Patent Application
20170167274
The present invention is directed to an article and a method of forming an article. More particularly, the present invention is directed to a cooled article and a method of forming a cooled article.
Turbine systems are continuously being modified to increase efficiency and decrease cost. One method for increasing the efficiency of a turbine system includes increasing the operating temperature of the turbine system. To increase the temperature, the turbine system must be constructed of materials which can withstand such temperatures during continued use.
One common method of increasing a temperature capability of a turbine component includes the use of cooling features. The cooling features are often formed from metals and alloys used in high temperature regions of gas turbines. Typically, the cooling features are cast on or within the component during manufacturing, although it is difficult to form most complex cooling features through currently available casting techniques.
Additionally, a surface microstructure of the cooling features formed through casting of the component is generally determined by the specific casting process. While varying process parameters of the casting process may vary the mechanical properties, modifying a surface structure usually includes machining or surface treating. However, for certain components, such as articles with internal cooling features, access to the inner surface of the article as well as the surface of the internal cooling features is highly limited. Due to the limited access, modifying the surface structure of the cooling features is difficult, time consuming, and expensive. Furthermore, it may not always be possible to reach each cooling feature or portion of the inner surface of the article during the machining process.
In an embodiment, an article includes a body portion having an inner surface and an outer surface, the inner surface defining an inner region, and at least one cooling feature positioned within the inner region. At least one of the inner surface of the body portion and the at least one cooling feature has a surface roughness of between about 100 microinches (about 2.54 microns) and about 3,000 microinches (about 76.2 microns).
In another embodiment, an article includes a body portion having an inner surface and an outer surface, the inner surface defining an inner region, and at least one cooling feature positioned within the inner region. The inner surface of the body portion and the at least one cooling feature include an additive manufacturing microstructure having a surface roughness of between about 100 microinches (about 2.54 microns) and about 3,000 microinches (about 76.2 microns), and the at least one cooling feature is selected from the group consisting of impingement targets, film holes, slots, pin banks, pin fins, turbulators, bumps, cooling holes, and combinations thereof.
In another embodiment, a method of forming an article includes manufacturing a body portion by an additive manufacturing technique, and manufacturing at least one cooling feature by the additive manufacturing technique. The additive manufacturing integrally forms a surface roughness of between about 100 microinches (about 2.54 microns) and about 3,000 microinches (about 76.2 microns) on at least one of an inner surface of the body portion and the at least one cooling feature.
Other features and advantages of the present invention will be apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.
Provided are an article and method of forming an article. Embodiments of the present disclosure, for example, in comparison to concepts failing to include one or more of the features disclosed herein, increase cooling effectiveness of cooling features, increase cooling efficiency, increase wall temperature consistency, decrease or eliminate over cool regions, increase heat transfer coefficients within an article, increase friction loss, maintain fluid flow with an increased number of slots, increase cooling surface area with decreased fluid flow, provide varied heat transfer within an article, provide increased control of article cooling, increase article life, facilitate use of increased system temperatures, increase system efficiency, provide increased article cooling with decreased cooling fluid, or a combination thereof.
Referring to
As illustrated in
Each of the one or more cooling features 208 is formed on and/or in the body portion 201, or on and/or in an insert 401 (see
In addition, each of the one or more cooling features 208 may be positioned in any suitable orientation on and/or in the body portion 201, the inner region 207, and/or the insert 401 to provide cooling of the article 100. For example, as illustrated in
As will be appreciated by those skilled in the art, the cooling features 208 are not limited to the examples discussed above, and may include any other suitable cooling features or combination of cooling features. In one suitable combination, the one or more cooling features 208 include corresponding cooling features 208 formed on and/or in both the body portion 201 and the insert 401. For example, in one embodiment, as shown in
In each of the embodiments disclosed herein, the inner surface 205 and/or at least one of the cooling features 208 includes an integrally formed rough surface 601, an example of which is shown in
The integrally formed rough surface 601 increases the heat transfer coefficient of the inner surface 205 and/or the cooling feature(s) 208 as compared to inner surfaces and/or cooling features without a rough surface. This increased heat transfer coefficient increases cooling efficiency of the article 100, which facilitates cooling of the article 100 with decreased cooling flow. Additionally or alternatively, the integrally formed rough surface 601 increases friction loss as compared to inner surfaces and/or cooling features without a rough surface. The increased friction loss decreases flow through the film holes 215, slots 217, and other openings in the article 100, permitting the formation of more openings in the article 100 without increasing fluid flow to the article 100. The formation of more openings in the article 100 increases the surface area available for cooling, which increases heat transfer, increases cooling efficiency, provides cooling of the article 100 with decreased cooling flow, increases engine efficiency, or a combination thereof.
