Patent Application
20140311156
The present application and the resultant patent relate generally to gas turbine engines and more particularly relate to a combustor for a gas turbine engine with a combustor cap used as a Helmholtz-type resonator for damping low frequency dynamics therein.
Generally described, gas turbine engines combust a mixture of compressed air and compressed fuel to produce hot combustion gases. The hot combustion gases may be used to provide useful mechanical work and drive different types of loads. Combustion may occur in multiple combustors positioned radially around a longitudinal axis of the gas turbine engine. Because of the turbulent nature of the combustion process and the large volumetric energies released in closed cavities, such combustors may be susceptible to a wide range of frequencies and unsteady pressure oscillations of large magnitudes. If one of the combustion frequency bands corresponds to a natural frequency of a part or a subsystem within the gas turbine engine, damage to that part or to the entire engine may result.
Known methods to suppress these pressure oscillations, referred to herein as “dynamics”, traditionally have focused on decoupling the excitation source from the feedback mechanism. Such suppression means generally are effective only over a limited operational range of the combustor. Damping low frequency dynamics is particularly a difficult design issue because a resonator with relatively large dimensions may be needed. Depending upon the location of the resonator, additional cooling also may be needed.
There is thus a desire for improved combustor designs and methods of operations. Preferably, these designs and methods may limit combustor dynamics and the frequency ranges thereof so as to prevent damage to the combustor and insure adequate component lifetime. Damped lower frequency dynamics also should provide overall increased reliability. Moreover, operations closer to an even fuel split between the nozzles of the combustor may be possible without dynamics so as to provide reduced overall emissions of nitrogen oxides and the like.
The present application and the resultant patent thus provide a combustor cap for use with a number of fuel nozzles. The combustor cap may include a cold side plate, a hot side plate, and a cap cavity extending between the cold side plate and the hot side plate with the number of fuel nozzles extending therethrough. A resonator tube may extend from the cold side plate into the cap cavity.
The present application and the resultant patent further provide a method of operating a combustor of a gas turbine engine. The method may include the steps of combusting a flow of air and a flow of fuel, producing combustion dynamics, sizing one or more resonator tubes to dampen the combustion dynamics, and positioning the one or more resonator tubes in a cold side plate of a combustor cap.
The present application and the resultant patent further provide a combustor for a gas turbine engine. The combustor may include a number of fuel nozzles, a combustor cap with the fuel nozzles positioned therein, and a number of resonator tubes positioned about a cold side plate of the combustor cap.
These and other features and improvements of the present application and the resultant patent 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 numerals refer to like elements throughout the several views,
The gas turbine engine 10 may use natural gas, various types of syngas, and/or other types of fuels. The gas turbine engine 10 may be anyone of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y. and the like. The gas turbine engine 10 may have different configurations and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment also may be used herein together.
The flow of air may enter the combustor 25 from the compressor 15 via the incoming air path 75. The flow of air 20 then may reverse direction for mixing with the flow of fuel 30 about the fuel nozzles 55. In the case of gas fuel operation, the flow of air 20 and the flow of fuel 30 mix within the fuel nozzles. In the case of liquid fuel operation, the liquid fuel 30 is supplied directly into the combustion chamber 70. In either case, the mixed flow of air 20 and the flow of fuel 30 may be combusted within the combustion chamber 70. The flow of combustion gases 35 then may be exhausted through the transition piece 90 towards the turbine 40 to produce useful work. The combustor 25 may use a primary fuel that may be a fuel gas; a secondary fuel and a tertiary fuel that may be a premixed fuel gas; and a lean pre-nozzle fuel injection system that may inject the small amount of fuel just upstream of the fuel nozzles 55. Other types of fuel circuits and other combustor configurations may be used herein.
The combustor cap 110 also may include a number of resonator tubes 180. Each resonator tube 180 may have an inlet 190 positioned about the cold side plate 160 and an outlet 200 terminating within the cap cavity 170. The resonator tubes 180 may be positioned between each of the outer fuel nozzles 130. As such, five (5) resonator tubes 180 may be used in this example. Any number of resonator tubes 180 may be used herein. Likewise, the size, shape, configuration of each resonator tube 180 may vary. Resonator tubes 180 of varying configurations also may be within the same combustor cap 110. Resonator tubes 180 also may be positioned in other locations about the combustor cap 110. A number of radial baffle plates may be used to divide the cap cavity as desired.
As is shown in
As above, the resonate frequency of the Helmholtz resonator 210 is determined mainly by its geometric configuration. Specifically, a cylindrical Helmholtz resonator 210 produces a resonant frequency “f” based in part upon the following equation: f=c/2Π*√d2/LHD2. In this equation, “c” is the speed of sound through the fluid (e.g., air, fuel, diluent, etc.), “d” is the diameter of the throat 230, “L” is the length of the throat 230, “H” is the length of the body 220, and “D” is the diameter of the body 220. In this example, the configuration of the body 220, i.e., the cap cavity 170, is fixed such that the resonant frequency may be varied by varying the length and diameter of the throat 230, i.e., the resonator tubes 180. As such, the resonator tubes 180 may be sized to dampen certain frequency ranges such as those most severe for the combustion hardware. Any number of resonator tubes 180 may be used herein in any desired size, shape, or configuration. Resonator tubes 180 of different configurations also may be used herein together so as to dampen different frequency ranges. The resonator tubes 180 used herein thus may be designed so as to dampen lower frequency ranges although any frequency or range of frequencies may be targeted herein. For example, a resonator 210 with a natural frequency range of about 170 Hz may be used for damping oscillations from about 80 to about 400 Hz.
The positioning of the Helmholtz resonator 210 about the cold side plate 160 may be more effective than positioning about the hot side plate 150. Specifically, the flow of air 20 about the cold side plate 160 may have a higher density and a lower sound speed as compared to the hot side plate 150 facing the combustion chamber 70. Moreover, positioning the Helmholtz resonator 210 about the cold side plate 160 does not require any further and/or different cooling schemes. Rather, the configuration of the existing combustor cap 110 may be used herein. The resonator tubes 180 may be welded onto the cold side plate 160 and/or otherwise attached. Combustion operations closer to an even fuel split may be used herein with reduced dynamics so as to provide overall lower emissions of nitrogen oxides and the like.
The resonator tubes 180 also may provide the flow of air 20 into the cap cavity 170 so as to provide cooling to the hot side plate 150. The diameter of the resonator tubes 180 thus may be varied according to the desired cooling flow. The resonator tubes 180 thus may be more effective in providing cooling as compared to the use of small perforations therein.
It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. 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.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/RU2011/000726 | 9/22/2011 | WO | 00 | 3/19/2014 |
