Patent Application
20200240290
This application claims priority to German Patent Application DE102019200985.9 filed Jan. 25, 2019, the entirety of which is incorporated by reference herein.
The invention relates to an engine component having at least one cooling duct and to a production method.
Engine components, especially those for a combustion chamber of an engine, are generally provided with a multiplicity of cooling holes in order to protect the respective engine component from the hot combustion space of the combustion chamber by appropriate cooling. Thus, for example, there is a known practice of providing (effusion) cooling holes in engine components such as heat shields, combustion chamber shingles or even combustion chamber walls. Here, a corresponding cooling hole always extends through the engine component from an inlet opening on a first side of the respective engine component to an outlet opening on a second side of the engine component.
Particularly in the case of (effusion) cooling holes of small cross section, the cross section and course of the cooling hole extending in the manner of a duct through the engine component are decisive for enabling a sufficient quantity of air for cooling to be used effectively. In this context, widely differing geometries for corresponding cooling holes designed as cooling ducts are proposed in US 2016/0097285 A1 and US 2017/176006 A1, for example. In particular, consideration has already been given in this context to providing a cooling hole with a varying cross section and/or with a deflecting region for deflecting the cooling air in the course of its extent from the inlet opening to the outlet opening.
Particularly in the case of cooling ducts provided with a deflecting region which are produced in the course of an additive manufacturing process, the problem can arise that the duct walls cannot be produced in an optimum manner in the deflecting region, in which a deflection of the fluid passed through the cooling duct is achieved. Particularly in the case of a deflection of the fluid in the cooling duct by more than 90°, it can happen, for example, that partially unmelted powder remains on an inner duct wall of the cooling duct during additive manufacture, especially during manufacture by laser sintering. At a corresponding inner duct wall of a deflecting region, said wall having a convex curvature for example, the cooling duct is therefore not of optimum design, and, as a result, not only the throughflow but also the mechanical integrity of the cooling duct can be negatively affected. Comparable problems may also occur with additively manufactured cooling ducts which are rectilinear and therefore do not deflect the fluid carried therein.
Consequently, there is a need for engine components that are improved in this respect and for production methods that are improved in this respect.
The proposed solution provides a remedy here with an engine component according to Claim 1 and a production method according to Claim 12.
In this case, the proposal is for an engine component having at least one cooling duct, which
The second, inner duct wall has a recess relative to the first, outer duct wall in a region of the cooling duct situated between the inlet opening and the outlet opening, said recess being of V-shaped design in a cross-sectional view through the cooling duct and in a direction of view along a direction of extent of the cooling duct.
In this case, the cooling duct can in principle be rectilinear, e.g. in the form of a cylindrical through-opening. However, it is also possible, in particular, for the cooling duct to deflect a fluid flowing in at the inlet opening in a deflecting region along its length in such a way to the outlet opening that the fluid flows out along the outflow direction at the outlet opening with a direction component which is opposite to a direction component of the inflow direction along which the fluid flows into the cooling duct at the inlet opening. The cross-sectional view through the engine component and in a direction of view transverse to the inflow and outflow directions then shows the deflecting course of the cooling duct from the inlet opening to the outlet opening. The second, inner duct wall then has the recess relative to the first, outer duct wall precisely in the deflecting region of the cooling duct situated between the inlet opening and the outlet opening, said recess being of V-shaped design in the cross-sectional view.
This variant embodiment thus proceeds from the basic concept of forming a recess that is V-shaped in a cross-sectional view precisely in a second, inner duct wall, in a deflecting region of the cooling duct, in which that point in the flow profile of the fluid passed through the cooling duct at which a direction vector of the fluid flow changes sign is situated. By means of this recess, a flow cross section of the cooling duct is enlarged locally in the deflecting region but, at the same time, this may, for example, then be independent of a geometry of the flow cross section which also changes (continuously) in the direction of the outlet opening, outside the deflecting region. Thus, an enlargement, defined by the recess, of the flow cross section is superposed only locally on a larger-scale change in the geometry of the flow cross section in the direction of the outlet opening, for example. In this case, the recess of V-shaped cross section can, in principle, be of elongate design and its shape (in the deflecting region) can follow the direction of extent of the cooling duct.
While any large-scale change in the geometry of the flow cross section serves primarily to ensure that the cooling duct influences the fluid flow in a certain way, the proposed formation of a V-shaped recess in the inner duct wall in the cross-sectional view through the cooling duct aims primarily at improved suitability for manufacture of the engine component and of the cooling duct of said component. Thus, it has been found that an appropriate recess geometry, particularly in the inner duct wall of the cooling duct, in a deflecting region, makes it possible to avoid unwanted, partially unmelted powder residues during additive manufacture of the engine component, e.g. in the course of laser sintering. However, such powder residues are often associated with a reduction in the flow cross section and hence with reduced cooling effectiveness as well as a nonspecific deviation from the specified contour of the flow cross section. With the recess geometry proposed, such disadvantages can be reduced or even completely avoided. By specifying the specific recess geometry proposed, it is also easily possible to reproduce the advantages explained above.
