TURBINE ENGINE

PRIORITY CLAIM

[0001] This application claims priority under International Application serial number PCT/US 17/44827, filed on August 1, 2017, entitled "AIR-COOLED COMPONENT FOR TURBINE ENGINE, WITH MONOLITHIC, VARYING DENSITY, THREE- DIMENSIONAL LATTICE", which is incorporated by reference herein.

TECHNICAL FIELD

[0002] The disclosure relates to combustion dynamic pressure- or noise-attenuation components for combustion or gas turbine engines. More particularly, the disclosure relates to acoustic combustor liners, including anechoic combustor liners, incorporating meta-structures that attenuate acoustic noise generated by dynamic pressure variations in the combustion gas, for use in combustion sections of combustion or gas turbine engines. Such meta-structures are also referred to as meta- materials.

BACKGROUND

[0003] Emission level requirements, established for industrial combustion or gas turbine engines, limit the quantity of oxide of nitrogen (NOx) and other combustion gases produced during engine operation. A known way to reduce emissions of nitrogen oxides is to reduce the combustion reaction temperature through lean- premixed combustion. This combustion mode, particularly when operating near the extinction limit, is prone to combustion instabilities that lead to dynamic pressure fluctuations. Dynamic pressure fluctuations are also referred to as noise. Those fluctuations couple with the acoustic resonance or Eigen modes of the combustor. Those modes are defined by the acoustic boundaries of the combustion system, such as the combustor liner, but also the rest of the combustor basket components and the transition section. Coupling of combustor resonance modes and combustion gas- generated acoustic waves, which are attributed to dynamic pressure fluctuations in the gas, can generate unwelcome combustion pressure amplitude fluctuations. These pressure amplitude fluctuations disrupt combustion efficiency and can reduce combustor component operating life. It is desirable to control and regulate engine vibration resonance, acoustic noise waves generated by combustion gas, and inhibit coupling of vibration resonance/acoustic noise, for engine operating efficiency, reduced emissions, reliability, and increased service life.

[0004] Traditional acoustic dampers, such as single-chamber, Helmholtz resonators, have been employed in combustion sections of gas turbine engines. Generally, individual resonators dampen a limited range of frequencies, which requires employment of multiple resonator units that are tuned to specific frequency ranges. Dimensional volumes of traditional, single-chamber, Helmholtz resonators and resonant tubes, such as quarter-wave tubes, approach wavelengths of the dampened acoustic wave frequencies. By way of example, a Helmholtz resonator used to dampen frequencies below or equal to 1000 Hertz has a length of approximately 100 millimeters. It has not been practical to package traditional Helmholtz resonators of such length in the small volumetric confines of combustor sections of combustion turbine engines. As larger Helmholtz resonators or resonator tubes are needed for lower frequency, longer wavelength acoustic waves, e.g., below or equal to 1000- Hertz frequency, it has not been practical to incorporate those traditional resonators within combustor sections of such engines. However, some combustion turbine engines are susceptible to coupling of vibration resonance/acoustic noise at frequencies below or equal to 1000 Hertz.

SUMMARY

[0005] An acoustic combustor liner for a combustion turbine engine dampens acoustic wave vibrations that are attributable to dynamic pressure variations generated in the combustion gas, by utilization of meta-structures as resonators. Meta-structures are also referred to as meta-materials. In some embodiments, the combustor liner is an anechoic combustor liner that absorbs all acoustic wave vibrations within a specific frequency range. In other embodiments, the acoustic liner dampens acoustic wave vibrations below or equal to 1000 Hertz that are generated in the combustion gas. Such damping is beneficial for mitigation of potential coupling of vibration resonance/acoustic noise in combustion turbine engines. The acoustic combustor liner includes a panel, in fluid communication with the combustion gas, which incorporates a meta-material or meta-structure acoustic damper. The acoustic damper includes a channel formed in the panel, in communication with the combustion gas. In some embodiments, the channel is formed within the panel, between its inner or outer faces, while in other embodiments the channel is formed through both faces of the panel. In some embodiments, the channel projects outwardly from a surface of the panel. The channel defines a channel cavity. A plurality of resonant structures is formed in the channel, respectively defining resonant structure cavities that are in communication with the channel cavity. The channel cavity and each of the respective resonant structure cavities define cavity dimensions that are all smaller than the wavelength(s) of corresponding frequency or frequencies of the damped acoustic wave. In some embodiments, the damped acoustic wave has one or more frequencies that are below or equal to 1000 Hertz. By damping and absorbing acoustic waves, the acoustic combustor liner inhibits coupling of combustion gas pulsation and resonant frequency (Eigen modes) of the combustion section volume and of the components that define the volume.

[0006] The meta-material or meta-structure constructions that are employed in the exemplary acoustic combustor liners, including anechoic combustor liners, disclosed herein, allow the collective, coupled groups of resonant structures to damp acoustic waves of frequencies, including frequencies below or equal to 1000 Hertz, even though individual resonant structures have cavity volumes and dimensions that are smaller than that of corresponding, known single-chamber Helmholtz resonator. The plurality of meta-material or meta-structure, resonant structures, in combination, in effect, slow perceived sound speed through their channel and branched structure cavities. The slower perceived sound in the meta-material damper allows the damper to be tuned to attenuate a given frequency using a smaller total cavity volume, than otherwise would be required for attenuation by traditional, single chamber resonators.

[0007] In exemplary embodiments, the meta-structure resonant structures are miniaturized Helmholtz resonators or tube resonators, including quarter-wave tube resonators, or other types of resonant structures. In exemplary embodiments, pluralities of the meta-structure resonant structures share a common channel cavity. In other exemplary embodiments, the resonant structures branch off each other as respective primary, secondary, and tertiary structures. In other exemplary embodiments, the resonant structures are incorporated in positive-pressure cooling passages of combustor liners, including anechoic combustor liners. In yet other embodiments, the resonant structures extend from an opposite face of the panel, away from the combustion gasses, to aid heat transfer from the combustor liner to cooling air circulating outside of the liner. In some embodiments, the meta-structure resonant structures of the combustor liner are formed by additive manufacture.

