Patent Publication Number: US-10781697-B2

Title: Double wall turbine gas turbine engine blade cooling configuration

Description:
BACKGROUND 
     This disclosure relates to gas turbine engines and particularly to internally cooled rotor blades. 
     A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustor section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow. The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section typically includes low and high pressure compressors, and the turbine section includes low and high pressure turbines. 
     As is well known, the aircraft engine industry is experiencing a significant effort to improve the gas turbine engine&#39;s performance while simultaneously decreasing its weight. The ultimate goal has been to attain the optimum thrust-to-weight ratio. One of the primary areas of focus to achieve this goal is the “hot section” of the engine since it is well known that engine&#39;s thrust/weight ratio is significantly improved by increasing the temperature of the turbine gases. However, turbine gas temperature is limited by the metal temperature constraints of the engine&#39;s components. Significant effort has been made to achieve higher turbine operating temperatures by incorporating technological advances in the internal cooling of the turbine blades. 
     Serpentine core cooling passages have been used to cool turbine blades. The serpentine cooling passage is arranged between the leading and trailing edge core cooling passages in a chord-wise direction. One typical serpentine configuration provides “up” passages arranged near the leading and trailing edges fluidly joined by a “down” passage. This type of cooling configuration may have inadequacies in some applications. To this end, a double wall cooling configuration has been used to improve turbine blade cooling. 
     In a double wall blade configuration, thin hybrid skin core cavity passages extend radially and are provided in a thickness direction between the core cooling passages and each of the pressure and suction side exterior airfoil surfaces. Double wall cooling has been used as a technology to improve the cooling effectiveness of a turbine blades, vanes, blade out air seals, combustor panels, or any other hot section component. Often, core support features are used to resupply air from a main body core, which creates the core passages, into the hybrid skin core cavity passages, which creates the skin passages. 
     With traditional double wall configurations, a cooling benefit is derived from passing coolant air from the internal radial flow and/or serpentine cavities through the “cold” wall via impingement (resupply) holes and impinging the flow on the “hot” wall. These core support (resupply) features are typically oriented perpendicular to the direction of flow in the hybrid skin core cooling cavities. These perpendicular core supports (resupply) features induce local flow vortices which generate a significant amount of turbulent mixing to occur locally within the hybrid skin core cavity passage. Although the impingement flow field characteristics associated with the resupply holes may appear beneficial they create local flow characteristics which are not advantageous from an internal cooling perspective. Adverse impacts due to disruptive impingement resupply features oriented perpendicular to the streamwise flow direction with in the hybrid skin core cavity generate pressure and momentum mixing losses that mitigate the favorable convective cooling flow field characteristics. Potential improvements in the internal flow field cooling qualities are diminished due to the disruptive nature of the injection of high pressure and velocity resupply cooling air flow normal to main hybrid skin core cooling passage flow direction. The potential decrease in bulk fluid cooling temperature may be adversely impacted by the additional cooling air heat pickup incurred due to the high impingement heat transfer and subsequent heat removal from the exterior hot wall. In a purely convective hybrid skin core cooling channel passage the locally high impingement heat transfer generated by the resupply features oriented normal to the downstream cooling flow may produce large local metal temperature gradients that result in locally high thermal strain and subsequent thermal mechanical fatigue crack initiation and propagation failure mechanisms. 
     Improving the mixing characteristics of the two different flows through the incorporation of “in-line” or “angled” resupply orientation and unique geometric features can improve the overall convective cooling characteristics of the internal flow field and increase the thermal cooling effectiveness of resupplied hybrid skin core cooling cavity passages. The intent of this invention is improve the relative alignment of the resupply cooling flow with the downstream cooling flow within the hybrid skin core cooling channel passages. Additionally it is also desirable to introduce the resupply cooling flow at a mass and momentum flux ratio that is ≥ the mass and momentum flux of the downstream cooling flow within the hybrid skin core cooling channel passage immediately adjacent to the internal surface of the hot exterior airfoil wall. By introducing resupply flow through a diffused geometric feature the relative mass and momentum mixing of the two different flow streams is more easily controlled by modifying the expansion ratio and geometry shape of the diffusing section of the resupply geometry. 
