Patent Publication Number: US-2021172337-A1

Title: Turbine vane with dust tolerant cooling system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 16/035,173 filed on Jul. 13, 2018. The relevant disclosure of the above application is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to gas turbine engines, and more particularly relates to a turbine vane having a dust tolerant cooling system associated with a turbine of the gas turbine engine. 
     BACKGROUND 
     Gas turbine engines may be employed to power various devices. For example, a gas turbine engine may be employed to power a mobile platform, such as an aircraft. Gas turbine engines employ a combustion chamber upstream from one or more turbines, and as high temperature gases from the combustion chamber are directed into these turbines these high temperature gases contact downstream airfoils, such as the airfoils of a turbine vane. Typically, the leading edge of these airfoils experiences the full effect of the high temperature gases, which may increase the risk of oxidation of the leading edge. As higher turbine inlet temperature and higher turbine engine speed are required to improve gas turbine engine efficiency, additional cooling of the leading edge of these airfoils is needed to reduce a risk of oxidation of these airfoils associated with the gas turbine engine. 
     Further, in the example of the gas turbine engine powering a mobile platform, certain operating environments, such as desert operating environments, may cause the gas turbine engine to ingest fine sand and dust particles. These ingested fine sand and dust particles may pass through portions of the gas turbine engine and may accumulate in stagnation regions of cooling circuits within turbine components, such as the airfoils of the turbine vane. The accumulation of the fine sand and dust particles in the stagnation regions of the cooling circuits in the turbine components, such as the airfoil, may impede the cooling of the airfoil, which in turn, may reduce the life of the airfoil leading to increased repair costs and downtime for the gas turbine engine. 
     Accordingly, it is desirable to provide improved cooling for an airfoil of a turbine vane with a dust tolerant cooling system that reduces the accumulation of fine sand and dust particles while cooling the airfoil in the leading edge region of the airfoil, for example. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
     SUMMARY 
     According to various embodiments, provided is a turbine vane. The turbine vane includes an airfoil that extends from an inner diameter to an outer diameter, and from a leading edge to a trailing edge. The turbine vane includes an inner platform coupled to the airfoil at the inner diameter. The turbine vane includes a cooling system defined in the airfoil including a first conduit in proximity to the leading edge to cool the leading edge and a second conduit to cool the trailing edge. The first conduit has an inlet at the outer diameter to receive a cooling fluid and an outlet portion that is defined at least partially through the inner platform. The first conduit includes a plurality of cooling features that extend between a first surface and a second surface of the first conduit, and the first surface of the first conduit is opposite the leading edge. 
     Also provided is a turbine vane. The turbine vane includes an airfoil that extends from an inner diameter to an outer diameter, and from a leading edge to a trailing edge. The turbine vane includes an inner platform coupled to the airfoil at the inner diameter, and an outer platform coupled to the airfoil at the outer diameter. The outer platform is in fluid communication with a source of cooling fluid. The turbine vane includes a cooling system defined in the airfoil including a first conduit in proximity to the leading edge to cool the leading edge and a second conduit to cool the trailing edge. The first conduit has an inlet at the outer diameter to receive the cooling fluid and an outlet portion that diverges within the airfoil into at least two flow paths, and one of the at least two flow paths is defined at least partially within the inner platform. The first conduit includes a plurality of cooling features that extend between a first surface and a second surface of the first conduit, and the first surface of the first conduit is opposite the leading edge. 
     Further provided is a turbine vane. The turbine vane includes an airfoil that extends from an inner diameter to an outer diameter, and from a leading edge to a trailing edge. The turbine vane includes an inner platform coupled to the airfoil at the inner diameter, and an outer platform coupled to the airfoil at the outer diameter. The outer platform is in fluid communication with a source of cooling fluid. The turbine vane includes a cooling system defined in the airfoil including a first conduit in proximity to the leading edge to cool the leading edge and a second conduit to cool the trailing edge. The first conduit has an inlet at the outer diameter to receive the cooling fluid and an outlet portion that is defined at least partially through the inner platform. The first conduit includes a plurality of cooling pins that extend between a first surface and a second surface of the first conduit, and the first surface of the first conduit is opposite the leading edge. The plurality of cooling pins include at least one pair of the plurality of cooling pins that has a first end coupled to the first surface and a second end coupled to the second surface such that the second end is offset from an axis that extends through the first end of the pair of the plurality of cooling pins. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The exemplary embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  is a schematic cross-sectional illustration of a gas turbine engine, which includes an exemplary turbine vane with a dust tolerant cooling system in accordance with the various teachings of the present disclosure; 
         FIG. 2  is a detail cross-sectional view of the gas turbine engine of  FIG. 1 , taken at  2  of  FIG. 1 , which illustrates the turbine vane that includes the dust tolerant cooling system that cools a leading edge of an airfoil of the turbine vane; 
         FIG. 3  is a perspective view of a portion of the turbine vane of  FIG. 2 , in which each airfoil of the turbine vane includes a respective dust tolerant cooling system associated with each one of the airfoils in accordance with various embodiments; 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 3 , which illustrates an exemplary plurality of cooling features associated with a first conduit of the dust tolerant cooling system in accordance with various embodiments; 
         FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 4 , which illustrates a side view of one of the plurality of cooling features of the first conduit of  FIG. 4 ; 
         FIG. 6  is an end view of one of the plurality of cooling features of  FIG. 4 ; 
         FIG. 7  is a cross-sectional view taken from the perspective of line  4 - 4  of  FIG. 3 , which illustrates another exemplary plurality of cooling features associated with a first conduit of the dust tolerant cooling system in accordance with various embodiments; 
         FIG. 8  is a cross-sectional view taken from the perspective of line  4 - 4  of  FIG. 3 , which illustrates another exemplary plurality of cooling features associated with a first conduit of the dust tolerant cooling system in accordance with various embodiments; 
         FIG. 9  is a cross-sectional view taken from the perspective of line  4 - 4  of  FIG. 3 , which illustrates another exemplary plurality of cooling features associated with a first conduit of the dust tolerant cooling system in accordance with various embodiments; 
         FIG. 10  is a detail cross-sectional view of the gas turbine engine of  FIG. 1 , taken at  2  of  FIG. 1 , which illustrates an exemplary turbine vane that includes another dust tolerant cooling system that cools a leading edge of an airfoil of the turbine vane; 
         FIG. 11  is a detail cross-sectional view of the gas turbine engine of  FIG. 1 , taken at  2  of  FIG. 1 , which illustrates an exemplary turbine vane that includes another dust tolerant cooling system that cools a leading edge of an airfoil of the turbine vane; 
         FIG. 11A  is a detail perspective view of a portion of the turbine vane of  FIG. 11 , which illustrates the dust tolerant cooling system cooling an inner platform of the turbine vane; 
         FIG. 11B  is a detail cross-sectional view of the gas turbine engine of  FIG. 1 , taken at  2  of  FIG. 1 , which illustrates an exemplary turbine vane that includes another dust tolerant cooling system that cools a leading edge of an airfoil of the turbine vane; and 
         FIG. 12  is a detail cross-sectional view of the gas turbine engine of  FIG. 1 , taken at  2  of  FIG. 1 , which illustrates an exemplary turbine vane that includes another dust tolerant cooling system that cools a leading edge of an airfoil of the turbine vane. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any type of device that would benefit from increased cooling via a dust tolerant cooling system, and that the airfoil described herein for use with a turbine vane of a gas turbine engine is merely one exemplary embodiment according to the present disclosure. Moreover, while the turbine vane including the dust tolerant cooling system is described herein as being used with a gas turbine engine onboard a mobile platform, such as a bus, motorcycle, train, motor vehicle, marine vessel, aircraft, rotorcraft and the like, the various teachings of the present disclosure can be used with a gas turbine engine on a stationary platform. Further, it should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the present disclosure. In addition, while the figures shown herein depict an example with certain arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment. It should also be understood that the drawings are merely illustrative and may not be drawn to scale. 
     As used herein, the term “axial” refers to a direction that is generally parallel to or coincident with an axis of rotation, axis of symmetry, or centerline of a component or components. For example, in a cylinder or disc with a centerline and generally circular ends or opposing faces, the “axial” direction may refer to the direction that generally extends in parallel to the centerline between the opposite ends or faces. In certain instances, the term “axial” may be utilized with respect to components that are not cylindrical (or otherwise radially symmetric). For example, the “axial” direction for a rectangular housing containing a rotating shaft may be viewed as a direction that is generally parallel to or coincident with the rotational axis of the shaft. Furthermore, the term “radially” as used herein may refer to a direction or a relationship of components with respect to a line extending outward from a shared centerline, axis, or similar reference, for example in a plane of a cylinder or disc that is perpendicular to the centerline or axis. In certain instances, components may be viewed as “radially” aligned even though one or both of the components may not be cylindrical (or otherwise radially symmetric). Furthermore, the terms “axial” and “radial” (and any derivatives) may encompass directional relationships that are other than precisely aligned with (e.g., oblique to) the true axial and radial dimensions, provided the relationship is predominately in the respective nominal axial or radial direction. As used herein, the term “transverse” denotes an axis that crosses another axis at an angle such that the axis and the other axis are neither substantially perpendicular nor substantially parallel. Also as used herein, the terms “integrally formed” and “integral” mean one-piece and exclude brazing, fasteners, or the like for maintaining portions thereon in a fixed relationship as a single unit. 