For example, one variant embodiment envisages that two wall portions of the second, inner duct wall, which define two legs of the V-shaped recess in the cross-sectional view through the cooling duct, enclose between them an angle (of spread) which is greater than or equal to 60°. By means of the appropriate angle, the opening width of the recess is thus characterized more specifically.
Particularly with a view to creating a self-supporting structure during manufacture of the inner duct wall with the recess, it may be advantageous in one possible development for the two wall portions of the second, inner duct wall to enclose between them an angle in a range of from 60 to 150°, in particular in a range of from 70° to 120°, 76° to 110° or 84° to 94°. For example, one variant embodiment envisages an angle of 90° between the two wall portions which define the V-shaped recess in the second, inner duct wall in the cross-sectional view through the cooling duct. Here, an appropriate orientation of the two wall portions relative to one another can assist self-support of the wall portions during the layered buildup.
Particularly with a view to specifying specific parameters for the creation of the engine component in the course of additive manufacture, a definition of the course of a wall portion of the second, inner duct wall for the formation of a recess geometry in accordance with the proposed solution has furthermore proven to be easily manageable as an alternative or supplementary measure. In this case, reliance is once again placed on two wall portions of the second, inner duct wall, which each define one of two legs of the V-shaped recess in the cross-sectional view through the cooling duct. In a cross-sectional view through the cooling duct, in the region having the recess, at least one of these two wall portions extends at a buildup angle greater than or equal to 15° to a centerline of the cooling duct, with respect to which a base flow cross section of the cooling duct which does not have the recess is formed in mirror symmetry in the region having the recess. Here, the recess represents a local variation in the base flow cross section with which the cooling duct extends in the region having the recess, e.g. in a deflecting region. For example, a base flow cross section of this kind is circular, oval or rectangular. Thus, the recess, which is V-shaped in the cross-sectional view, locally widens a base flow cross section of this kind by the V shape. In this configuration, the recess represents a local change in the corresponding peripheral contour of the base flow cross section in the second, inner duct wall. The virtual centerline or axis of symmetry of this base flow cross section is then selected as a reference line in order to specify the buildup angle at which one or more of the wall portions must extend relative to the centerline for the correct formation of the recess geometry.
For example, at least one of the two wall portions extends at a buildup angle in a range of from 15° to 60°, in particular in a range of from 30° to 55°, 35° to 52° or 43° to 48°, to the centerline in the cross-sectional view through the cooling duct. For example, at least one of the two wall portions can extend at a buildup angle of 45° to the centerline in the cross-sectional view through the cooling duct.
Of course, provision can be made for the cooling duct to have a flow cross section which—based on a direction of extent from the inlet opening to the outlet opening—corresponds to the base flow cross section before and/or after the region having the recess.
In one illustrative embodiment, the proposed solution is employed in the case of an engine component, the cooling duct of which provides an entry angle α for the fluid flow which is greater than or equal to 70° and an exit angle β at the outlet opening which is greater than or equal to 70°. In each case based on a mathematically positive direction of rotation, in the cross-sectional view through the engine component and in a direction of view transverse to the inflow and outflow directions, the inflow direction extends at an (acute) angle α≥70° to a boundary, bounding the inlet opening, of the first side of the engine component, and hence at a corresponding angle α≥70° to a plane in which the inlet opening lies. A boundary, bounding the outlet opening, of the second side of the engine component and thus a plane in which the outlet opening lies likewise extends at an (acute) exit angle β≥70° to the outflow direction.
In principle, the proposed engine component can be a component of a combustion chamber of an engine, for example. In particular, the engine component can be a heat shield, a combustion chamber shingle or a combustion chamber wall. For example, one illustrative embodiment envisages that the engine component is formed by a combustion chamber shingle, in particular by an additively manufactured combustion chamber shingle for an engine combustion chamber or a fixed gas turbine combustion chamber.
Another aspect of the proposed solution relates to a method for the additive manufacture of an engine component having a cooling duct. Here, one method proposed can comprise the production of the engine component by laser sintering, for example.
It is envisaged that the engine component is built up in layers in a buildup direction with a cooling duct which
The second, inner duct wall is formed with a recess relative to the first, outer duct wall in a region of the cooling duct situated between the inlet opening and the outlet opening, said recess being of V-shaped design in a cross-sectional view through the cooling duct and in a direction of view along a direction of extent of the cooling duct.
