Patent Application
20170363007
This disclosure relates to gas turbine engines, and more particularly to gas turbine engine components having lattice structures. The lattice structures include heat transfer devices configured to isothermally cool portions of the components.
Gas turbine engines typically include a compressor section, a combustor section, and a turbine section. In general, during operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases flow through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads.
Due to exposure to hot combustion gases, numerous components of the gas turbine engine include internal cooling schemes that circulate airflow to cool the component during engine operation. Thermal energy is transferred from the component to the airflow as the airflow circulates through the cooling scheme to thermally manage the component. It is desirable to provide cooling schemes that are efficient and that provide structural integrity.
A component according to an exemplary aspect of the present disclosure includes, among other things, a first wall section, a second wall section spaced from the first wall section, a plurality of branches between the first wall section and the second wall section, and a heat transfer device disposed either between adjacent branches of the plurality of branches or inside at least one branch of the plurality of branches.
In a further non-limiting embodiment of the foregoing component, the heat transfer device includes a wick structure and a working medium.
In a further non-limiting embodiment of either of the foregoing components, the wick structure includes a sintered metal powder.
In a further non-limiting embodiment of any of the foregoing components, the heat transfer device is an enclosed structure that holds a working medium.
In a further non-limiting embodiment of any of the foregoing components, passages extend between the adjacent branches of the plurality of branches.
In a further non-limiting embodiment of any of the foregoing components, the heat transfer device is located within one of the passages.
In a further non-limiting embodiment of any of the foregoing components, the component is an additively manufactured component.
In a further non-limiting embodiment of any of the foregoing components, the heat transfer device is disposed between the adjacent branches of the plurality of branches and a second heat transfer device is disposed inside the at least one branch of the plurality of branches.
In a further non-limiting embodiment of any of the foregoing components, the heat transfer device includes an evaporation section and a condenser section.
In a further non-limiting embodiment of any of the foregoing components, a working medium of the heat transfer device moves between the evaporation section and the condenser section in response to absorbing or releasing heat.
In a further non-limiting embodiment of any of the foregoing components, locations of the evaporation section and the condenser section vary based on localized temperatures of the component.
In a further non-limiting embodiment of any of the foregoing components, the first wall section and the second wall section are part of a blade, a vane, a blade outer air seal (BOAS), a combustor panel, or a turbine exhaust case liner of a gas turbine engine.
In a further non-limiting embodiment of any of the foregoing components, the heat transfer device includes a first working medium and a second heat transfer device of the component includes a second working medium.
A component according to another exemplary aspect of the present disclosure includes, among other things, a wall and a lattice structure arranged inside the wall. The lattice structure includes a plurality of nodes, a plurality of branches that extend between the plurality of nodes, a plurality of passages extending between the plurality of nodes and the plurality of branches, and a heat transfer device adapted to transfer thermal energy within the lattice structure by selectively evaporating and condensing a working medium.
In a further non-limiting embodiment of the foregoing component, the lattice structure is a vascular engineered lattice structure.
In a further non-limiting embodiment of either of the foregoing components, the vascular engineered lattice structure is configured such that airflow is communicated through the plurality of passages and the heat transfer device is disposed inside at least one node of the plurality of nodes or inside at least one branch of the plurality of branches.
In a further non-limiting embodiment of any of the foregoing components, the vascular engineered lattice structure includes a hollow lattice structure in which airflow is communicated inside the plurality of nodes and the plurality of passages and the heat transfer device is disposed within at least one passage of the plurality of passages.
In a further non-limiting embodiment of any of the foregoing components, the working medium is at least partially carried by a wick structure of the heat transfer device.
In a further non-limiting embodiment of any of the foregoing components, the wick structure includes a sintered metal powder.
In a further non-limiting embodiment of any of the foregoing components, the heat transfer device is an enclosed structure that holds the working medium.
The embodiments, examples, and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.
