COMPOSITE CAST POROUS METAL TURBINE COMPONENT

A component for a gas turbine engine including: a body portion enclosing an interior compartment of the component, the body portion including an interior surface defining the interior compartment, an exterior surface opposite the interior surface, and one or more cooling holes within the body portion, wherein each of the one or more cooling holes extend from the interior surface to the exterior surface; and a porous mesh liner at least partially enclosing the exterior surface of the body portion, the porous mesh liner being fluidly connected to the one or more cooling holes, wherein the cooling holes in operation direct cooling airflow from the interior compartment of the component into the porous mesh liner.

BACKGROUND

The subject matter disclosed herein generally relates to components of gas turbine engines and, more particularly, to a method and apparatus for cooling components of a gas turbine engine.

Commonly, discrete film cooling holes may be utilized in components in hot sections of a turbine engine. Discrete film cooling holes may result in uneven cooling as the areas immediately downstream from the cooling holes are cooler than the areas further away. Uneven cooling occurs due to the cool air mixing with hot air as the distance from the cooling hole exit increases. The uniformity of cooling can be affected by parameters such as spacing between cooling holes, turbulence in the cooling air flow, and other considerations. Inefficiency from uneven cooling requires more cooling air to be used than theoretically necessary. This decreases overall engine efficiency.

SUMMARY

According to an embodiment, a component for a gas turbine engine is provided. The component including: a body portion enclosing an interior compartment of the component, the body portion including an interior surface defining the interior compartment, an exterior surface opposite the interior surface, and one or more cooling holes within the body portion, wherein each of the one or more cooling holes extend from the interior surface to the exterior surface; and a porous mesh liner at least partially enclosing the exterior surface of the body portion, the porous mesh liner being fluidly connected to the one or more cooling holes, wherein the cooling holes in operation direct cooling airflow from the interior compartment of the component into the porous mesh liner.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the component is a blade for the gas turbine engine.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the component is a vane for the gas turbine engine.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include: an attachment point located in the exterior surface of the body portion, wherein the porous mesh liner is attached to the exterior surface of the body portion via the attachment point.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the attachment point extends away from the exterior surface of the body portion.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the attachment point extends into the exterior surface of the body portion.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the attachment point includes a protruding undercut portion.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the porous mesh liner is a metal mesh liner.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the porous mesh liner is a composite matrix.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the porous mesh liner includes one or more torturous paths leading from an outlet of the cooling hole toward outside of the component.

According to another embodiment, a method of fabricating a component for a gas turbine engine is provided. The method including: manufacturing a body portion enclosing an interior compartment of the component, the body portion including an interior surface defining the interior compartment, an exterior surface opposite the interior surface, an attachment point on the exterior surface, and one or more cooling holes within the body portion, wherein each of the one or more cooling holes extends from the interior surface to the exterior surface; placing a fugitive mold defining an opening against the exterior surface such that the opening aligns with the attachment point; filling the opening with powdered metallic material; heating the cast metallic component and the powdered metallic material to a temperature above a sintering temperature of the powdered metallic material and below a melting temperature of the component; and attaching a porous mesh liner to body portion via the attachment point, the porous mesh liner at least partially enclosing the exterior surface of the body portion, the porous mesh liner being fluidly connected to the one or more cooling holes, wherein the cooling holes in operation direct cooling airflow from the interior compartment of the component into the porous mesh liner.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the component is a blade for the gas turbine engine.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the component is a vane for the gas turbine engine.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the attachment point extends away from the exterior surface of the body portion.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the attachment point extends into the exterior surface of the body portion.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the attachment point includes a protruding undercut portion.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the porous mesh liner is a metal mesh liner.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the porous mesh liner is a composite matrix.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the porous mesh liner includes one or more torturous paths leading from an outlet of the cooling hole toward outside of the component.

DETAILED DESCRIPTION

As mentioned above, discrete film cooling holes may be utilized in components in hot sections of a gas turbine engine20. Discrete film cooling holes may result in uneven cooling as the areas immediately downstream from the cooling holes are cooler than the areas further away. Uneven cooling occurs due to the cool air mixing with hot air as the distance from the cooling hole exit increases. The uniformity of cooling can be affected by parameters such as spacing between cooling holes, turbulence in the cooling air flow, and other considerations. Inefficiency from uneven cooling requires more cooling air to be used than theoretically necessary. This decreases overall engine efficiency. Embodiments disclosed herein seek to improve uniformity of cooling thereby reducing the amount of air necessary for adequate cooling.

