DE102017213399A1 - Method for producing a sealing element for sealing a flow path in a gas turbine, sealing element and gas turbine - Google Patents

Abstract

A method is disclosed for producing a sealing element for sealing a flow path in a gas turbine comprising a lattice structure 1, wherein the lattice structure 1 is produced by means of an additive manufacturing method. Further, a seal member for sealing a flow path in a gas turbine having a lattice structure 1 made of a lattice material, wherein the lattice material composition changes within the lattice structure 1, and a turbine with such a seal member are given.

Description

Gas turbines typically have a primary flow path for the gas that extends from an air intake via a compressor, a combustor, a turbine, to a gas outlet. Gas leakage from this flow path from a higher pressure region to a lower pressure region is generally undesirable.

For example, gas leakage in the turbine region of a gas turbine may result in a reduction in the efficiency of the gas turbine, so that more fuel is needed to achieve the same power. Gas leakage in the combustor region of a gas turbine may require an increase in combustion temperature to achieve the same turbine performance. As a result, pollutants such. As nitrogen oxides and carbon monoxide arise.

Gas leaks occur through gaps between individual gas turbine components, such as gas turbine components. At the transition between combustor and turbine, or through spaces between individual component segments, such as through gaps between combustor shell segments or vane segments within the turbine.

Numerous static sealing concepts are known for preventing gas leaks. Depending on the problem, so z. B. depending on the geometric shape and the thermal load of the gap or the gap limiting components, for example, metallic flat gaskets in a straight or specially shaped design, such. B. in O-form, C-form or E-form used. In addition to a special shaping, these flat gaskets can also be designed with a corrugated surface or in a perforated pattern.

The seals are high in operation, z. T. exposed to changing mechanical and thermal loads. Operational challenges may include: a. a high temperature and alternating pressure loads, non-uniform sealing gaps due to different thermal expansions of the materials adjacent to the seal and the seal itself, relative movements between the components adjacent to the seal or component segments (offset of the sealing surfaces), vibrations and vibrations, so that the seal is not continuously applied to the sealing surface. Other challenges include ensuring sufficient cooling / cooling air supply and end gap sealing. An end gap is to be understood as meaning a residual gap which often forms at the transition between adjoining sealing segments and at the lateral ends of the seals with respect to the surrounding border or groove.

A disadvantage of the said, mainly rigid sealing concepts is a high wear on the seal itself and on the sealing surfaces of the components or component segments to be sealed against each other due to the aforementioned challenges. High wear in turn leads to the overall efficiency reducing gas leaks and shorter maintenance and repair intervals and thus increased repair costs due to high wear.

Also known are so-called "cloth-seals", as they are known for. In Dogu, Y., Aksit, M. et al., "Thermal and Flow Analysis of Cloth-Seal in Slot for Gas Turbine Shroud Applications", AIAA-98-3174, 1998 and Aksit, M., Bagepalli, BS et al., "Advanced Flexible Seals for Gas Turbine Shroud Applications" AIAA-99-2827, 1999 to be discribed. These consist of a support structure ("shim") and a surrounding metal fabric ("cloth").

The arrangement of fabric and support structure may vary. For example, the fabric and support structure can be stacked in individual layers or the support structure can be encased or wrapped by the fabric structure, whereby a flat composite of different components is always formed.

For the connection between carrier and tissue structure different methods are known. For example, a connection can be made by means of spot welding or peripheral edge welding connections. In addition, a jamming of the carrier with the tissue structure is possible.

A disadvantage of such cloth seals are the separate production of the carrier and fabric structure and the necessary connection of both structures in a further production step, so that the overall production process is complicated. A flexible adaptation to the specific sealing requirements, eg. As the production of seals with different geometric shape or different elastic behavior is - if at all - possible only with high production costs.

In addition, the connection points between the two structures, ie z. As the spot welded joints, weak points that can reduce the life of the seal.

Object of the present invention is therefore to provide a method for producing a sealing element and a sealing element, with the mentioned disadvantages can be reduced or eliminated.