The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
This disclosure details a lattice structure for thermally managing gas turbine engine components. The lattice structure includes a plurality of branches, or struts, disposed inside a wall or between adjacent wall sections of the component. A heat transfer device of the lattice structure may be disposed between adjacent branches of the plurality of branches, disposed inside one or more branches of the plurality of branches, or both. The heat transfer device functions like a heat pipe to evenly and effectively cool the component without a significant net energy loss. These and other features are discussed in greater detail in the following paragraphs of this detailed description.
The gas turbine engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine centerline longitudinal axis A. The low speed spool 30 and the high speed spool 32 may be mounted relative to an engine static structure 33 via several bearing systems 31. It should be understood that other bearing systems 31 could alternatively or additionally be provided.
The low speed spool 30 generally includes an inner shaft 34 that interconnects a fan 36, a low pressure compressor 38, and a low pressure turbine 39. The inner shaft 34 can be connected to the fan 36 through a geared architecture 45 to drive the fan 36 at a lower speed than the low speed spool 30. The high speed spool 32 includes an outer shaft 35 that interconnects a high pressure compressor 37 and a high pressure turbine 40. In this non-limiting embodiment, the inner shaft 34 and the outer shaft 35 are supported at various axial locations by bearing systems 31 positioned within the engine static structure 33.
A combustor 42 is arranged between the high pressure compressor 37 and the high pressure turbine 40. A mid-turbine frame 44 may be arranged generally between the high pressure turbine 40 and the low pressure turbine 39. The mid-turbine frame 44 supports one or more bearing systems 31 of the turbine section 28. The mid-turbine frame 44 may include one or more airfoils 46 that extend within the core flow path C.
The inner shaft 34 and the outer shaft 35 are concentric and rotate via the bearing systems 31 about the engine centerline longitudinal axis A, which is co-linear with their longitudinal axes. The core airflow is compressed by the low pressure compressor 38 and the high pressure compressor 37, is mixed with fuel and burned in the combustor 42, and is then expanded over the high pressure turbine 40 and the low pressure turbine 39. The high pressure turbine 40 and the low pressure turbine 39 rotationally drive the respective high speed spool 32 and the low speed spool 30 in response to the expansion.
The pressure ratio of the low pressure turbine 39 can be pressure measured prior to the inlet of the low pressure turbine 39 as related to the pressure at the outlet of the low pressure turbine 39 and prior to an exhaust nozzle of the gas turbine engine 20. In one non-limiting embodiment, the bypass ratio of the gas turbine engine 20 is greater than about ten (10:1), the fan diameter is significantly larger than that of the low pressure compressor 38, and the low pressure turbine 39 has a pressure ratio that is greater than about five (5:1). It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines, including direct drive turbofans.
In another non-limiting embodiment of the exemplary gas turbine engine 20, a significant amount of thrust is provided by the bypass flow path B due to the high bypass ratio. The fan section 22 of the gas turbine engine 20 is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet. This flight condition, with the gas turbine engine 20 at its best fuel consumption, is also known as bucket cruise Thrust Specific Fuel Consumption (TSFC). TSFC is an industry standard parameter of fuel consumption per unit of thrust.
Fan Pressure Ratio is the pressure ratio across a blade of the fan section 22 without the use of a Fan Exit Guide Vane system. The low Fan Pressure Ratio according to one non-limiting embodiment of the example gas turbine engine 20 is less than 1.45. Low Corrected Fan Tip Speed is the actual fan tip speed divided by an industry standard temperature correction of [(Tram ° R)/(518.7° R)]0.5. The Low Corrected Fan Tip Speed according to one non-limiting embodiment of the example gas turbine engine 20 is less than about 1150 fps (351 m/s).
The compressor section 24 and the turbine section 28 each include alternating rows of rotor assemblies and vane assemblies (shown schematically) that carry airfoils that extend into the core flow path C. For example, the rotor assemblies carry a plurality of rotating blades 25, while each vane assembly carries a plurality of vanes 27 that extend into the core flow path C. The blades 25 create or extract energy (in the form of pressure) from the core airflow that is communicated through the gas turbine engine 20 along the core flow path C. The vanes 27 direct the core airflow to the blades 25 to either add or extract the energy.