In one embodiment, both the inner surface 205 and the cooling feature(s) 208 include the integrally formed rough surface 601 having the same or substantially the same surface roughness. In another embodiment, the surface roughness of the integrally formed rough surface 601 on the cooling feature(s) 208 differs from that of the inner surface 205. In a further embodiment, the surface roughness varies within the integrally formed rough surface 601 of the inner surface 205 and/or the cooling feature(s) 208.
The varying of the surface roughness varies the heat transfer coefficient within the article 100, providing increased control over cooling of the article 100. In one embodiment, the surface roughness of the integrally formed rough surface 601 is varied as a function of a heat load on the article 100, such as that from a hot gas path in a gas turbine. By varying the surface roughness as a function of the heat load, the integrally formed rough surface 601 increases a consistency of the temperature of the body portion 201, decreases or eliminates over cooling of the article 100, decreases or eliminates unnecessary heating of the cooling fluid, or a combination thereof. For example, the inner surface 205 on a pressure side of the airfoil 107, which has a comparatively lower heat load, may include a surface roughness of about 300 μin, while the inner surface 205 on the suction side of the airfoil 107, which has a comparatively higher heat load, may include a surface roughness of about 2,000 μin. The greater surface roughness on the suction side provides increased heat transfer as compared to the pressure side, facilitating increased cooling of the suction side and/or decreasing or eliminating over cooling of the pressure side. In another example, the surface roughness of the integrally formed rough surface 601 is varied from the inlet to the outlet of the slots 217 in the trailing edge of the airfoil 107. The varying surface roughness within the slots 217 increases the heat transfer coefficient of the slots 217 as the heat load increases and/or the temperature of the cooling fluid increases.
According to one or more of the embodiments disclosed herein, the inner surface 205 and/or the cooling feature(s) 208 having the rough surface 601 also have an additive manufacturing microstructure. For example, forming the inner surface 205 and/or the cooling feature(s) 208 having the rough surface 601 may include any suitable method of additive manufacturing. Suitable methods of additive manufacturing include, but are not limited to, direct metal laser melting (DMLM), direct metal laser sintering (DMLS), selective laser melting (SLM), selective laser sintering (SLS), electron beam melting (EBM), fused deposition modeling (FDM), any other additive manufacturing technique, or a combination thereof.
In one embodiment, the FDM method includes supplying a material to a nozzle, heating the nozzle, and extruding the material through the nozzle. The heating of the nozzle melts the material as the material passes through the nozzle. Upon extrusion of the material through the nozzle the material hardens, forming the body portion 201 and/or the one or more cooling features 208 having the integrally formed rough surface 601.
In another embodiment, as illustrated in
Integrally forming the rough surface 601 during the additive manufacturing facilitates increased control over the average surface roughness and/or location of the rough surface 601 within the article 100. For example, in one embodiment, the depositing and/or melting of the metal alloy powder 701 is varied during the additive manufacturing process to increase or decrease the surface roughness in the corresponding portion of the article 100. In another embodiment, the integral forming of the rough surface 601 during additive manufacturing permits the formation of the rough surface 601 in portions of the article 100 that are not accessible by traditional manufacturing and/or machining techniques. In a further embodiment, the integrally formed rough surface 601 provides increased heat transfer and/or cooling of the article 100, as compared to other rough surfaces formed through machining and/or attachment to the article 100.
The final component formed by the additive manufacturing method includes any suitable net or near-net shape structure. As used herein “near-net shape” means that the component is formed very close to the final shape, not requiring significant traditional mechanical finishing techniques such as machining or grinding following the additive manufacturing. Additionally, as used herein “net shape” means that the component is formed in the final shape, requiring no traditional mechanical finishing techniques following the additive manufacturing. Suitable net or near-net shape structures include, but not limited to, the article 100, the body portion 201, the inner surface 205, the cooling feature(s) 208, the insert 401, the integrally formed rough surface 601, or a combination thereof. For example, although the final component is shown in
While the invention has been described with reference to one or more embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. In addition, all numerical values identified in the detailed description shall be interpreted as though the precise and approximate values are both expressly identified.
