Patent Application
20150013342
The present disclosure relates to a fuel injector for gas turbine engines and more particularly to fuel injectors for uniformly mixing air and fuel in gas turbine engines.
In recent years, emission norms for engines have become increasingly stringent. In order to meet the stringent emission norms, engine manufacturers are continually striving to achieve emission levels that may be well below the permissible limits specified in the emission norms. Some commonly known pollutants resulting from combustion of fuels are carbon monoxide (CO), carbon dioxide (CO2), and NOx.
In some cases, the permissible limits for pollutants, given in parts per million (ppm), may be met by varying air-fuel ratios in the engines during operation. Previously known systems accomplished variation to the air-fuel ratios. However, these systems may not evenly distribute the air and fuel to accomplish an uniform mixing pattern of the air and fuel and hence, may produce a heterogeneous air-fuel mixture for use in combustion.
U.S. Pat. No. 8,186,162 relates to a fuel nozzle for a turbine engine. The fuel nozzle has a central body member with a pilot, a surrounding barrel housing, a mixing duct and an air inlet duct. The fuel nozzle additionally has a main fuel injection device located between the air inlet duct and the mixing duct. The main fuel injection device is configured to introduce a flow of fuel into the barrel member to create a fuel/air mixture which is then premixed with a swirler. The fuel/air mixture then further mixes in the mixing duct and exits the nozzle into a combustor for combustion.
In one aspect, the present disclosure discloses a fuel injector for a gas turbine engine. The fuel injector includes a central body, an air inlet duct, a mixing duct, a swirler, and a flow conditioner. The air inlet duct and the mixing duct are positioned around the central body to define an air flow passage. The swirler is positioned between the air inlet duct and the mixing duct. The flow conditioner is disposed in the air flow passage upstream with respect to the swirler. The flow conditioner has a perforated plate configured to uniformly distribute air circumferentially within the air inlet duct.
In another aspect, the present disclosure discloses a gas turbine engine including a combustion chamber, and one or more fuel injectors associated with the combustion chamber. The fuel injectors include a central body, an air inlet duct, a mixing duct, a swirler, and a flow conditioner. The air inlet duct and the mixing duct are positioned around the central body to define an air flow passage. The swirler is positioned between the air inlet duct and the mixing duct. The flow conditioner is disposed in the air flow passage upstream with respect to the swirler. The flow conditioner has a perforated plate configured to uniformly distribute air circumferentially within the air inlet duct.
In another aspect, the present disclosure discloses a method of delivering air-fuel mixture into a combustor chamber of a gas turbine engine. The method includes receiving pilot fuel from pilot fuel injectors into a central body of the fuel injector. The method further includes receiving fuel from vanes on a swirler into a mixing duct of the fuel injector. The method further includes receiving air from an air inlet duct into the mixing duct. The method further includes uniformly distributing the air circumferentially within an air inlet duct of the fuel injector by a perforated plate of a flow conditioner disposed upstream with respect to the swirler. The method further includes mixing fuel with the distributed air in the mixing duct. The method further includes receiving air-fuel mixture from the mixing duct together with the pilot fuel from the central body at the combustion chamber.
Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.
The present disclosure relates to air flow conditioners for fuel injectors used in gas turbine engines. Although, the present disclosure focusses on gas turbine engines, structures, processes, and methods disclosed herein may be similarly applicable to fuel injectors used in other types of engines such as internal combustion engines.
The gas turbine engine 100 may include a compressor section 102, a combustor section 104, a turbine section 106, and an exhaust section 108. The compressor section 102 may include a series of compressor blades 110 fixedly connected about a central shaft 112. The compressor blades 110 may be rotatable to compress air. As the central shaft 112 is rotated, the compressor blades 110 may draw air into the gas turbine engine 100 and pressurize the air. This pressurized air may then be directed towards the combustor section 104. It is contemplated that compressor section 102 may further include compressor blades (not shown) that are separate from central shaft 112 and remain stationary during operation of turbine engine.
The combustor section 104 may mix a liquid and/or gaseous fuel with the compressed air from compressor section 102 and combust the mixture to produce a mechanical work output. The combustor section 104 may include a combustion chamber 114, and one or more fuel injectors 116 associated with the combustion chamber 114. In an embodiment as shown in
The turbine section 106 may include a series of rotatable turbine rotor blades 118 fixedly connected to the central shaft 112. As the turbine rotor blades 118 are bombarded with high-energy molecules from the combustor section 104, the expanding molecules may cause central shaft 112 to rotate, thereby converting combustion energy into useful rotational power. This rotational power may then be drawn from the gas turbine engine 100 and used for a variety of purposes. In addition to powering various external devices, the rotation of the turbine rotor blades 118 and the central shaft 112 may drive the rotation of the compressor blades 110. The exhaust section 108 may direct the exhaust from combustor and turbine sections 104, 106 to the atmosphere.