Various components of the gas turbine engine 20, including but not limited to the airfoils of the blades 25 and the vanes 27 of the compressor section 24 and the turbine section 28, may be subjected to repetitive thermal cycling under widely ranging temperatures and pressures. The hardware of the turbine section 28 is particularly subjected to relatively extreme operating conditions. Therefore, some components may require cooling schemes for cooling the parts during engine operation.
Among other features, this disclosure relates to gas turbine engine component cooling schemes that include lattice structures inside the walls of the gas turbine engine components. The lattice structures described herein provide effective localized cooling, and is some embodiments, provide isothermalized cooling inside components subject to compressor air or hot combustion gases communicated through the core flow path C. Isothermalized cooling evenly cools the components and substantially reduces hot spots within the components while achieving a near zero net energy loss.
In the illustrated non-limiting embodiment, the body portion 52 is representative of an airfoil. For example, the body portion 52 could be an airfoil that extends from a platform and a tip portion (i.e., where the component is a blade), or could alternatively extend between inner and outer platforms (i.e., where the component 50 is a vane). In yet another non-limiting embodiment, the component 50 is a non-airfoil component, including but not limited to, a blade outer air seal (BOAS), a combustor liner, a turbine exhaust case liner, or any other part that requires dedicated cooling.
A gas path 62 is communicated axially downstream through the gas turbine engine 20 in a direction that extends from the leading edge portion 54 toward the trailing edge portion 56 of the body portion 52. The gas path 62 represents the communication of core airflow along the core flow path C (see, e.g.,
A cooling scheme 64 is disposed inside the body portion 52 for cooling the internal and external surface areas of the component 50. For example, the cooling scheme 64 can include one or more cavities 72 that may radially, axially, and/or circumferentially extend inside the body portion 52 to establish cooling passages for receiving an airflow 68 (or some other fluid). The airflow 68 may be communicated into one or more of the cavities 72 from an airflow source 70 that is external to the component 50 to cool the component 50. In one non-limiting embodiment, the airflow 68 is communicated to the cooling scheme 64 through a root portion of the component 50 (e.g., where the component is a blade).
The airflow 68 is generally a lower temperature than the airflow of the gas path 62 that is communicated across an exterior of the body portion 52. In one particular non-limiting embodiment, the airflow 68 is a bleed airflow that can be sourced from the compressor section 24 or any other portion of the gas turbine engine 20 that has a lower temperature than the component 50. The airflow 68 is circulated through the cooling scheme 64 to transfer thermal energy from the component 50 to the airflow 68, thereby cooling the component 50.
In a non-limiting embodiment, the exemplary cooling scheme 64 includes a plurality of cavities 72 that extend inside of the body portion 52. However, the cooling scheme 64 is not necessarily limited to the configuration shown, and it will be appreciated that a greater or fewer number of cavities, including only a single cavity, may be defined inside of the body portion 52. The cavities 72 communicate the airflow 68 through the cooling scheme 64, such as along a serpentine path or a linear path, to cool the body portion 52.
Ribs 74 extend between the first side wall 58 and the second side wall 60 of the body portion 52. The ribs 74 also radially extend over a span of the body portion 52.
The exemplary cooling scheme 64 may additionally include one or more lattice structures 80 that are disposed inside sections of the body portion 52 of the component 50. For example, discrete sections of one or more walls of the component 50 may embody a lattice structure, or the entire component 50 could be constructed of lattice structures. Exemplary lattice structures are described in further detail below.
A lattice structure 80 extends between a first wall section 82 and a second wall section 84 of the section 99. The term “lattice structure” denotes a structure that can be heated or cooled by allowing airflow to be circulated through openings formed within the lattice structure. The first wall section 82 and the second wall section 84 could be part of a single wall or could be different walls of the component 50. Thus, in a non-limiting embodiment, the lattice structure 80 is considered to be disposed “inside” a wall or a rib of the component 50.