[0008] In other embodiments, noise-attenuating, acoustic combustor liners are modeled virtually in simulated operational engines. Cavity dimensions and relative orientation of their meta-structure resonant structures are selectively varied, in order to simulate acoustic damping.

Exemplary embodiments of the invention feature an acoustic combustor liner for a combustion turbine engine, which includes a panel for installation in a combustion turbine engine. The panel has a first face, and an opposing second face for fluid communication with engine combustion gas that generates acoustic waves, having a first wavelength and a first corresponding frequency. An acoustic damper is coupled to the panel, for damping the acoustic waves having the first wavelength. The acoustic damper has a channel defining a channel cavity that is formed in the second face, for communication with the acoustic waves generated by the combustion gas. A plurality of resonant structures are formed in the channel, respectively defining resonant structure cavities that are in communication with the channel cavity and with the acoustic waves generated by the combustion gas. The channel cavity and each of the respective resonant structure cavities define dimensions that are all smaller than the first wavelength.

[0009] Other exemplary embodiments of the invention feature a combustion turbine engine, having compressor, combustion, and turbine section stages. The combustion section includes a combustor liner having a panel having a first face, and an opposing second face in fluid communication with engine combustion gas that generates acoustic waves. The acoustic waves have a first wavelength and a first corresponding frequency. An acoustic damper is coupled to the panel, for damping acoustic waves having the first wavelength. The acoustic damper has a channel defining a channel cavity, formed in the second face. The channel is in fluid communication with the acoustic waves generated by the combustion gas. A plurality of resonant structures are formed in the channel, respectively defining resonant structure cavities that are in communication with the channel cavity and with the acoustic waves generated by the combustion gas. The channel cavity and each of the respective resonant structure cavities define dimensions that are all smaller than the first wavelength.

[0010] Additional exemplary embodiments of the invention feature a method for damping acoustic waves generated in combustion gasses within a combustion turbine engine. The method is practiced by modeling structure of a combustion turbine engine, including compressor, combustion, and turbine section stages. The modeled combustion section includes an air intake plenum, receiving compressed air from the compressor section; a fuel delivery system, for delivering fuel; and a combustion chamber, coupled to the air intake plenum and the fuel delivery system, for combusting fuel provided by a fuel delivery system and compressed air provided by the compressor section. The combustion chamber contains and exhausts combustion gas that generates acoustic waves having respective wavelengths and corresponding frequencies. In the model, a transition is coupled to the combustion chamber and the turbine section, for directing exhausted combustion gas out of the combustion section into the turbine section. The modeled combustion section also includes a first acoustic combustor liner (ACL) having a panel. The panel has a first face, and an opposing second face for fluid communication with the engine combustion gas. The ACL also has an acoustic damper coupled to the panel, for damping the acoustic waves. The acoustic damper has a channel defining a channel cavity, formed in the second face, for communication with the acoustic waves; and a plurality of resonant structures formed in the channel, respectively defining resonant structure cavities that are in communication with the channel cavity and with the acoustic waves. The channel cavity and each of the respective resonant structure cavities define dimensions that are all smaller than one or more of the wavelengths and corresponding frequencies of the acoustic waves. Flow of fuel, air, fuel and air mixture, and combustion gas are simulated in at least the combustion section of the modeled combustion engine, for determining temperatures and bulk flow of combustion gasses within the modeled engine and determining one or more wavelengths of simulated acoustic waves generated within the simulated combustion gas flow that correspond to those frequencies of the simulated acoustic waves. Acoustic properties of the simulated combustion gas and acoustic Eigen modes of the first modeled ACL are modeled, using the previously determined, bulk gas flow and temperature of the simulated combustion gas. Structure of a second ACL is modeled in the same modeled, combustion turbine engine, by selectively altering in the modeled, first ACL one or more of quantity, or location or structure or dimensions of the channel cavity and the respective resonant structure cavities, so that all of the altered dimensions thereof are smaller than one or more wavelengths, which correspond to frequencies, of the simulated acoustic waves generated within the combustion gas, for damping acoustic waves of said one or more wavelengths. A determination is then made whether the modeled, second ACL achieves a better- desired acoustic wave damping than the modeled, first ACL. The model of the second ACL is stored, if it achieves a better-desired acoustic wave damping than the modeled, first ACL. A combustion turbine engine is fabricated, incorporating the modeled, second ACL, if it achieves a better-desired acoustic wave damping of said one or more wavelengths than the modeled, first ACL.

[0011] The respective features of the exemplary embodiments of the invention that are described herein may be applied jointly or severally in any combination or subcombination. BRIEF DESCRIPTION OF DRAWINGS

[0012] The exemplary embodiments are further described in the following detailed description in conjunction with the accompanying drawings, in which:

[0013] FIG. 1 is a fragmentary, side elevational view of a gas turbine engine that incorporates an embodiment of an anechoic combustor liner described herein;

[0014] FIG. 2 is a schematic, fragmentary, perspective view of an acoustic combustor liner, constructed in accordance an embodiment described herein, wherein the resonant structures are coupled to and extend laterally from an opposite side of the liner's panel, away from the combustion-facing side thereof;

[0015] FIG. 2A is a cross-sectional, elevational view of the acoustic combustion liner of FIG. 2, taken along 2A-2A thereof, showing impingement cooling of one of the acoustic damper structures;

[0016] FIG. 3 is a fragmentary, perspective view of a portion of an acoustic combustor liner, that is constructed in accordance with another embodiment that is described herein, wherein the resonant structures extend from an opposite side of the liner's panel, away from the combustion-facing side thereof;

[0017] FIG. 4 is a cross-sectional, elevational view of meta-structure resonant structures, incorporating sub -wavelength, quarter-wave resonant tubes, of the panel of FIG. 3, taken along 4-4 thereof;

[0018] FIG. 5 is a cross-sectional, elevational view of meta-structure resonant structures, incorporating sub -wavelength Helmholtz resonators; [0019] FIG. 6 is a cross-sectional, elevational view of meta-structure resonant structures, incorporating both sub -wavelength Helmholtz resonators and sub- wavelength, quarter-wave resonant tubes;