As illustrated in
In an embodiment as shown in
The mixing duct 122 may be configured to axially direct the fuel/air mixture from fuel injector 116 into the combustion chamber 114. The mixing duct 122 may include a central opening 128 that fluidly communicates the barrel housing 124 with the combustion chamber 114. The fuel injector 116 further includes a central body 130. The central body 130 may be disposed radially inward of the barrel housing 124 and aligned along a common axis 131.
The air inlet duct 120 and the mixing duct 122 are positioned around the central body 130 to define an air flow passage 132 therebetween. The air flow passage 132 is configured to receive compressed air from the compressor section 102. The fuel injector 116 may also include a pilot fuel injector 134 located within the central body 130. The pilot fuel injector 134 may be configured to inject a pilot stream of pressurized fuel through a tip end 136 of the central body 130 into the combustion chamber 114 to facilitate engine starting, idling, cold operation, and/or lean burn operations of the gas turbine engine 100.
The fuel injector 116 further includes a swirler 138 positioned between the air inlet duct 120 and the mixing duct 122. In an embodiment as shown in
In an embodiment as shown in
One or more vanes 140 may include a liquid fuel jet 142 and a plurality of gaseous fuel jets 144 to facilitate fuel injection within the barrel housing 124. It is contemplated that any number or configuration of vanes 140 may include the liquid fuel jets 142. The location of vanes 140 along the common axis 131 and the resulting axial fuel introduction point within the fuel injector 116 may vary depending on specific requirements of an application. The gaseous fuel jets 144 may be associated with the vane to receive gaseous fuel from an external source (not shown).
The fuel injector 116 further includes a flow conditioner 146 disposed in the air flow passage 132 upstream with respect to the swirler 138. In an embodiment as shown in
Further, the flow conditioner 146 has a perforated plate 154 configured to uniformly distribute the air circumferentially within the air inlet duct 120 (referring to
In one embodiment, the perforations 158 may be chosen such that uniform mixing pattern of fuel and air is achieved across the mixing duct 122. However, a shape, size, number and configuration of the perforations 158 may vary based on various factors such as but not limited to a distribution of air required within the air flow passage 132, mixing pattern required in the air-fuel mixture, wake associated with operation of the gas turbine engine 100, or emission requirements to be met by the gas turbine engine 100. Therefore, although a specific number, size, shape and configuration of the perforations 158 are shown on the perforated plate 154 of
Typically, gas turbine engines experience wake that may disrupt a mixing pattern of the air and fuel at a mixing duct of a fuel injector. In some cases, wake occurring in gas turbine engines may further lead to a heterogeneous mixing of air and fuel within the fuel injectors. Use of such heterogeneous air-fuel mixture may increase a possibility of incomplete combustion and promote the production of pollutants. Hence, pollutants may be produced by the gas turbine engine even if the air-fuel ratios are varied to suit one or more operating parameters of the gas turbine engine.
The flow conditioner 146 of the present disclosure may serve to reduce any wake occurring upstream of the flow conditioner 146. The flow conditioner 146 may be formed to include any number of perforations 158 of various sizes, shapes, and configurations such that wake is reduced and a pre-determined mixing pattern of the air-fuel mixture is achieved. With implementation of the flow conditioner 146 disclosed herein, the flow conditioner 146 may present a required amount of restriction and deflection to the air in the air flow passage 132 such that the mixing pattern of the air and fuel is uniform across the mixing duct 122 of the fuel injector 116. The uniform mixing pattern of the air and fuel to form the homogenous air-fuel mixture may entail complete combustion of the air-fuel mixture at the combustion chamber 114. Consequently, the level of emissions from the gas turbine engine 100 may reduce and may be equal to or lesser than the permissible limit determined by the emission requirements for the gas turbine engine 100. Moreover, the openings 152 provided on the cylindrical body 148 may avoid creation of any dead spaces upon installation of the flow conditioner 146 into the fuel injector 116 thus, preventing fuel to inadvertently migrate and combust at the dead spaces.
Prolonged use of the flow conditioner 146 in conjunction with fuel injectors 116 may improve fuel economy of the gas turbine engines 100 and save fuel costs. Therefore, the flow conditioner 146 disclosed herein may increase profitability associated with operation of the gas turbine engine 100.
At step 608, the method 600 further includes uniformly distributing the air circumferentially within the air inlet duct 120 of the fuel injector 116 by the perforated plate 154 of the flow conditioner 146 disposed upstream with respect to the swirler 138. In an embodiment, the step 608 of uniformly distributing the air circumferentially within the air inlet duct 120 further comprises passing the air through the round perforations 158 of the perforated plate 154. In another embodiment, the step of the step 608 of uniformly distributing the air circumferentially within the air inlet duct 120 further comprises passing the air through the curved rectangular perforations 158 of the perforated plate 154.
At step 610, the method 600 further includes mixing the fuel with the distributed air in the mixing duct 122. At step 612, the method 600 further includes receiving the air-fuel mixture from the mixing duct 122 together with the pilot fuel from the central body 130 at the combustion chamber 114.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machine, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