     With reference to  FIG. 1 , a partial, cross-sectional view of an exemplary gas turbine engine  100  is shown with the remaining portion of the gas turbine engine  100  being axisymmetric about a longitudinal axis  140 , which also comprises an axis of rotation for the gas turbine engine  100 . In the depicted embodiment, the gas turbine engine  100  is an annular multi-spool turbofan gas turbine jet engine within an aircraft  99 , although other arrangements and uses may be provided. As will be discussed herein, with brief reference to  FIG. 2 , the gas turbine engine  100  includes a turbine vane  208  that has a dust tolerant cooling system  202  for providing improved cooling of a leading edge  204  of an airfoil  200 . In one example, the airfoil  200  is incorporated into the turbine vane  208  and by providing the airfoil  200  with the dust tolerant cooling system  202 , the cooling of the leading edge  204  of the airfoil  200  is increased by convective heat transfer between the dust tolerant cooling system  202  and a low temperature cooling fluid F received into the turbine vane  208 . The dust tolerant cooling system  202  improves cooling of the leading edge  204  of the airfoil  200  associated with the turbine vane  208  by providing improved convective heat transfer between the leading edge  204  and the cooling fluid F, which reduces a risk of oxidation of the airfoil  200 , while also reducing an accumulation of dust and fine particles within the dust tolerant cooling system  202 . 
     In this example, with reference back to  FIG. 1 , the gas turbine engine  100  includes fan section  102 , a compressor section  104 , a combustor section  106 , a turbine section  108 , and an exhaust section  110 . The fan section  102  includes a fan  112  mounted on a rotor  114  that draws air into the gas turbine engine  100  and accelerates it. A fraction of the accelerated air exhausted from the fan  112  is directed through an outer (or first) bypass duct  116  and the remaining fraction of air exhausted from the fan  112  is directed into the compressor section  104 . The outer bypass duct  116  is generally defined by an inner casing  118  and an outer casing  144 . In the embodiment of  FIG. 1 , the compressor section  104  includes an intermediate pressure compressor  120  and a high pressure compressor  122 . However, in other embodiments, the number of compressors in the compressor section  104  may vary. In the depicted embodiment, the intermediate pressure compressor  120  and the high pressure compressor  122  sequentially raise the pressure of the air and direct a majority of the high pressure air into the combustor section  106 . A fraction of the compressed air bypasses the combustor section  106  and is used to cool, among other components, turbine blades in the turbine section  108 . 
     In the embodiment of  FIG. 1 , in the combustor section  106 , which includes a combustion chamber  124 , the high pressure air is mixed with fuel, which is combusted. The high-temperature combustion air is directed into the turbine section  108 . In this example, the turbine section  108  includes three turbines disposed in axial flow series, namely, a high pressure turbine  126 , an intermediate pressure turbine  128 , and a low pressure turbine  130 . However, it will be appreciated that the number of turbines, and/or the configurations thereof, may vary. In this embodiment, the high-temperature air from the combustor section  106  expands through and rotates each turbine  126 ,  128 , and  130 . As the turbines  126 ,  128 , and  130  rotate, each drives equipment in the gas turbine engine  100  via concentrically disposed shafts or spools. In one example, the high pressure turbine  126  drives the high pressure compressor  122  via a high pressure shaft  134 , the intermediate pressure turbine  128  drives the intermediate pressure compressor  120  via an intermediate pressure shaft  136 , and the low pressure turbine  130  drives the fan  112  via a low pressure shaft  138 . 
     With reference to  FIG. 2 , a portion of the high pressure turbine  126  of the gas turbine engine  100  of  FIG. 1  is shown in greater detail. In this example, the dust tolerant cooling system  202  is employed with airfoils  200  associated with the turbine vane  208 . As discussed, the dust tolerant cooling system  202  provides for improved cooling for the respective leading edges  204  of the airfoils  200  by increasing heat transfer between the leading edge  204  and the cooling fluid F while reducing the accumulation of dust and fine particles. 
     With reference to  FIG. 3 , a perspective view of a portion of the turbine vane  208  is shown. In this view, three airfoils  200  associated with the turbine vane  208  are shown, however, it will be understood that the turbine vane  208  generally includes a plurality of airfoils  200 , and is axisymmetric with respect to the longitudinal axis  140 . The turbine vane  208  includes a pair of opposing endwalls or platforms  214 ,  216 , and the airfoils  200  are arranged in an annular array between the pair of opposing platforms  214 ,  216 . The platforms  214 ,  216  have an annular or circular main or body section. The platforms  214 ,  216  are positioned in a concentric relationship with the airfoils  200  disposed in the radially extending annular array between the platforms  214 ,  216 . In this example, the platform  216  is an outer platform and the platform  214  is an inner platform. The outer platform  216  circumscribes the inner platform  214  and is spaced therefrom to define a portion of the combustion gas flow path in the gas turbine engine  100 . The plurality of airfoils  200  is generally disposed in the portion of the combustion gas flow path. In one example, the inner platform  214  is coupled to each of the airfoils  200  at an inner diameter, and the outer platform  216  is coupled to each of the airfoils  200  at an outer diameter. 
     Each of the airfoils  200  has a generally concave pressure sidewall  218  and an opposite, generally convex suction sidewall  220 . The pressure and suction sidewalls  218 ,  220  interconnect the leading edge  204  and a trailing edge  224  ( FIG. 2 ) of each airfoil  200 . The airfoil  200  includes a tip  226  and a root  228 , which are spaced apart by a height H of the airfoil  200  or in a spanwise direction. The tip  226  is at the outer diameter of the airfoil  200  and is coupled to the outer platform  216  and the root  228  is at the inner diameter and is coupled to the inner platform  214 . 
     In one example, for each of the airfoils  200 , the dust tolerant cooling system  202  is defined through the outer platform  216  and the inner platform  214  associated with the respective one of the airfoils  200 , and a portion of the dust tolerant cooling system  202  is defined between the pressure and suction sidewalls  218 ,  220  of the respective airfoil  200 . In this example, the dust tolerant cooling system  202  includes a first, leading edge conduit or first conduit  230  and a second, trailing edge conduit or second conduit  232 . The first conduit  230  is in fluid communication with a source of a cooling fluid F ( FIG. 2 ) to cool the leading edge  204  of the airfoil  200 , and the second conduit  232  is in fluid communication with the source of the cooling fluid F ( FIG. 2 ) to cool the airfoil  200  downstream of the leading edge  204  to the trailing edge  224 . Thus, the first conduit  230  is in proximity to the leading edge  204  to cool the leading edge  204 , and the second conduit  232  is to cool the trailing edge  224 . In one example, the source of the cooling fluid F may comprise flow from the high pressure compressor  122  ( FIG. 1 ) exit discharge air. It should be noted, however, that the cooling fluid F may be received from other sources upstream or downstream of the turbine vane  208 . 
     In one example, the first conduit  230  includes an outer platform inlet bore  234 , an airfoil inlet  236  ( FIG. 2 ), an outlet portion  238 , a first surface  240 , a second surface  242  and a plurality of cooling features  244  ( FIG. 4 ). For clarity, the plurality of cooling features  244  is not shown in  FIG. 3 . The outer platform inlet bore  234  is defined through the outer platform  216 . The outer platform inlet bore  234  fluidly couples the source of the cooling fluid F to the airfoil inlet  236  to supply the first conduit  230  with the cooling fluid F. In other embodiments, the first conduit  230  may be fed from the inner platform  214 , such that the cooling fluid F flows into the airfoil  200  at the root  228 . In yet another embodiment, the second conduit  232  may also be fed from the inner platform  214 , such that the cooling fluid F flows into the airfoil  200  at the root  228 . 
     With reference to  FIG. 2 , the airfoil inlet  236  is defined at the tip  226  so as to be positioned at the outer diameter. Thus, the first conduit  230  has an inlet defined at the outer diameter. The airfoil inlet  236  is in fluid communication with the outer platform inlet bore  234  to receive the cooling fluid F. In one example, the outlet portion  238  is defined at least partially through the inner platform  214 . In this example, the outlet portion  238  includes a turning vane or flow splitter  246 . The flow splitter  246  is defined within the airfoil  200  so as to separate the flow into the outlet portion  238 . The flow splitter  246  extends between the pressure and suction sidewalls  218 ,  220  within outlet portion  238  of the first conduit  230 . The flow splitter  246  separates the outlet portion  238  into a first outlet flow path  248  and a second outlet flow path  250 . Stated another way, the outlet portion  238  diverges within the airfoil  200  into at least two flow paths (the first outlet flow path  248  and the second outlet flow path  250 ), with one of the flow paths (the second outlet flow path  250 ) defined at least partially within the inner platform  214 . In one example, the first outlet flow path  248  is defined so as to be contained wholly within the airfoil  200 , while the second outlet flow path  250  is defined such that at least a portion of the second outlet flow path  250  is defined through a portion of the inner platform  214 . Stated another way, the second outlet flow path  250  is defined through the airfoil  200  and a portion of the inner platform  214 . The flow splitter  246  may have any predetermined size and shape to direct the cooling fluid F into the first outlet flow path  248  and the second outlet flow path  250 . 
     In this regard, the inner platform  214  has a first platform surface  214 . 1  opposite a second platform surface  214 . 2 , and a first platform end  214 . 3  opposite a second platform end  214 . 4 . In this example, the second outlet flow path  250  is defined within the first platform surface  214 . 1  and spaced a distance apart from the first platform end  214 . 3  and the second platform end  214 . 4 . Generally, the second outlet flow path  250  is defined as a concave recess through the first platform surface  214 . 1 . By defining the second outlet flow path  250  through the inner platform  214 , the cooling fluid F cools the inner platform  214 , thereby increasing the life of the inner platform  214 . The first outlet flow path  248  and the second outlet flow path  250  converge downstream from the flow splitter  246  within the airfoil  200  to define a single outlet  252  for the first conduit  230 . In one example, the outlet  252  is defined to exhaust the cooling fluid F at the trailing edge  224  of the airfoil  200  near the root  228 . Stated another way, the outlet  252  is in fluid communication with the trailing edge  224 . 