Referring now toFIGS. 2 and 3, with continued reference toFIG. 1, a cross-sectional view of a component200of the gas turbine engine20ofFIG. 1. The component is illustrated as an airfoil of a blade or a vane for the gas turbine engine20. The component200shown inFIG. 2is an example illustration of a possible component (e.g., an airfoil) that may be utilized with embodiments disclosed herein and thus the embodiments disclosed herein may be utilized with components other than an airfoil. The component200includes a leading edge202, a trailing edge204opposite the leading edge202, a pressure side206, and a suction side208opposite the pressure side206.

The component200includes an interior compartment250and an exterior260(i.e. outside) of the component200. The component200includes cooling holes230that fluidly connects the interior compartment250to the exterior260of the component200. The component200includes a body portion210that encloses interior compartment250. The body portion210includes an interior surface212defining the interior compartment250and an exterior surface214opposite the interior surface202. The cooling holes230extend from an inlet232located on the interior surface212in the interior compartment250to an outlet234located on the exterior surface214of the component200.

The component200includes a porous mesh liner270fluidly connected to at least one of the cooling holes230. The cooling holes230in operation direct cooling airflow from the interior compartment250of the component200into the porous mesh liner270. The porous mesh liner270may at least partially enclose the exterior surface214of the component200. The cooling holes230lead cooling air290from interior compartment250to the porous mesh liner270at the outlet234of the cooling hole230. The porous mesh liner270may be a metal mesh, a composite matrix, a screen, a woven filter, a non-woven filter, a porous film, or a combination thereof. The porous mesh liner270may be composed of a metal, including but not limited to any metal that can be processed by spark plasma sintering, ceramics, cermets, ceramic matrix composites, metal matrix composites, carbides, hybrid composites, other materials currently available or yet to be developed, or any combination thereof. The porous mesh liner270includes one or more torturous paths272leading from the outlet234of the cooling hole230toward the exterior260of the component200. The porous mesh liner270may include a porous mesh design having an internal microstructure to diffuse the cooling air290and improve uniformity of cooling along the exterior surface214of the component200. Advantageously, the porous mesh design helps evenly spread cooling airflow across the exterior surface and throughout the porous mesh liner270to improve uniformity of cooling.

The porous mesh liner270is attached to the exterior surface214of the component200. The porous mesh liner270may be attached to the exterior surface214via one or more attachment points300that may be positive protrusions that extend away from the exterior surface214or negative indentations that extend into the exterior surface214, as shown inFIG. 2. The attachment points300are located in the exterior surface214of the body portion210. The attachment points300may be formed through the use of TOMO, additive manufacturing, or other advanced manufacturing system. TOMO refers to the Tomo Lithographic Molding (TLM) process developed by Mikro Systems, Inc. of Charlottesville, V.A. as described in U.S. Pat. No. 9,879,861 B2, which is incorporated herein by reference in its entirety. The attachment point300may be include protruding undercut portions302(e.g. dovetail, mushroom shaped, screw/spiral, zig-zag, or other multiple protrusions or indentations in different directions) to mechanically fasten the porous mesh liner270to the exterior surface214of the component200. Advantageously, the attachment points300may also increase the specific surface area for the adhesion between the porous mesh liner270and the exterior surface214of the component200.

Advantageously, the interface between the body portion210and the porous mesh liner270increases the adhesion of the porous mesh liner270to the body portion210thereby improving the durability and extending the useful life of the component200. Also advantageously, the ability of the porous mesh liner270to adapt to complex designs specific to the component200allows for the effective distribution and diffusion of the cooling air within the porous mesh liner270. The resulting transpiration cooling can provide more uniform heat transfer and require less cooling air than traditional film cooling based only on discrete cooling holes. Further, the improved cooling uniformity can decrease the amount of cooling air required and thus improves the efficiency and/or performance of the gas turbine engine20. The more uniform cooling provided by the porous mesh liner270may also improve the performance, efficiency, and/or durability of the component200. Efficiency improvements may also lead to emissions reductions and improved environmental impact. Furthermore, the improved cooling efficiency provided by the porous mesh liner270may negate the need for more complicated cooling path geometry inside the component200, which can simplify the required ceramic core geometry during manufacturing of the body portion thereby increasing yields and decreasing cost compared to more difficult to produce cores and castings.

