Patent Publication Number: US-10760430-B2

Title: Adaptively opening backup cooling pathway

Description:
BACKGROUND OF THE INVENTION 
     The disclosure relates generally to cooling of components, and more particularly, to a primary cooling pathway near an outer surface of a hot gas path component and a backup, secondary cooling pathway internal of the primary cooling pathway. 
     Hot gas path components that are exposed to a working fluid at high temperatures are used widely in industrial machines. For example, a gas turbine system includes a turbine with a number of stages with blades extending outwardly from a supporting rotor disk. Each blade includes an airfoil over which the hot combustion gases flow. The airfoil must be cooled to withstand the high temperatures produced by the combustion gases. Insufficient cooling may result in undo stress and oxidation on the airfoil and may lead to fatigue and/or damage. The airfoil thus is generally hollow with one or more internal cooling flow circuits leading to a number of cooling holes and the like. Cooling air is discharged through the cooling holes to provide film cooling to the outer surface of the airfoil. Other types of hot gas path components and other types of turbine components may be cooled in a similar fashion. 
     Although many models and simulations may be performed before a given component is put into operation in the field, the exact temperatures to which a component or any area thereof may reach vary greatly due to component specific hot and cold locations. Specifically, the component may have temperature dependent properties that may be adversely affected by overheating. As a result, many hot gas path components may be overcooled to compensate for localized hot spots that may develop on the components. Such excessive overcooling, however, may have a negative impact on overall industrial machine output and efficiency. 
     Despite the presence of cooling passages many components also rely on a thermal barrier coating (TBC) applied to an outer surface thereof to protect the component. If a break or crack, referred to as a spall, occurs in a TBC of a hot gas path component, the local temperature of the component at the spall may rise to a harmful temperature. This situation may arise even though internal cooling circuits are present within the component at the location of the spall. One approach to a TBC spall provide a plug in a cooling hole under the TBC. When a spall occurs, the plug is removed typically through exposure to heat sufficient to melt the plug, the cooling hole opens and a cooling medium can flow from an internal cooling circuit fluidly coupled to the cooling hole. The plug may be porous to assist in its removal. This process reduces overcooling. Formation of the plug however is complex, requiring precise machining and/or precise thermal or chemical processing of materials to create the plug. 
     Another challenge regarding cooling is addressing the situation where a particular cooling feature becomes no longer operational, or the amount of cooling required to prevent further overheating increases. 
     BRIEF DESCRIPTION OF THE INVENTION 
     A first aspect of the disclosure provides a component for use in a hot gas path of an industrial machine, the component comprising: a body including an outer surface exposed to a working fluid having a high temperature in the hot gas path; an internal cooling circuit in the body carrying a cooling medium; a primary cooling pathway spaced internally from the outer surface in the body and in fluid communication with the internal cooling circuit, the primary cooling pathway fluidly communicating a primary flow of the cooling medium therethrough from the internal cooling circuit; and a secondary cooling pathway in the body and in fluid communication with the internal cooling circuit, the secondary cooling pathway fluidly incommunicative and spaced internally from the primary cooling pathway, wherein in response to an overheating event, the secondary cooling pathway opens at a first opening to at least one of the outer surface and the primary cooling pathway to allow a secondary flow of cooling medium through to the at least one of the outer surface and the primary cooling pathway from the secondary cooling pathway, wherein the primary flow of the cooling medium flows in the primary cooling pathway prior to the overheating event, and wherein the secondary flow of cooling medium does not flow in the plurality of interconnected secondary cooling pathways until after the overheating event. 
     A second aspect of the disclosure provides a component for use in a hot gas path of an industrial machine, the component comprising: a body including an outer surface; a thermal barrier coating over the outer surface, the thermal barrier coating exposed to a working fluid having a high temperature in the hot gas path; an internal cooling circuit in the body carrying a cooling medium; a primary cooling pathway spaced internally from the outer surface in the body and in fluid communication with the internal cooling circuit, the primary cooling pathway fluidly communicating a primary flow of the cooling medium therethrough from the internal cooling circuit; and a plurality of interconnected secondary cooling pathways in the body and in fluid communication with the internal cooling circuit, the plurality of interconnected secondary cooling pathways fluidly incommunicative and spaced internally from the primary cooling pathway, wherein in response to an overheating event, at least one of the plurality of interconnected secondary cooling pathways opens at a first opening to at least one of the outer surface and the primary cooling pathway to allow a secondary flow of cooling medium through to the at least one of the outer surface and the primary cooling pathway from the at least one of the plurality of interconnected secondary cooling pathways, wherein the primary flow of the cooling medium flows in the primary cooling pathway prior to the overheating event, and wherein the secondary flow of cooling medium does not flow in the plurality of interconnected secondary cooling pathways until after the overheating event. 
     The illustrative aspects of the present disclosure are designed to solve the problems herein described and/or other problems not discussed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features of this disclosure will be more readily understood from the following detailed description of the various aspects of the disclosure taken in conjunction with the accompanying drawings that depict various embodiments of the disclosure, in which: 
         FIG. 1  is a schematic diagram of an illustrative industrial machine having a hot gas path component in the form of a gas turbine system. 
         FIG. 2  is a perspective view of a known hot gas path component in the form of a turbine blade. 
         FIG. 3  is a perspective view of a portion of a hot gas path component according to embodiments of the disclosure without a thermal barrier coating (TBC) thereon. 
         FIG. 4  is a perspective view of a portion of the HGP component of  FIG. 3  including a thermal barrier coating according to embodiments of the disclosure. 
         FIG. 5  is a first cross-sectional view of a portion of the HGP component including primary and secondary cooling pathways according to embodiments of the disclosure. 
         FIG. 6  is a second cross-sectional view of the portion of the HGP component of  FIG. 5  including primary and secondary cooling pathways according to embodiments of the disclosure. 
         FIG. 7  is a first cross-sectional view of a portion of the HGP component including primary and secondary cooling pathways according to another embodiment of the disclosure. 
         FIG. 8  is a second cross-sectional view of the portion of the HGP component of  FIG. 7  including primary and secondary cooling pathways according to embodiments of the disclosure. 
         FIG. 9  is a schematic plan view of a portion of the HGP component illustrating an arrangement of the primary and secondary cooling pathways according to embodiments of the disclosure. 
