Patent Application
20100287938
The present application relates generally to gas turbine engines and more particularly relates to a cross flow swozzle vane that reduces flame holding and pressure drop.
A jet in cross flow occurs when a flow of a fluid exits an orifice to interact with an intersecting flow of a fluid that is flowing across the orifice. Jets in cross flow are central to a variety of applications such as gas turbine combustors, fuel injectors, and pollution controls in smoke stacks. A jet in cross flow typically creates a zone of recirculation downstream from where the cross flow is introduced. The recirculation zone typically has a reduced flow velocity that may cause a variety of detrimental effects depending upon the configuration of the flow.
More specifically, the recirculation zone behind a jet in cross flow of a turbine swozzle vane may hold the air fuel mixture. Due to the high temperatures in the combustor, flames may flash back and try to hold in the low velocity region. Further, a local spark may ignite the air fuel mixture trapped in the recirculation zone. The recirculation zone thus aids in holding the flame. The problem may be more prominent in cases of fuels with high BTU such as hydrogen (H2) due to higher flame speed. Likewise for low BTU fuels such as BFG (Blast Furnace Gas), the recirculation zone may form due to the high volumetric flow rate.
There is thus a desire for improved swozzle vane jets particularly in a jet in cross flow design. The improved design should reduce flame holding and the pressure drop therethrough so as to improve overall system performance and efficiency.
The present application thus provides a cross flow vane for a turbine. The cross flow vane may include a number of jets positioned therein and a divider positioned within one or more of the jets so as to form a number of fuel slots therein.
The present application further provides a cross flow system for a gas turbine. The cross flow system may include a vane, a first flow flowing over the vane, a jet positioned on the vane, a second flow exiting the jet and intersecting the first flow, a divider positioned within the jet so as to divide the second flow, and a fuel curtain slot positioned about the jet to guide the first flow.
The present application further provides a cross flow swozzle vane for a gas turbine. The cross flow swozzle vane may include a number of jets positioned therein, a divider positioned within one or more of the jets so as to form a number of fuel slots therein, and a fuel curtain slot positioned about one or more of the jets.
These and other features of the present application will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.
Referring now to the drawings, in which like numbers refer to like elements throughout the several views,
The second flow 160 may be a jet of combustible fuel such as gasoline, natural gas, propane, diesel, kerosene, E85 (85% ethanol and 15% gasoline), bio-diesel, biogas, or any other fuel used for combustion. The second flow 160 also may be any other flow of a gaseous or liquid substance or combination thereof. As described above, the first flow may be a compressed airflow or any other type of flow. Although the cross flow jets 140 are shown to be generally circular, the jets 140 may be ovular, polygonal, curved, or any other shape or combination thereof.
In this example, at least one of the cross flow jets 230 may include a divider 240 positioned therein. The divider 240 bisects the cross flow jet 230 and forms two fuel slots 250 therein. The divider 240 and the fuel slots 250 may take any desired size or shape. One or more of the cross flow jets 230 also may have one or more fuel curtain slots 260 positioned thereabout. Although the fuel curtain slot 260 is shown as somewhat curved and angled, any size, shape, or orientation may be used herein. The fuel curtain slots 260 may be similar to those shown in commonly-owned U.S. patent Ser. No. 12/262,358 and similar structures.
The use of the fuel curtain slots 260 about the cross flow jets 230 may act as a flow curtain to minimize the recirculation zone 235 behind the jet 230 by redirecting part of the air stream into the wake region. This redirection helps in mitigating flame holding in such jet in cross flow situations. The fuel slots 250 may be sized with enough of a gap therebetween caused by the divider 240 so as to allow air to pass through and wash away the wake that has formed behind the jets 230. The bifurcation of the jet 230 by the divider 240 thus may help in further reducing the recirculation zone 235 behind the jet 230 while at the same time enhancing the fuel air mixing and providing a lower pressure drop.
The cross flow jets 230 thus provide better fuel air mixing so as to provide a low risk of flame holding and, hence, greater fuel flexibility. The pressure drop thereacross likewise may be reduced by providing a larger area for the flow of fuel. Further, a lower pressure drop thus may permit a smaller fuel compressor. The cross flow jet 230 has no hard blockage for the flows so as to provide improved structural integrity. The jets 230 also may be easy to manufacture and can be retrofitted in existing frames.
It should be apparent that the foregoing relates only to certain embodiments of the present application and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.
