surface of the nozzle body. In embodiments, the first fuel circuit, the second fuel circuit, and the third fuel circuit can all be fluidly isolated from one another within the nozzle body.

The prefilmer surface of the nozzle body is a radially inward facing cylindrical or conical (e.g., converging or diverging) surface of a prefilmer wall radially outward from a fuel circuit portion of the nozzle body where the first, second, and third fuel circuits are defined. A downstream end of the prefilmer defines the nozzle outlet, wherein an air circuit of the nozzle body extends from the nozzle inlet, between the prefilmer wall and fuel circuits portion of the nozzle body, to the nozzle outlet. The second outlet orifice and the third outlet orifice form a common nozzle outlet orifice radially outward of the first outlet orifice.

In certain embodiments, the second outlet orifice can be radially inward and axially upstream of the third outlet orifice. In certain such embodiments, the second outlet orifice can be configured to issue the second fuel flow through the second outlet orifice, then the third outlet orifice. In embodiments, the first outlet orifice can be configured to issue the first fuel flow along a first spray axis, the second outlet orifice can be configured to issue the second fuel flow along a second spray axis, and the third outlet orifice can be configured to issue the third fuel flow along a third spray axis. In certain embodiments, the first spray axis, the second spray axis, and third spray axis can all be parallel. In certain embodiments, the second spray axis and the third spray axis can be coaxial.

In certain embodiments, the second fuel circuit can extend into the third outlet orifice such that the second outlet orifice and the third outlet orifice are concentric. In such embodiments, the first spray axis, the second spray axis, and third spray axis can all be parallel, where no axes are coaxial. In such embodiments, the second fuel circuit and the third fuel circuit can be fluidly isolated within the nozzle body and within the third outlet orifice. In certain embodiments, the third fuel circuit further can further include a swirler upstream of the third outlet orifice configured to swirl the third fuel to produce a hollow cone spray.

In certain embodiments, the second outlet orifice and the third outlet orifice can be positioned adjacent to each other within the common nozzle outlet orifice. In certain such embodiments, the second outlet orifice can be radially inward of the third outlet orifice within the common nozzle outlet orifice relative to the second and third spray axes. In such embodiments, the second and third spray axes can be parallel or the second and third spray axes can diverge, or the second and third spray axes can converge and intersect.

In accordance with another aspect of the invention, a method uses the nozzle according to claim <NUM>, and comprises issuing an atomized first fuel flow into a combustor via a first fuel circuit to light the combustor, issuing a second fuel flow towards a prefilmer surface via a second fuel circuit at a different pressure than the first fuel flow, issuing a third fuel flow to towards a prefilmer surface via a third fuel circuit, and staging off the second fuel flow after during issuing the third fuel flow. In certain embodiments, issuing the first fuel flow, the second fuel flow, and the third fuel flow can occur sequentially. In certain embodiments, the order of issuance of the first, second, and third fuel flows can occur in the order of the first fuel flow, the third fuel flow, then the second fuel flow.

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, an illustrative 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 and/or aspects of this disclosure are shown in <FIG>.

In accordance with at least one aspect of this disclosure, as shown in <FIG>, a system <NUM> can include a fuel injector <NUM> mounted to an engine case <NUM>. A fuel nozzle <NUM> can be mounted to the fuel injector <NUM> to issue a fuel flow into a combustion chamber <NUM> of an engine <NUM>. The fuel nozzle <NUM> includes a nozzle body <NUM> defining a central axis A from a nozzle inlet <NUM> to a nozzle outlet <NUM>. An air swirler <NUM> can be mounted to the nozzle body <NUM> defining at least a portion of an air circuit <NUM> configured to issue an air flow <NUM> from a compressor section <NUM> of the engine <NUM> into the combustion chamber <NUM>.