[0020] FIG. 7 is a schematic, plan view of coiled secondary quarter-wave tube resonators, and tertiary, quarter-wave tube resonators, and tertiary, Helmholtz resonators, for reduced-volume packaging of meta-structure resonant structures;

[0021] FIG. 8 is a fragmentary, schematic, cross-sectional, plan view of an array of internal lattice webs, cooling-air passages, holes, and meta-structure resonant structures, in another embodiment of the panel, prior to shaping the panel into an anechoic combustor liner;

[0022] FIG. 9 is a fragmentary, schematic, perspective view of an array of meta- structure resonant structures formed between two flat metallic sheets, in a bonded panel embodiment of an anechoic combustor liner;

[0023] FIG. 10 is a fragmentary, schematic, cross-sectional, elevational view of an array of meta-structure, acoustic dampers, integrated cooling-air passages, and integrated holes formed within a 3-D, lattice structure of internal lattice webs and interstices, in another embodiment of an anechoic combustor liner, with the 3-D lattice structure sandwiched between two sheets of a bonded panel structure;

[0024] FIGs. 11-13 are perspective, schematic views showing sequential construction of different embodiments of anechoic combustor liners by additive manufacture, wherein 3-D, lattice webs and interstices between the webs are applied to a flat sheet substrate; and

[0025] FIG. 14 is a flowchart showing an embodiment of a method for damping acoustic vibrations within an anechoic combustor liner for an engine, by designing and manufacturing the liner in accordance with embodiments described herein. [0026] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale.

DESCRIPTION OF EMBODIMENTS

[0027] Exemplary embodiments of the invention utilize anechoic combustor liners for combustion turbine engines. The combustor liner dampens acoustic wave vibrations of one or more frequencies, including frequencies below or equal to 1000 Hertz and their corresponding wavelengths, generated in the combustion gas. A panel, in fluid communication with the combustion gas incorporates a meta-structure acoustic damper, which includes a channel formed in the panel, in communication with the combustion gas. The channel defines a channel cavity. A plurality of resonant structures is formed in the channel, respectively defining resonant structure cavities that are in communication with the channel cavity. The channel cavity and each of the respective resonant structure cavities define cavity dimensions that are all smaller than the wavelength(s) of the damped acoustic wave, including those waves that have frequencies below or equal to 1000 Hertz. The total volume of each respective resonant structure cavity of an embodiment described herein is also less than the total volume of a corresponding single-cavity, Helmholtz resonator that targets the same corresponding frequency range. In some embodiments, the meta-structure construction, acoustic damper is incorporated within air-cooled combustor liners. In some embodiments, portions of the air-cooled combustor liner has a monolithic, three-dimensional lattice structure of selectively oriented metallic surfaces, and webs with locally varying lattice density, and asymmetrical- and serpentine-shaped passages formed between the metallic webs for providing acoustic compliance for incident pressure waves. The component lattice structure locally varies one or more of channel size, shape, volume, or arrangement, for locally varying vibration damping properties of the component. In some embodiments, at least portions of the acoustic damper are incorporated within three-dimensional lattice structure, by forming solid surfaces that define interior boundaries of the meta-structure, resonant structures. [0028] Past emission and vibration challenges associated with fuel, air and combustion flows within combustion turbine engines are described, and inventive solutions described in the aforementioned International Application serial number PCT/US 17/ 16420, entitled "COMBUSTOR WITH THREE-DIMENSIONAL LATTICE PREMIXER", and International Application serial number PCT/US 17/16391, entitled "METHOD FOR NORMALIZING FUEL- AIR MIXTURE WITHIN A COMBUSTOR" , both filed on February 3, 2017, which are incorporated by reference in their entirety herein. The premixer embodiments of the invention described in those applications locally vary structure of one or more of air ducts, fuel delivery passages, fuel and air mixing ducts, and/or fuel and air discharge ducts, in order to normalize fuel-air ratio at any location about the premixer' s three- dimensional volume, or in the combustion chamber, during steady-state operating conditions, and/or in order to stabilize fluctuations in compressed air supply to the premixer, and/or in order to stabilize fluctuations in combustion gas backpressure upstream into the premixer, and/or in order to stabilize combustion mass flow within the combustor. The described premixer includes a monolithic, three-dimensional lattice structure of selectively oriented, asymmetrical- and serpentine-shaped metallic webs.

[0029] The aforementioned International Application serial number PCT/US 17/44827, filed on August 1, 2017, entitled "AIR-COOLED COMPONENT FOR TURBINE ENGINE, WITH MONOLITHIC, VARYING DENSITY, THREE- DIMENSIONAL LATTICE", which is incorporated by reference in its entirety herein, describes localized variation of cooling passages in an air-cooled component, by varying one or more of lattice density, or cooling airflow rate, or flow volume or flow direction throughout its three-dimensional volume. Selective, localized, variation in the air-cooled component structure enables localized variation in heat transfer and/or vibration damping properties of the component.

[0030] In this application, selective, localized variation of meta-material or meta- structure acoustic dampers within a panel of a combustor liner locally varies sound absorption and damping properties of the liner. Meta-structures have effective dynamic properties that are not found in nature. As explained below, the plurality of meta-structure, resonant structures, in combination, in effect, slow down and alter the perceived sound phase speed of dynamic pressure waves (acoustic noise) generated during gas combustion when they travel through the damper structure, even though the acoustic damper structure has smaller physical dimensions than the noise wavelength.