The first wall section 82 is spaced from the second wall section 84. The first wall section 82 is exposed to the gas path 62, whereas the second wall section 84 is remote from the gas path 62. For example, the second wall section 84 could face toward or into a cooling source cavity 72 of the cooling scheme 64 (see
In a non-limiting embodiment, the lattice structure 80 includes a plurality of branches 86 disposed between the first wall section 82 and the second wall section 84. In a non-limiting embodiment, the branches 86 extend across the entire thickness T from the first wall section 82 to the second wall section 84. The branches 86 may extend orthogonally or non-orthogonally relative to the first and second wall sections 82, 84. In other non-limiting embodiments, a portion of the branches 86 extend orthogonally relative to the first and second wall sections 82, 84 while another portion of the branches 86 extend non-orthogonally relative to the first and second wall sections 82, 84. In yet another non-limiting embodiment, a portion of the branches 86 extend between other branches 86. In yet another non-limiting embodiment, a portion of the branches 86 extend between branches 86 and wall portions. A passage 88 extends between adjacent branches 86 of the lattice structure 80.
The lattice structure 80 may additionally include one or more heat transfer devices 90. Each heat transfer device 90 is a sealed or enclosed structure integrally formed as part of the lattice structure 80. The heat transfer devices 90 include a wick structure 92, or capillary action structure such as a porous medium, and a working medium 94 that can move within the heat transfer device 90 and the wick structure 92 to transfer thermal energy. The enclosed structure of the heat transfer device 90 holds the working medium 94.
The heat transfer devices 90 additionally include a vaporization section 96 and a condenser section 98. It should be recognized that the particular sizes, shapes, and locations of the vaporization section 96 and the condenser section 98 can vary. In fact, in a non-limiting embodiment, the sizes, shapes, and locations of these sections are defined by the local temperatures at any given time within the section 99 of the component 50. Thus, the locations of the vaporization section 96 and the condenser section 98 could change depending on the operating environment within which the component 50 has been disposed.
In another non-limiting embodiment, the heat transfer devices 90 function like heat pipes that use an evaporative cooling cycle to transfer thermal energy by continuously evaporating and condensing the working medium 94. For example, the heat transfer devices 90 may utilize an evaporative cooling cycle to transfer thermal energy from the component 50 to cooling flow such as air 68 passing through the lattice structure 80. Thermal energy absorbed by the component 50 from hot combustion gases, such as at the first wall section 82, heats the vaporization section 96 of one or more of the heat transfer devices 90. This causes the working medium 94 in the vaporization section 96 to evaporate. The relatively cool air 68 communicated through the lattice structure 80 absorbs thermal energy from the condenser section 98, thus causing the (vaporized) working medium 94 to condense back into a liquid phase.
The working medium 94 physically moves between the vaporization section 96 and the condenser section 98 to transfer thermal energy between the locations where the evaporation and condensation occur within the heat transfer devices 90. The wick structures 92 primarily facilitate the movement of the liquid working medium 94. In a non-limiting embodiment, the wick structure 92 of the heat transfer device 90 is a sintered metal powder. The sintered metal powder may be additively manufactured. Other wick or capillary action structures are also contemplated within the scope of this disclosure.
The composition of the working medium 94 of each heat transfer device 90 may be selected according to the particular operating conditions at which heat transfer is desired. Typically, working media conventionally used with evaporative cooling cycles are dependent upon operation within a particular range of temperature conditions (as well as pressure conditions). It is therefore necessary to select a suitable working medium based on the particular conditions under which each heat transfer device 90 is expected to operate. Temperatures in gas turbine engines can reach 1,649° C. (3,000° F.) or more, although actual engine temperatures will vary for different applications, and under different operating conditions. For example, during operation, the gas turbine engine is configured such that the average gas path temperature will generally not exceed the maximum temperature limits for the materials (e.g., metals and ceramics) used in and along the core flow path C. A non-limiting list of potential working medium is provided in Table 1, although those skilled in the art will recognize that other working medium could alternatively or additionally be utilized. In addition, it should be recognized that different working medium may be utilized within separate heat transfer devices of a given lattice structure.