This object is achieved by the subject matters of the independent claims. The dependent claims contain embodiments of these inventive solutions.
According to the inventive method for producing a sealing element for sealing a flow path in a gas turbine with a lattice structure is provided to produce the lattice structure by means of an additive manufacturing process or 3D printing process.

The grid structure comprises a grid material, which may include, for example, a metallic material, a metal-ceramic material, a ceramic material or a composite material, or may consist of one of the materials mentioned, wherein areas between the discrete areas of the grid material without grid material are arranged. The lattice structure may preferably be formed as a planar structure with respect to the side surfaces of the lattice structure significantly larger base and top surfaces. During use of the sealing element, the base and top surfaces are arranged substantially parallel to the sealing surfaces.

The grid structure can also be understood as a network or pore structure and be formed in one or more layers. The sealing element may have one or more identical or different lattice structures, which may be arranged directly adjacent to each other or separated from each other.

The grid structure may be gas-tight. In this case, the lattice structure is one or the sealing component of the sealing element. If the lattice structure is not gas-tight, then at least one other sealing component, e.g. Example in the form of a support structure, be present, so that the sealing element may have a sealing effect.

According to the invention, the lattice structure is produced by means of an additive manufacturing process. Depending on the grating material, different additive manufacturing processes can be used, such. For example, selective laser melting (SLM), electron beam melting (EBM), laser deposition welding (LMD), laser metal deposition (LMD). or the cold gas spraying (CS process, "cold spray").

An additive manufacturing process is to be understood as meaning a process for producing a three-dimensional object, in which case material is applied and solidified in thin layers in a simplified manner and / or adhesively bonded. The generative production takes place from informal (powder, liquids, o. Ä.) Or form neutral (band-shaped, wire-shaped, o. Ä.) Materials by means of chemical and / or physical processes.

A sealing element produced according to the invention can have an improved sealing effect by ensuring a continuous surface contact over the entire operating period and under all operating conditions between the contact partners sealing element and sealing surface by elastic behavior of the grid structure or the mesh material, as well as the influence of vibrations occurring and relative movements between the contact partners weakened or damped (so-called "damping effect").

As a result, the wear of the two contact surfaces and the leakage occurring can be significantly reduced. The damping effect and flexibility can be achieved by the specific design of the grid structure, for. B. their geometric design and material composition can be influenced. For example, depending on the structure and arrangement, the mechanical behavior of the sealing element, for. B. its elasticity and rigidity, are influenced direction-dependent. In addition, it is possible to exploit special physical effects, such as z. B. structures with negative Poisson number (transverse strain) or bionic structures. The lattice structure also makes it possible to improve the cooling of the sealing element as well as of the optionally local sealing point, since the porous or permeable structure, if designed accordingly, can have a self-cooling effect or a targeted cooling air supply.

The production by means of an additive manufacturing process enables the use of defined, complex structures. The mechanical behavior of the selected grating structure, optionally as explained below in combination with a support structure, can vary in the spatial direction and can be calculated mathematically (advance), i. H. Likewise, the mechanical loads and the behavior of the sealing element can be simulated under these loads.

This makes it possible to adapt the properties of the sealing element to the mechanical loads or to consider them. Thus, both the sealing function and the mechanical function, as they occur in cyclic or static stress of the previously known seals can be improved. Furthermore, the use of the additive manufacturing method not only allows the above-mentioned complex structures perform as a flat seal, but according to the existing sealing gap also different types of shapes / geometries to print.

In other words, an application-oriented interpretation of the seal design, z. B. using a mathematical prediction or simulation of the mechanical behavior, possible, the directional dependence of the mechanical behavior can be considered. A defined design of the lattice structure and the seal design may result in an optimized performance with respect to the application and improved integrity of the sealing element.