[0031] Through use of acoustic dampers, which are constructed with meta-material or meta-structure resonant structures, with acoustic cavities having sub -wavelength dimensions, it is possible to achieve an effective volume change out of phase with applied dynamic pressure frequencies, implying negative effective bulk modulus. In some frequency ranges, it is also possible to achieve effective acceleration out of phase with the dynamic pressure gradient; this creates a negative effective mass density effect. Therefore, by controlling the structure of the meta-structure it is possible to control relevant acoustic properties of the acoustic damper in certain ranges of frequencies. For such an acoustic damper, the inertial (i.e., dynamic) response is not the same as its static behavior at high enough frequencies. As a result, it is possible to control bulk modulus, of the acoustic damper, and thus control the effective sound speed in a material. A low sound speed material makes it possible to attenuate low frequencies of below or equal to 1000 Hertz, using Helmholtz resonators, or quarter-wave tubes, or other types of meta-structure resonant structures that have small dimensions, specifically much smaller dimensions, and volumes than with traditional resonators. By way of non-limiting example a meta-structure, resonant structure constructed in accordance with an embodiment described herein, having a cavity volume with dimensions of 2mm x 6mm x 30-40 mm dampens a 660- Hertz frequency acoustic wave. The ability to control density and sound speed also makes it possible to tune the impedance of a hard boundary to match the impedance of the medium it contains, effectively cloaking the boundary. In embodiments herein, one "hard boundary" is the combustor liner that envelops the combustion gas. Other exemplary "hard boundaries" include the fuel injector, at the inlet boundary of the combustor, or the transition between the combustor and the turbine section of the engine. [0032] In various embodiments disclosed herein, meta-structures are formed into acoustic dampers, within anechoic combustor liners that do not reflect incident acoustic waves, thereby preventing the onset of standing waves or Eigen modes in the combustor. In some embodiments the combustor liner panel is backed by meta- structure, resonant structures that are in fluid communication with combustion gasses (and sound waves propagating within the combustion gas), via channel openings within the liner surface that is exposed to the combustion gas. Those resonant structures are designed to have multiple resonance frequencies to achieve broadband performance and/or specific resonances are optimized to maximize the attenuation or cloaking behavior at certain frequencies. Exemplary combustor liners incorporating acoustic dampers with meta-structure, resonant structures are shown in FIGs. 1, 2, 2 A and 3-10. In some embodiments, the combustor liner panels and their acoustic damper structures are constructed by known additive manufacture techniques, such as 3D printing. FIGs. 8 and 10 show exemplary combustor liners that incorporate structures formed by additive manufacture.

[0033] Referring to FIG. 1, an industrial gas turbine engine 20 comprises in axial flow series an inlet 22, a compressor section 24, a combustion section 26 (also sometimes referred to as a combustion chamber assembly), a turbine section 28, a power turbine section 30, and an exhaust 32. The compressor section includes rotating compressor blades 25A, which are circumscribed by a compressor ring segment 25B. The turbine section 28 includes stationary vanes 27 A, which are inscribed by vane ring segment 27B, and rotating turbine blades 29A, which are circumscribed by a turbine ring segment 29B. The rotating turbine blades 29 A are arranged to drive the compressor blades 25A in the compressor section 24, via one or more shafts (not shown). The power turbine section 30 is arranged to drive an electrical generator 36 via a shaft 34.

[0034] The combustion section 26 comprises a plurality of equally circumferentially spaced combustors 38. Longitudinal axes of the combustors 38 are arranged to extend generally in the radial directions. The combustors 38 are encased within a combustor liner 38 A. Respectively, the inlets of the combustors 38 are at their radially outermost ends and their outlets are at their radially innermost ends of the combustor liner 38 A. The casing of the combustion section 26 incorporates an air intake plenum, which is in communication with the compressor section compressed air output, for providing compressed air to the inlets of the combustors 38. Combustion gas generated within the combustor 38 and contained within the combustor liner 38A flows through a corresponding transition 39, and thereafter into the turbine section 28. Known combustor designs include, without limitation, so-called can, annular, and can-annular designs. Each of the combustors 38 has at least one premixer (in Dry Low Emissions combustion systems), which receives compressed air from an air intake plenum that is in communication with the engine's compressor, and fuel from a fuel delivery system. The premixer has a fuel and air-mixing duct, which mixes the fuel and air at a desired fuel-air ratio and transfers the mixture, via a fuel and air discharge duct, into a combustion zone of the combustion chamber. In multi-stage combustors, respective secondary, and in some embodiment's tertiary, fuel and air mixing ducts supply a mixture of fuel and air into secondary or tertiary combustion zones in the combustor liner 38 A, via respective fuel and air discharge ducts.

[0035] Exemplary acoustic damper structure embodiments that are in acoustic combustor liners are shown in FIGs. 2, 2A, and 3-10. Some acoustic combustor liner embodiments are anechoic liners, which absorb all sound waves within a specific frequency range. Generally, these acoustic damper structures comprise a channel defining a channel cavity, to which a plurality of resonant structures is coupled and in mutual fluid communication with acoustic waves that are generated in the combustion gas. Often, the resonant structures are Helmholtz resonators and resonant tubes, such as quarter-wave tubes. In some embodiments one or a plurality of secondary, tertiary and quaternary resonant structures branch off a main channel cavity. In some of those branching acoustic damper structures, the main channel cavity comprises a primary resonant structure. Various resonance frequencies are achieved via different resonator dimensions or quarter-wave tube lengths. In other embodiments, resonance frequencies are attenuated by varying dimensions between respective resonant structures, where structure is identical in profile. The length of the cavity channel, the number of resonant structures, all of their respective shapes and their dimensions are selectively tuned and oriented on the combustor liner periphery to achieve the required properties for localized combustion noise attenuation while minimizing the space occupied by acoustic damper structure. In some embodiments, the acoustic damper structures are compacted by bending the resonant structures. In some embodiments, the acoustic damper structures extend from outside the combustor liner toward cooling air, so that they are skewed relative to the liner face that is exposed to combustion gasses. Yet, in other embodiments, the acoustic damper structures are oriented parallel to the liner face that is exposed to combustion gasses, such as damper structures that are embedded within the liner or formed on the cooling gas side of the panel. In some embodiments, the damper structures, whether or not embedded in the panel, have integrated impingement-effusion cooling holes, which reduce material needed for panel construction, and minimize cooling air consumption). Specific acoustic damper structures are now described.

