DE102018211592A1 - CMC molded body with cooling system - Google Patents

Abstract

The invention relates to a CMC molded body with a cooling system. A CMC molded body is a component made of a ceramic fiber-reinforced composite material, the ceramic matrix composite or “CMC” material. These components are particularly suitable for hot gas applications and can be used, for example, as turbine components, in particular gas turbine components and / or as components of an exhaust line. The invention for the first time discloses the principle of a two-component cooling system, comprising impingement cooling with relatively large, first cavities and a finely chased second cooling structure with relatively small second cavities, the cooling structure with smaller cavities, especially in areas of large wall thickness of the CMC molded body is provided and vice versa.

Description

The invention relates to a CMC molded body with a cooling system. A CMC molded body is a component made of a ceramic fiber-reinforced composite material, the ceramic matrix composite or “CMC” material. These components are particularly suitable for hot gas applications and can be used, for example, as turbine components, in particular gas turbine components and / or as components of an exhaust line.

For example, molded bodies such as turbine blades, for example for stationary gas turbines, made of nickel-based superalloys with additional protective coatings, e.g. TBC coatings used. Although the properties of these materials are constantly being developed, this technology seems to be quite exhausted and, according to the general assessment of the experts, only a small substantial increase is still possible.

In contrast, the technology of component construction with CMCs, that is, fiber-reinforced ceramic materials, is an alternative that can be used alone and / or in combination with partial elements made of metals and in particular of superalloys, as CMC moldings or so-called CMC-metal hybrid moldings. can still be used profitably for the creation of new types of hot gas-stable products such as turbine components and / or components in an exhaust line, that is, leading to substantial increases. In combination with alloys, in particular the superalloys mentioned, or also other metals, one then speaks of a shaped body made of hybrid material, which comprises CMC sub-elements and metal sub-elements in a composite.

As a rule, a CMC molded body comprises layers which in turn comprise fibers, also in the form of a fiber composite, a woven fabric and / or a three-dimensional composite made of - ceramic - fibers which are embedded in a - ceramic - matrix. To produce the CMC shaped body, CMC prepreg layers are preferably laminated to one another and subsequently sintered to form the ceramic CMC shaped body.

From the DE 102018201555 a CMC molded body is known in which the so-called wrap stack construction concept is implemented. The CMC moldings produced in this way are very robust and can also withstand large thermal gradients and / or stresses. In principle, they can be operated with convective cooling, because the first CMC sub-elements realized in the wrap structure define, for example, a cavity where the wrap structure has been placed on a core or a support structure to form the laminate.

Here, a core, a support structure and / or free-standing prepreg CMC laminate layers are laminated in the wrap construction concept, i.e. in the wrap construction concept. This laminate is then surrounded as an internal CMC sub-element of a CMC molded body by a second outer CMC sub-element, the outer CMC sub-element being at least partially implemented in the stack construction concept.

As a cooling system with the DE 102018201555 known structure, for example cavities, which are defined by the first CMC sub-element implemented in the WRAP construction concept.

At the so-called "trailing edge", the trailing edge of a guide or rotor blade of a turbine, which can be produced using the CMC design using this technology, this cooling is usually not sufficient, for example, so that alternatives and / or additions are sufficient the one from the DE 102018201555 proposed cooling is sought.

The object of the present invention is therefore to provide a cooling structure for CMC molded parts.

This object is achieved by the subject matter of the present invention as disclosed in the description, the figures and the claims.

Accordingly, the present invention relates to a molded body made of ceramic fiber composite material “CMC”, which, according to the wrap stack construction concept, has at least one internal CMC sub-element designed in the wrap construction and at least one external CMC sub-element designed in the stack construction , wherein first cavities are provided in the first CMC sub-element and second cavities in the second CMC sub-element for guiding a cooling medium.

In principle, it is provided that the first cavities, which are preferably produced by laminating through a recess during the construction of the CMC shaped body, are used for impingement cooling of the CMC shaped body. Impact cooling is primarily provided in areas of the CMC molded body with a small wall thickness.

The second cavities, which are preferably created in the CMC molded body after lamination, are used for effective cooling of the regions of the CMC molded body with a large wall thickness.

It is particularly advantageous if the CMC molded body, which has cavities according to the wrap stack construction concept, is such that the first cavities through cutouts when laminating a first wrap partial element and the second cavities through subsequent production - for example, drilling into the finished laminate - in the second CMC sub-element can be produced. The subsequent production can take place both in the stage of the prepreg layer laminate and in the finished sintered molded body.