     With reference to  FIG. 4 , the first surface  240 , the second surface  242  and the plurality of cooling features  244  of the airfoil  200  are shown in greater detail. The first surface  240  and the second surface  242  cooperate to define the first conduit  230  within the airfoil  200 . The first surface  240  is opposite the leading edge  204 , and extends along the airfoil  200  from the tip  226  to the root  228  ( FIG. 2 ). In one example, the airfoil  200  includes a rib  260  that separates the first conduit  230  from the second conduit  232 . The rib  260  extends from an inner surface  218 . 1  of the pressure sidewall  218  to an inner surface  220 . 1  of the suction sidewall  220 . The rib  260  defines the second surface  242 , and includes a third surface  262  opposite the second surface  242 . In this example, the rib  260  includes a concave protrusion  264 , which extends toward the first surface  240 . It should be noted that the concave protrusion  264  is optional, and the rib  260  need not include the concave protrusion  264 . Moreover, while the concave protrusion  264  is shown to be defined along both the second surface  242  and the third surface  262 , the concave protrusion  264  may be defined so as to extend outwardly along the second surface  242 , such that the third surface  262  is flat or planar. 
     The plurality of cooling features  244  are arranged in sub-pluralities or rows  266  that are spaced apart radially relative to the longitudinal axis  140  of the gas turbine engine  10  from the root  228  to the tip  226  of the airfoil  200  ( FIG. 2 ). Depending on the size of the turbine vane  208 , the number of rows  266  of the cooling features  244  may be between about 4 to about 20. In other embodiments, the number of rows of cooling features  244  may be greater than about 20 or less than about 4. The sub-pluralities of the plurality of cooling features  244  are spaced apart radially in the rows  266  along the height H ( FIG. 3 ) of the airfoil  200  within the first conduit  230  ( FIG. 2 ). As shown in  FIG. 4 , in one example, each row  266  of the plurality of cooling features  244  includes a plurality of cooling pins  268 . In this example, each row  266  includes about five cooling pins  268  and includes about two half cooling pins  268 . 1 . The half cooling pins  268 . 1  comprise one-half of the cooling pin  268  cut along a central axis A of the cooling pin  268 . It should be noted that instead of two half cooling pins  268 . 1 , a single cooling pin  268  may be employed. Each of the cooling pins  268 ,  268 . 1  extends from the first surface  240  to the second surface  242  to facilitate convective heat transfer between the cooling fluid F and the leading edge  204 , while reducing an accumulation of dust and fine particles. In this example, each of the half cooling pins  268 . 1  extends from the first surface  240  and extends along the second surface  242  of the rib  260  to facilitate heat transfer, while also reducing an accumulation of dust and fine particles. 
     With reference to  FIG. 5 , each cooling pin  268  includes a first pin end  270 , and an opposite second pin end  272 . The first pin end  270  is coupled to or integrally formed with the first surface  240  and the second pin end  272  is coupled to or integrally formed with the second surface  242 . In one example, each cooling pin  268  also includes a first fillet  274  and a second fillet  276 . In this example, the first fillet  274  is defined along a first, top surface  278  of the cooling pin  268 , while the second fillet  276  is defined along an opposite, second, bottom surface  280  of the cooling pin  268 . The first fillet  274  is defined along the top surface  278  at the first pin end  270  to extend toward the second pin end  272 , and has a greater fillet arc than the second fillet  276 . The second fillet  276  is defined along the bottom surface  280  at the first pin end  270  to extend toward the second pin end  272 . The first fillet  274  and the second fillet  276  are predetermined based on an optimization of the fluid mechanics, heat transfer, and stress concentrations in the cooling pin  268  as is known to one skilled in the art. Such fluid mechanics and heat transfer methods may include utilizing a suitable commercially available computational fluid dynamics conjugate code such as STAR CCM+, commercially available from Siemens AG. Stress analyses may be performed using a commercially available finite element code such as ANSYS, commercially available from Ansys, Inc. To minimize dust accumulation on the upstream first fillet  274 , the first fillet  274  may be larger than the second fillet  276 . In some embodiments, the first fillet  274  may be about 10% to about 100% larger than the second fillet  276 . However, in other embodiments, results from the optimization analyses based on fluid mechanics, heat transfer, and stress analyses may require that first fillet  274  be equal to the second fillet  276  or less than the second fillet  276 . In addition, small fillets  275  are also employed to minimize stress concentrations at the interface between the cooling pin  268  and the second surface  242 . The small fillets  275  may be between about 0.005 inches (in.) and about 0.025 inches (in.) depending on the size of the turbine vane  208 . By providing the first fillet  274  with a larger fillet arc at the first pin end  270 , vorticity in the cooling fluid F is increased and conduction from the leading edge  204  is improved. 
     With reference to  FIG. 6 , an end view of one of the cooling pins  268  taken from the second pin end  272  is shown. As can be appreciated, each of the cooling pins  268  are the same, and thus, only one of the cooling pins  268  will be described in detail herein. In this example, the cooling pin  268  has the top surface  278  and the bottom surface  280  that extend along an axis A 1 . The top surface  278  is upstream from the bottom surface  280  in the cooling fluid F. Stated another way, the top surface  278  faces the outer platform inlet bore  234  ( FIG. 2 ) so as to be positioned upstream in the cooling fluid F. The top surface  278  has a first curved surface  282  defined by a minor diameter D 2 , and the bottom surface  280  has a second curved surface  284  defined by a major diameter D 1 . The minor diameter D 2  is smaller than the major diameter D 1 . In one example, the minor diameter D 2  is about 0.010 inches (in.) to about 0.050 inches (in.); and the major diameter D 1  is about 0.020 inches (in.) to about 0.100 inches (in.). The center of minor diameter D 2  is spaced apart from the center of major diameter D 1  by a length L. In one example, the length L is about 0.005 inches (in.) to about 0.150 inches (in.). The first curved surface  282  and the second curved surface  284  are interconnected by a pair of surfaces  286  that are defined by a pair of planes that are substantially tangent to a respective one of the first curved surface  282  and the second curved surface  284 . It should be noted, however, that the first curved surface  282  and the second curved surface  284  need not be interconnected by a pair of planes that are substantially tangent to a respective one of the first curved surface  282  and the second curved surface  284 . Rather, the first curved surface  282  and the second curved surface  284  may be interconnected by a pair of straight, concave, convex, other shaped surfaces. 
     Generally, the shape of the cooling pin  268  is defined in cross-section by a first circle  288 , a second circle  290  and a pair of tangent lines  292 ,  294 . As the shape of the cooling pin  268  in cross-section is substantially the same as the shape of the each of the plurality of shaped cooling pins  262  of commonly assigned U.S. application Ser. No. 15/475,597, filed Mar. 31, 2017, to Benjamin Dosland Kamrath et. al., the relevant portion of which is incorporated herein by reference, the cross-sectional shape of the cooling pin  268  will not be discussed in detail herein. Briefly, the first circle  288  defines the first curved surface  282  at the top surface  278  and has the minor diameter D 2 . The second circle  290  defines the second curved surface  284  at the bottom surface  280  and has the major diameter D 1 . The first circle  288  includes a second center point CP 2 , and the second circle  290  includes a first center point CP 1 . The first center point CP 1  is spaced apart from the second center point CP 2  by the length L. The length L is greater than zero. Thus, the first curved surface  282  is spaced apart from the second curved surface  284  by the length L. 
     The tangent lines  292 ,  294  interconnect the first curved surface  282  and the second curved surface  284 . Generally, the tangent line  292  touches the first curved surface  282  and the second curved surface  284  on a first side  296  of the cooling pin  268 . The tangent line  294  touches the first curved surface  282  and the second curved surface  284  on a second side  298  of the cooling pin  268 . By having the top surface  278  of the cooling pin  268  formed with the minor diameter D 2 , the reduced diameter of the top surface  278  minimizes an accumulation of sand and dust particles in the stagnation region on the top surface  278  of the cooling pin  268 . 
     It will be understood that the cooling features  244  associated with first conduit  230  described with regard to  FIGS. 4-6  may be configured differently to provide improved cooling of the leading edge  204  within the first conduit  230 . In one example, with reference to  FIG. 7 , an exemplary first conduit  330  having a plurality of cooling features  344  for use with the airfoil  200  is shown. As the first conduit  330  includes features that are substantially similar to or the same as the first conduit  230  discussed with regard to  FIGS. 1-6 , the same reference numerals will be used to denote the same or similar features. Similar to the first conduit  230  of  FIGS. 1-6 , the first conduit  330  is in fluid communication with the source of the cooling fluid F to cool the leading edge  204  of the airfoil  200 . The first conduit  330  includes the outer platform inlet bore  234  ( FIG. 2 ), the airfoil inlet  236  ( FIG. 2 ), the outlet portion  238  ( FIG. 2 ), the first surface  240 , a second surface  342  and the plurality of cooling features  344 . The first surface  240  and the second surface  342  cooperate to define the first conduit  330  within the airfoil  200 . The first surface  240  is opposite the leading edge  204 , and extends along the airfoil  200  from the tip  226  to the root  228  ( FIG. 2 ). In this example, instead of the rib  260 , the airfoil  200  includes a rib  360  that separates the first conduit  330  from the second conduit  232 . The rib  360  extends from the inner surface  218 . 1  of the pressure sidewall  218  to the inner surface  220 . 1  of the suction sidewall  220 . The rib  360  defines the second surface  342 , and includes a third surface  362  opposite the second surface  342 . In this example, the rib  360  is substantially planar such that the second surface  342  and the third surface  362  are substantially flat or planar. 