[0036] In the exemplary embodiment of FIGs. 2 and 2A, an air-cooled panel 202 is incorporated into structure of an acoustic combustor liner 200, such as for the combustion turbine engine 20 of FIG. 1. In some embodiments, the panel 202 is rolled into a cylindrical profile, such as in the acoustic combustor liner 38A of FIG. 1. More specifically, the panel 202 of the acoustic combustor liner 200 of FIGs. 2 and 2A includes a first face 206 that is in fluid communication with cooling gas, and an opposing second face 204 for fluid communication with engine combustion gas that generates acoustic waves S, having a first wavelength and a first corresponding frequency.

[0037] In FIG. 2, a meta-structure, acoustic damper 210 is coupled externally to the panel 202 on its first face 206, for damping the acoustic waves having the first wavelength. The acoustic damper 210 has a channel 212 defining a channel cavity 214 that is in communication with the acoustic waves generated by the combustion gas, via the aperture 216 formed within the second face 204 of the panel 202. A plurality of resonant structures 220 and 226 are formed in the channel 212, respectively defining resonant structure cavities 222, 228. Cavity 222 is in communication with the channel cavity 214 via the neck 218. Cavity 228 is in communication with the channel cavity 214 via the neck 224. Thus, the acoustic damper 210 is a structural cluster of the channel 212 and the resonant structures 220 and 226, which are all in communication with the acoustic waves S generated by the combustion gas. The channel cavity 214 and each of the respective resonant structure cavities 222 and 228 define dimensions that are all smaller than the wavelength of the sound waves S. Locally varying the density and tuning sound attenuation properties of a plurality of meta-structure, acoustic dampers, such as 210, enables local modification of sound attenuation properties of the acoustic liner 200.

[0038] In FIGs. 2 and 2A, acoustic damper 240 incorporates localized impingement- effusion cooling capabilities within the channel 244 and the clustered, resonant structures 250 and 254. The channel 244 defines a channel cavity 246 that is in communication with the acoustic waves S generated by the combustion gas, via the aperture 242 formed within the second face 204 of the panel 202. Respective cavities 252 and 256 of the respective resonant structures 250 and 254 are in common communication with the channel cavity 246 formed in the channel 212. Impingement-effusion cooling holes 248 allow passage of higher-pressure cooling gas F into the cavities 246, 252 and 256, where the gas contacts the first surface 206 of the panel 202, and provides impingement cooling to the panel. The cooling gas F also provides effusion cooling to the first surface 206 of the panel 202 through the aperture 242. Simultaneously, the aperture 242 allows sound waves S to enter the channel cavity 246 and the resonator cavities 252 and 256. Thus, the acoustic damper 240 fulfills a dual purpose of attenuating the sound waves S, while cooling the acoustic combustor liner 200.

[0039] Local sizing and orientation of the acoustic dampers 240 and effusion cooling holes 270 facilitates more uniform spatial and temporal temperature distribution of the acoustic combustor liner 200, which in turn facilitates more uniform combustion noise attenuation. Attenuation properties of the acoustic dampers are influenced by temperature variations within their associated resonant structure cavities. Maintenance of relatively constant temperature, both spatially and temporally about the acoustic combustor liner maintains more consistent attenuation properties of the acoustic dampers. Cooling hole 248 and/or 270 pitch, array, density, porosity, shape, profile, and angular orientation relative to the corresponding surfaces 204 or 206 of the panel 202 are selectively varied in order to achieve desired heat transfer and/or vibration damping properties. In some embodiments, location of the cooling holes 248 and/or 270 and the acoustic dampers 210 and/or 240 are varied locally to achieve stable spatial and temporal temperatures within the cavities formed within the acoustic dampers, to achieve stable noise attenuation. Often, the cavities 214, 222, 228, 246, 252 and 256 are dimensioned to attenuate specific ranges of noise frequencies within specific temperature ranges. Temperature about the panel 202 is homogenized by selectively varying localized cooling about the panel 202.

[0040] In the embodiment of FIGs. 3-5, the combustor liner 300 dampens acoustic wave vibrations of one or more frequencies and wavelengths that are generated in the combustion gas generated by the engine. A panel 302 has a first face 306 that is in communication with cooling air, such as pressurized cooling air supplied by an engine compressor. The first face 306 incorporates exemplary meta-structure acoustic dampers 320 and 340. In some embodiments, the acoustic dampers 320 and 340 provide additional surface area to the combustor liner 300, for normalizing temperatures of their internal cavities with the temperature of the cooling air flowing along the first face 306. The panel 302 has a second face 304 that is in fluid communication with the combustion gas. The second face 304 includes a plurality of channels 308 that are formed in the panel 302; each respectively defining a channel cavity, In some embodiments, the air cooling passages 310 in the second face 304 of the panel 302 transport pressurized cooling air from the first side 306, directly through the panel or via internal passages formed within the panel, toward the combustion gasses.

[0041] As shown in FIGs. 4 and 5, the meta-structure acoustic dampers 320 and 340 respectively incorporate channel cavities 321 and 341 in communication with the combustion gas, via channels 308 formed in the second face 304 of the panel 302. A plurality of resonant structures is formed in each respective channel. The respective channel cavities and their respective pluralities of resonant structures within the acoustic dampers 320 and 340 are tuned to attenuate one or more acoustic frequencies and their respective wavelengths, or bandwidth ranges of acoustic frequencies. For example, it is desirable to attenuate frequencies generated by the combustion gas that are within excitation frequency ranges (as well as harmonics thereof), of combustor or other engine components. Such attenuation reduces risk of undesirable coupling of combustion noise with the acoustic resonance or Eigen modes of the combustor or other engine components.

