Patent Application
20160230993
The disclosure relates generally to gas turbine engines, and more particularly to effusion cooling holes in gas turbine engines.
Gas turbine engines typically comprise compressor stages which feed compressed air to a combustor. A portion of the compressed air is mixed with fuel and ignited in the combustor. A portion of the compressed air is directed through cooling holes in the combustor and protects the combustor from the high temperatures caused by the combustion. The cooling holes are typically drilled through the combustor liner, at an angle relative to the combustor liner. The holes are typically linear, as it is difficult to create complex hole shapes with known drilling techniques. The loss or pressure drop across the linear holes is generally small and fixed so that it is difficult to increase the number density of the holes without increasing the cooling flow. Therefore, the spacing and pitch distance for the linear holes are generally very large, resulting in poor film cooling effectiveness. In addition, compared to the liner backside or impingement convective cooling, the convective cooling within the linear effusion holes is generally small due to small surface area, which is related to the number, passage length, and diameter of the holes.
There is continuous effort to reduce the cooling flow of the combustor liner in order to improve combustor performance. In recent times, gas turbine engines have been designed with higher overall pressure ratios (“OPR”). The temperature of the cooling air in these high OPR engines is higher compared to engines with lower OPRs. The higher temperature of the cooling air results in less heat transfer from the combustor liner to the cooling air. A larger portion of the compressed air may be utilized for cooling air, which significantly impacts combustor design and combustor performance.
A gas turbine engine component may comprise an outer surface of a first wall, an inner surface of the first wall, and a first cooling hole extending from the outer surface of the first wall to the inner surface of the first wall. The first cooling hole may be nonlinear.
In various embodiments, the gas turbine engine component may be manufactured by an additive manufacturing process. The first cooling hole may comprise a first straight passage connected to a second straight passage by a first bend. The first straight passage may be parallel to the second straight passage. The gas turbine engine component may be a combustor liner. A length of the first cooling hole may be at least twice a thickness of the combustor liner. The gas turbine engine component may comprise a second wall comprising a second cooling hole, wherein the second cooling hole is configured to direct cooling air to the first wall. The second cooling hole may be a linear cooling hole. The combustor liner may comprise a segmented wall coupling the first wall to the second wall.
A combustor for a gas turbine engine may comprise a first wall comprising a first cooling hole, wherein the cooling hole comprises an inlet, a first straight passage connected to the inlet by a first bend, and a second straight passage connected to the first straight passage by a second bend.
In various embodiments, the combustor may be manufactured by an additive manufacturing process. A length of the first cooling hole may be at least five times a thickness of the first wall. The combustor may comprise a second wall comprising an impingement hole, wherein the impingement hole is configured to direct cooling air to the first wall. The impingement hole may be a linear cooling hole. The combustor liner may be a single-wall liner comprising the first wall, a second wall, and a segmented wall between the first wall and the second wall. A combustor liner may comprise the first wall only as a single-wall liner. A combustor liner may also comprise both the first and second wall with these two walls bolted together. In addition, using additive manufacturing process or welding, a combustor liner may be built as a single-wall liner by adding a segmented wall to combine the first and second wall together.
A combustor liner may be manufactured by an additive manufacturing process. The combustor liner may comprise a nonlinear cooling hole.
In various embodiments, the nonlinear cooling hole may extend through a first wall of the combustor liner. A length of the cooling hole may be at least five times a thickness of the first wall. The combustor liner may be a single-wall liner comprising the first wall, a second wall, and a segmented wall between the first wall and the second wall. The cooling hole may comprise an inlet, a first straight passage connected to the inlet by a first bend, a second straight passage connected to the first straight passage by a second bend, a third straight passage connected to the second straight passage by a third bend, and an outlet connected to the third straight passage by a fourth bend.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures.
The detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the spirit and scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full, and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact.
Referring to
The forward-aft positions of gas turbine engine 100 lie along axis of rotation 120. For example, fan 140 may be referred to as forward of turbine section 190 and turbine section 190 may be referred to as aft of fan 140. Typically, during operation of gas turbine engine 100, air flows from forward to aft, for example, from fan 140 to turbine section 190. As air flows from fan 140 to the more aft components of gas turbine engine 100, axis of rotation 120 may also generally define the direction of the air stream flow.
Referring to
The combustor liner 200 may comprise cooling holes 210. Cooling air from the last compressor stage may impinge on the outer surface 201 of the combustor liner 200. The cooling air may flow through the cooling holes 210. Heat may transfer from the combustor liner 200 to the cooling air as the cooling air travels through the cooling holes 210. The cooling air may then flow along the inner surface 202 and create a film cooling layer along the inner surface 202.
In high OPR engines, the temperature of the cooling air may be 1300° F. (700° C.) or greater. In combustors with conventional drilled cooling holes, the heat transfer from the combustor liner 200 to the cooling air in the cooling holes may be decreased due to the higher temperature of the cooling air.
Recent advances in additive manufacturing techniques allows for the construction of combustors with complex shapes. The combustor liner 200 may be manufactured by an additive manufacturing process, such as direct metal laser sintering (“DMLS”). DMLS may comprise fusing metal powder into a solid part by melting it locally using a laser. Using DMLS or other additive manufacturing techniques to manufacture the combustor liner 200 may allow the cooling holes 210 to be nonlinear. As used herein, a nonlinear cooling hole refers to a cooling hole that causes the cooling air to change direction as the cooling air flows through the nonlinear cooling hole.
Although described herein primarily with reference to combustor liners, those skilled in the art will appreciate that many gas turbine engine components or other components which utilize effusive cooling may be manufactured with nonlinear cooling holes using an additive manufacturing process. For example, referring to
Referring to
Using additive manufacturing for manufacturing the combustor liner 200 allows for the cooling holes 210 to be formed in complex shapes. Those skilled in the art will recognize that an infinite number of nonlinear hole shapes may be consistent with the present disclosure, and the shape illustrated in
The cooling holes 210 may have a longer flow path (the path of the cooling air through the cooling holes 210) than straight drilled cooling holes. The cooling holes 210 may have an increased length as compared to conventional linear drilled cooling holes. In various embodiments, the length of the cooling holes 210 may be at least twice the thickness T of the combustor liner. However, in various embodiments, the length of the cooling holes may be at least 5 times, or at least 10 times the thickness T. Such ratios may not be possible with conventional drilled cooling holes. The increased length may increase the surface area of the cooling holes 210, and increase the amount of heat transferred from the combustor liner 200 to the cooling air in the cooling holes 210. Additionally, the increased length may increase the pressure drop across each cooling hole 210, e.g. four times compared with linear holes, which may allow for the combustor liner 200 to be manufactured with more cooling holes 210 than a combustor with linear cooling holes. In various embodiments, the length of the flow path through the cooling holes 210 may be at least twice as long as the distance between the inlet 211 and the outlet 212. The cooling holes 210 may also have a larger surface area as compared to straight cooling holes, which may increase the amount of heat transferred from the combustor liner 200 to the cooling air. Therefore, if keeping the same number density as straight holes, the cooling flow will be significantly reduced while still being effective.
Referring to
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Those skilled in the art will appreciate that the present disclosure is not limited to the particular shapes and configurations of cooling holes and segmented walls described herein. Rather, the use of additive manufacturing allows for a variety of new shapes for cooling holes and segmented walls which improve the cooling effect in combustor liners. The particular shapes disclosed herein are merely examples of such configurations.
Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “various embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
