Patent Application
20080184707
The present invention generally relates to fuel manifolds for combustion systems, and more particularly relates to fuel manifolds for manifold-fed slinger gas turbine combustors with a fuel drip guide.
Combustion systems in gas turbine engines typically ignite and combust an air/fuel mixture to drive a turbine. The combustion system can include a fuel manifold that supplies a stream of fuel to a rotary fuel slinger that atomizes the fuel. The atomized fuel is then mixed with air in the combustion chamber and ignited by an igniter. The efficiency of atomization impacts the efficiency of the combustion system and the engine overall. Typically, the exit orifices of the fuel manifold are sized to maintain distinct, cleanly separated fuel jets to the rotary fuel slinger, even at low fuel flow rates such as those that might occur during ignition. Given the wide turn-down ratio of modern gas turbine engines, however, the sizing of the fuel manifold orifices for ignition may result in a relatively high pressure differential under maximum power conditions. This can result in the need for a more expensive high-pressure fuel delivery system, and may also result in the tendency for the high-velocity fuel jets to break-up and splatter, either before or upon making contact with the slinger. Without the high-pressure fuel delivery system, low flow conditions can result in the fuel dribbling out of the fuel manifold and not reaching the slinger. Either condition can adversely impact the effectiveness of the slinger and result in fuel contamination in the area surrounding the fuel manifold.
Accordingly, it is desirable to provide an improved combustion system. In addition, it is desirable to provide a fuel manifold for a combustion system that can provide fuel to the slinger to be atomized during any operating condition and without a high-pressure fuel delivery system. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
A combustion system can include a fuel manifold adapted to receive a flow of fuel from a fuel source. The fuel manifold can include at least one exit orifice from which the received fuel is discharged. The system can further include a rotary fuel slinger disposed adjacent to, and adapted to receive the flow of fuel from, the fuel manifold and to atomize the received fuel, and a combustor including at least a forward radial liner and an aft radial liner spaced apart from one another to form a combustion chamber therebetween that receives the atomized fuel from the rotary fuel slinger. The forward and aft radial liners can each include a plurality of openings for receiving compressed air into the combustion chamber to mix with the atomized fuel. The system can further include an igniter extending at least partially into the combustion chamber and configured to ignite the atomized fuel and the compressed air mixture; and a fuel drip guide disposed adjacent the fuel manifold exit orifice.
A fuel manifold is provided for receiving a flow of fuel from a fuel source and delivering the flow of fuel to a rotary fuel slinger. The fuel manifold can include a housing having an end face and defining a cavity for receiving the flow of fuel; at least one exit orifice formed in the housing end face and in fluid communication with the cavity; and a fuel drip guide extending from the end face.
A method is provided for delivering a flow of fuel to a rotary fuel slinger from a fuel manifold having at least one exit orifice and a fuel drip guide. The method includes, during normal operating conditions, providing the flow of fuel directly from the at least one exit orifice to the rotary fuel slinger; and during low flow operating conditions, directing the flow of fuel from the at least one exit orifice to the rotary fuel slinger via the fuel drip guide.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and
The following detailed description of the invention is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description of the invention.
The combustion system 100 includes a combustor 106, a fuel supply tube 108, a rotary fuel slinger 110, and an igniter 112. The combustor 106 can be a radial-annular combustor, and include a forward annular liner 114, and an aft annular liner 116. The forward and aft annular liners 114, 116 are spaced apart from one another and form a combustion chamber 118. The forward and aft annular liners 114, 116 each include a plurality of air inlet orifices 120, and a plurality of effusion cooling holes (not shown). As noted above, compressed air 102 from the compressor flows into the combustion chamber 118 via the air inlet orifices 120 in both the forward and aft annular liners 114, 116. The air inlet orifices 120 can be configured to generate a single toroidal recirculation flow pattern 122 in the combustion chamber 118.
The fuel supply tube 108 extends into a plenum 124 just forward of the combustor 106 and is adapted to receive a flow of fuel from the fuel source, for example, via diffuser vanes (not shown). The fuel supplied to the fuel supply tube 108 passes through the tube 108, and is directed into a fuel manifold 126. In the depicted embodiment, the fuel manifold 126 has a housing defining a circumferential cavity, although it will be appreciated that other configurations could also be used. The fuel manifold 126 includes an end face with a plurality of equally spaced orifices 128 formed therein, through which the fuel is delivered to the rotary fuel slinger 110. In an exemplary embodiment, the fuel supply tube 108 only supplies liquid fuel to the fuel manifold 126.
The rotary fuel slinger 110, which is shown more clearly in
The slinger 136 is coupled to, and can be formed as an integral part of, the vertical shoulder 134 and thus also rotates with the coupler shaft 132. In the depicted embodiment, the slinger 136 has a substantially cup-shaped radial cross section, and includes a plurality of relatively small, equally spaced holes or slots 138. As the slinger 136 rotates, fuel is centrifuged through these holes 138 and atomized into tiny droplets to distribute the fuel into the combustion chamber 118. The distributed fuel droplets are readily evaporated and ignited in the combustion chamber 118.
During most operating conditions, the fuel separates from the fuel manifold 126 at the orifices 128 and streams directly onto the rotary fuel slinger 110, as shown in
In an exemplary embodiment, the fuel drip guide 140 is only utilized during low flow conditions, for example, during ignition. In the absence of the fuel drip guide 140, fuel can adhere to the side and bottom portions of the fuel manifold 126. This can result in the fuel not reaching the rotary fuel slinger 110 and not being atomized, which in turn results in the un-atomized fuel contaminating portions of the combustor system and reducing the efficiency and performance of the engine, particularly at ignition.
The fuel drip guide 140 provides a mechanism for ensuring a controlled fuel delivery from the fuel manifold 126 to the rotary fuel slinger 110, particularly at low fuel flow rates associated with ignition conditions. Particularly, the fuel drip guide 140 can provide fuel delivery to the fuel manifold 126 when the fuel flow rates are such that the pressure differential across the fuel manifold 126 is insufficient for the fuel to separate from the fuel manifold 126, for example at less that 0.5 psid. Even at high flow or normal operating conditions, the fuel drip guide 140 can direct any fuel that is splattered out of the fuel jet as a result of sputtering. One embodiment of the present invention can extend the effective turn-down ratio of the combustion system 100 without requiring a high-pressure fuel delivery system. The combustion system 100 can be utilized in, for example, an auxiliary power unit or a propulsion gas turbine engine.
The igniter 112 extends through the aft annular liner 116 and partially into the combustion chamber 118. The igniter 112, which may be any one of numerous types of igniters, is adapted to receive energy from an exciter (not shown) in response to the exciter receiving an ignition command from an external source, such as an engine controller (not shown). In response to the ignition command, the igniter 112 generates a spark of suitable energy, which ignites the fuel-air mixture in the combustion chamber 118, and generates the high-energy combusted gas that is supplied to the turbine.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without-departing from the scope of the invention as set forth in the appended claims.
