Turbine airfoil with leading edge impingement cooling

BACKGROUND

0001This application relates generally to an array of features configured to influence airflow from an airfoil baffle.

0002Gas turbine engines are known and typically include multiple sections, such as a fan section, a compression section, a combustor section, a turbine section, and an exhaust nozzle section. The fan section moves air into the engine. The air is compressed in the compression section. The compressed air is mixed with fuel and is combusted in the combustor section. As known, some components of the engine operate in high temperature environments.

0003The engine includes vane arrangements that facilitate guiding air. The engine also includes blade arrangements mounted for rotation about an axis of the engine. The vane arrangements and the blade arrangements have multiple airfoils extending radially from the axis. As known, the airfoils are exposed to high temperatures and removing thermal energy from the airfoils is often necessary to avoid melting the airfoils.

0004Accordingly, engines often route bypass air to cavities within the airfoils. The air then removes thermal energy from the airfoils through impingement cooling, film cooling, or both. Some airfoils are configured to receive an impingement baffle. The bypass air moves through holes in the impingement baffle and impinges on interior surfaces of the airfoil. The bypass air then moves through film cooling holes or slots within the airfoil. Some areas of the airfoil must withstand higher temperatures than other areas of the airfoil. Manipulating the size and position of the holes within the baffle can increase thermal energy removal from some areas of the airfoil. However, removing thermal energy from areas near the leading edges and radial centers of the airfoils is especially difficult.

0005An airfoil having features on an internal surface of a leading edge is disclosed in <patcit id="pcit0001" dnum="EP1921268A"><text>EP-A-1921268</text></patcit>. A further airfoil of this type is disclosed in <patcit id="pcit0002" dnum="EP1473439A"><text>EP-A-1473439</text></patcit>. A turbine vane having an insert having holes for ejecting cooling air onto an inner wall of the vane is disclosed in <patcit id="pcit0003" dnum="US2006210399A1"><text>US 2006/210399 A1</text></patcit>.

SUMMARY

0006From a first aspect, the invention provides a gas turbine engine airfoil assembly as set forth in claim 1.

0007From a second aspect, the invention provides a method of cooling a gas turbine engine airfoil as set forth in claim 15.

0008These and other features of the example disclosure can be best understood from the following specification and drawings. The following is a brief description of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

0009<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Figure 1</figref> shows a schematic view of an example gas turbine engine.</li><li><figref idref="f0001">Figure 2</figref> shows a perspective view of an example airfoil of the <figref idref="f0001">Figure 1</figref> engine.</li><li><figref idref="f0002">Figure 3</figref> shows a partially cut away view of the <figref idref="f0001">Figure 2</figref> airfoil.</li><li><figref idref="f0002">Figure 4</figref> shows a cross-sectional view at line 4-4 of <figref idref="f0001">Figure 2</figref>.</li><li><figref idref="f0003">Figure 5</figref> shows a cross-sectional view at line 5-5 of <figref idref="f0002">Figure 4</figref>.</li><li><figref idref="f0003">Figure 5A</figref> shows the <figref idref="f0003">Figure 5</figref> cross-sectional view with the baffle removed.</li><li><figref idref="f0004">Figure 6</figref> shows a cross-sectional view at line 5-5 of <figref idref="f0002">Figure 4</figref>.</li><li><figref idref="f0004">Figure 6A</figref> shows the <figref idref="f0004">Figure 6</figref> cross-sectional view with the baffle removed.</li></ul>

DETAILED DESCRIPTION

0010<figref idref="f0001">Figure 1</figref> schematically illustrates an example gas turbine engine 10 including (in serial flow communication) a fan section 14, a low-pressure compressor 18, a high-pressure compressor 22, a combustor 26, a high-pressure turbine 30, and a low-pressure turbine 34. The gas turbine engine 10 is circumferentially disposed about an engine centerline X. During operation, air is pulled into the gas turbine engine 10 by the fan section 14, pressurized by the compressors 18 and 22, mixed with fuel, and burned in the combustor 26. The turbines 30 and 34 extract energy from the hot combustion gases flowing from the combustor 26.