     SUMMARY 
     In one exemplary embodiment, an airfoil includes pressure and suction side walls that extend in a chord-wise direction between leading and trailing edges. The pressure and suction side walls extend in a radial direction to provide an exterior airfoil surface. A core cooling passage is arranged between the pressure and suction walls in a thickness direction and extends radially toward a tip. A skin passage is arranged in one of the pressure and suction side walls to form a hot side wall at an outer surface and a cold side wall at an inner surface. The skin passage extends a height in the radial direction, a width in a width direction, and a thickness in a thickness direction. The thickness is less than the width. The hot side wall defines a portion of the exterior airfoil surface and the cold side wall defines a portion of the core passage at a core passage surface. The core passage and the skin passage are configured to have a same direction of fluid flow. A resupply hole fluidly interconnects the core and skin passages. A centerline of the resupply hole is arranged at an first angle relative to the direction of fluid flow in the core passage. The first angle lies in a plane parallel to the thickness direction. The centerline of the resupply hole is arranged at a second angle relative to the direction of fluid flow in the core passage. The second angle lies in a plane parallel to the width direction. The second angle is at an acute angle. The first and second angles are configured to provide a low turbulence flow region in the skin passage. 
     In a further embodiment of any of the above, the first angle is acute. 
     In a further embodiment of any of the above, the first angle is in a range of 5°-45°. 
     In a further embodiment of any of the above, the second angle is in a range of 15°-75°. 
     In a further embodiment of any of the above, the second angle is in a range of 30°-60° 
     In a further embodiment of any of the above, the skin passage has an aspect ratio that may vary between 3:1≥H/W≥1:5. H corresponds to a passage height and W corresponds to a passage width. 
     In a further embodiment of any of the above, the passage height (H) is in a range of 0.010-0.200 inches (0.25-5.08 mm). 
     In a further embodiment of any of the above, the resupply hole has an exit at the skin passage, the exit has a diffuser. 
     In a further embodiment of any of the above, the exit has an edge at the inner surface that is perpendicular to the direction of fluid flow. 
     In a further embodiment of any of the above, the exit has an edge at the inner surface that is perpendicular to the centerline. 
     In a further embodiment of any of the above, a serpentine cooling passage has first, second and third cooling passages. The first and third cooling passages have a direction of fluid flow toward the tip. The second cooling passage has a direction of fluid flow away from the tip. The core passage provided by one of the first, second and third cooling passages. 
     In a further embodiment of any of the above, a film cooling hole extends from the skin passage to the exterior airfoil surface. 
     In a further embodiment of any of the above, the airfoil is a turbine blade. 
     In another exemplary embodiment, a gas turbine engine includes a combustor section arranged fluidly between compressor and turbine sections. An airfoil is arranged in the turbine section. The airfoil includes pressure and suction side walls that extend in a chord-wise direction between leading and trailing edges. The pressure and suction side walls extend in a radial direction to provide an exterior airfoil surface. A core cooling passage is arranged between the pressure and suction walls in a thickness direction and extends radially toward a tip. A skin passage is arranged in one of the pressure and suction side walls to form a hot side wall at an outer surface and a cold side wall at an inner surface. The skin passage extends a height in the radial direction, a width in a width direction, and a thickness in a thickness direction. The thickness is less than the width. The hot side wall defines a portion of the exterior airfoil surface and the cold side wall defines a portion of the core passage at a core passage surface. The core passage and the skin passage are configured to have a same direction of fluid flow. A resupply hole fluidly interconnects the core and skin passages. A centerline of the resupply hole is arranged at a first angle relative to the direction of fluid flow in the core passage. The first angle lies in a plane parallel to the thickness direction. The centerline of the resupply hole is arranged at a second angle relative to the direction of fluid flow in the core passage. The second angle lies in a plane parallel to the width direction. The second angle is at an acute angle and the first and second angles are configured to provide a low turbulence flow region in the skin passage. 
     In a further embodiment of any of the above, the first angle is acute. 
     In a further embodiment of any of the above, the second angle is in a range of 15°-75°. 
     In a further embodiment of any of the above, the skin passage has an aspect ratio that may vary between 3:1≥H/W≥1:5. H corresponds to a passage height and W corresponds to a passage width. The passage height (H) is in a range of 0.010-0.200 inches (0.25-5.08 mm). 