Gap changes due to operational influences (thermal strains, vibrations, etc.) can be compensated by the elastic behavior of the grid structure, possibly in cooperation with the support structure as explained below, whereby the sealing function can be maintained over a long period of time. As a result of reduced wear, a higher sealing effect, i. H. a reduction of leakage, and increased longevity of the sealing element over the operating period can be achieved. As a result, the maintenance intervals can also be extended, so that repair, maintenance and repair costs can be reduced.

For example, the method of the present invention can be used to make a seal member for the combustor seal, sealing off the side gap at the combustor exit between the circumferentially spaced tube combustors ("transition side seals"). Another example of use is the sealing of the stator-platform space, wherein the gaps are sealed between the circumferentially adjacent turbine vane mate-face seals.

According to various embodiments, the grid structure can be applied to a support structure, in particular imprinted. Optionally, the support structure itself can be produced by means of an additive manufacturing process. For example, carrier structure and grid structure can be produced in a common 3D printing process, so that the separate production of grid structure and carrier structure is eliminated. It is also possible to provide or be provided with a plurality of grid and / or carrier structures, so that, for example, sandwich structures can result.

The carrier structure comprises a carrier material which, for example, may comprise a metallic material, a metal-ceramic material, a ceramic material or a composite material or may consist of one of the abovementioned materials. The support structure may preferably be formed as a planar structure with respect to the side surfaces of the support structure significantly larger base and top surfaces. During use of the sealing element, the base and top surfaces are arranged substantially parallel to the sealing surfaces.

The support structure can serve to improve the mechanical stability of the lattice structure. In the event that the grid structure itself is not formed gas-impermeable, the support structure may be formed or gas impermeable. For this purpose, the carrier structure can be produced, for example, as a plate-like compact structure. Due to the thickness and shape of the support structure, the rigidity of the seal or of the sealing element can be influenced.

Both by printing the grid structure onto the carrier structure and by jointly producing the grid and carrier structure in a single additive manufacturing step, an additional welding or joining step for connecting the grid structure and carrier structure can be avoided. The properties of the sealing element influencing local welding or joints can also be avoided. Due to the reduction of the working and Verteilschritte the total manufacturing cost for the sealing element can be reduced. In addition, there are no costs for the production and storage of the semi-finished products and the spare parts supply can be secured independently of the production line. Overall, procurement times can be reduced by using additive manufacturing techniques.

The additive manufacturing method allows a cohesive connection between grid and support structure at defined connection points, the number of connection points and the execution of the connection can be selectively influenced and designed. For example, a cohesive connection between the support structure and the lattice structure may be provided at all points of contact.

According to further embodiments, the lattice and / or support structure can be produced with a material composition changing within the lattice structure and / or the support structure and the lattice structure can be produced from different materials.

In other words, different materials can be combined with each other in the overall composite of the sealing element, wherein under different materials both the use of completely different materials, eg. Metal and ceramics, as well as the change in the proportions of various components of the lattice or support material is to be understood, for. B. increasing the metal content in a metal-ceramic material. As a result, a further precise adaptation to the required, flexible operating characteristic of the sealing element and ultimately to the required sealing effect can be achieved by taking the material composition into account as a further option for influencing the operating characteristic. In contrast, in the known "cloth seals" only individual homogeneous materials can be combined.

According to further embodiments, cooling air channels can be integrated into the grid and / or carrier structure. This can allow a targeted cooling air supply of the sealing element and protect the sealing element from damage due to excessive thermal stress. The number and position of the cooling channels can be determined according to the concrete planned location of the sealing element. Optionally, a simulation of the necessary cooling at certain positions of the sealing element to set the number and position of the cooling channels can be performed.

According to further embodiments, an at least partially curved grid and / or support structure, i. H. a grid and / or support structure with an at least partially concave or convex base and top surfaces are generated. As a result, a better adaptation of the sealing element to concave or convex sealing surfaces can advantageously take place. The concrete geometric design can be determined according to the concrete planned location (sealing point) of the sealing element. Optionally, a simulation of the sealing of the sealing point can be performed.