In a first non-limiting embodiment, shown in
In a first non-limiting embodiment, the airflow 68 absorbs thermal energy from the heat transfer devices 90 as it passes through the branches 86. In this way, the lattice structure 80 isothermally cools the component 50 with a near zero net energy loss. In this cooling embodiment, the temperature of the airflow 68 is lower than that of the component to be cooled.
In an alternative embodiment, the lattice structure 80 can be utilized to heat the component 50. In such an embodiment, the airflow 68 is a heating airflow that includes a temperature that is higher than that of the component to be heated.
In a second non-limiting embodiment, shown in
As discussed in greater detail below, the vascular engineered lattice structure 180 of
The specific design and configuration of the vascular engineered lattice structure 180 of
The exemplary vascular engineered lattice structure 180 extends between a first wall section 182 and a second wall section 184 of a component 50. The first wall section 182 is spaced from the second wall section 184. The first wall section 182 may be exposed to the gas path 62, whereas the second wall section 184 is remote from the gas path 62. For example, the second wall section 184 could face into one of the cooling source cavities 72 of the cooling scheme 64 (see, e.g.,
Airflow 68 migrates through the vascular engineered lattice structure 180 to cool the component 50. In this non-limiting embodiment, the vascular engineered lattice structure 180 embodies a hollow configuration in which the airflow 68 may be circulated inside of the various passages defined by the vascular engineered lattice structure 180. For example, the hollow configuration of the vascular engineered lattice structure 180 may establish a porous flow area for the circulation of airflow 68. Additionally, airflow 68 could be communicated over and around the vascular engineered lattice structure 180.
The lattice structure 80 or the vascular engineered lattice structure 180 can be manufactured by using a variety of manufacturing techniques. For example, the lattice structure 80 or the vascular engineered lattice structure 180 may be created using an additive manufacturing process such as direct metal laser sintering (DMLS). Another additive manufacturing process that can be used to manufacture the lattice structure 80 and the vascular engineered lattice structure 180 is electron beam melting (EBM). In another non-limiting embodiment, select laser sintering (SLS) or select laser melting (SLM) processes may be utilized.
In yet another non-limiting embodiment, a casting process can be used to create the lattice structure 80 or the vascular engineered lattice structure 180. For example, an additive manufacturing process can be used to first produce a molybdenum based Refractory Metal Core (RMC) that can subsequently be used to cast the lattice structure 80 or the vascular engineered lattice structure 180. In one embodiment, the additive manufacturing process includes utilizing a powder bed technology for direct fabrication of airfoil lattice geometry features, while in another embodiment, the additive manufacturing process can be used to produce “core” geometry features which can then be integrated and utilized directly in the investment casting process using a lost wax process.
The exemplary vascular engineered lattice structure 180 includes a plurality of nodes 192, a plurality of branches 194 that extend between the nodes 192, and a plurality of hollow passages 196 spanning between the branches 194 and the nodes 192. The number, size and distribution of nodes 192, branches 194, and hollow passages 196 can vary from the specific configuration shown. In other words, the configuration illustrated by
The branches 194 may extend orthogonally or non-orthogonally between the nodes 192. The nodes 192 and branches 194 can be manufactured as a single contiguous structure made of the same material. In one non-limiting embodiment, the nodes 192 and branches 194 are uniformly distributed throughout the vascular engineered lattice structure 180. In another non-limiting embodiment, the nodes 192 and branches 194 are non-uniformly distributed throughout the vascular engineered lattice structure 180.