In the case where the engine component to be formed with the cooling duct is built up in layers, a recess which is V-shaped in the cross-sectional view through the cooling duct is thus provided in the region (e.g. central region) of the cooling duct and here in the inner, second duct wall, which lies opposite the first, outer duct wall, which will lie in the direction of the subsequent inflow direction. Here, the proposed V shape in the relevant cross-sectional view has the advantage, for example, that the probability of partially unmelted powder residues in a laser sintering process can be avoided or at least reduced to a degree which is not disruptive, precisely at the inner duct wall. It is thereby also possible to exert a positive influence on the mechanical integrity of the cooling wall structure to be produced.
In particular, it is possible for the cooling duct to deflect a fluid flowing in at the inlet opening in a deflecting region along its length in such a way to the outlet opening that the fluid flows out along the outflow direction at the outlet opening with a direction component which is opposite to a direction component of the inflow direction along which the fluid flows into the cooling duct at the inlet opening. The cross-sectional view through the engine component and in a direction of view transverse to the inflow and outflow directions then shows the deflecting course of the cooling duct from the inlet opening to the outlet opening. The second, inner duct wall is then formed with the recess relative to the first, outer duct wall precisely in the deflecting region of the cooling duct situated between the inlet opening and the outlet opening, said recess being of V-shaped design.
In one variant embodiment, the wall portions of the second, inner duct wall, which form the recess to be produced, are embodied in such a way as to be self-supporting during the buildup of the engine component, for example. Depending, in particular, on the material used and the type of additive manufacturing method employed, the wall portions of the second, inner duct wall which form the recess thus remain true to shape, even without a supporting structure, and have a certain (inherent) stability, with the result that they retain the structure built up in layers without further measures, even if the second, inner duct wall of the cooling duct has not yet been completely produced.
This is advantageous particularly if the second, inner duct wall is situated above the first, outer duct wall in the buildup direction and is therefore built up fully only after the first, outer duct wall during the additive manufacture of the engine component. Thus, based on the buildup direction, a region having the recess in the second, inner duct wall is built up while forming an overhang during the additive manufacture of the engine component. Here, the statement that the second, inner duct wall is situated above the first, outer duct wall in the buildup direction does not refer to an orientation of the engine component in its correct installation position but to the orientation during the layered buildup of the component, e.g. on a base plate of a 3-D printer.
In one variant embodiment, a buildup angle is furthermore specified which, in a reference plane extending parallel to the buildup direction (and lying in the cross-sectional view through the cooling duct), is enclosed between a centerline extending transversely to the buildup direction and a wall portion, to be produced, of the second, inner duct wall, which is intended to form one leg of the V-shaped recess in the cross-sectional view through the duct wall. The wall portion to be produced is then built up in a computer-assisted manner in such a way that the wall portion extends at a buildup angle greater than or equal to 15° to the centerline. This includes, in particular, the situation where the wall portion extends at a buildup angle in a range of from 15° to 60°, in particular in a range of from 30° to 55°, 35° to 52° or 43° to 48°, to the centerline. A buildup angle of 45° is provided, for example.
In this case, the centerline of the cooling duct to be produced can be defined by a virtual line with respect to which an unrecessed base flow cross section of the cooling duct is formed in mirror symmetry in the deflecting region. Consequently, if the V-shaped contour of the recess is imagined to be absent in the cross-sectional view, the base flow cross section is obtained, which is built up in mirror symmetry with respect to the centerline and, for example, is circular, oval or rectangular.
The engine component to be produced can be, in particular, a combustion chamber shingle, for example.
A production method proposed furthermore also enables a proposed engine component to be produced, and therefore advantages and features explained above and below for variant embodiments of a proposed engine component also apply to variant embodiments of a proposed production method and vice versa.
The appended figures illustrate, by way of example, possible design variants of the proposed solution.
In the figures:
The air conveyed into the primary flow duct by means of the compressor V passes into a combustion chamber portion BKA of the core engine, in which the drive energy for driving the turbine TT is generated. For this purpose, the turbine TT has a high-pressure turbine 113, a medium-pressure turbine 114 and a low-pressure turbine 115. Here, the energy released during the combustion is used by the turbine TT to drive the rotor shaft S and thus the fan F in order to generate the required thrust by means of the air conveyed into the bypass duct B. Both the air from the bypass duct B and the exhaust gases from the primary flow duct of the core engine flow out via an outlet A at the end of the engine T. In this arrangement, the outlet A generally has a thrust nozzle with a centrally arranged outlet cone C.
In principle, the fan F may also be coupled via a connecting shaft and an epicyclic planetary transmission to the low-pressure turbine 115, and be driven by the latter. It is furthermore also possible to provide other, differently designed gas turbine engines in which the proposed solution can be used. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of connecting shafts. As an example, the engine may have a split-flow nozzle, meaning that the flow through the bypass duct B has its own nozzle, which is separate from and situated radially outside the core engine nozzle. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass duct B and the flow through the core are mixed or combined before (or upstream of) a single nozzle, which may be referred to as a mixed-flow nozzle. One or both nozzles (whether mixed or split flow) can have a fixed or variable area. While the example described relates to a turbofan engine, the proposed solution may be applied for example to any type of gas turbine engine, such as an open-rotor engine (in which the fan stage is not surrounded by an engine nacelle) or a turboprop engine.
