Patent Publication Number: US-2016222794-A1

Title: Incidence tolerant engine component

Description:
BACKGROUND 
     Gas turbine engines typically include a compressor section, a combustor section and a turbine section. During operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases are communicated through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads. 
     Both the compressor and turbine sections may include alternating series of rotating blades and stationary vanes that extend into the core flow path of the gas turbine engine. Engine components, such as turbine blades and vanes, are known to be cooled by routing a cooling fluid radially within a main core body passageway. In some examples, cooling fluid is directed out an exterior surface of the component via a plurality of showerhead holes to create a showerhead film, which protects the component from the relatively hot gases flowing within the core flow path. 
     SUMMARY 
     One exemplary embodiment of this disclosure relates to a gas turbine engine including a component having a leading edge, a pressure side and a suction side. The component includes a first group of holes in the leading edge and a second group of holes in one of the pressure side and the suction side. The component further includes a first core passageway and a second core passageway separate from the first core passageway. The first core passageway and the second core passageway are in communication with a respective one of the first group of holes and the second group of holes. 
     In a further embodiment of the foregoing, the first and second groups of holes are groups of showerhead holes. 
     In a further embodiment of any of the foregoing, the component includes a third group of showerhead holes in the other of the pressure side and the suction side. The component further includes a third core passageway separate from the first and second core passageways. The third core passageway is in communication with the third group of showerhead holes. 
     In a further embodiment of any of the foregoing, the component includes a pressure side wall and a suction side wall, and further includes a first passageway provided in one of the pressure side wall and the suction side wall configured to communicate fluid from the second core passageway to the second group of showerhead holes. 
     In a further embodiment of any of the foregoing, the first passageway feeds the second group of showerhead holes in series. 
     In a further embodiment of any of the foregoing, the component includes a second passageway provided in the other of the pressure side wall and the suction side wall configured to communicate fluid from the third core passageway to the third group of showerhead holes. 
     In a further embodiment of any of the foregoing, the second passageway feeds the third group of showerhead holes in series. 
     In a further embodiment of any of the foregoing, the component includes an airfoil section, and wherein the first and second core passageways prevent a flow of fluid within the first core passageway from intermixing with a flow of fluid within the second core passageway when flowing within the airfoil section. 
     In a further embodiment of any of the foregoing, the component is a turbine blade. 
     Another exemplary embodiment of this disclosure relates to a component for a gas turbine engine including an airfoil section having a leading edge, a pressure side, and a suction side. The component further includes a first group of showerhead holes in the leading edge and a second group of showerhead holes in one of the pressure side and the suction side. The component also includes a first core passageway and a second core passageway configured to communicate fluid within the airfoil section. The second core passageway is separate from the first core passageway. The first core passageway and the second core passageway are in communication with a respective one of the first group of showerhead holes and the second group of showerhead holes. 
     In a further embodiment of any of the foregoing, the component includes a pressure side wall and a suction side wall, and includes a first passageway provided in one of the pressure side wall and the suction side wall configured to communicate fluid from the second core passageway to the second group of showerhead holes. 
     In a further embodiment of any of the foregoing, the component includes a third group of showerhead holes in the other of the pressure side and the suction side. The component also includes a third core passageway separate from the first core passageway and the second core passageway. The third group of showerhead holes are in communication with the third core passageway. 
     In a further embodiment of any of the foregoing, the component includes a second passageway provided in the other of the pressure side wall and the suction side wall configured to communicate fluid from the third core passageway to the third group of showerhead holes. 
     In a further embodiment of any of the foregoing, the component is a turbine blade. 
     In a further embodiment of any of the foregoing, a variable vane is upstream of the turbine blade. 
     Another exemplary embodiment of this disclosure relates to a method of operating a gas turbine engine. The method includes cooling a first location on an exterior of an engine component with a first flow of fluid. The method further includes cooling a second location on an exterior of the engine component with a second flow of fluid separate from the first flow of fluid. 