         FIG. 10  is a schematic plan view of a portion of the HGP component illustrating an arrangement of the primary and secondary cooling pathways according to embodiments of the disclosure. 
         FIG. 11  is a schematic plan view of a portion of the HGP component illustrating an arrangement of the primary and secondary cooling pathways according to embodiments of the disclosure. 
         FIG. 12  is a schematic plan view of a portion of the HGP component illustrating an arrangement of the primary and secondary cooling pathways according to embodiments of the disclosure. 
         FIG. 13  is a cross-sectional view of the portion of the HGP component of  FIG. 5  including a first opening from the secondary cooling pathway according to embodiments of the disclosure. 
         FIG. 14  is a cross-sectional view of the portion of the HGP component of  FIG. 5  including a first opening from the secondary cooling pathway and a second opening from the primary cooling pathway according to embodiments of the disclosure. 
         FIG. 15  is a cross-sectional view of the portion of the HGP component of  FIG. 5  including a first opening to the primary cooling pathway and a second opening from the primary cooling pathway according to another embodiment of the disclosure. 
         FIG. 16  is a cross-sectional view of the portion of the HGP component of  FIG. 5  including a first opening from the secondary cooling pathway according to embodiments of the disclosure. 
         FIG. 17  is a cross-sectional view of an portion of an HGP component including a first opening from the second cooling pathway to an outer surface thereof according to embodiments of the disclosure. 
         FIG. 18  is a cross-sectional view of a portion of an HGP component including openings to the primary and secondary cooling pathways according to embodiments of the disclosure. 
         FIG. 19  is a cross-sectional view of the portion of the HGP component including an opening from the second cooling pathway to an outer surface and including a thermal barrier coating (TBC) according to embodiments of the disclosure. 
         FIG. 20  is a cross-sectional view of a portion of the HGP component including openings to the primary and secondary cooling pathways and including a thermal barrier coating (TBC) according to embodiments of the disclosure. 
         FIG. 21  is a block diagram of an additive manufacturing process including a non-transitory computer readable storage medium storing code representative of an HGP component according to embodiments of the disclosure. 
     
    
    
     It is noted that the drawings of the disclosure are not to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     As an initial matter, in order to clearly describe the current disclosure it will become necessary to select certain terminology when referring to and describing relevant machine components within an industrial machine such as a gas turbine system. When doing this, if possible, common industry terminology will be used and employed in a manner consistent with its accepted meaning. Unless otherwise stated, such terminology should be given a broad interpretation consistent with the context of the present application and the scope of the appended claims. Those of ordinary skill in the art will appreciate that often a particular component may be referred to using several different or overlapping terms. What may be described herein as being a single part may include and be referenced in another context as consisting of multiple components. Alternatively, what may be described herein as including multiple components may be referred to elsewhere as a single part. 
     In addition, several descriptive terms may be used regularly herein, and it should prove helpful to define these terms at the onset of this section. These terms and their definitions, unless stated otherwise, are as follows. The term “radial” refers to movement or position perpendicular to an axis. In cases such as this, if a first component resides closer to the axis than a second component, it will be stated herein that the first component is “radially inward” or “inboard” of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is “radially outward” or “outboard” of the second component. It will be appreciated that such terms may be applied in relation to the center axis of the turbine. 
     As indicated above, the disclosure provides a hot gas path (HGP) component including adaptively opening cooling pathways therein. A primary cooling pathway is spaced internally from the outer surface in the body and in fluid communication with an internal cooling circuit. A secondary cooling pathway is also in the body and in fluid communication with an internal cooling circuit. The secondary cooling pathway is fluidly incommunicative and spaced internally from the primary cooling pathway. In response to an overheating event occurring, the secondary cooling pathway opens at a first opening to at least one of the outer surface and the primary cooling pathway to allow a secondary flow of cooling medium through to the at least one of the outer surface and the primary cooling pathway from the secondary cooling pathway. The overheating event may include any event in which a temperature reaches or exceeds a predetermined temperature of the body, causing the first opening to form from the secondary cooling pathway through the outer surface of the body and/or to the secondary cooling pathway. Where the first opening opens to the primary cooling pathway, and the overheating event warrants, the primary cooling pathway may open at a second opening to the outer surface. Various forms of an overheating event will be described in more detail herein. The HGP component can be made by additive manufacturing or conventional manufacturing. 
     Referring now to the drawings, in which like numerals refer to like elements throughout the several views,  FIG. 1  shows a schematic view of an illustrative industrial machine in the form of a gas turbine system  10 . While the disclosure will be described relative to gas turbine system  10 , it is emphasized that the teachings of the disclosure are applicable to any industrial machine having a hot gas path component requiring cooling. Gas turbine system  10  may include a compressor  15 . Compressor  15  compresses an incoming flow of air  20 , and delivers the compressed flow of air  20  to a combustor  25 . Combustor  25  mixes the compressed flow of air  20  with a pressurized flow of fuel  30  and ignites the mixture to create a flow of combustion gases  35 . Although only a single combustor  25  is shown, gas turbine system  10  may include any number of combustors  25 . Flow of combustion gases  35  is in turn delivered to a turbine  40 . Flow of combustion gases  35  drives turbine  40  so as to produce mechanical work. The mechanical work produced in turbine  40  drives compressor  15  via a shaft  45  and an external load  50  such as an electrical generator and the like. 
     Gas turbine system  10  may use natural gas, liquid fuels, various types of syngas, and/or other types of fuels and blends thereof. Gas turbine system  10  may be any one of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y. and the like. Gas turbine system  10  may have different configurations and may use other types of components. Teachings of the disclosure may be applicable to other types of gas turbine systems and or industrial machines using a hot gas path. Multiple gas turbine systems, or types of turbines, and or types of power generation equipment also may be used herein together. 
