Patent Description:
A small, independent torch igniter system offers many advantages for gas turbine engines. It offers an independent heat source from the main combustor which is used to ignite, stabilize, and relight the main combustor. The isolated nature of this system allows it to be stable regardless of the conditions within the main combustor. A torch ignitor can provide rapid relight capabilities.

The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved systems and methods for improved torch ignitor systems and methods. This disclosure provides a solution for this need.

<CIT> and <CIT> describe torch ignitor systems.

A fuel injector according to the invention is described in claim <NUM>.

The main flow passage can define a main outlet for flame from the torch ignitor. The main outlet for flame can be radially bigger than the fuel outlet with respect to the injection axis. The torch ignitor can include a torch wall defining a combustion chamber therein. The combustion chamber can be connected to outlet flame through the flame outlet passing out of the torch wall and into the main flow passage of the fuel nozzle. A torch fuel injector can be mounted to the torch wall to issue fuel into the combustion chamber. At least one ignitor can be mounted to the torch wall, positioned to ignite fuel issued from the torch fuel injector. The combustion chamber can be connected to the flame outlet by flame tube. The flame tube and flame outlet can be oriented tangential relative to the injection axis to swirl flame from the combustion chamber around the main flow passage of the fuel nozzle.

The fuel nozzle can include an upstream air swirler of the main flow passage, the upstream air swirler defining a plurality of passages configured to impart swirl on a flow of air flowing therethrough. The plurality of passages of the upstream air swirler can be upstream of the flame outlet with respect to the downstream direction along the injection axis. The fuel nozzle can include a heat shield outboard of the nozzle body with an insulation gap defined between the heat shield and the nozzle body. The injection fuel line can pass through the heat shield and nozzle body at an upstream end of the fuel nozzle. The torch ignitor can pass through the heat shield and nozzle body. A downstream air swirler can be defined by a circumferential array of radial passages through the heat shield and nozzle body at a position downstream of the flame outlet with respect to the downstream direction along the injection axis.

The fuel nozzle can include a pressure atomizer in fluid communication with the fuel outlet at an upstream end of the nozzle body. The fuel nozzle can include an air blast atomizer in fluid communication with the fuel outlet in an upstream end of the nozzle body. The injection fuel line can be thermally isolated from the torch ignitor. The nozzle body can be conical and can open in the downstream direction along the injection axis. The nozzle body can be cylindrical. The injection fuel line and torch ignitor define a feed arm that extends perpendicular relative to the injection axis of the fuel nozzle.

A system includes an engine case. A combustor is included within the engine case. A plurality of fuel injectors connect from outside the engine case to the combustor to issue fuel and air into the combustor for combustion. Each of the fuel injectors in the plurality of fuel injectors is as described above, with the fuel nozzle connected to the combustor to issue a spray of fuel from a fuel outlet in a downstream direction along an injection axis.

The fuel injectors of the plurality of fuel injectors can be oriented tangential relative to a main combustor axis of the combustor. The fuel injectors of the plurality of fuel injectors can be oriented radially inward relative to a main combustor axis of the combustor.

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 fuel injector 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 fuel injectors with torch ignitors.

The fuel injector <NUM> includes a fuel nozzle <NUM> configured to issue a spray of fuel from a fuel outlet <NUM> in a downstream direction D along an injection axis A. The fuel nozzle <NUM> includes a nozzle body <NUM> that defines a main flow passage <NUM> therethrough. An injection fuel line <NUM> is in fluid communication with the fuel nozzle <NUM> to supply fuel to the fuel nozzle <NUM>. A torch ignitor <NUM> with a flame outlet <NUM> opens into the main flow passage <NUM> of the fuel nozzle <NUM> for issuing flame into the main flow passage <NUM>. The flame outlet <NUM> meets the main flow passage <NUM> at a position that is downstream of the fuel outlet <NUM> with respect to the downstream direction D along the injection axis A.