In this “hollow lattice” structure configuration, airflow 68 can be circulated inside hollow passages 197 of the nodes 192 and the branches 194 to cool the component 50 in the spaces between the wall sections 182, 184. For example, the “hollow” lattice structure may include multiple continuous hollow spoke cavity passages 197 through which the airflow 68 is passed. The airflow 68 flows from each of the hollow branches 194 and coalesces into the nodes 192, which serve as a plenum for the airflow 68 to be redistributed to the next set of hollow branches 194 and nodes 192. The “hollow” lattice structure forms multiple, circuitous, continuous passages in which the airflow 68 flows to maximize the internal convective cooling surface area and coolant mixing. Additionally, airflow 68 could be communicated over and around the nodes 192 and branches 194 of the vascular engineered lattice structure 180.
The nodes 192 and the branches 194 additionally act as structural members that can be tailored to “tune” steady and unsteady airfoil vibration responses in order to resist and optimally manage steady and unsteady pressure forces, centrifugal bending and curling stresses, as well as provide for improved airfoil local and section average creep and untwist characteristics and capability. In a non-limiting embodiment, one or more of the nodes 192 and the branches 194 include augmentation features 195 (shown schematically in
In yet another non-limiting embodiment, the vascular engineered lattice structure 180 include one or more heat transfer devices 190 disposed within the hollow passages 196 that extend between the various nodes 192 and branches 194. The heat transfer devices 190 can be integrally manufactured as part of the contiguous structure of the vascular engineered lattice structure 180. Although shown generically in this embodiment, the heat transfer devices 190 work in the substantially the same manner as the heat transfer devices 90 described above by utilizing an evaporative cooling cycle to transfer thermal energy from the component 50 to the airflow 68 as it is circulated inside the hollow passages 197 of the nodes 192 and the branches 194 of the vascular engineered lattice structure 180.
As mentioned above, the vascular arrangement of the vascular engineered lattice structure 180 can be tailored to the specific cooling and structural needs of any given gas turbine engine component. For example, a first portion of the vascular engineered lattice structure 180 can include a different combination of nodes 192, branches 194, hollow passages 196, and heat transfer devices 190 compared to a second portion of the vascular engineered lattice structure 180. In one embodiment, a first portion of the vascular engineered lattice structure 180 may include a greater amount of cooling area whereas a second portion of the vascular engineered lattice structure 180 may provide a greater amount of structural area.
The vascular engineered lattice structure 280 includes a plurality of nodes 292, a plurality of branches 294 that extend between the nodes 292, a plurality of open passages 296 between the branches 294 and the nodes 292, and heat transfer devices 290 disposed inside at least a portion of the nodes 292 and the branches 294. The nodes 292, branches 294, open passages 296, and heat transfer devices 290 can be manufactured as a single contiguous structure, in one non-limiting embodiment.
In this lattice structure configuration, airflow 68 is circulated through the open passages 296 to cool the component 50 in the space between the wall sections 282, 284. In other words, in contrast to the hollow lattice structure embodiment which communicates airflow inside the nodes 292 and the branches 294, the airflow 68 is circulated over and around these parts as part of a porous flow area. For example, the lattice structure includes multiple continuous branches 294 over which airflow 68 is passed. The lattice structure forms circuitous passages for the airflow 68 to traverse around as it migrates through the vascular engineered lattice structure 280 to maximize the convective cooling surface area and coolant mixing around the nodes 292 and the branches 294. The nodes 292 and the branches 294 additionally act as structural members that resist and dampen pressure, rotation forces, and vibratory loads.
The exemplary vascular engineered lattice structure 280 establishes a ratio of cooling area to structural area. The cooling area is established by the open passages 296, while the nodes 292 and branches 294 determine the amount of structural area. In one embodiment, the amount of cooling area exceeds the structural area (cooling area>structural area). In another embodiment, a ratio of the cooling area to the structural area is less than 1 (cooling area<structural area). In yet another embodiment, a ratio of the cooling area to the structural area is between 1 and 4. Other configurations are also contemplated.
In another non-limiting embodiment, the heat transfer devices 290 are disposed inside one or more of the various nodes 292 and branches 294. This is best depicted in
Although the different non-limiting embodiments are illustrated as having specific components, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.
It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure.
The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.