     The plurality of cooling features  344  are arranged in the sub-pluralities or rows  266  that are spaced apart radially relative to the longitudinal axis  140  of the gas turbine engine  10  from the root  228  to the tip  226  of the airfoil  200  ( FIG. 2 ). Depending on the size of the turbine vane  208 , the number of rows  266  of the cooling features  344  may be between about 4 to about 20. In other embodiments, the number of rows of cooling features  344  may be greater than about 20 or less than about 4. In one example, each row  266  of the plurality of cooling features  344  includes a plurality of cooling pins  268 ,  350 . In this example, each row  266  includes a first pair  352  of the cooling pins  268  and a second pair  354  of the cooling pins  350 . The first pair  352  of the cooling pins  268  extends from the first surface  240  to the second surface  342  substantially along a respective first longitudinal axis L 2  of each of the first pair  352  of the cooling pins  268 . 
     Each cooling pin  350  includes a third pin end  356 , and a fourth pin end  358 . The third pin end  356  is coupled to or integrally formed with the first surface  240  and the fourth pin end  358  is coupled to or integrally formed with the second surface  342 . The fourth pin end  358  is coupled to or integrally formed with the second surface  342  such that the fourth pin end  358  is offset from a respective second axis A 2  that extends through the third pin end  356  of the second pair  354  of the cooling pins  350 . Each of the cooling pins  350  also includes the first fillet  274  defined along the top surface  278  ( FIG. 6 ) and the second fillet  276  defined along the bottom surface  280  ( FIG. 6 ). The top surface  278  is upstream from the bottom surface  280  in the cooling fluid F ( FIG. 6 ). The top surface  278  has the first curved surface  282  defined by the minor diameter D 2 , and the bottom surface  280  has the second curved surface  284  defined by the major diameter D 1  ( FIG. 6 ). The center of minor diameter D 2  is spaced apart from the center of major diameter D 1  by a length L ( FIG. 6 ). The first curved surface  282  and the second curved surface  284  are interconnected by the pair of surfaces  286  that are defined by a pair of planes that are substantially tangent to a respective one of the first curved surface  282  and the second curved surface  284  ( FIG. 6 ). In this example, the shape of each of the cooling pins  350  is also defined in cross-section by the first circle  288 , the second circle  290  and the pair of tangent lines  292 ,  294  ( FIG. 6 ). The cooling pins  350  may also include the small fillets  275  ( FIG. 5 ) at the fourth pin end  358 . By providing the plurality of cooling features  344  with the first pair  352  of the cooling pins  268  and the second pair  354  of the cooling pins  350 , vorticity in the cooling fluid F is also increased within the first conduit  330 , while conductive heat transfer is improved within the first conduit  330 . Further, the cross-sectional shape of the cooling pins  268 ,  350  reduces an accumulation of dust and fine particles within the first conduit  330 . 
     In addition, it will be understood that the cooling features  244  associated with first conduit  230  described with regard to  FIGS. 4-6  may be configured differently to provide improved cooling of the leading edge  204  within the first conduit  230 . In one example, with reference to  FIG. 8 , an exemplary first conduit  430  having a plurality of cooling features  444  for use with the airfoil  200  is shown. As the first conduit  430  includes features that are substantially similar to or the same as the first conduit  230  discussed with regard to  FIGS. 1-6  and the first conduit  330  discussed with regard to  FIG. 7 , the same reference numerals will be used to denote the same or similar features. Similar to the first conduit  230  of  FIGS. 1-6 , the first conduit  430  is in fluid communication with the source of the cooling fluid F to cool the leading edge  204  of the airfoil  200 . The first conduit  430  includes the outer platform inlet bore  234  ( FIG. 2 ), the airfoil inlet  236  ( FIG. 2 ), the outlet portion  238  ( FIG. 2 ), the first surface  240 , the second surface  242  and the plurality of cooling features  444 . The first surface  240  and the second surface  242  cooperate to define the first conduit  430  within the airfoil  200 . The first surface  240  is opposite the leading edge  204 , and extends along the airfoil  200  from the tip  226  to the root  228  ( FIG. 2 ). In one example, the airfoil  200  includes the rib  260  that separates the first conduit  430  from the second conduit  232 . The rib  260  defines the second surface  242 , and includes the third surface  262  opposite the second surface  242 . 
     In this example, the plurality of cooling features  444  are arranged in the sub-pluralities or rows  266  that are spaced apart radially relative to the longitudinal axis  140  of the gas turbine engine  10  from the root  228  to the tip  226  of the airfoil  200  ( FIG. 2 ). Depending on the size of the turbine vane  208 , the number of rows  266  of the cooling features  444  may be between about 4 to about 20. In other embodiments, the number of rows of cooling features  444  may be greater than about 20 or less than about 4. In one example, each row  266  of the plurality of cooling features  444  includes a plurality of pins  450 , which extend into the first conduit  430  from the first surface  240 . In this example, each row  266  includes about five pins  450 , but each row  266  may include any number of pins  450 . Moreover, it should be understood that the pins  450  need not be arranged in rows, but rather, the pins  450  may be coupled to or integrally formed with the first surface  240  in any pre-defined pattern or arrangement that improves heat transfer into the cooling fluid F through the generation of turbulent cooling fluid flow. In this example, each of the pins  450  are shown with a substantially conical shape, however, the pins  450  may have any desired shape. The conical pins  450  comprise an upstream diameter that is smaller than a downstream diameter, with both diameters monotonically decreasing from a base  450 . 1  of the conical pins  450  at the first surface  240  to a free end  450 . 2  of the conical pins  450  (closest to the second surface  342 ). Stated another way, the base  450 . 1  of the conical pins  450  at the first pin end  450 . 1  are shaped as shown for the first pin end  270  of the cooling pin  268  in  FIG. 6 . The cross sectional area of the pin  450  monotonically reduces away from the first pin end  450 . 1  such that the area becomes zero at the free end  450 . 2  of the conical pin  450 . Stated another way, the parameters D 1 , D 2 , and L shown in  FIG. 6  all reduce to zero at the free end  450 . 2  of the pins  450 . In an alternate embodiment, the conical pins  450  may also be integrally formed with the second surface  242  to extend from the second surface  242  toward the first surface  240  to increase the velocity in the first conduit  430  to promote additional heat transfer from leading edge  204 . 
     It will be understood that the cooling features  244  associated with first conduit  230  described with regard to  FIGS. 4-6  may be configured differently to provide improved cooling of the leading edge  204  within the first conduit  230 . In one example, with reference to  FIG. 9 , an exemplary first conduit  530  having a plurality of cooling features  544  for use with the airfoil  200  is shown. As the first conduit  530  includes features that are substantially similar to or the same as the first conduit  230  discussed with regard to  FIGS. 1-6 , the same reference numerals will be used to denote the same or similar features. Similar to the first conduit  230  of  FIGS. 1-6 , the first conduit  530  is in fluid communication with the source of the cooling fluid F to cool the leading edge  204  of the airfoil  200 . The first conduit  530  includes the outer platform inlet bore  234  ( FIG. 2 ), the airfoil inlet  236  ( FIG. 2 ), the outlet portion  238  ( FIG. 2 ), the first surface  240 , the second surface  242  and the plurality of cooling features  544 . The first surface  240  and the second surface  242  cooperate to define the first conduit  530  within the airfoil  200 . The first surface  240  is opposite the leading edge  204 , and extends along the airfoil  200  from the tip  226  to the root  228  ( FIG. 2 ). The airfoil  200  includes the rib  260  that separates the first conduit  530  from the second conduit  232 . The rib  260  defines the second surface  242 , and includes the third surface  262  opposite the second surface  242 . 
     In this example, the plurality of cooling features  544  comprises the cooling pins  268  and a central rib  551 . The cooling pins  268  and the central rib  551  extend from the first surface  240  to the second surface  242 . The central rib  551  divides the first conduit  530  into a first flow passage  552  and a second flow passage  553 . Stated another way, the central rib  551  extends between the first surface  240  and the second surface  242  from the tip  226  to the root  228  of the airfoil  200  ( FIG. 2 ) and thereby divides the first conduit  530  into the first flow passage  552  and the second flow passage  553 . The first flow passage  552  is further separated into a plurality of the first flow passages  552  by a sub-plurality  555  of the cooling pins  268  positioned within or integrally formed within the first flow passage  552 ; and the second flow passage  553  is further separated into a plurality of the second flow passages  553  by a sub-plurality  557  of the cooling pins  268  positioned within or integrally formed within the second flow passage  553 . As shown in  FIG. 9 , in one example, the plurality of cooling features  544  includes about four cooling pins  268  and includes about two half cooling pins  268 . 1 . The half cooling pins  268 . 1  comprise one-half of the cooling pin  268  cut along the central axis A of the cooling pin  268 . Each of the cooling pins  268  extends from the first surface  240  to the second surface  242  to facilitate convective heat transfer between the cooling fluid F and the leading edge  204 . In this example, each of the half cooling pins  268 . 1  extends from the first surface  240  and extends along the second surface  242  to facilitate heat transfer. In this example, each of the first flow passage  552  and the second flow passage  553  includes two cooling pins  268  and one half cooling pin  268 . 1 ; however, it will be understood that the first flow passage  552  and the second flow passage  553  may include any number of the cooling pins  268 , and moreover, the first flow passage  552  and the second flow passage  553  may include a different number of the cooling pins  268 . 