       FIG. 2  shows an example of a hot gas path (HGP) component  52  in the form of a turbine blade  55  that may be used in a hot gas path (HGP)  56  of turbine  40  and the like. While the disclosure will be described relative to HGP component  52  in the form of turbine blade  55  and more specifically an airfoil  60  or wall thereof, it is emphasized that the teachings of the disclosure are applicable to any HGP component requiring cooling. Generally described, turbine blade  55  may include airfoil  60 , a shank portion  65 , and a platform  70  disposed between airfoil  60  and shank portion  65 . Airfoil  60  generally extends radially upward from platform  70  and includes a leading edge  72  and a trailing edge  74 . Airfoil  60  also may include a concave surface defining a pressure side  76  and an opposite convex surface defining a suction side  78 . Platform  70  may be substantially horizontal and planar. Shank portion  65  may extend radially downward from platform  70  such that platform  70  generally defines an interface between airfoil  60  and shank portion  65 . Shank portion  65  may include a shank cavity  80 . Shank portion  65  also may include one or more angel wings  82  and a root structure  84  such as a dovetail and the like. Root structure  84  may be configured to secure, with other structure, turbine blade  55  to shaft  45  ( FIG. 1 ). Any number of turbine blades  55  may be circumferentially arranged about shaft  45 . Other components and or configurations also may be used herein. 
     Turbine blade  55  may include one or more cooling circuits  86  extending therethrough for flowing a cooling medium  88  such as air from compressor  15  ( FIG. 1 ) or from another source. Steam and other types of cooling mediums  88  also may be used herein. Cooling circuits  86  and cooling medium  88  may circulate at least through portions of airfoil  60 , shank portion  65 , and platform  70  in any order, direction, or route. Many different types of cooling circuits and cooling mediums may be used herein in any orientation. Cooling circuits  86  may lead to a number of cooling holes  90  or other types of cooling pathways for film cooling about airfoil  60  or elsewhere. Other types of cooling methods may be used. Other components and or configurations also may be used herein. 
       FIGS. 3-8  show an example of a portion of an HGP component  100  as may be described herein.  FIG. 3  is a perspective view of HGP component  100  without a thermal barrier coating (TBC) thereon,  FIG. 4  is a perspective view of HGP component  100  with a TBC  102  thereon, and  FIGS. 5-8  are cross-sectional views of a portion of HGP component without TBC  102 . In this example, HGP component  100  may be an airfoil  110  and more particularly a sidewall thereof. HGP component  100  may be a part of a blade or a vane and the like. HGP component  100  also may be any type of air-cooled component including a shank, a platform, or any other type of hot gas path component of a blade or vane. As noted, other types of HGP components and other configurations may be used herein. Similar to that described above, airfoil  110  may include a leading edge  120  and a trailing edge  130 . Likewise, airfoil  110  may include a pressure side  140  and a suction side  150 . 
     Airfoil  110  also may include one or more internal cooling circuits  160  ( FIGS. 3 and 5 ) therein. As shown in phantom in  FIG. 3  and shown in cross-section in  FIGS. 5 and 7 , internal cooling circuits  160  may lead to a number of open cooling pathways  170  such as a number of cooling holes  175 . A variety of internal cooling circuits  160  may be employed, not all of which are shown. Cooling holes  175  may extend through an outer surface  180  of airfoil  110  or elsewhere. Outer surface  180  is exposed to a working fluid having a high temperature in HGP  56 . As used herein, “high temperature” depends on the form of industrial machine, e.g., for gas turbine system  10 , high temperature may be any temperature greater than 100° C. Internal cooling circuits  160  and cooling holes  175  serve to cool airfoil  110  and components thereof with a cooling medium  190  ( FIG. 5 ) therein. Any type of cooling medium  190 , such as air, steam, and the like, may be used herein from any source. While one common source of cooling medium  190  is shown, one or more sources may be employed. Cooling holes  175  may have any size, shape, or configuration. Any number of cooling holes  175  may be used herein. Cooling holes  175  may extend to outer surface  180  in an orthogonal or non-orthogonal manner. Other types of open cooling pathways  170  may be used herein. Other components and or configurations may be used herein. 
     As shown in  FIG. 3-4 , HGP component  100 , e.g., airfoil  110 , also may include a number of other adaptively opening cooling pathways  200  including: a primary cooling pathway  202  and a backup, secondary cooling pathway  204  (hereinafter “secondary cooling pathway  204 ”) according to embodiments of the disclosure. As will be described herein, secondary cooling pathway  204  may, in certain embodiments, include a plurality of interconnected secondary cooling pathways  204 , i.e., they are fluidly communicative with one another. Similarly, primary cooling pathway  202  may include a plurality of primary cooling pathways  202  that may or may not be interconnected. HGP component  100  may include a body  112 , e.g., sidewall of airfoil  110 , including outer surface  180 . Internal cooling circuit  160  and pathways  200  may be in body  112  carrying cooling medium  190 . While internal cooling circuit  160  will be described herein and generally shown as a singular circuit or pathway, it is understood that the circuit may be duplicated and that pathways  202 ,  204  as shown may be coupled to the same internal cooling circuit or different internal cooling circuits. Cooling pathways  200  may have any size, shape (e.g., circular, round, polygonal, etc.), or configuration. In one embodiment, cooling pathways  200  may have a dimension of approximately 0.25 millimeters (mm) to 2.5 mm, and nominally, approximately 0.76 mm to 1.52 mm. In one embodiment, primary and secondary cooling pathways  202 ,  204  may have different sizes, e.g., secondary cooling pathway  204  may be smaller than primary cooling pathway  202 . (See e.g.,  FIGS. 6 and 8 ) In one embodiment, cooling pathways  200  have a circular cross-section. 
     As shown for example in  FIGS. 5-8 , cooling pathways  200  are positioned internally from outer surface  180 . Primary cooling pathway  202  may extend along and may be spaced internally from outer surface  180  in a substantially consistent manner such that primary cooling pathway  202  extends parallel along and internally from outer surface  102 , e.g., within +/−1-3° variance.  FIGS. 5 and 6  show primary cooling pathway  202  and secondary cooling pathway  204  aligned relative to outer surface  180  (i.e., over one another as viewed perpendicularly from outer surface  180 ), while  FIGS. 7 and 8  shows primary cooling pathway  202  and secondary cooling pathway  204  laterally offset relative to one another (i.e., into and out of page in  FIG. 7 ) so they are not aligned relative to outer surface  180 . Hence, primary cooling pathway  202  is shown in phantom in  FIG. 7 .  FIG. 6  shows the same portion of HGP component  100  from  FIG. 5  in a lateral cross-section (perpendicular to longitudinal cross-section of  FIG. 5 ). 