     In a further embodiment of any of the foregoing, the method includes creating a showerhead film adjacent a leading edge and at least one of a suction side and a pressure side of the component, and directing a portion of a core airflow toward the component. 
     In a further embodiment of any of the foregoing, the method includes changing an angle of incidence of the portion of the core airflow relative to the component. 
     In a further embodiment of any of the foregoing, the method includes creating a showerhead film adjacent both of the pressure side and the suction side of the component. 
     In a further embodiment of any of the foregoing, the method includes providing the first flow of fluid from a first core passageway of the component to create the showerhead film adjacent the leading edge, and providing the second flow of fluid from a second core passageway of the component to create a showerhead film adjacent one of the pressure side and the suction side. 
     In a further embodiment of any of the foregoing, the method includes providing a third flow of fluid from a third core passageway of the component to create a showerhead film adjacent the other of the pressure side and the suction side. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings can be briefly described as follows: 
         FIG. 1  schematically illustrates a gas turbine engine. 
         FIG. 2  illustrates a prior art engine component. 
         FIG. 3  illustrates a component according to this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates an example gas turbine engine  20  that includes 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 while the compressor section  24  draws air in along a core flow path C where air is compressed and communicated to a combustor section  26 . In the combustor section  26 , air is mixed with fuel and ignited to generate a high pressure exhaust gas stream that expands through the turbine section  28  where energy is extracted and utilized to drive the fan section  22  and the compressor section  24 . 
     Although the disclosed non-limiting embodiment depicts a turbofan gas turbine engine, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines; for example a turbine engine including a three-spool architecture in which three spools concentrically rotate about a common axis and where a low spool enables a low pressure turbine to drive a fan via a gearbox, an intermediate spool that enables an intermediate pressure turbine to drive a first compressor of the compressor section, and a high spool that enables a high pressure turbine to drive a high pressure compressor of the compressor section. The concepts disclosed herein can further be applied outside of gas turbine engines. 
     The example 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. 
     The low speed spool  30  generally includes an inner shaft  40  that connects a fan  42  and a low pressure (or first) compressor section  44  to a low pressure (or first) turbine section  46 . The inner shaft  40  drives the fan  42  through a speed change device, such 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 high pressure (or second) compressor section  52  and a high pressure (or second) turbine section  54 . The inner shaft  40  and the outer shaft  50  are concentric and rotate via the bearing systems  38  about the engine central longitudinal axis X. 
     A combustor  56  is arranged between the high pressure compressor  52  and the high pressure turbine  54 . In one example, the high pressure turbine  54  includes at least two stages to provide a double stage high pressure turbine  54 . In another example, the high pressure turbine  54  includes only a single stage. As used herein, a “high pressure” compressor or turbine experiences a higher pressure than a corresponding “low pressure” compressor or turbine. 
     The example low pressure turbine  46  has a pressure ratio that is greater than about five (5). The pressure ratio of the example low pressure turbine  46  is measured prior to an inlet of the low pressure turbine  46  as related to the pressure measured at the outlet of the low pressure turbine  46  prior to an exhaust nozzle. 
     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  as well as setting airflow entering the low pressure turbine  46 . 
     The core airflow C is compressed by the low pressure compressor  44 , then by the high pressure compressor  52 , mixed with fuel and ignited in the combustor  56  to produce high speed exhaust gases that are then expanded through the high pressure turbine  54  and low pressure turbine  46 . The mid-turbine frame  57  includes vanes  60 , which are in the core airflow path and function as an inlet guide vane for the low pressure turbine  46 . Utilizing the vane  60  of the mid-turbine frame  57  as the inlet guide vane for low pressure turbine  46  decreases the length of the low pressure turbine  46  without increasing the axial length of the mid-turbine frame  57 . Reducing or eliminating the number of vanes in the low pressure turbine  46  shortens the axial length of the turbine section  28 . Thus, the compactness of the gas turbine engine  20  is increased and a higher power density may be achieved. 