     The central rib  551  includes a first rib end  570 , and an opposite second rib end  572 . The first rib end  570  is coupled to or integrally formed with the first surface  240  and the second rib end  572  is coupled to or integrally formed with the second surface  242 . The first rib end  570  faces the outer platform inlet bore  234  ( FIG. 2 ) so as to be positioned upstream in the cooling fluid F. The central rib  551  extends radially from the outer platform inlet bore  234  to near the outlet portion  238  to enable local tailoring of the individual heat loads in the first flow passage  552  and the second flow passage  553 . This local tailoring of heat transfer may be accomplished by changing the size and/or density of the cooling pins  268  in the respective first flow passage  552  and the second flow passage  553 . In one example, the central rib  551  also includes the first fillet  274  ( FIG. 6 ). The first fillet  274  is defined along a top surface (not shown) of the central rib  551  at the first rib end  570  to extend toward the second rib end  572 . The central rib  551  may also include a bottom surface (not shown) opposite the top surface. The bottom surface of the central rib  551  may include the second fillet  276  ( FIG. 6 ). The second fillet  276  is defined along the bottom surface at the first rib end  570  to extend toward the second rib end  572 . In addition, the central rib  551  may include the small fillets  275  ( FIG. 6 ) to minimize stress concentrations at the interface between the central rib  551  and the second surface  242 . It should be noted, however, that while the central rib  551  is described herein as including the first fillet  274 , the second fillet  276  and the small fillets  275 , the central rib  551  may include fillets along the first rib end  570  and the second rib end  572  that are different in size and shape than those of the cooling pins  268 . 
     As can be appreciated, each of the cooling pins  268  of  FIG. 9  are the same as the cooling pins  268  shown in  FIG. 4 . The top surface  278  is upstream from the bottom surface  280  ( FIG. 5 ) in the cooling fluid F. The top surface  278  faces the outer platform inlet bore  234  ( FIG. 2 ) so as to be positioned upstream in the cooling fluid F. 
     With reference back to  FIG. 2 , the second conduit  232  is shown in greater detail. In this example, the second conduit  232  includes a second outer platform inlet bore  600 , a second airfoil inlet  602 , a second outlet portion  604 , the third surface  262 ,  362 , a fourth surface  608  and a fifth surface  610 . Optionally, the second conduit  232  may include a second plurality of cooling features  606 , such as a pin fin array or bank. For clarity, the second plurality of cooling features  606  is shown in  FIG. 4 , but not in  FIGS. 7-9  with the understanding that the second conduit  232  of each of  FIGS. 7-9  optionally includes the second plurality of cooling features  606 . The second outer platform inlet bore  600  is defined through the outer platform  216 . The second outer platform inlet bore  600  fluidly couples the source of the cooling fluid F to the second airfoil inlet  602  to supply the second conduit  232  with the cooling fluid F. 
     With continued reference to  FIG. 2 , the second airfoil inlet  602  is defined at the tip  226  so as to be positioned at the outer diameter. Thus, the second conduit  232  also has an inlet defined at the outer diameter. The second airfoil inlet  602  is in fluid communication with the second outer platform inlet bore  600  to receive the cooling fluid F. The second outlet portion  604  is defined through the trailing edge  224  of the airfoil  200 . In one example, the second outlet portion  604  is defined through the trailing edge  224  to exhaust the cooling fluid F along the trailing edge  224  of the airfoil  200  between the tip  226  and the root  228 . In this example, with reference to  FIG. 4 , the second outlet portion  604  may be defined between the inner surface  218 . 1  of the pressure sidewall  218  and the inner surface  220 . 1  of the suction sidewall  220 . The second outlet portion  604  may define a single outlet, or may define a plurality of individual outlets along the trailing edge  224  from the tip  226  to the root  228  ( FIG. 2 ). The second plurality of cooling features  606  may be defined to extend between the inner surface  218 . 1  of the pressure sidewall  218  and the inner surface  220 . 1  of the suction sidewall  220  from the tip  226  to the root  228  of the airfoil  200  within the second conduit  232 . 
     The second conduit  232  is defined within the airfoil  200  to extend from the respective third surface  262 ,  362  of the respective rib  260 ,  360  to the trailing edge  224 . The respective third surface  262 ,  362  is in fluid communication with the second airfoil inlet  602  to receive the cooling fluid F. The fourth surface  608  defines a downstream boundary of the second conduit  232 , and extends from the respective third surface  262 ,  362  to the trailing edge  224 . The fifth surface  610 , adjacent to the tip  226 , may define an upper boundary of the second conduit  232 . The respective third surface  262 ,  362 , the fourth surface  608  and the fifth surface  610  cooperate to direct the cooling fluid F from the second airfoil inlet  602  through the second outlet portion  604 . 
     With reference to  FIG. 4 , in one example, each of the cooling features  244 ,  344 ,  444 ,  544 ,  606  are integrally formed, monolithic or one-piece, and are composed of a metal or metal alloy. In this example, the dust tolerant cooling system  202 , including each of the cooling features  244 ,  344 ,  444 ,  544 ,  606  is integrally formed, monolithic or one-piece with the airfoil  200 , and the cooling features  244 ,  344 ,  444 ,  544 ,  606  are composed of the same metal or metal alloy as the airfoil  200 . Generally, the airfoil  200  and the cooling features  244 ,  344 ,  444 ,  544 ,  606  are composed of an oxidation and stress rupture resistant, single crystal, nickel-based superalloy, including, but not limited to, the nickel-based superalloy commercially identified as “CMSX 4” or the nickel-based superalloy identified as “SC180.” Alternatively, the airfoil  200  and the cooling features  244 ,  344 ,  444 ,  544 ,  606  may be composed of directionally solidified nickel base alloys, including, but not limited to, Mar-M-247DS. As a further alternative, the airfoil  200  and the cooling features  244 ,  344 ,  444 ,  544 ,  606  may be composed of polycrystalline alloys, including, but not limited to, Mar-M-247EA. 
     In one example, in order to manufacture the airfoil  200  including the dust tolerant cooling system  202  with the respective one of the cooling features  244 ,  344 ,  444 ,  544 , a core that defines the airfoil  200  including the respective one of the cooling features  244 ,  344 ,  444 ,  544 , the respective first conduit  230 ,  330 ,  430 ,  530  and the second conduit  232  with the second plurality of cooling features  606 , if included, is cast, molded or printed from a ceramic material. In this example, the core is manufactured from a ceramic using ceramic additive manufacturing or with fugitive cores. With the core formed, the core is positioned within a die. With the core positioned within the die, the die is injected with liquid wax such that liquid wax surrounds the core. A wax sprue or conduit may also be coupled to the cavity within the die to aid in the formation of the airfoil  200 . Once the wax has hardened to form a wax pattern, the wax pattern is coated or dipped in ceramic to create a ceramic mold about the wax pattern. After coating the wax pattern with ceramic, the wax pattern may be subject to stuccoing and hardening. The coating, stuccoing and hardening processes may be repeated until the ceramic mold has reached the desired thickness. 
     With the ceramic mold at the desired thickness, the wax is heated to melt the wax out of the ceramic mold. With the wax melted out of the ceramic mold, voids remain surrounding the core, and the ceramic mold is filled with molten metal or metal alloy. In one example, the molten metal is poured down an opening created by the wax sprue. It should be noted, however, that vacuum drawing may be used to fill the ceramic mold with the molten metal. Once the metal or metal alloy has solidified, the ceramic is removed from the metal or metal alloy, through chemical leaching, for example, leaving the dust tolerant cooling system  202 , including the respective one of the cooling features  244 ,  344 ,  444 ,  544 , the respective first conduit  230 ,  330 ,  430 ,  530  and the second conduit  232  (optionally with the second plurality of cooling features  606 ), formed in the airfoil  200 , as illustrated in  FIG. 4 . It should be noted that alternatively, the respective one of the cooling features  244 ,  344 ,  444 ,  544 ,  606  may be formed in the airfoil  200  using conventional dies with one or more portions of the core (or portions adjacent to the core) comprising a fugitive core insert. As a further alternative, the airfoil  200  including the dust tolerant cooling system  202  may be formed using other additive manufacturing processes, including, but not limited to, direct metal laser sintering, binder jet printing, etc. 
     The above process may be repeated to form a plurality of the airfoils  200 . With the plurality of airfoils  200  formed, the airfoils  200  may be positioned in an annular array. The outer platform  216  may be cast around the outer diameter or tip  226  of each of the airfoils  200  and the inner platform  214  may be cast around the inner diameter or root  228  of each of the airfoils  200 . Generally, the outer platform  216  and the inner platform  214  are composed of a suitable metal or metal alloy, including, but not limited to, a nickel superalloy, such as Mar-M-247DS or Mar-M-247EA. The outer platform  216  may be cast about the outer diameter or tips  226  of the airfoils  200 , and the inner platform  214  may be cast about the inner diameter or roots  228  of the airfoils  200 . The outer platform inlet bore  234  and the second outer platform inlet bore  600  may be defined through the casting of the outer platform  216  using a suitable die, or may be formed by machining the outer platform  216  after casting. The second outlet flow path  250  may be defined in the inner platform  214  through the casting of the inner platform  214  using a suitable die, or may be defined by machining the inner platform  214  after casting. Although not shown herein, the airfoil  200  may be formed with one or more features that enable the attachment of the airfoil  200  to the inner platform  214  and/or outer platform  216 , such as an extension for forming a slip joint (not shown). While the exemplary embodiment described herein employs a bi-cast or full-ring casting, it should be understood that the airfoil  200  and the cooling features  244 ,  344 ,  444 ,  544  (and optionally, the second plurality of cooling features  606 ) may be formed as traditional cast segments such as doublets, triplets, or other numbers of airfoils per segment. In this example, the appropriate number of segments is then assembled to form the full turbine vane  208  assembly. 