Referring now to <FIG>, which show enlarged views of embodiments of the fuel nozzle <NUM> according to the invention, a first fuel circuit <NUM> is defined in the nozzle body <NUM> configured to issue a first fuel flow <NUM> from a first outlet orifice <NUM> into the combustor <NUM>. A second fuel circuit <NUM> is defined in the nozzle body <NUM> radially outward from the first fuel circuit <NUM> configured to issue a second fuel flow <NUM> from a second outlet orifice <NUM> at a prefilmer surface <NUM> of the nozzle body <NUM>. A third fuel circuit <NUM> is defined in the nozzle body <NUM> radially outward from the second fuel circuit <NUM> configured to issue a third fuel flow <NUM> from a third outlet orifice <NUM> at the prefilmer surface <NUM>. In certain embodiments, there can be some amount of fluid communication between the second fuel circuit <NUM> and the third fuel circuit <NUM> (e.g., as shown in <FIG>), where the fuel circuits cross paths (as described further below). In certain embodiments (e.g., as shown in <FIG>), the first fuel circuit <NUM>, the second fuel circuit <NUM>, and the third fuel circuit <NUM> can all be fluidly isolated from one another within the nozzle body <NUM>.

As shown in <FIG>, the prefilmer surface <NUM> of the nozzle body <NUM> is a radially inward facing cylindrical or conical (e.g., converging or diverging) surface of a prefilmer wall <NUM> radially outward from a fuel circuit portion <NUM> of the nozzle <NUM> where the first <NUM>, second <NUM>, and third <NUM> fuel circuits are defined. A downstream end <NUM> of the prefilmer defines the nozzle outlet <NUM>. The air circuit <NUM> can extend from the nozzle inlet <NUM>, between the prefilmer wall <NUM> and fuel circuits portion <NUM> of the nozzle body <NUM>, to the nozzle outlet <NUM>. The second outlet orifice and the third outlet orifice form a common nozzle outlet orifice <NUM> radially outward of the first outlet orifice <NUM>. The first outlet orifice <NUM> can be configured to issue the first fuel flow <NUM> along a first spray axis 124A, the second outlet orifice <NUM> can be configured to issue the second fuel flow <NUM> along a second spray axis 130A, and the third outlet orifice <NUM> can be configured to issue the third fuel flow <NUM> along a third spray axis 138A.

With reference now to <FIG> specifically, in certain embodiments, the second outlet orifice <NUM> can be radially inward and axially upstream of the third outlet orifice <NUM>. In certain such embodiments, the second outlet orifice <NUM> can be configured to issue the second fuel flow <NUM> through the second outlet orifice <NUM>, crossing into the third fuel circuit <NUM>, then issue through the third outlet orifice <NUM>, and ultimately out of the nozzle body <NUM> through the common nozzle outlet orifice <NUM>. The second outlet orifice <NUM> can have a smaller diameter than the third outlet orifice <NUM> so that the secondary fuel circuit <NUM> can issue a smaller mass flow of fuel and at a higher pressure than the third fuel circuit <NUM>, penetrating further through the air circuit <NUM> than the first and third fuel flows <NUM>, <NUM>. In embodiments, there may or may not be a fuel flow passing through the second fuel circuit <NUM> and the third fuel circuit <NUM> at the same time. As shown in <FIG>, the first spray axis 124A, the second spray axis 130A, and third spray axis 138A can all be parallel, and the second spray axis 130A and the third spray axis 138A can be coaxial.

With reference now to <FIG>, the second fuel circuit <NUM> can extend into the third outlet orifice <NUM> such that the second outlet orifice <NUM> and the third outlet orifice <NUM> are concentric in forming the common nozzle outlet orifice <NUM>. In such embodiments, the first spray axis 424A, the second spray axis 430A, and third spray axis 438A can all be parallel, but no axes are coaxial. In such embodiments, the second fuel circuit <NUM> and the third fuel circuit <NUM> can be fluidly isolated from one another within the nozzle body <NUM> and within the third outlet orifice <NUM> to limit interaction between the second fuel flow <NUM> and the third fuel flow <NUM> within the nozzle body <NUM>. The diameter of the second outlet orifice <NUM> can be more similar in size to the third outlet orifice <NUM>, for example larger than that of second outlet orifice <NUM> of nozzle body <NUM>, or than in a typical dual fuel circuit nozzle. In certain embodiments, such as shown in <FIG>, the third fuel circuit <NUM> further can further include a swirler <NUM> within or upstream of the third outlet orifice <NUM>, and upstream of the common nozzle outlet orifice <NUM>, configured to swirl the third fuel flow <NUM> to produce a hollow cone spray. In such embodiments, the second 530A and third 538A spray axes may no longer be parallel.