     As shown in  FIGS. 5 and 6 , primary cooling pathway  202  may be parallel with secondary cooling pathway  204 . Further, primary cooling pathway  202  is aligned with secondary cooling pathway  204  relative to outer surface  180 , i.e., directly over one another as viewed perpendicular to outer surface  180 . In contrast, as shown in  FIG. 8 , primary cooling pathway  202  and secondary cooling pathway  204  may be parallel with each other but laterally offset from one another. That is, they may be not be over one another along their lengths  212  relative to outer surface  180 , i.e., they are not directly over one another as viewed perpendicular to outer surface  180 . In any event, primary cooling pathway  202  may be positioned internally at a first spacing D 1  from outer surface  180 , and secondary cooling pathway  204  may be positioned internally at a secondary spacing D 2  from outer surface  180 . In one embodiment, second spacing D 2  may be approximately 0.25 mm to 3.56 mm, and nominally, approximately 0.51 mm to 1.52 mm, and first spacing D 1  may be approximately 0.12 mm to 1.27 mm, and nominally, approximately 1.02 mm. In any event, first spacing D 1  is less than second spacing D 2 . In the  FIGS. 5-8  embodiments, first spacing D 1  and second spacing D 2  are substantially consistent along lengths  212  such that cooling pathways  200  extends parallel along and internally from outer surface  180 . In other embodiments, some variation of first and second spacing D 1 , D 2  may be possible to accommodate structural variations such as but not limited to: a varied shape of outer surface  180 , surface roughness of outer surface  180 , variation of cooling pathways  200  as they progress through body  112 , other internal structure that must be routed around, etc. First spacing D 1  can vary so long as it is sufficiently thin to allow for opening of body  112  to outer surface  180  at a location when necessary, as will be described herein. Similarly, second spacing D 2 , and more particularly, a third spacing D 3  between primary cooling pathway  202  and secondary cooling pathway  204 , can vary. For example, second spacing D 2  can be sized sufficiently thin to allow for opening of body  112  from secondary cooling pathway  204  to outer surface  180  when necessary. Further, third spacing D 3  can be sized sufficiently thin to allow for opening of body  112  at a location within primary cooling pathway  202  when necessary, i.e., from primary cooling pathway  202  to secondary cooling pathway  204 . In one embodiment, third spacing D 3  may be approximately 0.13 mm to 1.54 mm, and nominally, approximately 0.51 mm. 
     In one embodiment, as shown in  FIGS. 5 and 7 , primary cooling pathway  202  extend towards outer surface  180  and is open to outer surface  180  (including any TBC) at an open end  210  in a manner similar to cooling holes  175 . However, primary cooling pathway  202  need not exit through outer surface  180  in all instances, i.e., it could simply supply another cooling pathway. In contrast, as shown in  FIGS. 5 and 7 , each second cooling pathway  204  may connect at both ends  211 ,  213  to internal cooling circuit  160 . Alternatively, only one end  211  or  213  may be coupled to internal cooling circuit  160 , and the other end may terminate at a terminating end  215  (see e.g.,  FIGS. 11 and 18 ) in body  112 . Secondary cooling pathways  204  are not open through outer surface  180 , when constructed. Thus, secondary cooling pathways  204  are distinguishable from open cooling pathways  170  and cooling holes  175  that are permanently open to outer surface  180 . Lengths  212  of either pathway  202 ,  204  can be any distance desired. As will be described herein, any number of cooling pathways  200  may be used herein, and they can extend in any direction and have any orientation within HGP component  100 . In any event, cooling medium  190  does not flow through secondary cooling pathway  204  until an overheating event creates a first opening  230  to allowing flow therethrough. Consequently, as will be described further herein, a primary flow  192  (e.g.,  FIG. 5 ) of cooling medium  190  may flow in primary cooling pathway  202  prior to an overheating event, but a secondary flow  194  (e.g.,  FIGS. 13-20 ) of cooling medium  190  may not flow in secondary cooling pathway  204  until after an overheating event. 
     With reference to  FIGS. 5 and 7 , each cooling pathway  200  may include a length  212  extending along and spaced internally from outer surface  180 . An additional connecting cooling pathway  214  may also fluidly couple cooling pathways  200 , i.e., lengths  212 , to internal cooling circuit(s)  160 , but this segment may not be necessary depending on the location of internal cooling circuit(s)  160 . (While internal cooling circuit  160  is labeled as one circuit or pathway herein, it is understood that it may include any number of cooling medium circuits or pathways). 
     It is emphasized that  FIGS. 5-8  show just a couple of embodiments of how primary and secondary cooling pathways  202 ,  204  can be arranged for initial description purposes. Practically any arrangement in which secondary cooling pathways  204  can open to outer surface  180  and/or secondary cooling pathways  202  are possible. In the latter case, primary cooling pathway  202  and secondary cooling pathway  204  can overlap so that secondary cooling pathway  204  can open to primary cooling pathway  202  alone, or to primary cooling pathway  202  and outer surface. Practically any arrangement in which pathways  202 ,  204  overlap such that an opening from secondary cooling pathway  204  can open to outer surface  180  and/or primary cooling pathway  202  is within the scope of the disclosure. 
     To further illustrate,  FIGS. 9-12  show schematic plan views of various arrangements of primary cooling pathway  202  relative to secondary cooling pathways  204 . It is emphasized that the examples shown are not comprehensive and that a large variety of alternatives may be possible. In  FIGS. 9-12 , primary cooling pathways  202  are shown with solid lines and secondary cooling pathways  204  are shown with dashed lines. Potential locations for internal cooling circuit  160  to cooling pathways  200  are shown with circles or ovals, and terminating ends  215  ( FIG. 11 ) are shown with dots. Any number of internal cooling circuits  160  may couple to cooling pathways  200 , e.g., one for both, one for each, more than one for each, etc. In any of the embodiments, secondary cooling pathway(s)  204  is spaced internally from primary cooling pathway  202 , as in  FIGS. 5-8 . 