[0042] In FIG. 4, the acoustic damper 320 includes the channel cavity 321 with a plurality of resonant structures formed in the channel cavity. Those resonant structures comprise resonator tubes, such as the quarter-wave resonator tubes 322, 324, and 326. Each of the resonant tubes 322, 324, and 326 has a hollow, cylindrical construction, defining a resonant structure cavity with a cavity length LR, a cross- sectional width WR and a cavity volume VR. Some embodiments of resonant tubes have non-cylindrical cross-sections, such as elliptical or triangular cross-sections. The cavities of the resonant structures of the resonant tubes 322, 324, and 326, are in communication with their common channel cavity 321. Here, the channel cavity 321 is a main quarter-wave resonator tube, to which are coupled secondary resonant quarter-wave resonator tubes 322, 324, and 326. The channel cavity 321 and each of the respective resonant structure cavities of resonant tubes 322, 324, and 326 define cavity dimensions LR, WR and VR that are all smaller than the wavelength(s) of the damped acoustic wave or the bandwidth of acoustic waves in the combustion gas that correspond to frequencies below or equal to 1000 Hertz. By way of non-limiting example, as previously discussed, a resonant structure having internal cavity dimensions of 2mm X 6mm X 30-40mm attenuates a 660 Hertz-frequency acoustic wave.

[0043] In FIG. 5, the acoustic damper 340 includes the channel cavity 341 with a plurality of resonant structures formed in the channel cavity. Those resonant structures comprise Helmholtz resonators 342, 346 and 350. Each of the respective Helmholtz resonators 342, 346, and 350 comprises a respective neck 344, 347, 351 and resonator cavity 345, 348, 354. The neck portions 344, 347 and 351 have neck lengths LN, neck cross- sectional width WN, while the resonator cavities have cavity length LH, a cross-sectional width WH, and a cavity volume VH. While the resonators 342, 346, and 350 are shown having cylindrical cross-sections, some embodiments have non-cylindrical cross sections. The cavities of the resonant structures of the Helmholtz resonators 342, 346 and 350 are in communication with their common channel cavity 341. Here, the channel cavity 341 is a main quarter-wave resonator tube, to which are coupled secondary Helmholtz resonators 342, 346 and 350. The channel cavity 341 and each of the respective resonant structure cavities of Helmholtz resonators 342, 346 and 350 define cavity dimensions LN, WN, LH, WH, and VH that are all smaller than the wavelength(s) of the damped acoustic wave or the bandwidth of acoustic waves in the combustion gas that correspond to frequencies below or equal to 1000 Hertz.

[0044] In the embodiment of FIG. 6, the combustor liner 300 incorporates an acoustic damper 360, projecting from the first face 306 of the panel 302. The acoustic damper is in fluid communication with combustion gas via cavity 308 that is formed in the second face 304of the panel 302. The channel and channel cavity of the acoustic damper 360 comprises a main tube resonator 361, with secondary resonator tubes 362-366, and secondary Helmholtz resonators 367 and 368. Again, dimensions of the main tube resonator 361, all of the secondary resonator tubes 362-366, and all of the secondary Helmholtz resonators 367 and 368 are smaller than the attenuated wavelength(s) of the corresponding combustion noise frequencies below or equal to 1000 Hertz.

[0045] In some embodiments, circumferential surface area and/or volume occupied by the acoustic dampers within a combustor liner is minimized by helical or serpentine coiling of channel cavities and their pluralities of resonant structures. In FIG. 7, the combustor liner 300 incorporates a coiled acoustic damper 400 projecting from, and parallel to the first face 306 of the panel 302, similar to the embodiment of FIGs. 2 and 2A, and in communication with combustion gas on the other side of the panel, via cavity 408. The cavity 408 is a resonant tube-type resonant structure or a non-resonant aperture. The resonant tubes 410 and 420 are coiled to reduce their length and surface area footprint on the combustion liner, while maintaining their dampening properties. The resonant tube 410 is in communication with a secondary Helmholtz resonator 412, while the resonant tube 420 is in communication with a secondary, coiled resonator tube 422 and a non-coiled, cylindrical resonator tube 424.

[0046] In some embodiments, the acoustic meta-structures are embedded or otherwise incorporated within an air-cooled combustor liner. In some embodiments, portions of the air-cooled combustor liner has a monolithic, three-dimensional lattice structure of selectively oriented metallic webs with locally varying lattice density, and asymmetrical- and serpentine-shaped passages formed between the metallic webs for receiving compressed cooling air. The component lattice structure locally varies one or more of lattice density, or cooling airflow rate, or flow volume or flow direction throughout its three-dimensional volume, for locally varying heat transfer and/or acoustic damping properties of the component. In some embodiments, at least portions of the acoustic damper are incorporated within three-dimensional lattice structure of the combustor liner's panel.

[0047] FIG. 8 shows schematically, respective local variations in 3-D lattice density and porosity for cooling airflow in the panel 500 of an exemplary combustor liner. Acoustic meta-structures are bounded by the solid walls. Lattice webs that form the cooling passages are shown schematically as the letter X, in varying web thickness, pitch density and clustering. Spaces or interstices between the X characters are cooling-air passages. Cooling air channels of various shapes, pitch, and cross section, for passage of purging air in or out of the panel-structure are also shown schematically. More particularly, FIG. 8 is an internal, planar cross section above the top surface 506 of the planar sheet 502, which is exposed to cooling airflow. The lower, outer surface 504 is exposed to combustion gasses. Topology of the clusters of the serpentine, solid walls 510, 512, 514, 516, 518 and 526 define boundaries of meta- structures. The webs 520, 522, 524, 528, 530 and 532 define corresponding cooling passages 540, 542, 544, 546, 550. An array of cooling holes 556, 558 560 facilitate passage of cooling air F between the lattice and the outer surface 504 of the panel 500. The passage 534 is a channel cavity for an acoustic damper 561, which is shown schematically as a Helmholtz resonator 562, with resonator cavity 536, and a resonator tube 564, with tube cavity 538. The acoustic damper comprises a plurality of resonant structure cavities that are in communication with the channel cavity 534, which can comprise more than the single Helmholtz resonator 562 and a resonator tube 564 shown in FIG. 8.

[0048] In the past, bonded panels have been employed to provide both impingement and effusion cooling of engine components that are exposed to combustion flames and gasses, such as transitions 39 and combustion liners 38 A. In embodiments herein, acoustic dampers are incorporated within bonded panel by embedding them between panel layers, or by incorporating acoustic dampers within additive manufacture layers between the panel layers.