According to further embodiments, the lattice structure on one or both sides of the support structure, d. H. applied to the base and / or top surface of the support structure, in particular imprinted, and / or applied to the lattice structure, a further support structure, in particular imprinted, are. If a further carrier structure is applied, a sandwich structure results, in which the grid structure is enclosed between two carrier structures.

If a grid structure is applied on both sides of the carrier structure, identical or different grid structures can be applied on both sides of the carrier structure. Likewise, in the case of a further carrier structure, this may be or may be formed identically or differently to the first carrier structure to which the grid structure is applied. Due to the different arrangement of grid and support structure, the properties of the sealing element can be flexibly adapted to the required sealing of the sealing point. The determination of the arrangement can be determined by means of a simulation.

According to further embodiments, the lattice structure can be produced with a tetrahedral structure, a prism structure, a wave structure, a honeycomb structure or a bionic structure defined or undefined with respect to the contact points and the angles of the discrete areas of the lattice material relative to one another in the layer structure. For example, the lattice structure may be formed so that by the arrangement of the grid material areas are formed without a grid material having a tetrahedral or prismatic shape, for. B. with in cross-section diamond-shaped areas having. The mentioned structural examples can be arranged both regularly, i. H. defined repeating, as well as in irregular arrangement, d. H. indiscriminately. Due to the different structural design of the grid structure, the properties of the sealing element can be flexibly adapted to the required sealing of the sealing point. The definition of the structural design can be determined by means of a simulation.

According to further embodiments, a desired mechanical behavior of the sealing element can be predetermined and the lattice and / or support structure can be produced such that the resulting sealing element exhibits the desired mechanical behavior. In other words, a simulation of the sealing of the sealing point, possibly under different conditions such. As different temperatures are performed. The mechanical behavior of the seal can u. a. by the choice of the grid structure (material, geometric shape, etc.), the number of layers of grid and / or support structure, the definition of the contact and joints and the arrangement of the support structure can be varied.

The parameters determined by the simulation can then be used to design the sealing element, e.g. As to determine the specific geometric shape, the materials, the surface design, etc., are used, so that by means of the additive manufacturing process, the desired sealing element can be generated directly without further processing steps are necessary or at least so that the number of further processing steps minimized can be.

An inventive sealing element for sealing a flow path in a gas turbine has a lattice structure of a Grid material, wherein the grid material composition changes within the lattice structure. The change in the composition of the material can be targeted in order to adapt the properties to the sealing effect required for the sealing of the sealing point.

Thus, it is conceivable to manufacture individual layers of the lattice and / or support structure from different materials and / or structures in order not only to select the elasticity / flexibility of the sealing element by selecting the lattice structure but also by combining different materials or different material properties to influence. So z. For example, a harder, wear-resistant material and a more rigid structure can be selected in the outer contact region of the sealing element, whereas the inner structure can be made of a material of lower strength and higher elasticity. For example, the grid material composition can also be chosen so that the thermal expansion corresponds approximately to the thermal expansion of the material of the sealing surface.

Furthermore, the production of a composite material consisting of a matrix structure of an elastic, metallic material of lesser strength and a fiber structure of a higher-strength, metallic material of lower elasticity would be conceivable. This metallic composite material can consist of different metal alloy pairings as well as metallic ceramics. Depending on the combination and configuration of the materials u. a. the overall material behavior improves as well as the fretting wear can be reduced.

The grid structure may be formed gas-impermeable. The grid structure can also be combined with another gas-impermeable element, so that the grid structure itself does not necessarily have to be gas-impermeable.

The sealing element according to the invention can be produced for example by means of the method according to the invention described above. Therefore, the above explanations serve to explain the method according to the invention also for the description of the sealing element according to the invention. The advantages of the sealing element according to the invention correspond to those of the method according to the invention and its corresponding variants.

According to various embodiments, the grid structure may be arranged on a support structure made of a carrier material. For example, the support structure can serve to improve the mechanical stability of the sealing element. The support structure may be gas-tight. In this case, the grid structure may also be formed gas permeable.

