The invention relates to an injector for a combustion chamber of a gas turbine, in particular for a turbo-engine, comprising a dual fuel injection circuit. The invention also relates to a combustion chamber provided with at least one such dual circuit injector and with single circuit injectors.
An appropriate mixture of compressed air and fuel is in general injected into the combustion chamber with the help of a plurality of injectors. The injectors are mounted on the wall of a flame tube being arranged preferably in the chamber bottom. This allows the mixtures from the various injectors to be homogenously distributed.
In each injector, a nozzle introduces fuel into the end of a manifold. The fuel is adjusted in a centering guide. The air origin is the last stage of a compressor of the gas machine and the air is introduced into the injector in an annular way. Air and fuel are in general introduced into swirling devices with contra-rotation oriented channels or spins, and then the fuel particles are sprayed out in the air through a mixer. The mixture being ignited through a plug located at a determined distance is burnt out within the chamber. The gases being generated then possess a high kinetic energy that is used to generate propulsion or mechanical energy.
Nowadays, the chamber ignition is provided by two injectors being dedicated to starting, each starting injector being associated with a plug. The other injectors are dedicated to post-starting working conditions : acceleration or deceleration transient conditions and flight stabilized conditions. Such architecture needs to have available specific starting injectors, and thus, extra mass and specific mounting ports for such injectors on the flame tube supporting the set of injectors, as well as the positioning of resulting extra controls.
Furthermore, there are combustion chambers provided with injectors having a dual fuel supply circuit, an auxiliary circuit and a main circuit. The auxiliary circuit is dedicated to the idle operation, i.e. at low load, while the main circuit or both circuits is or are biased at intermediate and stabilized ratings. At full power rate, the ratio of flow rates between both circuits is inverted and the main circuit becomes dominant or the unique fuel supplier. Such a distribution is disclosed for example in patent document FR 2,906,868 or FR 2,896,030 filed in the name of the Applicant.
However, such dual circuit injectors are not adapted to be used in the starting phase, because the structure thereof does not allow any mixture ejection at a high starting speed. That is the reason why the presence of specific injectors continues with the above-mentioned disadvantages.
The invention aims at remedying such problem by providing a starting injector also adapted to be used in any flight rating with no extra cost or mass. To do so, such starting injector possesses a particular configuration of a dual fuel supply circuit and an air circuit.
More precisely, the object of the present invention is to provide an injector for a gas turbine combustion chamber, comprising a dual fuel supply circuit and an air circuit. The fuel injection circuits consist in a starting fuel supply circuit being able to trigger the chamber ignition, and then to operate in any flight mode, and a main fuel supply circuit being able to operate in any flight mode further to starting. The fuel supply circuits have parallel conducts made in a common tube with a longitudinal axis. The conduct of the starting circuit opens, on one end, substantially into the center of a spherical injector body extending the common tube. On such end, the conduct houses an injection ring being able to drive fuel into rotation before projecting it inside the chamber through a central channel passing through a central wall of a swirling device. The conduct of the main circuit opens into an annular channel made in the body facing jet channels radially arranged in the main wall around the central channel. The air circuit is guided between two concentric sphere portions consisting of the injector body and a sheath surrounding the injector body and presenting an opening through which the swirling device opens into.
Thus, the injector according to the invention shows a highly reduced bulk thanks to the dual spherical architecture thereof.
Moreover, the central starting circuit is thermally protected from any coking through the fuel circulation in the annular channel of the main circuit. The main circuit is itself thermally protected by the peripheral air flow circulating in the inter-spherical space.
Advantageously, the swirling device is located in a slanting position with respect to the longitudinal axis of the injector. Such slanting configuration allows the end of the starting circuit to be positioned in the center of the latter and the air and fuel jets to be oriented in the direction of the plug arranged in the bottom of the chamber.
According to particular embodiments:
The invention also relates to a combustion chamber provided of at least one dual circuit injector as shown above and single circuit injectors. All the injectors are mounted in alignment on the casing surrounding the combustion chamber and cross a flame tube through ports arranged along at least one line parallel to the longitudinal axis of the flame tube.
The dual circuit injectors are oriented towards the ignition plug so that such injectors are able to project an air/fuel cone on the output of the swirling device oriented towards the combustion chamber bottom.
In a preferred embodiment, the combustion chamber is provided with two dual circuit injectors being not adjacent on the line of injectors.