       FIG. 2  illustrates a prior art engine component  62  in cross-section. In this example, the component  62  is a turbine blade. The component  62  includes a leading edge  64 , a trailing edge  66 , and opposed pressure and suction sides  68 ,  70 , extending from the leading edge  64  to the trailing edge  66 . 
     As is known in the art, the component  62  is attached to a rotor hub at a root thereof, and extends generally radially outward, in the radial direction R, which is normal to the engine central longitudinal axis A. 
     The component  62  includes a plurality of core passageways  74 A- 74 F extending generally in the radial direction R. The core passageways  74 A- 74 F are configured to communicate a flow of cooling fluid within the engine component  62 . In one example, the core passageways  74 A- 74 F are arranged to provide a serpentine passageway within the component  62 , such as in prior U.S. Pat. No. 5,975,851 (assigned to United Technologies Corporation). In another example, the core passageways  74 A- 74 F are in communication with one another by a number of axial passageways  76 A- 76 E. 
     As is known in the art, a partial airflow C 1 , which is a portion of the core airflow C, is configured to be expanded over the engine component  62 . In this example, the partial airflow C 1  is directed toward the leading edge  64  (e.g., by an upstream set of vanes) toward a stagnation point  78 . The stagnation point  78  is the point at which the partial airflow C 1  diverges, with a portion of the partial airflow C 1  being directed along the pressure side  68  of the component  62 , and the other portion of the partial airflow C 1  being directed along the suction side  70  of the component  62 . 
     In order to protect the component  62  from the relatively high temperatures associated with the partial airflow C 1 , a showerhead film  80  is generated proximate the stagnation point  78 . The showerhead film  80  is generated by directing a portion of a flow of cooling fluid F 1  from the core passageway  74 A toward a plurality of showerhead holes  82 A- 82 C formed in the leading edge  64  of the engine component  62 . 
       FIG. 3  illustrates a cooling configuration for an engine component  84  according to this disclosure. For exemplary purposes, the illustrated component  84  is a turbine blade. It should be understood that this disclosure could apply to other components, including but not limited to compressor blades, stator vanes, fan blades, and blade outer air seals (BOAS). 
     As is known in the art, the component  84  includes an airfoil section (the cross-section of the leading portion of which is illustrated in  FIG. 3 ) provided radially between a root and a tip. The airfoil section includes a leading edge  86 , a trailing edge (not shown), and opposed pressure and suction sides  88 ,  90  extending from the leading edge  86  to the trailing edge. 
     The component  84  further includes a plurality of radially extending core passageways  92 A- 92 C. The core passageways  92 A- 92 C are configured to route separate flows of cooling fluid within the component  84 . In this example, the core passageways  92 A- 92 C are provided with a common source of fluid (e.g., collocated) at a point proximate the root portion of the component  84 . That common source of fluid is split into the core passageways  92 A- 92 C. The core passageways  92 A- 92 C are arranged such that the split flows of fluid do not intermix or otherwise communicate with one another when flowing within the airfoil section of the component  84  (unlike in the prior art example of  FIG. 2 ). 
     The component  84  includes a plurality of groups of showerhead holes. While some systems only refer to cooling holes in the leading edge  86  as showerhead holes, the term showerhead holes will be used to refer to cooling holes in the pressure side  88  and the suction side  90  herein. These showerhead holes are typically high efficiency decreasing the external enthalpy of the external working fluid in a range of 100 to 500 Btu/lbm/s (e.g., approximately 230 to 1163 kJ/kg/s). For example, the component  84  includes a plurality of leading edge showerhead holes  94 A- 94 C, a plurality of pressure side showerhead holes  96 A- 96 C, and a plurality of suction side showerhead holes  98 A- 98 C. Each group of showerhead holes  94 A- 94 C,  96 A- 96 C, and  98 A- 98 C are in communication with a dedicated one of the core passageways  92 A- 92 C, as will be explained below. 