With reference now to <FIG>, the main flow passage <NUM> defines a main outlet <NUM> for flame from the torch ignitor. The main outlet <NUM> for flame is radially bigger than the fuel outlet <NUM> with respect to the injection axis A. The torch ignitor <NUM> includes a torch wall <NUM> defining a combustion chamber <NUM> therein. The injection fuel line <NUM> is thermally isolated from the torch ignitor <NUM>, e.g. by being spaced apart therefrom and by the heat shield <NUM> of the fuel tube <NUM>. The heat shield <NUM> around injection fuel line <NUM> provides air gap which insulates the fuel line <NUM> to keep the fuel from getting too hot. The injection fuel line <NUM> and torch ignitor <NUM> define a feed arm that extends perpendicular relative to the injection axis A of the fuel nozzle <NUM>. The combustion chamber <NUM> is connected to outlet flame through the flame outlet <NUM> passing out of the torch wall <NUM> and into the main flow passage <NUM> of the fuel nozzle <NUM>. The combustion chamber <NUM> is connected to the flame outlet <NUM> by a flame tube <NUM>. As shown in <FIG>, the flame tube <NUM> and flame outlet <NUM> can be centered on and aligned with the central axis A, or as indicated in broken lines in <FIG>, they can be oriented tangential (offset as shown in <FIG>) relative to the injection axis A to swirl flame from the combustion chamber <NUM> around the main flow passage <NUM> of the fuel nozzle <NUM>. The tangential orientation can help the flame from the torch <NUM> it to go more with the main air flow path in the main flow passage <NUM> rather than interrupt it.

With reference again to <FIG>, a torch fuel injector <NUM> is mounted to the fitting portion of the torch wall <NUM> to issue fuel into the combustion chamber <NUM>. At least one ignitor <NUM> (not shown in <FIG>, but see <FIG>) is mounted to fixture portion of the torch wall <NUM>, passing through the torch wall <NUM> into the combustion chamber <NUM>, positioned to ignite fuel issued from the torch fuel injector <NUM>.

With reference again to <FIG>, the fuel nozzle <NUM> includes an upstream air swirler <NUM> of the main flow passage <NUM>. The upstream air swirler <NUM> defines a plurality of circumferentially distributed passages <NUM>, labeled in <FIG>, configured to impart swirl on a flow of air flowing therethrough. The plurality of passages <NUM> of the upstream air swirler are upstream of the flame outlet <NUM> with respect to the downstream direction D along the injection axis A. The fuel nozzle <NUM> includes a heat shield <NUM> outboard of the nozzle body <NUM> with an insulation gap <NUM> defined between the heat shield <NUM> and the nozzle body <NUM>. The injection fuel line <NUM> passes through the heat shield <NUM> and nozzle body <NUM> at an upstream end of the fuel nozzle <NUM>. The torch ignitor <NUM> including the flame outlet <NUM> passes through the heat shield <NUM> and nozzle body <NUM>. A downstream air swirler <NUM> is defined by a circumferential array of radial passages <NUM> through the heat shield <NUM> and nozzle body <NUM> at a position downstream of the flame outlet <NUM> with respect to the downstream direction D along the injection axis A.

The fuel nozzle <NUM> is allowed to grow (under thermal expansion/contraction) at different rates than heat shield <NUM>, which is not fixed at both ends to prevent breaking due to differential thermal expansion). The dome or backside surfaces can be back side cooled, e.g. by flow through the gap <NUM>, similarly to the cooling in the torch wall <NUM> to prevent heat from oxidizing the material.

The fuel nozzle <NUM> includes a pressure atomizer <NUM> in the outlet end of the fuel line <NUM> in fluid communication with the fuel outlet <NUM> at an upstream end of the nozzle body <NUM>. However, as shown in <FIG>, it is also contemplated that the fuel nozzle <NUM> can instead include an air blast atomizer <NUM> in fluid communication with the fuel outlet <NUM> in the upstream end of the nozzle body <NUM>. The nozzle body <NUM> as shown in <FIG> is conical and opens in the downstream direction D along the injection axis A. However, it is also contemplated that any suitable nozzle body shape can be used, such as the cylindrical nozzle body <NUM> in <FIG>.