     In a further embodiment of any of the above, the resupply hole has an exit at the skin passage and the exit has a diffuser. 
     In a further embodiment of any of the above, the airfoil is a turbine blade that includes a serpentine cooling passage that has first, second and third cooling passages. The first and third cooling passages have a direction of fluid flow toward the tip. The second cooling passage has a direction of fluid flow away from the tip. The core passage provided by one of the first, second and third cooling passages. 
     In a further embodiment of any of the above, a film cooling hole extends from the skin passage to the exterior airfoil surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  schematically illustrates a gas turbine engine embodiment. 
         FIG. 2A  is a perspective view of the airfoil having the disclosed cooling passage. 
         FIG. 2B  is a plan view of the airfoil illustrating directional references. 
         FIG. 2C  is a cross-sectional view taken along line  2 C- 2 C of  FIG. 2A . 
         FIG. 3  is a sectional view taken along line  3 - 3  of  FIG. 2A . 
         FIG. 3A  is a schematic view of a skin passage with a varying height and width along its length. 
         FIG. 4  depicts a portion of the core and skin passages and flow therethrough. 
         FIG. 5  illustrates a second angle of a resupply hole to the skin passage. 
         FIG. 6  depicts a resupply hole embodiment and diffuser geometry. 
         FIG. 7  depicts another resupply hole embodiment and diffuser geometry. 
         FIG. 8  depicts yet another resupply hole embodiment and diffuser geometry. 
     
    
    
     The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  is disclosed herein as a two-spool turbofan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmenter section (not shown) among other systems or features. The fan section  22  drives air along a bypass flow path B in a bypass duct defined within a nacelle  15 , and also drives air along a core flow path C for compression and communication into the combustor section  26  then expansion through the turbine section  28 . Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with two-spool turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures. 
     The exemplary engine  20  generally includes a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine central longitudinal axis X relative to an engine static structure  36  via several bearing systems  38 . It should be understood that various bearing systems  38  at various locations may alternatively or additionally be provided, and the location of bearing systems  38  may be varied as appropriate to the application. 
     The low speed spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a first (or low) pressure compressor  44  and a first (or low) pressure turbine  46 . The inner shaft  40  is connected to the fan  42  through a speed change mechanism, which in exemplary gas turbine engine  20  is illustrated as a geared architecture  48  to drive the fan  42  at a lower speed than the low speed spool  30 . The high speed spool  32  includes an outer shaft  50  that interconnects a second (or high) pressure compressor  52  and a second (or high) pressure turbine  54 . A combustor  56  is arranged in exemplary gas turbine  20  between the high pressure compressor  52  and the high pressure turbine  54 . A mid-turbine frame  57  of the engine static structure  36  is arranged generally between the high pressure turbine  54  and the low pressure turbine  46 . The mid-turbine frame  57  further supports bearing systems  38  in the turbine section  28 . The inner shaft  40  and the outer shaft  50  are concentric and rotate via bearing systems  38  about the engine central longitudinal axis X which is collinear with their longitudinal axes. 
     The core airflow is compressed by the low pressure compressor  44  then the high pressure compressor  52 , mixed and burned with fuel in the combustor  56 , then expanded over the high pressure turbine  54  and low pressure turbine  46 . The mid-turbine frame  57  includes airfoils  59  which are in the core airflow path C. The turbines  46 ,  54  rotationally drive the respective low speed spool  30  and high speed spool  32  in response to the expansion. It will be appreciated that each of the positions of the fan section  22 , compressor section  24 , combustor section  26 , turbine section  28 , and geared architecture  48  may be varied. For example, geared architecture  48  may be located aft of combustor section  26  or even aft of turbine section  28 , and fan section  22  may be positioned forward or aft of the location of geared architecture  48 . 
     The engine  20  in one example is a high-bypass geared aircraft engine. In a further example, the engine  20  bypass ratio is greater than about six (6), with an example embodiment being greater than about ten (10), the geared architecture  48  is an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3 and the low pressure turbine  46  has a pressure ratio that is greater than about five. In one disclosed embodiment, the engine  20  bypass ratio is greater than about ten (10:1), the fan diameter is significantly larger than that of the low pressure compressor  44 , and the low pressure turbine  46  has a pressure ratio that is greater than about five 5:1. Low pressure turbine  46  pressure ratio is pressure measured prior to inlet of low pressure turbine  46  as related to the pressure at the outlet of the low pressure turbine  46  prior to an exhaust nozzle. The geared architecture  48  may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3:1. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present invention is applicable to other gas turbine engines including direct drive turbofans. 