As will be described below, a fabrication method is provided in which composite components that have a robust structure are formed by cast metal and detailed complex features (e.g., attachment points300ofFIGS. 2 and 3) are formed by powdered metal. The fabrication method was developed by Mikro Systems, Inc. of Charlottesville, V.A. as described in U.S. patent application Ser. No. 16/023,879 filed on Jun. 29, 2018, which is incorporated herein by reference in its entirety.

With reference toFIGS. 4-9, a method of fabricating a composite component (e.g., component200) is provided. As shown inFIG. 4, a component200is cast in an initial operation with one or more appropriate fabrication techniques. The component200may be a cast metal component. The component200has an exterior surface214and is formed to define attachment points300. In the illustrated embodiment, each attachment point300extends inwardly relative to a body portion210of the component200from an uppermost portion310of the exterior surface214and, in accordance with embodiments, may have a dovetail-shaped cross-section. That is, each attachment point300may have a relatively narrow neck section320at or proximate to the uppermost portion310of the exterior surface214and a tapered section321. The tapered section321extends inwardly from the neck section320and has an increasing width with increasing depth from the neck section320and thus forms protruding undercut portions302.

With reference toFIG. 5and in accordance with alternative embodiments, it is to be understood that the attachment points can have various cross-sectional shapes and sizes and that, while the following description generally relates to the dovetail-shape case, this is not required. For example, as shown inFIG. 5, the attachment points300can be provided as zig-zag attachment points300a, spiral attachment points300b, curved attachment points300c, and multi-directional extrusion attachment points300d. In any case, the attachment points300should have a shape that can securely maintain a cured sintered element (seeFIGS. 8 and 9) therein.

Next, as shown inFIG. 6, one or more fugitive molds400is placed against the exterior surface214of the component200. The fugitive mold400may be configured to form or define engineered surface features or openings421that align with the attachment points300. As a general matter, each of the openings421may have a more complex geometry than the attachment points300and, for example, they may have diameters that correspond to the diameters of the neck sections320(seeFIG. 4) of the attachment points300and that may have protruding undercuts302or corrugations along longitudinal axes thereof.

Once the one or more fugitive molds400are placed against the exterior surface214, the openings421are filled with powdered metallic materials430as shown inFIG. 7.

As shown inFIGS. 8 and 9, the powdered metallic materials430cured into sintered elements432and remainders of the one or more fugitive molds400are removed. The curing involves heating the component200and the powdered metallic materials to a temperature which is above the sintering temperature of the powdered metallic materials and below the melting point of the component200. The heating continues until the powdered metallic materials are sufficiently densified and form the sintered elements432.

Each sintered element432has a cross-sectional shape which mimics the cross-sectional shapes of the attachment point300and the opening421it is formed in. Thus, each sintered element432has a first part431and a second part434. The first part431is formed within the neck portion320and the tapered portion321of the corresponding attachment point300. The second part434is integrally coupled to the first part431and extends from the first part431to protrude outwardly from the exterior surface214. In an event the corresponding attachment point300has a dovetail-shape and the corresponding opening421is corrugated, the first part431will have a corresponding dovetail-shape310and the second part434will have a corresponding corrugated shape320.

In accordance with embodiments, a final volume of each of the sintered elements432may be reduced from an initial volume of the powdered metallic material of the corresponding attachment point300and the corresponding opening421. This volume reduction is a consequence of the curing process and may result in up to 15% reduction in volume. This can be seen inFIG. 9in which the local edge433of the sintered element432is shown as having receded from the edge of the tapered section321of the corresponding attachment point300.

To the extent that the volume reduction or shrinkage illustrated inFIG. 9occurs, the cross-sectional shapes of the attachment points300are designed to secure the sintered elements432. For the dovetail-shaped attachment points300, the diameter of the neck portion320(seeFIG. 4) should be sufficiently small as compared to the proximal portion of the tapered section321(seeFIG. 4) so as to limit potential movement of the resulting sintered element432with the volume reduction having occurred.

With reference toFIG. 10and, in accordance with further embodiments of the disclosure, the securing of the sintered elements432in the attachment points300may be achieved by the use of fasteners to fasten the sintered elements432in the attachment points300or by the design or geometry of the attachment points300whereby the sintered elements432tighten into position even with the volume reduction occurring (seeFIG. 10).