[0049] FIG. 9 shows a sandwich-like construction, combustion liner 600, which is also referred to as a trans-ply, or a lamalloy panel, with bonded panels 602 and 604. Compressed cooling air impinges upon an exterior surface 607 of a cold side the panel 604, and enters inlet impingement holes or apertures formed within the cold side of the panel. The compressed air travels laterally (not shown) and transversely through internal cooling channels, where exhaust effusion holes or apertures 610 exhaust or expel cooling air out of the hot side 606 surface of the panel 602. In some embodiments, the exhaust effusion holes 610 have cross-sectional areas, profiles, pitch, and surface location that are sized as diffusion holes to provide film cooling to the exterior facing surface of the hot side 606 of the panel 602. A channel cavity 608 in the hot side face 606 allows acoustic communication between combustion gas and the embedded acoustic damper 612, which is shown schematically as comprising a clustered plurality of interconnected quarter-wave resonant tubes. In some embodiments, the acoustic damper 612 incorporates impingement-effusion cooling features, as was previously shown and described with respect to the acoustic damper 240 of FIGs. 2 and 2A. The bonded panels 602 and 604 are typically constructed by chemically eroding, cutting, or ablating the aperture 610, cavity 608 and the acoustic damper 612 through their respective metal sheets 602 and 604 that form, respectively, the hot and cold and sides of the panel. The respective metal sheets 602 and 604 often are of uniform thickness. The internal cooling channels (not shown) and the embedded acoustic damper 612 are formed by chemical erosion, cutting, or ablation of the inner, facing surfaces of those metal sheets 602 and 604. Then, the opposed metal sheets 602 and 604 are joined together, typically by diffusion bonding their opposed, inner facing surfaces together. The now bonded sheets are rolled into shapes, such as circumferential walls of the combustor liner 600.

[0050] Alternatively, in FIG. 10, the combustor liner 630 is formed by sandwich-like combinations of laminated sheets 632, 634, and one or more intermediate, additive- manufacture layer(s) 634. As noted, at least with respect to the air-cooled component embodiment of the combustion liner 630, the first face 642 has diffusion holes 646 and 648 formed therein, for flow of cooling air F. Cooling passages 650 and 652 facilitate transverse and lateral flow of cooling air F throughout the combustor liner 630 including out of effusion hole 644. The cooling passages 650 and 652 also function as a channel cavity in the first face 642 for transmission of acoustic waves S in the combustion gas into the effusion hole 644, where they propagate into an acoustic damper. The acoustic damper of FIG. 10 comprises a plurality of the Helmholtz resonators and quarter-wave resonator tubes formed within the 3-D lattice structure of the additive-manufacture layer(s) 634. Respective Helmholtz resonators 668 and 670 communicate with the dual-purpose cooling passage/acoustic damper channel-cavity 650 via respective necks 666 and 672. The respective quarter-wave tubes 660 and 662 also communicate with the dual-purpose cooling passage/acoustic damper channel-cavity 650. The acoustic damper and cooling passage structures are formed by varying locally one or more of lattice density, or lattice porosity, or cooling airflow rate, or flow volume or flow direction throughout the three-dimensional volume of the component. In such 3-D lattice component embodiments, the locally varying structure within the component locally varies heat transfer, vibration damping, and acoustic attenuation properties of the component.

[0051] FIGs. 11-13 illustrate methods for fabricating combustor liners or other air- cooled components for turbine engines, which incorporate, respectively, monolithic, three-dimensional lattice structures of selectively oriented metallic solid surface portions that form the meta-structure resonator structures of the acoustic dampers and/or faces of the panel; and metallic webs with locally varying lattice density, and asymmetrical- and serpentine-shaped passages formed between the metallic webs, for receiving compressed cooling air. In FIG. 11, construction of an exemplary air- cooled panel, such as a combustor liner panel 700, is initiated by placing, and optionally securing on a work surface 701, such as workpiece welding surface of an additive-manufacture, laser welder, a flat, first planar sheet 702, having an outer surface 704, and an inner surface 706. The first planar sheet 702 has optional array of pre-formed cooling and/or acoustic damper channel holes 760. In FIG. 12, a three- dimensional lattice structure 710 is formed on the inner surface 706 of the first planar sheet 702, by building up a web of solid surfaces with filaments 712, 713, 714, 715, 716, 718, 719, such as by an additive manufacture process. Interstices or spaces between those solid surfaces form asymmetrical- and serpentine-shaped passages 720, 722, 724 that can comprise resonant structure cavities for one or more acoustic dampers.

[0052] In the embodiment of FIG. 13, a second planar sheet 740, having an outer surface 742 and an inner surface 744, is applied to the panel 700, by additive manufacture, on top of the web filaments 711, so that the web filaments and the solid surfaces that form the second planar sheet have a monolithic structure. The cooling panel 700 forms cooling air internal passages and/or acoustic damper channel cavities, and/or resonant structure cavities 725 and 726 within the panel, between the first 702 and second 740 planar sheets, with the contours and topology of the passages established by the configuration of the solid surface formed by the aggregation of the fused, monolithic web filaments 711. An optional, second 3-D lattice array 750 of web filaments 752 and 754 is applied over the outer surface 742. One or more optional cooling holes 770 are formed during application of the solid surface, second planar sheet 740, of any desired shape, profile, dimensions, and/or angular orientation relative to the outer surface 742.

[0053] Embodiments of this invention include methods for determining structural profiles and orientations of the meta-structure construction and acoustic dampers. These methods include determining structural profiles of their channel cavities and individual, meta-structure, resonant structures, such as Helmholtz resonators and resonant tubes, as well as clustering and orientation of pluralities of such resonant structures. In some embodiments, the methods also include in tandem determining structural profiles and orientations of various other passages within the combustor liner, such as 3-D lattice structure webs and passages formed between web interstices, which form cooling air-flow channels, cooling holes, heat-transfer surface features throughout the three-dimensional lattice structure, or on exterior surfaces of a combustor liner or other component within a combustion section of a combustion turbine engine. With reference to FIGs. 1-13, this exemplary method is applied to local modifications of the exemplary embodiment of a panel that is used to fabricate a portion of the combustor liner 38A of the combustion chamber of the combustor 38, within the engine 20.