     A significant amount of thrust is provided by the bypass flow B due to the high bypass ratio. The fan section  22  of the engine  20  is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet (10,668 meters). The flight condition of 0.8 Mach and 35,000 ft (10,668 meters), with the engine at its best fuel consumption—also known as “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—is the industry standard parameter of lbm of fuel being burned divided by lbf of thrust the engine produces at that minimum point. “Low fan pressure ratio” is the pressure ratio across the fan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about 1.45. “Low corrected fan tip speed” is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram °R)/(518.7°R)] 0.5 . The “Low corrected fan tip speed” as disclosed herein according to one non-limiting embodiment is less than about 1150 ft/second (350.5 meters/second). 
     The disclosed cooling configuration is particularly beneficial for turbine blades of a gas turbine engine where internal cooling of the blades is desired, although the disclosed arrangement may also be used in the compressor section or for stator vanes. For exemplary purposes, a turbine blade  64  is described. 
     Referring to  FIGS. 2A and 2B , a root  74  of each turbine blade  64  is mounted to a rotor disk. The turbine blade  64  includes a platform  76 , which provides the inner flow path, supported by the root  74 . An airfoil  78  extends in a radial direction R from the platform  76  to a tip  80 . It should be understood that the turbine blades may be integrally formed with the rotor such that the roots are eliminated. In such a configuration, the platform is provided by the outer diameter of the rotor. The airfoil  78  provides leading and trailing edges  82 ,  84 . The tip  80  is arranged adjacent to a blade outer air seal (not shown). 
     The airfoil  78  of  FIG. 2B  somewhat schematically illustrates an exterior airfoil surface  79  extending in a chord-wise direction C from a leading edge  82  to a trailing edge  84 . The airfoil  78  is provided between pressure (typically concave) and suction (typically convex) walls  86 ,  88  in an airfoil thickness direction T, which is generally perpendicular to the chord-wise direction C. Multiple turbine blades  64  are arranged circumferentially in a circumferential direction A. The airfoil  78  extends from the platform  76  in the radial direction R, or spanwise, to the tip  80 . 
     The airfoil  78  includes a serpentine cooling passage  90  provided between the pressure and suction walls  86 ,  88 . The disclosed skin core and resupply hole arrangement may be used with other cooling passage configurations, including non-serpentine cooling passage arrangements. As will be appreciated from the disclosure below, it should be understood that the central core passages from which resupply flow is bled might consist of a single radial core passage, and or multiple radial central core passages. Additionally one or more radial flow central core cooling passages may also be combined with a central core passage serpentine consisting of two or more continuous central cooling passages from which resupply flow may also be supplied. 
     Referring to  FIG. 3 , leading and trailing edge cooling passages  94 ,  96  are respectively provided near the leading and trailing edges  82 ,  84  as “up” passages refer to cooling passages that transport cooling fluid radially outward away from the engine centerline, in a direction towards a larger radial outboard location. Conversely, “down” passages, refer to cooling passages that transport cooling fluid radially inward toward the engine centerline, in a direction towards a smaller inboard location. The serpentine cooling passage  90  includes a first (“up”) passage  90   a  near the leading edge cooling passage  94  that flows into a second (“down”) passage  90   b , which flows into a third (“up”) passage  90   c  near the trailing edge cooling passage  96 . The first, second and third passages  90   a ,  90   b ,  90   c  are separated by ribs  89 . The serpentine cooling passage  90  and the leading and trailing edge cooling passages  94 ,  96  are referred to as “central main-body core” passages. The airfoil&#39;s mean camber line bisects the core passages in the example shown. The exterior airfoil surface  79  may include multiple film cooling holes  91 ,  93  in fluid communication with the cooling passages  90 ,  94 ,  96  to create a thin film boundary layer that protects the exterior airfoil  78  from hot gases in the core flow path C. 