In certain embodiments, as shown in <FIG>, the second outlet orifice <NUM> and the third outlet orifice <NUM> can be positioned adjacent to each other within the common nozzle outlet orifice <NUM>. This arrangement can allow for a smaller diameter third outlet orifice <NUM> to provide high penetration through the air circuit. Further, the arrangement shown in <FIG> allows for cooling of the outer nozzle body via the third outlet orifice <NUM>. In certain such embodiments, the second outlet orifice <NUM> can be radially inward and axially downstream of the third outlet orifice <NUM> within the common nozzle outlet <NUM>, relative to the second and third spray axes 630A, 638A and the central axis A, respectively. In certain embodiments, such as shown in <FIG>, the second and third spray axes 630A, 638A can be parallel. In certain embodiments, such as shown in <FIG>, the second and third spray axes 730A, 738A can diverge. In certain embodiments, such as shown in <FIG>, the second and third spray axes 830A, 838A can converge and intersect.

In accordance with another aspect of the invention, a method includes issuing an atomized first fuel flow (e.g., fuel flow <NUM>) into a combustor (e.g., combustor <NUM>) via a first fuel circuit (e.g., fuel circuit <NUM>) to light the combustor, issuing a second fuel flow (e.g., fuel flow <NUM>) towards a prefilmer surface (e.g., surface <NUM>) via a second fuel circuit (e.g., fuel circuit <NUM>) at a different pressure than the first fuel flow (e.g., a pressure less than or greater than the first pressure based on a given engine power condition), issuing a third fuel flow (e.g., fuel flow <NUM>) to towards the prefilmer surface via a third fuel circuit (e.g.. fuel circuit <NUM>), and staging off the second fuel flow after during issuing the third fuel flow. In certain embodiments, issuing the first fuel flow, the second fuel flow, and the third fuel flow can occur sequentially. In certain embodiments, the order of issuance of the first, second, and third fuel flows can occur in the order of the first fuel flow, the third fuel flow, then the second fuel flow, for example, depending on the size of each circuit and or orifice, the flow need for the given engine condition, or the relative location of the orifices in the nozzle body. For example, in certain engine conditions, the fuel flow can start low, using only a single circuit, then increase flow up to three circuits.

In a traditional dual circuit nozzle, a secondary fuel circuit is included to add additional fuel flow to the primary circuit. For example, during engine startup, the primary fuel circuit can issue the first fuel flow, then when needed, the secondary circuit can issue additional fuel flow. However, in certain instances, the secondary fuel flow may still not provide enough fuel, or may provide too much additional fuel. Embodiments therefore allow for more precise control of fuel flow during all engine conditions, for example when a mass flow is needed that is between the primary flow alone and the primary flow plus the secondary flow.

Any suitable combination(s) of any disclosed embodiments and/or any suitable portion(s) thereof are contemplated herein as appreciated by those having ordinary skill in the art in view of this disclosure.

Claim 1:
A nozzle (<NUM>) for a fuel injector, comprising:
a nozzle body (<NUM>) defining a central axis from a nozzle inlet (<NUM>) to a nozzle outlet (<NUM>);
a first fuel circuit (<NUM>) defined in the nozzle body (<NUM>) configured to issue a first fuel flow from a first outlet orifice (<NUM>) into a combustor;
a second fuel circuit (<NUM>) defined in the nozzle body (<NUM>) radially outward from the first fuel circuit (<NUM>) configured to issue a second fuel flow from a second outlet orifice (<NUM>) at a prefilmer surface of the nozzle body (<NUM>); and
a third fuel circuit (<NUM>) defined in the nozzle body (<NUM>) radially outward from the second fuel circuit (<NUM>) configured to issue a third fuel flow from a third outlet orifice (<NUM>) at the prefilmer surface of the nozzle body (<NUM>);
wherein the prefilmer surface of the nozzle body (<NUM>) is a radially inward facing cylindrical or conical surface of a prefilmer wall (<NUM>) radially outward from a fuel circuit portion of the nozzle body (<NUM>) where the first, second, and third fuel circuits are defined;
wherein a downstream end of the prefilmer surface defines the nozzle outlet (<NUM>), wherein an air circuit of the nozzle body (<NUM>) extends from the nozzle inlet (<NUM>), between the prefilmer wall (<NUM>) and fuel circuits portion of the nozzle body (<NUM>), to the nozzle outlet (<NUM>);
characterized in that
the second outlet orifice (<NUM>) and the third outlet orifice (<NUM>) form a common nozzle outlet (<NUM>) orifice radially outward of the first outlet orifice (<NUM>).