       FIG. 9  shows an embodiment in which secondary cooling pathway  204  includes a plurality of secondary cooling pathways  204 A-D and the primary cooling pathway  202  includes a plurality of primary cooling pathways  202 A-D. Each of the pluralities may include any number of pathways. In any event, plurality of secondary cooling pathways  204  are spaced internally from plurality of primary cooling pathways  202 , as in  FIGS. 5-8 . Here as in other embodiments, secondary cooling pathway  204  does not parallel primary cooling pathway  202 . Rather, they cross under/over one another. 
       FIG. 10  shows an embodiment in which each cooling pathway  202 ,  204  are laid out in a sinusoidal pattern, but in a perpendicular manner to one another.  FIG. 11  shows an embodiment in which a plurality of interconnected secondary cooling pathways  204 A-K and a plurality of primary cooling pathways  202 A-E are provided. Interconnected secondary cooling pathways  202 A-K are spaced internally from plurality of primary cooling pathways  202 A-E and can feed secondary flow  194  of cooling medium  190  to at least one of the outer surface  180  and at least one of plurality of primary cooling pathways  202 A-E. In the example shown, plurality of secondary cooling pathways  204  are arranged in a net shape internally of plurality of primary cooling pathways  202 . That is, secondary cooling pathways  204  include a set of pathways  204 A-G that extend in a first direction (e.g., up/down page) and another set of pathways  204 H-K that extend in a perpendicular second direction (e.g., across page). In one embodiment, set of secondary cooling pathways  204 A-K are fluidly interconnected at their junctions  232  such that the same secondary flow  194  is in all of them and such that if one opens, they all feed to that opening. In this case, while all of the secondary cooling pathways  204 A-K are shown fluidly coupled to a respective internal cooling circuit  160 , only one of them need be so connected. In another embodiment, secondary cooling pathways  204 A-K do not join together at junctions  232  but are all separately coupled to an internal cooling circuit  160 . In  FIG. 11 , secondary cooling pathways  204  cross primary cooling pathways  202 , i.e., secondary pathways  204  pass under but are not fluidly communicative with and do not intersect primary pathways  202 . Here also, certain secondary cooling pathway(s), e.g.,  204 H-K, are laterally offset from and parallel primary cooling pathway(s)  204 . (This structure is similar to that of  FIGS. 7-8 ). In this case, it is possible for a first opening  230  to occur from outer surface  180  directly to secondary cooling pathway  204  where a temperature exceeds the predetermined temperature of body  112 , bypassing primary cooling pathway  202 . While a net shape has been illustrated in  FIG. 11 , pathways  200  can have any two dimensional or three dimensional arrangement necessary to provide the desired cooling, e.g., webbed, rounded, helical, etc. While arrangements are shown with plural cooling pathways  202 ,  204 , as shown in one example in  FIG. 11 , any of the arrangements can be implemented using one or more primary cooling pathways  202  and/or one or more secondary cooling pathways  204 . Further, cooling pathways  202 ,  204  need not meet at perpendicular angles, and need not be linear. In arrangements where a number of cooling pathways  202 ,  204  are used, spacing between adjacent pathways need not be equal. 
       FIG. 12  shows an embodiment in which a secondary cooling pathway  204  crosses (under) a primary cooling pathway  202  at a non-perpendicular angle. That is, secondary cooling pathway(s)  204  does not parallel (nor is perpendicular) to primary cooling pathway(s)  202 .  FIG. 12  also shows an embodiment including a single primary cooling pathway  202  over a plurality of secondary cooling pathways  204 . As noted, the teachings of the disclosure can be applied where there is a plurality of both cooling pathways  202 ,  204 , or just a plurality of one of them and a single version of the other. 
     Cooling pathways  200 , i.e., at least portions of outer surface  180 , may optionally include a thermal barrier coating (TBC)  102  thereover.  FIGS. 3, 5-8 and 13-18  show embodiments that do not include TBC  102 , and  FIGS. 4, 19 and 20  show embodiments that include TBC  102 . As shown in  FIGS. 4, 19 and 20 , in contrast to cooling holes  175  ( FIG. 3 ), TBC  102  is positioned over outer surface  180  in at least a portion of HGP component  100  to cover cooling pathways  200 . Open ends  210  of primary cooling pathway  202 , when provided, may extend through TBC  102 . When employed, TBC  102  extends over outer surface  180 , and is exposed to HGP  56  including a working fluid having a high temperature, as previously noted. TBC  102  may include any now known or later developed layers of materials configured to protect outer surface  180  from thermal damage (e.g., creep, thermal fatigue cracking and/or oxidation) such as but not limited to: zirconia, yttria-stabilized zirconia, a noble metal-aluminide such as platinum aluminide, MCrAlY alloy in which M may be cobalt, nickel or cobalt-nickel alloy. TBC  102  may include multiple layers such as but not limited to a bond coat under a thermal barrier layer. 
     According to embodiments of the disclosure, in response to an overheating event occurring, secondary cooling pathway  204  opens at first opening  230  to at least one of outer surface  180  and primary cooling pathway  202  to allow a secondary flow  194  of cooling medium  190  through from secondary cooling pathway  204 . Secondary flow  194  acts to cool the overheating area and possibly downstream areas, e.g., in or around outer surface  180  and/or primary cooling pathway  202 . A location  224  (e.g.,  FIG. 13 ) at which an opening occurs may be at, near or distanced from the cause of an overheating event and may be anywhere along lengths  212  of cooling pathways  200 . In this fashion, even though the exact positioning of on overheating event cannot be accurately predicted, secondary cooling pathway  204  can provide adequate cooling over length  212 . Further, with regard to primary cooling pathway  202 , location  224  can be at any location about primary cooling pathway  202 , e.g., above, below, within, to the side, etc. 
     An “overheating event” may take a number of forms according to embodiments of the disclosure. In one embodiment, the overheating event may include a temperature at a location reaching or exceeding a predetermined temperature of body  112 , causing an opening(s) to form from secondary cooling pathway  204  to provide a secondary flow  194  of cooling medium  190 , e.g., to primary cooling pathway  202  and/or outer surface  180 . As will be described, an opening may form from secondary cooling pathway  204  at, near or distant from the location of the overheating event. As used herein, the “predetermined temperature of body  112 ” is a temperature at which body  112  will change state in such a way as to allow its removal to create an opening, e.g., through sublimation, ashing, cracking, or melting thereof. That is, the high temperature causes a deterioration, or removal of a portion of body  112  at, near or distant from the overheating event, creating an opening, e.g., first opening  230  from secondary cooling pathway  204  allowing a secondary flow  194  of cooling medium  190  therethrough. The overheating event may have a variety of different causes such as but not limited to an at least partial blockage of a cooling pathway, a reduced cooling medium flow in a cooling pathway for reasons other than a blockage, or simply an unanticipated overheating area. In addition, in any of the embodiments described herein, an amount of overheating can determine a size of opening(s), which automatically provides increased cooling for higher temperatures and less cooling for lower temperatures. 