     Referring to  FIGS. 2A and 2C , a cooling source  92 , such as bleed air from the compressor section  24 , may be fluidly connected to the cooling passages  90 ,  94 ,  96  and hybrid skin core cavity cooling passages  98  to cool the blade  64 . 
     As shown in  FIGS. 2C and 3 , the hybrid skin core cavity cooling passages  98  may be provided in the pressure and suction walls  86 ,  88 , which separate these walls into a hot side wall  100  and a cold side wall  102 . The hybrid skin core cavity cooling passages  98  typically have a much lower aspect ratio H/W, cavity height (H) to cavity width (W), than the “central main-body core” passages. Typically hybrid skin core cavity cooling passages have a cavity height (H) to cavity width (W) ratio that may vary in cavity aspect ratio between 3:1≥H/W≥1:5 The height of the skin passage  98 , which is generally in the thickness direction and typically normal to a tangent line L at the exterior airfoil surface  79 , is in a range of 0.010-0.200 inches (0.25-5.08 mm). 
       FIG. 3A  is a schematic view of a skin passage with a varying height and width along its length. A variation in hybrid skin core cooling cavity aspect ratio is schematically shown. The height H and/or width W can be varied along the length (i.e., H 1 ≠H 2  and/or W 1 ≠W 2  in the radial span-wise and chord-wise directions). 
     The hot side wall  100  provides the exterior airfoil surface  79  and an outer surface  104  of the hybrid skin core cooling cavity cooling passage  98 . The cold side wall  102  provides an inner surface  106  of the hybrid skin core cavity cooling passage  98  and a central core cooling passage surface  108  of the central core cooling passage. The film cooling holes  93  may be fluidly connected to the hybrid skin core cavity cooling passages  98 . 
     Referring to  FIGS. 3 and 4 , resupply holes  110  extend through the cold side wall  102  to fluidly interconnect the core passages, for example, serpentine passage  90 , at an inlet  113  and an exit  114  of the hybrid skin core cavity cooling passages  98 . In the past, the resupply holes  110  have been oriented in a direction normal to the central core cooling passages and the hybrid skin core cavity cooling passages  98 , which typically generates pressure and momentum mixing losses due to the resupply jet velocities being introduced normal (perpendicular) to the downstream cooling flow in the hybrid skin core cavity cooling passage that mitigate the favorable convective cooling flow field characteristics. In this sense the impingement jet emanating from the normally oriented resupply flow impedes and disrupts the flow vortices and convective heat transfer augmentation within the hybrid skin core cavity cooling passage along the rib roughened (turbulators/trip strip) internal surface of the exterior hot wall. Instead, the disclosed cooling configuration angles the resupply holes  110  in a favorable orientation more aligned with the flow direction of downstream fluid flow F within the hybrid skin core cavity cooling passage, which improves the mixing quality of the two separate cooling flow streams emanating from the resupply feed holes  110  and the cooling fluid within the hybrid skin core cavity cooling passage  98 . It is also desirable to introduce the resupply cooling flow at a mass and momentum flux ratio that is ≥ the mass and momentum flux of the downstream cooling flow within the hybrid skin core cooling channel passage  98  immediately adjacent to the internal surface of the hot exterior airfoil wall. By introducing resupply flow through a geometric feature  110  comprising of a metering section  110   a  and a diffuser section  110   b  the relative mass and momentum mixing of the two different flow streams is more easily controlled by adjusting the expansion ratio of the diffuser section of the resupply hole geometry. Furthermore the expansion ratio of the resupply hole and diffuser geometry shape enables the control of both the magnitude and strength of the vortices within the flow region  112  being expelled into the hybrid skin core cavity cooling passage  98  downstream from the exit  114  of the resupply hole  110 . In the example, the direction of fluid flow F is in the radial direction R and toward the tip  80 . A centerline  116  of the resupply hole  110  has an acute angle G relative to the direction of fluid flow F in a range of 5°-45°. 
     The resupply holes  110  may have various shapes. One or more resupply holes  110  may be fluidly connected to each discrete skin passage  98 . The exit  114  may provide a diffuser (right resupply hole  110  in  FIG. 4 ), if desired. 