     With the turbine vane  208  formed, the turbine vane  208  is installed into the gas turbine engine  100  ( FIG. 1 ). In use, as the gas turbine engine  100  operates, the cooling fluid F is supplied to the first conduit  230  and the second conduit  232  through the outer platform inlet bore  234  and the second outer platform inlet bore  600 , respectively. With reference to  FIG. 2 , the cooling fluid F flows through the first conduit  230  along the leading edge  204 , and the cooling features  244 ,  344 ,  444 ,  544  cooperate to transfer heat from the leading edge  204  into the cooling fluid F while reducing an accumulation of dust and fine particles within the first conduit  230 . The cooling fluid F is split by the flow splitter  246  and flows into the first outlet flow path  248  and the second outlet flow path  250 . As cooling fluid F flows through the second outlet flow path  250 , the cooling fluid F cools the inner platform  214 . The cooling fluid F in the first outlet flow path  248  and the second outlet flow path  250  converges downstream of the flow splitter  246  and exits the outlet  252  of the airfoil  200  along the trailing edge  224 . The cooling fluid F that flows through the second conduit  232  cools the airfoil  200  downstream of the rib  260 ,  360  and may cooperate with the cooling features  606  to transfer heat into the cooling fluid F before the cooling fluid F exits the second conduit  232  along the trailing edge  224 . 
     It will be understood that the turbine vane  208 , the airfoil  200  and the dust tolerant cooling system  202  described with regard to  FIGS. 1-9  may be configured differently to provide dust tolerant cooling to the leading edge  204 . In one example, with reference to  FIG. 10 , an airfoil  700  with a dust tolerant cooling system  702  for use with a turbine vane  708  is shown. As the airfoil  700 , the dust tolerant cooling system  702  and the turbine vane  708  include components that are substantially similar to or the same as the airfoil  200 , the dust tolerant cooling system  202  and the turbine vane  208  discussed with regard to  FIGS. 1-9 , the same reference numerals will be used to denote the same or similar features. The dust tolerant cooling system  702  may be employed with the turbine vane  208  to provide improved cooling along the leading edge  204  of the airfoil  700 . 
     The turbine vane  708  includes a pair of opposing endwalls or platforms  714 ,  216 , and the airfoils  700  are arranged in an annular array between the pair of opposing platforms  714 ,  216 . The platforms  714 ,  216  have an annular or circular main or body section. The platforms  714 ,  216  are positioned in a concentric relationship with the airfoils  700  disposed in the radially extending annular array between the platforms  714 ,  216 . In this example, the platform  216  is an outer platform and the platform  714  is an inner platform. The outer platform  216  circumscribes the inner platform  714  and is spaced therefrom to define a portion of the combustion gas flow path in the gas turbine engine  100 . The plurality of airfoils  700  is generally disposed in the portion of the combustion gas flow path. In one example, the inner platform  714  is coupled to each of the airfoils  700  at an inner diameter, and the outer platform  216  is coupled to each of the airfoils  700  at an outer diameter. 
     Each of the airfoils  700  has the pressure sidewall  218  and the suction sidewall  220 . The pressure and suction sidewalls  218 ,  220  interconnect the leading edge  204  and the trailing edge  224  of each airfoil  700 . The airfoil  700  includes the tip  226  and the root  228 , which are spaced apart by a height H 1  of the airfoil  700  or in a spanwise direction. The tip  226  is at the outer diameter of the airfoil  700  and is coupled to the outer platform  216  and the root  228  is at the inner diameter and is coupled to the inner platform  714 . 
     In one example, for each of the airfoils  700 , the dust tolerant cooling system  702  is defined through the outer platform  216  and the inner platform  714  associated with the respective one of the airfoils  700 , and a portion of the dust tolerant cooling system  702  is defined between the pressure and suction sidewalls  218 ,  220  of the respective airfoil  700 . In this example, the dust tolerant cooling system  702  includes a first, leading edge conduit or first conduit  730  and a second, trailing edge conduit or second conduit  732 . The first conduit  730  is in fluid communication with the source of the cooling fluid F to cool the leading edge  204  of the airfoil  700 , and the second conduit  732  is in fluid communication with the source of the cooling fluid F to cool the airfoil  700  downstream of the leading edge  204  to the trailing edge  224 . 
     In one example, the first conduit  730  includes the outer platform inlet bore  234 , the airfoil inlet  236 , an outlet portion  738 , the first surface  240 , the second surface  242  and the plurality of cooling features  244  ( FIG. 4 ). In  FIG. 10 , the plurality of cooling features  244  are omitted for clarity. In addition, it should be noted that in certain embodiments, the airfoil  700  may include the plurality of cooling features  344  ( FIG. 7 ), the plurality of cooling features  444  ( FIG. 8 ) or the plurality of cooling features  544  ( FIG. 9 ). The outer platform inlet bore  234  fluidly couples the source of the cooling fluid F to the airfoil inlet  236  to supply the first conduit  730  with the cooling fluid F. The airfoil inlet  236  is defined at the tip  226  so as to be positioned at the outer diameter and is in fluid communication with the outer platform inlet bore  234  to receive the cooling fluid F. 
     In one example, the outlet portion  738  is defined through the inner platform  714 . In this regard, the inner platform  714  has a first platform surface  740  opposite a second platform surface  742 , and a first platform end  744  opposite a second platform end  746 . In this example, the outlet portion  738  is defined as a fluid flow conduit that is defined within the first platform surface  740  and spaced a distance apart from the first platform end  744 . The outlet portion extends from the first platform surface  740  toward the second platform surface  742  and defines an outlet  748  that is spaced a distance apart from the second platform end  746 . The cooling fluid F from the first conduit  730  exits the inner platform  714  at the outlet  748 . By exiting the inner platform  714  at the outlet  748 , as the cooling fluid F has a lower static pressure, the cooling fluid F suppresses hot fluid having a higher static pressure from flowing into a gap created between the turbine vane  208  and an adjacent turbine rotor  750 . 
     The second conduit  732  includes the second outer platform inlet bore  600 , the second airfoil inlet  602 , the second outlet portion  604 , the third surface  262 ,  362 , a fourth surface  752  and the fifth surface  610 . Optionally, the second conduit  732  may include a second plurality of cooling features  606 , such as a pin fin array or bank (shown in  FIG. 4  and omitted for clarity in  FIG. 10 ). The second outer platform inlet bore  600  is defined through the outer platform  216 . The second outer platform inlet bore  600  fluidly couples the source of the cooling fluid F to the second airfoil inlet  602  to supply the second conduit  732  with the cooling fluid F. 
     With continued reference to  FIG. 10 , the second airfoil inlet  602  is defined at the tip  226  so as to be positioned at the outer diameter. The second airfoil inlet  602  is in fluid communication with the second outer platform inlet bore  600  to receive the cooling fluid F. The second outlet portion  604  is defined through the trailing edge  224  of the airfoil  700 . In one example, the second outlet portion  604  is defined through the trailing edge  224  to exhaust the cooling fluid F along the trailing edge  224  of the airfoil  200  between the tip  226  and the root  228 . The second outlet portion  604  may define a single outlet, or may define a plurality of individual outlets along the trailing edge  224  from the tip  226  to the root  228 . 
     The second conduit  732  is defined within the airfoil  700  to extend from the respective third surface  262 ,  362  of the respective rib  260 ,  360  to the trailing edge  224 . The respective third surface  262 ,  362  is in fluid communication with the second airfoil inlet  602  to receive the cooling fluid F. The fourth surface  752  defines a downstream boundary of the second conduit  732 , and extends along the root  228  of the airfoil  700  from the respective third surface  262 ,  362  to the trailing edge  224 . The fifth surface  610 , adjacent to the tip  226 , may define an upper boundary of the second conduit  732 . The respective third surface  262 ,  362 , the fourth surface  752  and the fifth surface  610  cooperate to direct the cooling fluid F from the second airfoil inlet  602  through the second outlet portion  604 . 
     As the airfoil  700  and the dust tolerant cooling system  702  may be manufactured in the same manner as the airfoil  200  and the dust tolerant cooling system  202  discussed with regard to  FIGS. 1-9 , the manufacture of the airfoil  700  and the dust tolerant cooling system  702  will not be discussed in detail herein. Briefly, however, a core that defines the airfoil  700  including the respective cooling features  244 ,  344 ,  444 ,  544 , the first conduit  730  and the second conduit  732  (optionally with the second plurality of cooling features  606 ) is printed from a ceramic material, using ceramic additive manufacturing for example, and investment casting is performed to form the airfoil  700  including the integrally formed dust tolerant cooling system  702 . Alternatively, the dust tolerant cooling system  702  may be formed in the airfoil  700  using conventional dies with one or more portions of the core (or portions adjacent to the core) comprising a fugitive core insert. As a further alternative, the airfoil  700  including the dust tolerant cooling system  702  may be formed using other additive manufacturing processes, including, but not limited to, direct metal laser sintering, binder jet printing, etc. This process may be repeated to form a plurality of the airfoils  700 . With the plurality of airfoils  700  formed, the airfoils  700  may be positioned in an annular array. The outer platform  216  may be cast around the outer diameter or tip  226  of each of the airfoils  700  and the inner platform  714  may be cast around the inner diameter or root  228  of each of the airfoils  700 . The outlet portion  738  may be defined in the inner platform  714  through the casting of the inner platform  714  using a suitable die, or may be defined by machining the inner platform  714  after casting. While the exemplary embodiment described herein employs a bi-cast or full-ring casting, it should be understood that the airfoil  700  and the cooling features  244 ,  344 ,  444 ,  544 ,  606  may be formed as traditional cast segments such as doublets, triplets, or other numbers of airfoils per segment. In this example, the appropriate number of segments are then assembled to form the full turbine vane  708  assembly. 