     Reference will now be made to  FIGS. 13-20  to describe a variety of illustrative overheating events and ways in which secondary cooling pathway  204  may operate to provide adaptive, backup cooling. 
     In  FIGS. 13-15 , an overheating event is illustrated as an at least partial blockage  223  of primary cooling pathway  202 , e.g., by a collapse, clog or other failure, causing an at least reduced primary flow  192 ′ of cooling medium  190 .  FIGS. 13-15  show this form of overheating event relative to the  FIGS. 5 and 6  embodiments (with aligned pathways  202 ,  204 ); it is emphasized however that teachings of  FIGS. 13-15  are equally applicable to the  FIGS. 7 and 8  embodiments (laterally offset pathways  202 ,  204 ). Here, the overheating event includes a temperature in primary cooling pathway  202  reaching or exceeding the predetermined temperature of body  112  causing secondary cooling pathway  204  to open at first opening  230  (at or near blockage  223 ) to primary cooling pathway  202 , allowing secondary flow  194  of cooling medium  190  through to at least primary cooling pathway  202 .  FIG. 13  shows one example in which the overheating event creates only a first opening  230  (downstream of blockage  223 ) from secondary cooling pathway  204  to primary cooling pathway  202 , allowing a secondary flow  194  of cooling medium  190  to provide cooling to primary cooling pathway  202  downstream of the at least partial blockage  223 .  FIG. 14  shows another example, similar to  FIG. 13 , but in which not just first opening  230  is formed, but also a second opening  231  forms from primary cooling pathway  202  to outer surface  180 . In this case, the overheating event includes a temperature of outer surface  180  over primary cooling pathway  202  reaching or exceeding a predetermined temperature of body  112  causing primary cooling pathway  202  to open at second opening  231  to outer surface  180 , and a temperature in the open primary cooling pathway  202  reaching or exceeding the predetermined temperature of body  112  causing secondary cooling pathway  204  to open at first opening  230  to primary cooling pathway  202 , allowing secondary flow  194  of cooling medium through to  180  outer surface and primary cooling pathway  202 . Here, exposure of primary cooling pathway  202  to HGP  56 , despite primary flow  192  of cooling medium  190  flowing through second opening  231 , will still create a further unanticipated hot spot within third spacing D 3  (i.e., inner wall of primary cooling pathway  202 ). Where the temperature in open primary cooling pathway  202  reaches or exceeds the predetermined temperature of body  112 , secondary cooling pathway  204  may open at first opening  230  in open primary cooling pathway  202  to allow secondary flow  194  of cooling medium  190  therethrough to provide additional cooling. That is, the continuing high temperature of HGP  56  causes a deterioration, or removal of third spacing D 3 , creating first opening  230  to secondary cooling pathway  204  allowing a secondary flow  194  of cooling medium  190  therethrough. In addition, an amount of overheating can determine a size of first opening  230  to secondary cooling pathway  204 , which automatically provides increased cooling for higher temperatures and less cooling for lower temperatures. In this embodiment, either opening  230 ,  231  may occur first. In another alternative embodiment, first opening  230  may occur alone, i.e., the overheating event in the form of at least partial blockage  223  includes a temperature of outer surface  180  over primary cooling pathway  202  reaching or exceeding a predetermined temperature of body  112  causing second cooling pathway  204  to open directly to outer surface  180  (see e.g.,  FIGS. 17 and 19 ). This latter embodiment is more likely to occur relative to the laterally offset configurations of  FIGS. 7 and 8 . 
     In  FIG. 15 , the overheating event also includes at least partial blockage  223 , but openings  230 ,  231  occur upstream of the at least partial blockage  223 . In  FIGS. 14-15 , since primary cooling pathway  202  and secondary cooling pathway  204  are aligned, the locations of second opening  231  may be over first opening  230 , i.e., that is the locations of openings  230 ,  231  are aligned relative to outer surface  180 . That may not be the case in all instances, e.g., see  FIG. 18 . 
     As shown in  FIG. 16 , the overheating event may also simply include an unexpected hot spot  227 . That is, a location of the overheating event is an area that does not appear to have any damage, but has a high temperature exceeding the predetermined temperature of body  112 . Unexpected hot spot  227  may be, for example, the result of primary cooling pathway  202  or surrounding structure not having been designed to accommodate a higher than expected temperature. While  FIG. 16  has been shown only creating first opening  230  from secondary cooling pathway  204  to primary cooling pathway  202 , it is understood that second opening  231  from primary cooling pathway  202  to outer surface  180 , as in  FIGS. 14 and 15 , could also be formed with this type of overheating event. Indeed, either of the  FIGS. 14-15  embodiments are possible with an overheating event as described relative to  FIG. 16 . 
       FIG. 17  shows an embodiment in which primary and secondary cooling pathways  202 ,  204  are not aligned. While shown as perpendicular to one another, like in  FIG. 9 or 10 , cooling pathways  202 ,  204  could also be laterally offset (like secondary cooling pathways  204 H-K relative to primary cooling pathways  202 A-E in  FIG. 11 ) or are otherwise not aligned (like in any of  FIGS. 9-12 ). In this case, overheating event includes a temperature of outer surface  180  over secondary cooling pathway  204  reaching or exceeding a predetermined temperature of body  112  causing secondary cooling pathway  204  to open at first opening  230  to outer surface  180 , directing at least a portion of secondary flow  194  of cooling medium  190  therethrough. That is, secondary cooling pathway  204  opens directly to outer surface  180  through second spacing D 2 . In this fashion, overheating events that occur at locations where primary cooling pathways  202  are not present can still be adaptively cooled using secondary flow  194  of cooling medium  190 . 