A combustion chamber head 3 having a head plate 4 is provided at the front end of the combustion chamber BK. The fuel nozzle 3 is inserted through a corresponding through-opening in the head plate 4 and in the combustion chamber head 3, thus enabling a fuel-air mixture to be introduced into the combustion space 1 via the fuel nozzle 2. In the region of the fuel nozzle 2, a heat shield 5 is mounted on the head plate 4 from the inside of the combustion space 1, likewise as protection from heat generated in the combustion space 1. In this arrangement, the heat shield 5 also has effusion cooling holes 11 for cooling.
According to one variant embodiment of the proposed solution, in order to make effective use of the air quantity available for cooling and to improve production, it is now proposed to design the cooling holes 11 in an engine component, such as the heat shield 5, the combustion chamber shingle 6 or the combustion chamber wall 7, as a cooling duct with a geometry in which an inner duct wall has a recess relative to an opposite outer duct wall in a deflecting region of the cooling duct 11, which is situated between the inlet opening and the outlet opening and which is of V-shaped design in a cross-sectional view through the cooling duct 11 and over the direction of view along a direction of extent of the cooling duct 11.
Here,
In the cross-sectional view in
In the deflecting region U, the inner duct wall 11d has a convex curvature in the direction of the outer duct wall 11c in the cross-sectional view in
In this respect, the proposed solution provides a remedy, one illustrative embodiment of which is illustrated in
Here, in the case of the variant embodiment in
Here, the recess 11R is of V-shaped configuration in a cross-sectional view through the cooling duct 11 according to the reference plane A-A in
In principle, provision can be made, in a development, for a flow cross section of the cooling duct 11 to vary along its course from the inlet opening 11a to the outlet opening 11b. The cooling duct 11, in particular, can be designed to compensate the recess 11R at least locally enlarging the flow cross section in the region of the recess 11R with a smaller diameter.
Illustrative cross sections of the cooling duct 11 in the deflecting region U having the recess 11R are shown in
In the variant embodiment in
In the case of the cross-sectional views in
Before and after the deflecting region U with the elongate recess 11R (and therefore above and below the deflecting region U in the figure), the cooling duct 11 has the respective base flow cross section, i.e. a circular base flow cross section in the variant embodiment in
As already explained, it is possible, in particular, for disruptive unmelted powder residues PR on the inner duct wall 11d in the deflecting region U to be avoided during the additive manufacture of the combustion chamber shingle 6 by means of the recess 11R defined by the wall portions 11.1d and 11.2d, which intersect at a right angle or at an obtuse angle, if the combustion chamber shingle 6 is produced by laser sintering. Depending on the material used and the production method, it may also be possible by this means, during the layered buildup of the combustion chamber shingle 6 along the buildup direction BR, for the wall portions 11.1d and 11.2d to form a self-supporting structure which has adequate inherent stiffness without a supporting structure and, accordingly, remains in the desired shape until the inner duct wall 11d has been fully built up.
With a view to computer-assisted production of the combustion chamber shingle 6, it may furthermore be appropriate to define the profile of the wall portions 11.1d and 11.2d not only by way of the angle φ (of spread) but also in some other way, namely with (greater) reference to the base flow cross section. Thus, each of the base flow cross sections illustrated has a shape which is mirror-symmetrical with respect to a centerline L. By way of example, this is shown on an enlarged scale in
During this process, use is made of the fact that—based on the buildup direction BR—the inner duct wall 11d is situated above the outer duct wall 11c during the layered buildup of the combustion chamber shingle 6 on a base plate of a 3-D printer and therefore it is possible to impart to the wall portions 11.1d and 11.2d an inherent stability during the generation of the combustion chamber shingle 6 and thus a self-supporting geometry even during production by specifying an appropriate buildup angle γ.
At the same time, the proposed solution is of course not restricted to a constant (base flow) cross section outside the deflecting region U. For example, a flow cross section can change in the flow direction of the fluid—in this case the cooling air—through the cooling duct 11 from a substantially round cross section with a diameter D to a narrow slot with a width B (in the circumferential direction relative to the correctly installed state in the combustion chamber BK) and a height H (perpendicularly to the inner side IS of the combustion chamber shingle 6 and therefore to the hot side of the combustion chamber BK). B>D and H<D should apply here. In this case, the cross-sectional geometry modified locally by the recess 11R in the deflecting region U is superposed on a corresponding larger-scale change in cross section along the extent of the cooling duct 11.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 200 985.9 | Jan 2019 | DE | national |