     With the turbine vane  708  formed, the turbine vane  708  is installed into the gas turbine engine  100  ( FIG. 1 ). In use, as the gas turbine engine  100  operates, the cooling fluid F is supplied to the first conduit  730  and the second conduit  732  through the outer platform inlet bore  234  and the second outer platform inlet bore  600 , respectively. The cooling fluid F flows through the first conduit  730  along the leading edge  204 , and the cooling features  244 ,  344 ,  444 ,  544  cooperate to transfer heat from the leading edge  204  into the cooling fluid F. The cooling fluid F exits the first conduit  730  at the outlet  748 , thereby cooling the inner platform  714 . The cooling fluid F that flows through the second conduit  232  cools the airfoil  200  downstream of the rib  260 ,  360  and may cooperate with the cooling features  606  to transfer heat into the cooling fluid F before the cooling fluid F exits the second conduit  732  along the trailing edge  224 . 
     It will be understood that the turbine vane  208 , the airfoil  200  and the dust tolerant cooling system  202  described with regard to  FIGS. 1-9  may be configured differently to provide dust tolerant cooling to the leading edge  204 . In one example, with reference to  FIG. 11 , an airfoil  800  with a dust tolerant cooling system  802  for use with a turbine vane  808  is shown. As the airfoil  800 , the dust tolerant cooling system  802  and the turbine vane  808  include components that are substantially similar to or the same as the airfoil  200 , the dust tolerant cooling system  202  and the turbine vane  208  discussed with regard to  FIGS. 1-9  or the airfoil  700  and the dust tolerant cooling system  702  and the turbine vane  708  discussed with regard to  FIG. 10 , the same reference numerals will be used to denote the same or similar features. The dust tolerant cooling system  802  may be employed with the turbine vane  808  to provide improved cooling along the leading edge  204  of the airfoil  800 . 
     The turbine vane  808  includes a pair of opposing endwalls or platforms  814 ,  216 , and the airfoils  800  are arranged in an annular array between the pair of opposing platforms  814 ,  216 . The platforms  814 ,  216  have an annular or circular main or body section. The platforms  814 ,  216  are positioned in a concentric relationship with the airfoils  800  disposed in the radially extending annular array between the platforms  814 ,  216 . In this example, the platform  216  is an outer platform and the platform  814  is an inner platform. The outer platform  216  circumscribes the inner platform  814  and is spaced therefrom to define a portion of the combustion gas flow path in the gas turbine engine  100 . The plurality of airfoils  800  is generally disposed in the portion of the combustion gas flow path. In one example, the inner platform  814  is coupled to each of the airfoils  800  at an inner diameter, and the outer platform  216  is coupled to each of the airfoils  800  at an outer diameter. 
     Each of the airfoils  800  has the pressure sidewall  218  and the suction sidewall  220 . The pressure and suction sidewalls  218 ,  220  interconnect the leading edge  204  and the trailing edge  224  of each airfoil  800 . The airfoil  800  includes the tip  226  and the root  228 , which are spaced apart by a height H 2  of the airfoil  800  or in a spanwise direction. The tip  226  is at the outer diameter of the airfoil  800  and is coupled to the outer platform  216  and the root  228  is at the inner diameter and is coupled to the inner platform  814 . 
     In one example, for each of the airfoils  800 , the dust tolerant cooling system  802  is defined through the outer platform  216  and the inner platform  814  associated with the respective one of the airfoils  800 , and a portion of the dust tolerant cooling system  802  is defined between the pressure and suction sidewalls  218 ,  220  of the respective airfoil  800 . In this example, the dust tolerant cooling system  802  includes a first, leading edge conduit or first conduit  830  and the second conduit  732 . The first conduit  830  is in fluid communication with the source of the cooling fluid F to cool the leading edge  204  of the airfoil  800 , and the second conduit  732  is in fluid communication with the source of the cooling fluid F to cool the airfoil  800  downstream of the leading edge  204  to the trailing edge  224 . 
     In one example, the first conduit  830  includes the outer platform inlet bore  234 , the airfoil inlet  236 , an outlet portion  838 , the first surface  240 , the second surface  242  and the plurality of cooling features  244  ( FIG. 4 ). In  FIG. 11 , the plurality of cooling features  244  are omitted for clarity. In addition, it should be noted that in certain embodiments, the airfoil  800  may include the plurality of cooling features  344  ( FIG. 7 ), the plurality of cooling features  444  ( FIG. 8 ) or the plurality of cooling features  544  ( FIG. 9 ). The outer platform inlet bore  234  fluidly couples the source of the cooling fluid F to the airfoil inlet  236  to supply the first conduit  830  with the cooling fluid F. The airfoil inlet  236  is defined at the tip  226  so as to be positioned at the outer diameter and is in fluid communication with the outer platform inlet bore  234  to receive the cooling fluid F. 
     In one example, the outlet portion  838  is defined through the inner platform  814 . In this regard, the inner platform  814  has a first platform surface  840  opposite a second platform surface  842 , and a first platform end  844  opposite a second platform end  846 . In this example, the outlet portion  838  is defined as a fluid flow conduit that is defined within the first platform surface  840  and spaced a distance apart from the first platform end  844 . The outlet portion  838  extends from the first platform surface  840  toward the second platform surface  842  and defines a plurality of film cooling holes  850  that is spaced a distance apart from the second platform end  846 . In this regard, with reference to  FIG. 11A , in one example, the plurality of film cooling holes  850  are defined through a portion of the first platform surface  840  of the inner platform  814  that spans between the airfoil  800  and a second, adjacent one of the airfoils  800  that is coupled to the inner platform  814  so as to be spaced apart from the airfoil  800 . The cooling fluid F from the first conduit  830  exits the inner platform  814  at the plurality of film cooling holes  850 . By exiting the inner platform  814  at the plurality of film cooling holes  850 , the cooling fluid F cools the first platform surface  840  between adjacent ones of the airfoils  800 . 
     Alternatively, with reference to  FIG. 11B , the outlet portion  838  may be in communication with a plurality of cooling holes  850 . 1  that are in fluid communication with the second conduit  732 . In this example, the cooling fluid F from the first conduit  830  exits the inner platform  814  at the plurality of cooling holes  850 . 1  and mixes with the cooling fluid F flowing through the second conduit  732  before exiting the second conduit  732  at the trailing edge  224 . 
     As the airfoil  800  and the dust tolerant cooling system  802  may be manufactured in the same manner as the airfoil  200  and the dust tolerant cooling system  202  discussed with regard to  FIGS. 1-9 , the manufacture of the airfoil  800  and the dust tolerant cooling system  802  will not be discussed in detail herein. Briefly, however, with reference back to  FIG. 11 , a core that defines the airfoil  800  including the respective cooling features  244 ,  344 ,  444 ,  544 , the first conduit  830  and the second conduit  732  (optionally with the second plurality of cooling features  606 ) is printed from a ceramic material, using ceramic additive manufacturing for example, and investment casting is performed to form the airfoil  800  including the integrally formed dust tolerant cooling system  802 . Alternatively, the dust tolerant cooling system  802  may be formed in the airfoil  800  using conventional dies with one or more portions of the core (or portions adjacent to the core) comprising a fugitive core insert. As a further alternative, the airfoil  800  including the dust tolerant cooling system  802  may be formed using other additive manufacturing processes, including, but not limited to, direct metal laser sintering, binder jet printing, etc. This process may be repeated to form a plurality of the airfoils  800 . With the plurality of airfoils  800  formed, the airfoils  800  may be positioned in an annular array. The outer platform  216  may be cast around the outer diameter or tip  226  of each of the airfoils  800  and the inner platform  814  may be cast around the inner diameter or root  228  of each of the airfoils  800 . The outlet portion  838  may be defined in the inner platform  814  through the casting of the inner platform  814  using a suitable die, or may be defined by machining the inner platform  814  after casting. While the exemplary embodiment described herein employs a bi-cast or full-ring casting, it should be understood that the airfoil  800  and the cooling features  244 ,  344 ,  444 ,  544 ,  606  may be formed as traditional cast segments such as doublets, triplets, or other numbers of airfoils per segment. In this example, the appropriate number of segments are then assembled to form the full turbine vane  808  assembly. 
     With the turbine vane  808  formed, the turbine vane  808  is installed into the gas turbine engine  100  ( FIG. 1 ). In use, as the gas turbine engine  100  operates, the cooling fluid F is supplied to the first conduit  830  and the second conduit  732  through the outer platform inlet bore  234  and the second outer platform inlet bore  600 , respectively. The cooling fluid F flows through the first conduit  830  along the leading edge  204 , and the cooling features  244 ,  344 ,  444 ,  544  cooperate to transfer heat from the leading edge  204  into the cooling fluid F. The cooling fluid F exits the first conduit  830  at the plurality of film cooling holes  850 , thereby cooling the first platform surface  840  of the inner platform  814 . The cooling fluid F that flows through the second conduit  732  cools the airfoil  800  downstream of the rib  260 ,  360  and may cooperate with the cooling features  606  to transfer heat into the cooling fluid F before the cooling fluid F exits the second conduit  732  along the trailing edge  224 . 
     It will be understood that the turbine vane  208 , the airfoil  200  and the dust tolerant cooling system  202  described with regard to  FIGS. 1-9  may be configured differently to provide dust tolerant cooling to the leading edge  204 . In one example, with reference to  FIG. 12 , an airfoil  900  with a dust tolerant cooling system  902  for use with a turbine vane  908  is shown. As the airfoil  900 , the dust tolerant cooling system  902  and the turbine vane  908  include components that are substantially similar to or the same as the airfoil  200 , the dust tolerant cooling system  202  and the turbine vane  208  discussed with regard to  FIGS. 1-9  or the airfoil  700 , the dust tolerant cooling system  702  and the turbine vane  708  discussed with regard to  FIG. 10 , the same reference numerals will be used to denote the same or similar features. The dust tolerant cooling system  902  may be employed with the turbine vane  908  to provide improved cooling along the leading edge  204  of the airfoil  900 . 