     As described relative to  FIGS. 14 and 15 , in some embodiments, first opening  230  and second opening  231  may be aligned relative to outer surface  180  and relative to one another. It is emphasized however that opening  230 ,  231  alignment may not occur in all instances as the locations at which one opening occurs may not cause the other opening to be aligned. As illustrated in  FIG. 18 , for example, second opening  231  is not aligned with first opening  230  relative to outer surface  180 . For example, first opening  230  may be downstream of second opening  231  to outer surface  180  because the overheating event includes a sub-event that occurs downstream from where a portion of primary flow  192  is escaping through outer surface  180 . ( FIG. 18  also shows a secondary cooling pathway that terminates at a terminating end  215  within body  112 ). In other examples, as shown best by  FIG. 15 , first and second openings  230 ,  231  may be offset from each other relative to the plane of the page, or angularly offset from one another relative to primary cooling pathway  202 . 
       FIGS. 19 and 20  show embodiments of the disclosure including TBC  102  over outer surface  180 . That is, TBC  102  is over at least a portion of outer surface  180 , and TBC  102  is exposed to the working fluid having the high temperature in HGP  56 . Here, the overheating event may include the temperature of outer surface  180  reaching or exceeding the predetermined temperature of body  112  in response to a spall  222  occurring in TBC  102 . Spall  222  may include any change in TBC  102  creating a thermal path to outer surface  180  from HGP  56  not previously present, e.g., a break or crack in, or displacement. In one embodiment, spall  222  may have a dimension of approximately 6 mm diameter. When spall  222  occurs, outer surface  180  would normally be exposed to the high temperatures and other extreme environments of HGP  56 , where prior to spall  222  occurring outer surface  180  was protected by TBC  102 . 
     TBC  102  may be applied to any embodiment described herein.  FIGS. 19-20  show a couple of examples of overheating events with a TBC  102  that are similar to those of  FIGS. 17 and 14 , respectively. As shown in  FIG. 19 , in response to spall  222  in TBC  102  occurring over secondary cooling pathway  204  and the temperature reaching or exceeding a predetermined temperature of body  112 , secondary cooling pathway  204  opens at first opening  230  directly to outer surface  180  to allow secondary flow  194  of cooling medium  190  therethrough. That is, because internal cooling circuit(s)  160  are fluidly coupled to secondary cooling pathway  204 , secondary flow  194  of cooling medium  190  passes through first opening  230  and serves to cool airfoil  110  and body  112  and components thereof, despite spall  222 . As noted, any type of cooling medium  190 , such air, steam, and the like, may be used herein from any source. First opening  230  may be anywhere along length  212  of secondary cooling pathway  204 . In this fashion, even though the exact positioning of spall  222  cannot be accurately predicted, cooling pathway  200  can provide adequate cooling over length  212 . In addition, an extent of spall  222  determines a size of first opening  230  in secondary cooling pathway  204 , which automatically provides increased cooling for larger spalls  222  (larger opening) and less cooling for smaller spalls  222  (smaller openings  230 ). 
     Referring to  FIG. 20 , and similar to operation described relative  FIG. 14 , in response to a temperature of outer surface  180  reaching or exceeding a predetermined temperature of body  112  due to a spall  222  in TBC  102 , primary cooling pathway  202  may open at second opening  231 . Further, in response to a temperature of open primary cooling pathway  202  reaching or exceeding a predetermined temperature of body  112 , secondary cooling pathway  204  may open at first opening  230  to primary cooling pathway  202  to allow secondary flow  194  of cooling medium therethrough. In this example, first and second openings  230 ,  231  are aligned relative to outer surface  180 , but as noted herein they may not be aligned. In one example, as shown in  FIG. 20 , exposure of primary cooling pathway  202  to HGP  56 , despite primary flow  192  of cooling medium  190  flowing through second opening  231 , will still create a further unanticipated hot spot within third spacing D 3  (i.e., inner wall of primary cooling pathway  202 ). Where temperature in open primary cooling pathway  204  reaches or exceeds the predetermined temperature of body  112 , secondary cooling pathway  204  opens at second opening  231  in open primary cooling pathway  202  to allow secondary flow  194  of cooling medium  190  therethrough to provide additional cooling. An amount of overheating can determine a size of first opening  230  to secondary cooling pathway  204 , which automatically provides increased cooling for higher temperatures and less cooling for lower temperatures. In another alternative embodiment, first opening  230  may occur alone, i.e., the overheating event in the form of spall  22  may include a temperature of outer surface  180  over primary cooling pathway  202  reaching or exceeding a predetermined temperature of body  112  causing second cooling pathway  204  to open directly to outer surface  180 . This latter embodiment is more likely to occur relative to the laterally offset configurations of  FIGS. 7 and 8 . 
     In any of the embodiments described herein, an amount of overheating can determine a size of opening(s)  230 ,  231 , which automatically provides increased cooling for higher temperatures and less cooling for lower temperatures. While singular first openings  230  and singular second openings  231  have been illustrated, it is understood that each may include more than one opening of its type where the overheating event dictates. Further, while different overheating events have been described separately herein, it is understood that an overheating event may include one or more of the types of events described herein. While  FIGS. 13-18  have been described with no TBC  102  and  FIGS. 19-20  have been described relative to a TBC  102 , it is recognized that the various embodiments may be applied whether a TBC is present or not. Further, the different embodiments of HGP component  100  are not mutually exclusive to the particular examples as shown in the drawings. Features described herein can be taken from other embodiments and combined where necessary in a manner other than that explicitly described. 
     HGP component  100  and cooling pathways  200  may be constructed entirely using conventional techniques, e.g., casting, machining, etc. Referring to  FIG. 21 , in accordance with embodiments of the disclosure, HGP component  100  and cooling pathways  200  may be additively manufactured. Additive manufacturing also allows for easy formation of much of the structure described herein, i.e., without very complex machining. As used herein, additive manufacturing (AM) may include any process of producing an object through the successive layering of material rather than the removal of material, which is the case with conventional processes. Additive manufacturing can create complex geometries without the use of any sort of tools, molds or fixtures, and with little or no waste material. Instead of machining components from solid billets of plastic or metal, much of which is cut away and discarded, the only material used in additive manufacturing is what is required to shape the part. Additive manufacturing processes may include but are not limited to: 3D printing, rapid prototyping (RP), direct digital manufacturing (DDM), binder jetting, selective laser melting (SLM) and direct metal laser melting (DMLM). 