With reference now to <FIG>, a system <NUM> includes an engine case <NUM>, e.g. of a gas turbine engine, with a combustor <NUM> included within the engine case <NUM>. A plurality of fuel injectors <NUM> as described above connect from outside the engine case <NUM> to the upstream combustor dome wall <NUM> of the combustor <NUM> to issue fuel and air into the combustor <NUM> for combustion. Each of the fuel injectors <NUM> has its respective fuel nozzle <NUM> operatively connected (or associated even if it is not a hard connection) to the combustor <NUM> to issue a spray of fuel from the fuel outlet <NUM> (labeled in <FIG>) in a downstream direction along the injection axis A (labeled in <FIG>). While the fuel injectors <NUM> are shown oriented axially with the injection axes A aligned with the main axis M (which is schematically indicated in <FIG>) of the combustor <NUM> and engine case <NUM>, it is also contemplated that the fuel injectors <NUM> can be oriented tangential relative to the main combustor M axis of the combustor <NUM>, as shown schematically in the plan view of in <FIG>. This can allow for inducing swirl around the annular volume of the combustor <NUM>. It is also contemplated as shown schematically in <FIG> (which is viewed from the same cross-sectional view as in <FIG>), that the injection axes A of the fuel injectors <NUM> can be oriented radially inward or outward relative to a main combustor axis M of the combustor <NUM>.

In a gas turbine engine, replacement of one or more traditional fuel injectors with a continuous ignition device as disclosed herein allows complete control of each individual injection. This permits a large degree of fuel staging while still maintaining stability since each injection/torch system is independently controlled and isolated from disruptions of neighboring systems.

Potential benefits include the following. Systems and methods as disclosed herein can allow extensive turndown (one torch device can remain stable while all others are turned off, for example. They can allow extensive redundancy, e.g. even if one or more torch devices fail through some failure modes, others can be adjusted to compensate until replacement can occur. Light-around problems can be reduced or eliminated. Systems and methods as disclosed herein can greatly improve altitude relight as multiple systems can be simultaneously ignited. There can be a reduction in the probability of altitude flameout. Individual injector/torch control can be used to break acoustic issues. Further devices can be employed in the main combustor to allow for adequate temperature uniformity and combustion efficiency such as air swirlers surrounding the torches, dilution jets, and combustion liner cooling features. Torches can be aimed to maximize performance. For example, the elbow between the torch ignitor <NUM> and the fuel nozzle <NUM> can be given a partially tangential direction to improve main combustor mixing, as indicated in <FIG>, and can even have a tilt to the left or right as oriented as in <FIG> to suit given applications. Torches can be oriented for convenient locations and also to improve/maximize performance. Health monitoring can be setup for each fuel injector to provide feedback to monitor and improve overall health. For example, thermocouples can be used as sensors for detecting flames and temperatures of each torch device. This can be coupled with individual control valves to increase/decrease the fuel flow to an individual device if its performance needs adjusted. Power through the ignitors <NUM>, e.g. glow plugs, can be turned on if the device is not lit.

Claim 1:
A fuel injector (<NUM>) for a gas turbine engine comprising:
a fuel nozzle (<NUM>) configured to issue a spray of fuel from a fuel outlet (<NUM>) in a downstream direction along an injection axis, the fuel nozzle including a nozzle body (<NUM>) that defines a main flow passage (<NUM>) therethrough;
an injection fuel line (<NUM>) in fluid communication with the fuel nozzle (<NUM>) to supply fuel to the fuel nozzle; and
a torch ignitor (<NUM>) with a flame outlet (<NUM>) opening into the main flow passage (<NUM>) of the fuel nozzle (<NUM>) for issuing flame into the main flow passage, wherein the flame outlet (<NUM>) meets the main flow passage (<NUM>) at a position that is downstream of the fuel outlet (<NUM>) with respect to the downstream direction along the injection axis;
characterized in that the injection fuel line (<NUM>) and torch ignitor (<NUM>) define a feed arm that extends perpendicular relative to the injection axis of the fuel nozzle (<NUM>).