0011In a two-spool design, the high-pressure turbine 30 utilizes the extracted energy from the hot combustion gases to power the high-pressure compressor 22 through a high speed shaft 38. The low-pressure turbine 34 utilizes the extracted energy from the hot combustion gases to power the low-pressure compressor 18 and the fan section 14 through a low speed shaft 42. The examples described in this disclosure are not limited to the two-spool architecture described and may be used in other architectures, such as a single-spool axial design, a three-spool axial design, and still other architectures. That is, there are various types of engines that could benefit from the examples disclosed herein, which are not limited to the design shown.

0012Referring to <figref idref="f0001 f0002">Figures 2-4</figref> with continuing reference to <figref idref="f0001">Figure 1</figref>, an example airfoil 60 includes an airfoil wall 64 that extends axially between a leading edge portion 68 and a trailing edge portion 72. The example airfoil 60 is a vane of the engine 10. In another example, the airfoil 60 is a blade of the engine 10.

0013The airfoil wall 64 extends radially along a longitudinal axis 66 between an airfoil inner end 76 and an airfoil outer end 80. A central portion 82 of the leading edge portion 68 is radially equidistant the airfoil inner end 76 and the airfoil outer end 80. As known, areas of the airfoil 60 near the central portion 82 often experience higher temperatures than other areas of the airfoil 60 during operation of the engine 10.

0014The example airfoil wall 64 establishes a cavity 84 that receives a baffle 88. In this example, the baffle 88 is a sheet metal sock that is spaced from the leading edge portion 68 of the airfoil wall 64 to establish an impingement cooling area 92 between the baffle 88 and the leading edge portion 68 of the airfoil 60. A plurality of holes 96 established within a leading edge portion 100 of the baffle 88 are configured to communicate flow of fluid 104 from an interior 108 of the baffle 88 to the impingement cooling area 92. The cavity 84 includes the interior 108 and the impingement cooling area 92 in this example. As known, the fluid 104 is typically bypass air that is communicated to the interior 108 from an air supply 110 in another area of the engine 10.

0015Fluid 104 moving from the interior 108 through the plurality of holes 96 in the leading edge portion 100 of the baffle 88 moves across the impingement cooling area 92 and contacts an interior surface 112 of the airfoil wall 64 at the leading edge portion 68 of the airfoil 60. In this example, the leading edge portion 68 of the airfoil wall 64 corresponds to the area of the airfoil wall 64 adjacent a line 116. Fluid 104 then moves aftward from the impingement cooling area 92 around the baffle 88 toward the trailing edge portion 72. The baffle 88 is spaced from side walls 124 of the airfoil wall 64, which allows flow of fluid 104 from the impingement cooling area 92 around the baffle 88. Fluid 104 moves through a plurality of slots 128 at the trailing edge portion 72 of the airfoil 60.

0016In this example, a plurality of features 120 are disposed on the interior surface 112 of the leading edge portion 68. The features 120 influence flow of fluid 104 in the impingement cooling area 92 before the fluid 104 moves around the baffle 88. The features 120 facilitate cooling the leading edge portion 68. For example, the features 120 in this example redirect flow of fluid 104 and increase the turbulence of the fluid 104. The features 120 also expose more surface area of the interior surface 112 to the fluid 104 to facilitate cooling the leading edge portion 68.

0017In some examples, the leading edge portion 68 of the airfoil 60 establishes a plurality of holes (not shown) configured to communicate some of the fluid 104 from the impingement cooling area 92 through the airfoil wall 64 near the leading edge portion 68. These examples may establish holes, such as showerhead arrangements of holes, near the leading edge portion 68 or elsewhere within the airfoil 60.