     To illustrate an example of an additive manufacturing process,  FIG. 21  shows a schematic/block view of an illustrative computerized additive manufacturing system  500  for generating an object  502 , i.e., HGP component  100 . In this example, system  500  is arranged for DMLM. It is understood that the general teachings of the disclosure are equally applicable to other forms of additive manufacturing. AM system  500  generally includes a computerized additive manufacturing (AM) control system  504  and an AM printer  506 . AM system  500 , as will be described, executes code  520  that includes a set of computer-executable instructions defining HGP component  100  ( FIGS. 5-20 ) and cooling pathways  200 , to physically generate the component using AM printer  506 . Each AM process may use different raw materials in the form of, for example, fine-grain powder, liquid (e.g., polymers), sheet, etc., a stock of which may be held in a chamber  510  of AM printer  506 . In the instant case, HGP component  100  ( FIGS. 5-20 ) may be made of metal powder or similar materials. As illustrated, an applicator  512  may create a thin layer of raw material  514  spread out as the blank canvas from which each successive slice of the final object will be created. In other cases, applicator  512  may directly apply or print the next layer onto a previous layer as defined by code  520 , e.g., where the material is a polymer or where a metal binder jetting process is used. In the example shown, a laser or electron beam  516  fuses particles for each slice, as defined by code  520 , but this may not be necessary where a quick setting liquid plastic/polymer is employed. Various parts of AM printer  506  may move to accommodate the addition of each new layer, e.g., a build platform  518  may lower and/or chamber  510  and/or applicator  512  may rise after each layer. 
     AM control system  504  is shown implemented on computer  530  as computer program code. To this extent, computer  530  is shown including a memory  532 , a processor  534 , an input/output (I/O) interface  536 , and a bus  538 . Further, computer  530  is shown in communication with an external I/O device  540  and a storage system  542 . In general, processor  534  executes computer program code, such as AM control system  504 , that is stored in memory  532  and/or storage system  542  under instructions from code  520  representative of HGP component  100  ( FIGS. 5-20 ), described herein. While executing computer program code, processor  534  can read and/or write data to/from memory  532 , storage system  542 , I/O device  540  and/or AM printer  506 . Bus  538  provides a communication link between each of the components in computer  530 , and I/O device  540  can comprise any device that enables a user to interact with computer  530  (e.g., keyboard, pointing device, display, etc.). Computer  530  is only representative of various possible combinations of hardware and software. For example, processor  534  may comprise a single processing unit, or be distributed across one or more processing units in one or more locations, e.g., on a client and server. Similarly, memory  532  and/or storage system  542  may reside at one or more physical locations. Memory  532  and/or storage system  542  can comprise any combination of various types of non-transitory computer readable storage medium including magnetic media, optical media, random access memory (RAM), read only memory (ROM), etc. Computer  530  can comprise any type of computing device such as a network server, a desktop computer, a laptop, a handheld device, a mobile phone, a pager, a personal data assistant, etc. 
     Additive manufacturing processes begin with a non-transitory computer readable storage medium (e.g., memory  532 , storage system  542 , etc.) storing code  520  representative of HGP component  100  ( FIGS. 5-20 ). As noted, code  520  includes a set of computer-executable instructions defining object  502  that can be used to physically generate the object, upon execution of the code by system  500 . For example, code  520  may include a precisely defined 3D model of HGP component  100  ( FIGS. 5-20 ) and can be generated from any of a large variety of well-known computer aided design (CAD) software systems such as AutoCAD®, TurboCAD®, DesignCAD 3D Max, etc. In this regard, code  520  can take any now known or later developed file format. For example, code  520  may be in the Standard Tessellation Language (STL) which was created for stereolithography CAD programs of 3D Systems, or an additive manufacturing file (AMF), which is an American Society of Mechanical Engineers (ASME) standard that is an extensible markup-language (XML) based format designed to allow any CAD software to describe the shape and composition of any three-dimensional object to be fabricated on any AM printer. Code  520  may be translated between different formats, converted into a set of data signals and transmitted, received as a set of data signals and converted to code, stored, etc., as necessary. Code  520  may be an input to system  500  and may come from a part designer, an intellectual property (IP) provider, a design company, the operator or owner of system  500 , or from other sources. In any event, AM control system  504  executes code  520 , dividing HGP component  100  ( FIGS. 5-20 ) into a series of thin slices that it assembles using AM printer  506  in successive layers of liquid, powder, sheet or other material. In the DMLM example, each layer is melted to the exact geometry defined by code  520  and fused to the preceding layer. 
     Subsequent to additive manufacture, HGP component  100  ( FIGS. 5-20 ) may be exposed to any variety of finishing processes, e.g., minor machining, sealing, polishing, assembly to another part, etc. 
     In terms of the present disclosure, regardless of the manufacturing techniques used, TBC  102  may be optionally applied to outer surface  180  of HGP component  100  and over cooling pathways  200 . TBC  102  may be applied using any now known or later developed coating techniques, and may be applied in any number of layers. 
     HGP component  100  according to embodiments of the disclosure provides cooling pathways  200  that only open in a location where unanticipated overheating above a predetermined temperature of body  112  is observed. The use of primary cooling pathway  202  backed up by secondary cooling pathway  202 , where necessary, allows for cooling of overheating locations in an adaptive, autonomous manner and prevents overheating event to the underlying metal, which may significantly reduce nominal cooling flows. As noted relative to  FIGS. 17 and 19 , where secondary cooling pathway  204  is offset from primary cooling pathway  202 , so it may alone provide cooling of overheating locations in an adaptive, autonomous manner and prevent damage to the underlying metal, which may significantly reduce nominal cooling flows. The temperatures reached, the size of spall  222  and/or previously formed openings (e.g., second openings  231  in  FIG. 20 ) may dictate the size of the opening(s) created, and hence the amount of cooling. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not. 
     Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. “Approximately” as applied to a particular value of a range applies to both values, and unless otherwise dependent on the precision of the instrument measuring the value, may indicate +/−10% of the stated value(s). 
     The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiment was chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.