Other characteristics and advantages of the present invention will appear from the reading of the detailed exemplary embodiment that follows, referring to the accompanying figures wherein, respectively:
a and 1b show an exploded view and a sectional view of an exemplary dual circuit injector according to the invention;
a and 2b show a perspective view and a sectional view of a variation of the preceding example; and
Referring to the exploded view and the sectional view of respective
The dual fuel injection circuit consists in a starting fuel supply circuit C1 being able to trigger the ignition of the chamber 3 and to operate in any flight rate, and a main fuel supply circuit C2 able to operate in any flight rate further to starting.
The circuits C1 and C2 are coupled with fuel supply manifolds (not shown). Such circuits are made of access borings 2a, 2b formed in the fastening flange 10, in connection with the parallel longitudinal conducts, respectively 12a and 12b, extending in the tube 11 while abutting on sealing sleeves 13a and 13b housed within such tube. Such conducts extend in the tube 11 parallel to the longitudinal axis X′X and open into the combustion chamber 3 through the central wall 14.
Concerning the starting circuit C1, the conduct 12a opens—on one end 12e—substantially into the center of a hemispheric injector body 11s in the extension of the tube 11. Moreover, on such end, the conduct 12a houses—in a cylindrical recess 21 with a slanting axis merged into the axis Y′Y of the swirling device 4—a helical fuel ring 7. Advantageously, the recess 21 presents a conical end 21c coupled through the central wall 14 of the swirling device 4 with a central channel 41 with an axis merged into the axis Y′Y of the swirling device 4 or the recess 21. Such central channel 41 opens into the combustion chamber 3.
As regards the main circuit C2, a nozzle 8 is advantageously mounted in the access boring 2b of the flange 10. Such nozzle enables to calibrate the fuel flow rate that varies according to the flight phases. After an elbow 12c, the longitudinal conduct 12b is oriented into a final portion 12f parallel to the axis Y′Y and opens into an annular channel 16 arranged in the spherical body 11s. Such annular channel 16 has advantageously two ends 16e. In other words, such channel is not looped on itself. Thus, no “dead” zone is formed, where the fuel might stagnate.
The annular channel 16 is brazed on the central wall through an appropriate brazing 20, that makes the non looped shape of the annular channel 16 appear. Such an annular channel 16 communicates with jet channels 42 radially arranged and equally distributed around the central channel 41. Advantageously, such jet channels have the same diameter. The radial channels 42 advantageously have an orientation according to axes K′K symmetrically slanted with respect to the axis Y′Y of the central channel 41 (see in particular
Furthermore, the air flow on the input FE—such air coming from the last compression stage—crosses openings 170 formed in a flared cover 17 extending the tube 11 and is then guided in an air circuit C3, where the air is circulating within an inter-spherical space “E”. Such space “E” is formed between two portions of concentric spheres provided by the injector body 11s and partially by the sheath 5 in a spherical part 5s surrounding the injector body 11s. The sheath also presents a circular section cylindrical part 5c, which allows an abutment to be provided for the flame tube 6 and for the flared cover 17 of the tube 11. Thus, the injector according to the invention presents a minimal bulk thanks to such inter-spherical passageway.
Moreover, the central starting circuit C1 is thermally protected from coking by the fuel circulation flow within the annular channel 16 of the main circuit C2, such main circuit being itself thermally protected by the peripheral air flow F circulating within the inter-spherical space “E” of the air circuit C3.
On the injector output 1, the air flow FS advantageously forms, while passing between the fins 40, an air cone Ca surrounding the fuel discharge cone “E” of the main circuit C2.
According to an alternative embodiment referring to the perspective and sectional views of
The modifications essentially come from the configuration in the connection between the longitudinal tube 11 and the sheath 5. In the example illustrated on
Referring to
All the injectors 1, 100 are regularly mounted on the annular rim of the chamber 3. Ports 60 have been provided in the tube 6 so as to enclose the sheaths 5 of the injectors 1, 100.
The dual circuit injectors 1 are oriented towards the igniting plug 101. Thanks to the slanting orientation of the jet channels 42 and the central channels 41, the dual circuit injectors 1 are able to project air/fuel cones Ca/Cs on the output of the swirling devices towards the bottom 3f of the combustion chamber 3. After ignition, the flame is directed towards the bottom 3f, returns back and goes out through the opposite output 3s.
In the example being illustrated, the two dual circuit injectors 1 are separated by a single circuit injector 100 so as to make the orientation of the dual circuit injectors 1 easier towards the plug 101.
The invention is not limited to the embodiment being disclosed and represented. For example, the injector body can form a more or less complete sphere part according to the opening size or the diameter of the common tube. Furthermore it is possible to form various injector lines in the flame tube.
Number | Date | Country | Kind |
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11 50807 | Feb 2011 | FR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/FR12/50177 | 1/27/2012 | WO | 00 | 7/30/2013 |