0018Referring now to <figref idref="f0003">Figures 5 and 5A</figref> with continuing reference to <figref idref="f0001">Figure 2</figref>, in this example, the features 120 include a plurality of fins or ribs 132 disposed at angles θ1 and θ2 relative to the longitudinal axis 66. Generally, the ribs 132 that are radially outboard the central portion 82 are angled to direct the fluid 104 radially inboard toward the central portion 82, and the ribs 132 radially inboard the central portion 82 are angled to direct the fluid 104 radially outboard toward the central portion 82. Accordingly, regardless of the radial position of the fluid 104 flowing from the baffle 88, the fluid 104 is directed toward the central portion 82 by the features 120, which facilitates cooling the central portion 82. In another example, the fluid 104 is directed toward another radial area of the leading edge portion 68. For example, the features 120 can be configured to direct airflow to move toward a position that is radially inside the center portion 82 and is at between 10% and 40%, for example at between 10% and 20%, the radial length of the airfoil 60 as measured from the airfoil inner end 76. In another example, the features 120 are configured to direct airflow to move toward a position that is radially outside the center portion 82 and is at between 60% and 80% the radial length of the airfoil 60 as measurred from the airfoil inner end 76. Directing airflow is one way to influence airflow.

0019Arranging the example features 120 in a nonuniform array facilitates influencing the flow. In this example, the array is nonuniform because the angles of some of the features 120 vary relative to the longitudinal axis 66 and the spacing between adjacent ones of the features 120 varies. In another example, the array is nonuniform because the spacing between adjacent ones of the features 120 varies or the sizing of adjacent ones of the features 120 varies. In such examples, the ribs 132 may be perpendicular or parallel to the longitudinal axis 66. Directing more flow toward the central portion facilitates removing thermal energy from areas of the airfoil 60 near the central portion 82.

0020In this example, the ribs 132 extend about .0254 cm from the interior surface 112 into the impingement cooling area 92. The example ribs 132 have a width w of about .0254 cm and a length I of about .6350 cm. Other example ribs 132 include different widths, lengths, and extend different amounts from the interior surface 112.

0021The angle θ1 between one rib 132a and the longitudinal axis 66 is approximately 45°, and the angle θ2 between another rib 132b and the longitudinal axis 66 is 135° in this example. Other examples of the ribs 132 may include different combinations of angles depending on the desired influence on the fluid 104 within the impingement cooling area 92. The angle θ2 may generally be about 90° greater than the angle θ1.

0022The example airfoil wall 64 is a cast monolithic structure, and the ribs 132 are formed together with the airfoil wall 64 when the airfoil wall 64 is cast. In another example, the ribs 132 are added to the airfoil wall 64 after the airfoil wall 64 is cast.

0023Referring now to <figref idref="f0004">Figure 6 and 6A</figref> with continuing reference to <figref idref="f0001">Figure 2</figref>, the features 120 of another example array for influencing flow include a plurality of material deposits 140 having a generally circular profile. The material deposits 140 are configured to turbulate the fluid 104 within the impingement cooling area 92 to facilitate cooling. Turbulating the airflow increases the dwell time of fluid 104 near the leading edge portion 68, which facilitates removing thermal energy. Other examples of the features 120 include trip strips, bumps, grooves, etc.

0024In this example, the material deposits 140 are clustered more densely near the central portion 82. Accordingly, the fluid 104 near the central portion 82 is more turbulated than the fluid 104 away from the central portion 82. Increasing the turbulence of flow facilitates removing thermal energy from the central portion 82. Thus, in this example, the nonuniform array of features influences flow by increasing the turbulence of flow near the central portion 82 more than flow away from the central portion 82.

0025In this example, the material deposits 140 have a diameter d of about .0254 cm and extend about the .0254 cm from the interior surface 112 into the impingement cooling area 92. The example material deposits 140 are weld droplets deposited on the airfoil wall 64 after the airfoil wall 64 is cast. In another example, the material deposits 140 are raised areas of the airfoil wall 64 that are cast with the airfoil wall 64.

0026Although the features 120 are described as ribs 132 and material deposits 140, a person skilled in the art and having the benefit of this disclosure would understand other features and combination of the features 120 suitable for influencing flow within the impingement cooling area 92.

0027Features of the disclosed embodiments include facilitating cooling of an airfoil by influencing flow from a baffle within the airfoil.

0028Although a preferred embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.