[0054] In the exemplary method 800 of FIG. 14, at modeling step 802, structures of the engine 20, are modeled, in a computer workstation, running commercially available structural analysis software. Modeled engine structure includes, by way of non-limiting example, its meta-material or meta-structure, acoustic combustor liner 300 (ACL) of FIG. 3, with combustor liner panel 302 and its acoustic dampers 320 and 340, as well as the transition 39.

[0055] In step 804, these modeled engine structures of step 802 are used in a computer workstation, running commercially available computational fluid-dynamics (CFD) software to perform simulations of intake air flow from the compressor section, 24 localized mass flow of cooling-air bleed from the compressor section 24 to the ACL 300, fuel and air mixture in its combustor premixers and combustion gas flow dynamics within its combustion chamber formed within the ACL 300, as well as the transition 39. The modeled combustion gas flow dynamics include, by way of non-limiting example combustion backpressure dynamics within the combustor liner and upstream into the premixer and acoustic emissions generated during combustion. These simulated gas flows are used to determine temperatures and bulk flow of combustion gasses within the modeled engine, as well as one or more wavelengths of simulated acoustic waves generated within the simulated combustion gas flow that correspond to those frequencies of the simulated acoustic waves.

[0056] In step 806, a model of the acoustic properties of the simulated combustion gas and acoustic Eigen modes of the first modeled ACL 300 is made, by using the simulated bulk gas flow and temperature distribution acquired in step 804. The acoustic properties model is made through use of commercially available, acoustic analysis software in a computer workstation.

[0057] In step 808, the ACL 300 structure of the combustor liner 38A, including its panel 302, panel cavities 308, 321, 341 and the acoustic dampers 320, 340 are revised and altered, in order to achieve desired noise attenuation within the ACL 300, within any desired frequency range, such as in a frequency range of below or equal to 1000 Hertz. Optionally, other structural elements within ACL 300 or other air-cooled components within the modeled combustor section 26 of the modeled engine 20 are evaluated for any one or more of temperature distribution and/or combustion dynamics and/or vibration damping and/or noise attenuation. Other evaluated structural elements include, by way of non-limiting example, three-dimensional lattice structures, and/or, cooling passages and/or cooling holes 310, and or its channels 308, as well as structure of the panel 302 or of any other components in the combustor 38. For example, in FIG. 8, localized variations from desired temperature distribution and/or vibration, and/or noise attenuation within the panel 500 of the combustor liner 38 A, at different circumferential angular or axial positions, are compensated by altering locally structure and/or location of one or more of the solid surfaces, lattice webs, and/or lattices interstices, and/or cooling passages, and/or acoustic dampers, and/or cavities, identified by numbers in the range of 502-564. In some embodiments, alteration of structural features and location of elements within the modeled panel 500 and evaluation of how those modifications alter combustion noise attenuation or other engine performance properties is repeated iteratively, until achievement, in step 810, of satisfactory performance (i.e., achieving acceptable performance criteria in the design, such as achieving a design plan goal for noise attenuation). [0058] Upon achievement of satisfactory noise attenuation in the modeled ACL 300, and if desired other optional temperature and/or vibration damping results at one or more locations within the engine 20, after revision of the localized structure of the ACL 300, its revised structural model is stored in step 812. If desired, the modeling and evaluation steps 802, 804, 806 and 808, and storage of revised models of step 812 are sequentially repeated for other components within the engine 20.

[0059] In step 814 of FIG. 14, the stored, revised structural model of the ACL 300 of step 812 is used to construct the actual acoustic combustor liner 300. Optimally revised structural models of any other modeled engine component are also used to construct those actual components of the engine 20 of FIG. 1.

[0060] Metal alloys used to form the ACL 300, as well as other components within the engine that are exposed to engine combustion gasses, are typically nickel/cobalt/chromium-based, so-called superalloys. In ACL embodiments that are constructed in part or entirely of, monolithic, three-dimensional lattice structures, locally varying solid surfaces, web and passage profiles of one or more of the various embodiments of the ACL's 200, 300, 500, 600, 630 or 700 of FIGs. 2-13 is not readily accomplished by traditional metal component fabrication and welding methods but they are more readily manufactured by known additive-manufacture methods.

[0061] In performing step 814 of FIG. 14 of the method embodiments, monolithic, three-dimensional lattice structures of the respective monolithic, acoustic combustor liner embodiments of FIGs. 2-13 are advantageously fabricated, using additive manufacture methods. In some embodiments, at least the 3-D lattice structure of the ACL is directly constructed by additive manufacture. Exemplary additive- manufacture methods include by way of non-limiting example:

• Selective laser melting by powder bed fusion laser;

• Selective laser melting by powder bed electron beam melting;

• Atomic diffusion additive manufacturing (e.g., by 3-D printing and metal injection molding); and • Direct energy deposition (e.g., blown powder).

[0062] In other embodiments, all or portions of the monolithic, three-dimensional lattice and solid surface structures of the ACLs of FIGs. 2-14 are fabricated by a sacrificial-pattern, mold-casting process. A pattern mold, which replicates the structure of the desired, monolithic, three-dimensional lattice structure of selectively oriented metallic webs, and asymmetrical- and serpentine-shaped and passages between the webs, is formed by an additive manufacture process. The pattern mold is encased in a metal casting mold. The formed mold is filled with molten metal, which displaces the sacrificial mold pattern. After the molten metal hardens, the surrounding mold is removed. The completed cast-metal ACL replicates the desired, monolithic, three-dimensional lattice structure of selectively oriented, metallic webs and passages.

[0063] Although various embodiments that incorporate the invention have been shown and described in detail herein, others can readily devise many other varied embodiments that still incorporate the claimed invention. The invention is not limited in its application to the exemplary embodiment details of construction and the arrangement of components set forth in the description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including ' "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted", "connected", "supported", and "coupled" and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to direct physical or mechanical connections or couplings.