     The turbine vane  908  includes a pair of opposing endwalls or platforms  914 ,  216 , and the airfoils  900  are arranged in an annular array between the pair of opposing platforms  914 ,  216 . The platforms  914 ,  216  have an annular or circular main or body section. The platforms  914 ,  216  are positioned in a concentric relationship with the airfoils  900  disposed in the radially extending annular array between the platforms  914 ,  216 . In this example, the platform  216  is an outer platform and the platform  914  is an inner platform. The outer platform  216  circumscribes the inner platform  914  and is spaced therefrom to define a portion of the combustion gas flow path in the gas turbine engine  100 . The plurality of airfoils  900  is generally disposed in the portion of the combustion gas flow path. In one example, the inner platform  914  is coupled to each of the airfoils  900  at an inner diameter, and the outer platform  216  is coupled to each of the airfoils  900  at an outer diameter. 
     Each of the airfoils  900  has the pressure sidewall  218  and the suction sidewall  220 . The pressure and suction sidewalls  218 ,  220  interconnect the leading edge  204  and the trailing edge  224  of each airfoil  900 . The airfoil  900  includes the tip  226  and the root  228 , which are spaced apart by a height H 3  of the airfoil  900  or in a spanwise direction. The tip  226  is at the outer diameter of the airfoil  900  and is coupled to the outer platform  216  and the root  228  is at the inner diameter and is coupled to the inner platform  914 . 
     In one example, for each of the airfoils  900 , the dust tolerant cooling system  902  is defined through the outer platform  216  and the inner platform  914  associated with the respective one of the airfoils  900 , and a portion of the dust tolerant cooling system  902  is defined between the pressure and suction sidewalls  218 ,  220  of the respective airfoil  900 . In this example, the dust tolerant cooling system  902  includes a first, leading edge conduit or first conduit  930  and the second conduit  732 . The first conduit  930  is in fluid communication with the source of the cooling fluid F to cool the leading edge  204  of the airfoil  900 , and the second conduit  732  is in fluid communication with the source of the cooling fluid F to cool the airfoil  900  downstream of the leading edge  204  to the trailing edge  224 . 
     In one example, the first conduit  930  includes the outer platform inlet bore  234 , the airfoil inlet  236 , an outlet portion  938 , the first surface  240 , the second surface  242  and the plurality of cooling features  244  ( FIG. 4 ). In  FIG. 12 , the plurality of cooling features  244  are omitted for clarity. In addition, it should be noted that in certain embodiments, the airfoil  900  may include the plurality of cooling features  344  ( FIG. 7 ), the plurality of cooling features  444  ( FIG. 8 ) or the plurality of cooling features  544  ( FIG. 9 ). The outer platform inlet bore  234  fluidly couples the source of the cooling fluid F to the airfoil inlet  236  to supply the first conduit  930  with the cooling fluid F. The airfoil inlet  236  is defined at the tip  226  so as to be positioned at the outer diameter and is in fluid communication with the outer platform inlet bore  234  to receive the cooling fluid F. 
     In one example, the outlet portion  938  is defined through the inner platform  914 . In this regard, the inner platform  914  has a first platform surface  940  opposite a second platform surface  942 , and a first platform end  944  opposite a second platform end  946 . In this example, the outlet portion  938  includes an airfoil outlet  948 , a first platform outlet  950  and a second platform outlet  952 . The airfoil outlet  948  is defined through the root  228  of the airfoil  900  near the leading edge  204  and is in fluid communication with the first platform outlet  950 . The first platform outlet  950  is defined through the first platform surface  940  and the second platform surface  942  between the first platform end  944  and the second platform end  946 . The first platform outlet  950  is defined through a portion of the inner platform  914  that is coupled to the root  228  of the airfoil  900 . The first platform outlet  950  is in fluid communication with a chamber  954  defined between the inner platform  914  and a structure  956  associated with the gas turbine engine  100 . The second platform outlet  952  is defined through the first platform surface  940  and the second platform surface  942  between the first platform end  944  and the second platform end  946 , and is upstream from the first platform outlet  950 . The second platform outlet  952  is in fluid communication with the chamber  954  such that cooling fluid F flows from the airfoil  900  through the airfoil outlet  948 , into the first platform outlet  950 , into the chamber  954  and from the chamber  954 , the cooling fluid F flows into the second platform outlet  952 . From the second platform outlet  952 , the cooling fluid F flows into the main fluid flow M or combustion gas flow upstream from the airfoil  900 . Stated another way, the cooling fluid F flows from the second platform outlet  952  so as to be upstream from the leading edge  204  of the airfoil  900 . By flowing into the main fluid flow M and mixing with the main fluid flow M, the cooling fluid F, which has a lower temperature, may help cool the first platform surface  940 . In addition, the ejection of the cooling fluid F into the main fluid flow M does not cause loss of engine performance. In this regard, the cooling fluid F that exits the second platform outlet  952  is introduced upstream of a throat location for the turbine vane  208  and may be used by the downstream rotor blade row, which results in the cooling fluid F not being considered detrimental to the overall engine performance. 
     As the airfoil  900  and the dust tolerant cooling system  902  may be manufactured in the same manner as the airfoil  200  and the dust tolerant cooling system  202  discussed with regard to  FIGS. 1-9 , the manufacture of the airfoil  900  and the dust tolerant cooling system  902  will not be discussed in detail herein. Briefly, however, a core that defines the airfoil  900  including the respective cooling features  244 ,  344 ,  444 ,  544 , the first conduit  930  and the second conduit  732  (optionally with the second plurality of cooling features  606 ) is printed from a ceramic material, using ceramic additive manufacturing for example, and investment casting is performed to form the airfoil  900  including the integrally formed dust tolerant cooling system  902 . Alternatively, the dust tolerant cooling system  902  may be formed in the airfoil  900  using conventional dies with one or more portions of the core (or portions adjacent to the core) comprising a fugitive core insert. As a further alternative, the airfoil  900  including the dust tolerant cooling system  902  may be formed using other additive manufacturing processes, including, but not limited to, direct metal laser sintering, binder jet printing, etc. This process may be repeated to form a plurality of the airfoils  900 . With the plurality of airfoils  900  formed, the airfoils  900  may be positioned in an annular array. The outer platform  216  may be cast around the outer diameter or tip  226  of each of the airfoils  900  and the inner platform  814  may be cast around the inner diameter or root  228  of each of the airfoils  900 . The outlet portion  938  may be defined in the inner platform  914  through the casting of the inner platform  914  using a suitable die, or may be defined by machining the inner platform  914  after casting. While the exemplary embodiment described herein employs a bi-cast or full-ring casting, it should be understood that the airfoil  900  and the cooling features  244 ,  344 ,  444 ,  544 ,  606  may be formed as traditional cast segments such as doublets, triplets, or other numbers of airfoils per segment. In this example, the appropriate number of segments are then assembled to form the full turbine vane  908  assembly. 
     With the turbine vane  908  formed, the turbine vane  908  is installed into the gas turbine engine  100  ( FIG. 1 ). In use, as the gas turbine engine  100  operates, the cooling fluid F is supplied to the first conduit  930  and the second conduit  732  through the outer platform inlet bore  234  and the second outer platform inlet bore  600 , respectively. The cooling fluid F flows through the first conduit  930  along the leading edge  204 , and the cooling features  244 ,  344 ,  444 ,  544  cooperate to transfer heat from the leading edge  204  into the cooling fluid F. The cooling fluid F flows through the first platform outlet  950  and into the chamber  954 . From the chamber  954 , the cooling fluid F flows through the second platform outlet  952  and mixes with the main fluid flow M. The cooling fluid F that flows through the second conduit  732  cools the airfoil  900  downstream of the rib  260 ,  360  and may cooperate with the cooling features  606  to transfer heat into the cooling fluid F before the cooling fluid F exits the second conduit  732  along the trailing edge  224 . 
     Thus, the dust tolerant cooling system  202 ,  702 ,  802 ,  902  connects the leading edge  204  of the airfoil  200  to the rib  260 ,  360 , which is cooler than the leading edge  204  and enables a transfer of heat through the respective cooling features  244 ,  344 ,  444 ,  544  and the cooling fluid F to cool the leading edge  204 . Further, the cooling features  244 ,  344 ,  544  increase turbulence within the first conduit  230 ,  330 ,  530  by creating strong secondary flow structures due to the cooling features  244 ,  344 ,  544  traversing the first conduit  230 ,  330 ,  530  and extending between the first surface  240  and the second surface  242 ,  342 . Moreover, the cross-sectional shape of the cooling features  244 ,  344 ,  544  reduces an accumulation of dust and fine particles within the first conduit  230 ,  330 ,  530  as the reduced diameter of the first pin end  270  minimizes an accumulation of sand and dust particles on the respective top surface  278 . The first fillet  274  also increases vorticity in the cooling fluid F, which improves conduction from the leading edge  204 . Further, the dust tolerant cooling system  202 ,  702 ,  802 ,  902  provides for additional cooling to the inner platform  214 ,  714 ,  814 ,  914 . It should be noted that in certain embodiments, turbulators may be used in conjunction with the cooling features  244 ,  344 ,  444 ,  544  of the respective dust tolerant cooling system  202 ,  702 ,  802 ,  902  on the first surface  240 , and optionally, on the second surface  242 ,  342  to cool the leading edge  204 . 
     In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Numerical ordinals such as “first,” “second,” “third,” etc. simply denote different singles of a plurality and do not imply any order or sequence unless specifically defined by the claim language. The sequence of the text in any of the claims does not imply that process steps must be performed in a temporal or logical order according to such sequence unless it is specifically defined by the language of the claim. The process steps may be interchanged in any order without departing from the scope of the invention as long as such an interchange does not contradict the claim language and is not logically nonsensical. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.