     While only three showerhead holes are illustrated in each of the groups, it should be understood that there could be any number of leading edge, pressure side, and suction side showerhead holes. It should also be understood that while three groups of showerhead holes (e.g.,  94 A- 94 C,  96 A- 96 C, and  98 A- 98 C) are illustrated, additional groups of showerhead holes may be added. In that case, each additional group of showerhead holes would be provided with a source of cooling fluid from an additional, dedicated core passageway. 
     In this example, the leading edge showerhead holes  94 A- 94 C are provided with a flow of fluid F 1  from the core passageway  92 A. The fluid F 1  passes through the showerhead holes  94 A- 94 C and creates a leading edge showerhead film  100 . 
     Another, separate flow of fluid F 2  may be communicated from the core passageway  92 B to the suction side showerhead holes  98 C by way of a suction side passageway  102  formed in the suction side wall  90 W of the component  84 . In one example, the suction side passageway  102  is a microcircuit passageway. The suction side passageway  102  leads from the core passageway  92 B to the suction side showerhead holes  98 A- 98 C, and feeds the suction side showerhead holes  98 A- 98 C in series in a flow direction normal to the radial direction of the blade. This creates a suction side showerhead film  104 . Alternatively, the microcircuit could be fed directly from the foot feed of the blade negating the need for the dedicated passageway  92 B before feeding the microcircuit. 
     Similarly, yet another flow of fluid F 3  may be communicated from the core passageway  92 C to the pressure side showerhead holes  96 A- 96 C via a pressure side passageway  106 . In one example the pressure side passageway  106  is a microcircuit passageway. The pressure side passageway  106  is formed in the pressure side wall  88 W of the component  84 , and feeds the pressure side holes  96 A- 96 C in series. The flow of fluid F 3  generates a pressure side showerhead film  108 . 
     The component  84 , as mentioned above, may be a turbine blade in one example. In this example, there may be an upstream set of vanes configured to rotate to vary the effective area of the engine  20 , and to change the angle of incidence of the core airflow C. This rotation corresponds to different stages in the operational cycle of the engine  20 . The incidence angle into relative to the component  84  may be altered through direct mechanical means (e.g., an upstream or downstream articulating body, such as a vane) or through a fluidic means by the alteration of incidence flow through operation of the engine. It should be understood that other configurations with static vanes come within the scope of this disclosure. (e.g., where, under the normal operation of the engine, the incidence angle to the blade changes). 
     As the upstream set of vanes rotates, or the operating point of the engine changes, the angle of incidence of the core airflow C, and thus the stagnation point, may change an amount significant enough to cause degradation of cooling design, as shown in  FIG. 2 . For instance, if the component  84  is arranged such that a partial airflow C 1  is introduced, the stagnation point will be provided at the leading edge  86  of the component  84 . On the other hand, the partial airflow can be introduced from a positive angle of incidence, illustrated at C 2 , which would provide a pressure side  88  stagnation point. Further, the partial airflow would be introduced from a negative angle of incidence, as illustrated at C 3 , and the stagnation location would be provided on a suction side  90  of the component  84 . 
     The arrangement disclosed in  FIG. 3  is capable of accounting for changes in the angle of incidence of the core airflow C relative to the component  84  (e.g., such as between C 1 -C 3 ) by providing showerhead holes at the leading edge  86 , the pressure side  88 , and the suction side  90 . Further, by providing flows of fluid F 1 -F 3  that are sourced from separated, dedicated core passageways  92 A- 92 C, changes in the angle of incidence will not cause pressure imbalances that may lead to ingestion of a portion of the core airflow C into the engine component  84 . 
     Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure 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. 
     One of ordinary skill in this art would understand that the above-described embodiments are exemplary and non-limiting. That is, modifications of this disclosure would come within the scope of the claims. Accordingly, the following claims should be studied to determine their true scope and content.