     Using techniques typically used in external film cooling, one may orient the core support resupply cooling features in the streamwise direction of the cooling air flow in the hybrid skin core cavity cooling passage. By improving the relative alignment of the two separate flow streams the momentum mixing associated with the differences in the inertial Coriolis and buoyancy forces between the two separate flow streams will be significantly reduced. In so doing the high pressure losses typically observed between the two independent flow streams emanating from a resupply hole  110  oriented normal to the downstream flow field within the hybrid skin core cavity cooling passage  98  can be significantly reduced and the resulting mixing length can be dissipated quickly along the streamwise direction of cooling flow within the hybrid skin core cavity cooling passage. 
     Additive manufacturing and Fugitive Core casting processes enable design flexibility in gas turbine manufacturing. One of the design spaces that additive opens up is in the design of ceramic cores used in the investment casting process. Traditional ceramic cores are made with a core die, which has a finite number of “pull planes.” These pull planes restrict the design of ceramic cores to prevent features from overhanging in the direction that the die is pulled when the cores are removed. Additive manufacturing and Fugitive Core processes can remove those manufacturing restrictions, as dies are no longer required to create the ceramic cores of the internal cooling passages and internal convective cooling features, such as trip strips, pedestals, impingement ribs, resupply holes, etc. 
     An additive manufacturing process may be used to produce an airfoil. Alternatively, a core may be constructed using additive manufacturing and/or Fugitive Core manufacturing may be used to provide the correspondingly shaped resupply hole geometries when casting the airfoil. These advanced manufacturing techniques enable unique core features to be integrally formed and fabricated as part of the entire ceramic core body and then later cast using conventional loss wax investment casting processes. Alternatively powdered metals suitable for aerospace airfoil applications may be used to fabricate airfoil cooling configurations and complex cooling configurations directly. The machine deposits multiple layers of powdered metal onto one another. The layers are joined to one another with reference to CAD data, which relates to a particular cross-section of the airfoil. In one example, the powdered metal may be melted using a direct metal laser sintering process or an electron-beam melting process. With the layers built upon one another and joined to one another cross-section by cross-section, an airfoil with the above-described geometries may be produced, as indicated at. The airfoil may be post-processed to provide desired structural characteristics. For example, the airfoil may be heated to reconfigure the joined layers into a single crystalline structure. 
       FIG. 5  illustrates a second angle  120  that lies in a plane parallel to the width direction of the skin passage  98 . The second angle is at an acute angle in a range of 15°-75°, and in one example, in a range of 30°-60°. The first and second angles, G and  120 , respectively are configured to reduce mixing and provide a less turbulent flow region in the skin passage  98 . The second angle  120  being non-parallel with the direction of fluid flow enables the fluid in the skin passage  98  to provide more coverage, while the first angle G maintains a laminar flow. These compound angles allow the cooling film to have greater coverage than if it were axially oriented. This reduction in mixing and increase in coverage reduces fluid heating at the end of the skin passage  98  and provides a larger area of cooled resupplied flow into the skin passage  98 . 
     Supply holes  110  with a diffuser  118 ,  218 ,  318  are shown in  FIGS. 6-8 . In  FIG. 6 , the exit  114  has an edge  122  at the inner surface  106  that is perpendicular to the centerline  116 . In  FIGS. 7 and 8 , the edges  222 ,  322  are arranged at the inner surface  106  and perpendicular to the direction of fluid flow. Different diffuser geometries may be selected depending upon the desired flow characteristic. 
     The exit hole geometries, as illustrated in  FIGS. 5-8 , are exemplary. The geometries are chosen to attain a desired flow characteristic and a boundary layer within the hybrid skin core cooling cavity passage  98  based upon the desired pressure drop cooling and other characteristics for the airfoil in an application. 
     It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the embodiments of the present invention. Additionally it is important to note that any complex multi-facetted resupply geometries that bridge centrally located main body cooling passages and peripherally located hybrid skin core cooling cavity passages can be created at any number of radial, circumferential, and/or tangential locations within an internal cooling configuration. The quantity, size, orientation, and location will be dictated by the necessity to increase the local thermal cooling effectiveness and achieve the necessary thermal performance required to mitigate hot section part cooling airflow requirements, as well as, meet part and module level durability life, stage efficiency, module, and overall engine cycle performance and mission weight fuel burn requirements. 
     Although the different examples have specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
     Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.