Optionally, the grid and support structure can be bonded to each other at all points of contact. This can be achieved, for example, by production by means of a suitable additive manufacturing process.

According to further embodiments, the carrier material composition may change within the carrier structure. As a result, a better adaptation to the properties of the sealing point can be achieved.

According to further embodiments, the grid and / or support structure may have integrated cooling air channels. As a result, a targeted cooling can be achieved.

According to further embodiments, the grid and / or support structure may be at least partially curved. As a result, an improved adaptation to convex or concave sealing points can be achieved.

According to further embodiments, the grid structure can be arranged on one or both sides of the carrier structure and / or a further carrier structure can be arranged on the grid structure. If a further carrier structure is arranged on the lattice structure, the result is a sandwich construction in which the lattice structure is arranged between two carrier structures. This also allows an improved adaptation to the properties of the sealing point can be achieved.

According to further embodiments, the lattice structure may have a tetrahedral structure, a prism structure, a defined or undefined wave structure, a honeycomb structure or a bionic structure.

A turbine according to the invention, in particular a gas turbine, has one of the sealing elements described above. For example, the seal member may be provided for combustor seal or stator-platform clearance seal.

• 1 - 4 Beispiele für einseitig auf eine Trägerstruktur aufgebrachte Gitterstrukturen in Querschnittsdarstellung;
• 5 - 8 Beispiele für beidseitig auf eine Trägerstruktur aufgebrachte Gitterstrukturen in Querschnittsdarstellung;
• 9 - 12 Beispiele für zwischen zwei Trägerstrukturen angeordnete Gitterstrukturen in Querschnittsdarstellung;
• 13 - 16 Beispiele für Gitterstrukturen ohne Trägerstruktur in Querschnittsdarstellung.

The invention will be explained in more detail below with reference to embodiments, which relate to the illustration specific embodiments in which the invention may be practiced. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following description is therefore not to be construed in a limiting sense, and The scope of the present invention is defined by the appended claims. The accompanying drawings show:

• 1 - 4 Examples of one-sided applied to a support structure grid structures in cross-sectional view;
• 5 - 8th Examples of grid structures applied on both sides to a carrier structure in cross-sectional representation;
• 9 - 12 Examples of arranged between two support structures grid structures in cross-sectional view;
• 13 - 16 Examples of lattice structures without support structure in cross-sectional view.

The figures each show lattice structures 1 , if necessary in combination with carrier structures 2 as can be prepared by the method according to the invention.

The representation according to the 1 to 4 shows one each on the support structure 2 one-sided grid structure 1 , In 1 has the lattice structure 1 an undefined wave structure. In 2 has the lattice structure 1 a prism structure, which is in cross section as a diamond structure. In 3 has the lattice structure 1 a defined wave structure with defined contact points. In 4 has the lattice structure 1 a honeycomb structure on.

The representation according to the 5 to 8th shows one each on the support structure 2 arranged on both sides grid structure 1 , wherein the lattice structure 1 on both sides of the support structure 2 is the same. Optionally, the grid structure 1 on both sides of the support structure 2 also be designed differently. In 5 has the lattice structure 1 an undefined wave structure. In 6 has the lattice structure 1 a prism structure, which is in cross section as a diamond structure. In 7 has the lattice structure 1 a defined wave structure with defined contact points. In 8th has the lattice structure 1 a honeycomb structure on.

The representation according to the 9 to 12 shows one between two support structures 2 arranged grid structure 1 , wherein the support structures 2 on both sides of the grid structure 1 are the same. Optionally, the support structures 2 on both sides of the lattice structure 1 be formed differently. In 9 has the lattice structure 1 an undefined wave structure. In 10 has the lattice structure 1 a prism structure, which is in cross section as a diamond structure. In 11 has the lattice structure 1 a defined wave structure with defined contact points. In 12 has the lattice structure 1 a honeycomb structure on.