That is, as shown inFIG. 10, the geometry of the attachment point300includes two or more attachment features701for a given sintered element432. These attachment features701may be defined substantially opposite one another and may be designed such that the shrinkage of the sintered element432during the sintering thereof automatically results in a compression pressure being exerted between the sintered attachment protrusions702and the substrate material in and around the sintered attachment protrusions702. The compression pressure serves to prevent the movement of the sintered element432with respect to the component200and may increase an effective heat transfer between the component200and the sintered element432.

In particular, the attachment features701may extend into the body portion210of the component200curvi-linearly outwardly such that the resulting sintered attachment protrusions702similarly extend into the component200curvi-linearly. The attachment features701a taper away from each other with increasing depth into the component200and the sintered attachment protrusions702similarly taper away from each other with increasing depth into the component200. Each attachment feature701and each corresponding sintered attachment protrusion702can have a substantially similar radius of outward curvature. Outer surfaces7021of the sintered attachment protrusions702may be nearly aligned in a radial dimension with an exterior surface321of the second part434and inner surfaces7022of the sintered attachment protrusions702may be separated from one another by a radial distance DR. The first and second parts431and434of the given sintered element432thus cooperatively form a tooth-root shaped element710. While element432is shown to be a stand-alone feature, it can serve as a node that is connected to other similar nodes in a porous mesh. The connection between nodes are similarly formed by powdered metal in a fugitive mold and may entail one or more flexures designed to withstand applicable shrinkage should the porous mesh be manufactured by a process such as spark plasma sintering. The size of and the spacing between the flexures can be engineered to control the porosity of the mesh. In other embodiments, a separate porous mesh is attached to element432in a separate process.

Referring now toFIG. 11, while referencing components ofFIGS. 1-10.FIG. 11shows a flow chart of method800of fabricating a component200for a gas turbine engine20. At block804, a body portion210is manufactured by conventional investment casting, additive manufacturing, or other appropriate method. The body portion210encloses an interior compartment250of the component200and includes an interior surface212defining the interior compartment250, an exterior surface214opposite the interior surface212, an attachment point300on the exterior surface214, and one or more cooling holes230within the body portion extending from the interior surface212to the exterior surface214.

At block806, a fugitive mold400defining an opening421is placed against the exterior surface214such that the opening421aligns with the attachment point300. At block808, the opening421is filled with powdered metallic material430. At block810, the component200and the powdered metallic material430is heated to a temperature above a sintering temperature of the powdered metallic material430and below a melting temperature of the component200. In one embodiment, heating the powdered metallic material430at block810forms the porous mesh liner270. At block812, in embodiments where the powdered metallic material430did not entail the porous mesh270, a porous mesh liner270is attached to the body portion210via the attachment point300. As such, it should be seen that block812is an optional step that is not required for all embodiments of the disclosure. As mentioned above, the porous mesh liner270at least partially encloses the exterior surface214of the body portion210. The porous mesh liner270is fluidly connected to the one or more cooling holes230. The cooling holes230in operation direct cooling airflow from the interior compartment250of the component200into the porous mesh liner270.

While the above description has described the flow process ofFIG. 11in a particular order, it should be appreciated that unless otherwise specifically required in the attached claims that the ordering of the steps may be varied.

Benefits of the features described herein are the provision for production of a composite component that takes advantage of the beneficial properties of different manufacturing techniques and material systems. The fabrication methods can rely on a cast substrate for structural and creep resistance purposes and can use powdered metal features to create additional surface area or detailed geometry that could not be achievable with cast metal due to recrystallization, tooling costs or other limitations. Additionally, tooling costs for a fugitive mold is significantly less than for a traditional wax pattern tool set. This allows for multiple different fugitive molds to be used on a single substrate thereby allowing numerous and varying designs to be produced and tested while requiring less tooling cost and time as compared to having to use different traditional tool sets. This can in turn allow for multiple complex designs to be built and tested for less cost than a single complex design, which is fabricated using conventional techniques and can result in faster innovations and a more valuable final product.

Technical effects of embodiments of the present disclosure include adhering a porous mesh to a substantially solid substrate to create a composite cast/porous metal turbine component to enable cooling of the metal turbine component by passing cooling air through the porous mesh liner.