The representation according to the 13 to 16 shows lattice structures 1 without support structure 2 , In 13 has the lattice structure 1 an undefined wave structure. In 14 has the lattice structure 1 a prism structure, which is in cross section as a diamond structure. In 15 has the lattice structure 1 a defined wave structure with defined contact points. In 16 has the lattice structure 1 a honeycomb structure on.

The grid structures 1 and support structures 2 The embodiments have a metallic material, a metal-ceramic material, a ceramic material or a composite material. Optionally, the grid material composition may be within the grid structure 1 to change. Also, a change in the carrier material composition within the carrier structure 2 is possible.

In all embodiments, the grating structures 1 and, if present, the support structures 2 produced by an additive manufacturing process. Is a carrier structure 2 present, so can the production of the grid and support structure 1 . 2 both in a common additive manufacturing process as well as in a separate additive manufacturing process.

As used herein, the term "and / or" when used in a series of two or more elements means that each of the listed elements may be used alone, or any combination of two or more of the listed elements may be used. For example, when describing a composition containing components A, B and / or C, composition A may be alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C are included in combination.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Dogu, Y., Aksit, M. et al., "Thermal and Flow Analysis of Cloth-Seal in Slot for Gas Turbine Shroud Applications", AIAA-98-3174, 1998 [0007]
• Aksit, M., Bagepalli, B.S. et al., "Advanced Flexible Seals for Gas Turbine Shroud Applications" AIAA-99-2827, 1999 [0007]

Claims (17)

Method for producing a sealing element for sealing a flow path in a gas turbine comprising a grid structure (1), characterized in that the grid structure (1) is produced by means of an additive manufacturing method. Method according to Claim 1 , characterized in that the grid structure (1) on a support structure (2) applied, in particular printed, is. Method according to one of the preceding claims, characterized in that the support structure (2) is produced by means of an additive manufacturing process. Method according to one of the preceding claims, characterized in that the lattice and / or support structure (1, 2) are produced with a material composition changing within the lattice or support structure (1, 2) and / or that the lattice structure (1 ) and the support structure (2) are made of different materials. Method according to one of the preceding claims, characterized in that in the grid and / or support structure (1, 2) cooling air ducts are integrated. Method according to one of the preceding claims, characterized in that an at least partially curved grid and / or support structure (1, 2) is generated. Method according to one of Claims 2 to 6 , characterized in that the lattice structure (1) on one or both sides of the support structure (2) applied, in particular printed, and / or that on the lattice structure (1) applied a further support structure (2), in particular imprinted, is. Method according to one of the preceding claims, characterized in that the lattice structure (1) is produced with a tetrahedral structure, a prism structure, a defined or undefined wave structure, a honeycomb structure or a bionic structure. Method according to one of the preceding claims, characterized in that a desired mechanical behavior of the sealing element is given and the grid and / or support structure (1, 2) are produced so that the resulting sealing element shows the desired mechanical behavior. A sealing element for sealing a flow path in a gas turbine comprising a grid structure (1) made of a grid material, characterized in that the grid material composition changes within the grid structure (1). After sealing element Claim 10 , characterized in that the grid structure (1) is arranged on a carrier structure (2) made of a carrier material. After sealing element Claim 10 or 11 , characterized in that the carrier material composition changes within the carrier structure (2). Seal element according to one of Claims 10 to 12 , characterized in that the grid and / or support structure (1, 2) has cooling air channels. Seal element according to one of Claims 10 to 13 , characterized in that the grid and / or support structure (1, 2) is at least partially curved. Seal element according to one of Claims 11 to 14 , characterized in that the lattice structure (1) on one or both sides of the support structure (2) is arranged and / or that on the lattice structure (1), a further support structure (2) is arranged. Seal element according to one of Claims 10 to 15 , characterized in that the grid structure (1) has a tetrahedral structure, a prism structure, a defined or undefined wave structure, a honeycomb structure or a bionic structure. Turbine, in particular gas turbine, with a sealing element according to one of the preceding claims.

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