By subsequently creating cooling structures in the CMC molded part, cooling medium, particularly in the outer area of the CMC molded body, can be used very close to the surface of the CMC molded body, as so-called “near wall cooling”. This is a particular advantage, for example, at the "trailing edge" and / or at the "leading edge", the leading edge of a guide or rotor blade of a turbine.

According to an advantageous embodiment of the invention and in order to make the guidance of the cooling medium as defined as possible, holes in the prepreg laminate, for example, are provided with appropriate placeholders or stabilizers. These stabilizers can, for example, be removed again after the CMC shaped body has been sintered, that is to say they can be pulled or can also remain within the shaped body.

By introducing stabilizers into the cooling structures, such as bores, which are subsequently produced after lamination, leakage of the cooling structure can also be avoided, for example.

The placeholders / stabilizers can be, for example, narrow pipes, tubes or hoses.

The placeholders / stabilizers can be made of ceramic, metal and / or a metal alloy. These placeholders / stabilizers then preferably remain in the CMC molded body even during sintering, so that the material of the placeholder / stabilizer is preferably selected such that the thermal expansion and temperature stability are compatible with the surrounding CMC molded part.

The placeholders, for example the tubes, are fixed in the CMC molded body or in the CMC prepreg layer laminate by customary methods, for example a tube can be glued to the CMC wall or simply fixed by static friction.

A “CMC” molded body is a body that is made entirely or partially of ceramic matrix composite material, also known internationally as Ceramic Matrix Composite, or CMC for short. This material regularly includes reinforcing fibers in a ceramic matrix. The material is preferably processed in the form of CMC prepreg layers, which comprise fibers in dried slip, and then sintered.

CMC can be based on silicon carbide or metal oxide, for example. Prominent representatives of this class of materials are the “Ox-Ox-CMC and the SiC-CMC. With an Ox-Ox-CMC there are, for example, aluminum oxide fibers or corresponding fiber composites which are impregnated with an aluminum oxide and / or an aluminum oxide-mullite slip to form the CMC layer. This is similar for the SiC-based CMC variant, there are corresponding silicon carbide fibers which are then embedded in a silicon carbide slip which is burned out to form the matrix.

A “CMC molded body” comprises the finished sintered CMC layer matrix composite. The “intermediate product” comprises the fully laminated but not yet sintered prepreg CMC laminate layers.

A “CMC layer” is then a layer made of the fiber composite or fiber fabric covered with slip.

“Laminating” is the process by which the individual CMC layers are stacked on top of one another and / or connected in some other way. When laminating, for example, the CMC layers are neither tempered nor sintered, but may have already dried, not yet tempered and not yet sintered. To form a prepreg CMC layer, the dried CMC layers are also preferably subjected to a temperature treatment.

As an intermediate product, a molded body made of prepreg CMC layers is obtained before sintering. The layers are laminated, so that in the present case the intermediate product is also referred to as a prepreg-CMC layer laminate.

In the present case, the “cooling system” refers to the entirety of first and second cavities that are used to cool the CMC molded body during operation in a hot gas stream. This relates to the already known impingement cooling, which can be used above all in areas with a relatively thin CMC wall and which comprises the cooling medium in the first cavities. In addition, the cooling system includes the cooling structure described here for the first time, which is formed by subsequent processing of the prepreg-CMC laminate layer molded body and / or the finished sintered CMC molded body.

“Cooling structure”, on the other hand, refers here to the principle described here for the first time, consisting of second cavities created subsequently. “Afterwards” means here after the lamination of the prepreg CMC laminate layer molded body. The cooling structure comprises both simple cavities within the CMC molded body and parts of the CMC molded body stiffened by stabilizers / placeholders.

The dimensions of the bores depend on the cooling system, that is to say the required amounts of cooling medium which flow through the channels of the cooling structure produced and / or also on the stability of the CMC molded body at the affected point.

The bores can have the same or different diameters within a CMC molded body.

• Das Kühlmedium, wie beispielsweise Kühlluft, kann sehr nah an der heißen Oberfläche der CMC-Wand geführt werden und damit wird das sehr effektive Konzept des „near wall cooling“ realisiert.

The cooling medium routing described here has the following advantages:

• The cooling medium, such as cooling air, can be guided very close to the hot surface of the CMC wall, thus realizing the very effective concept of "near wall cooling".

According to a preferred embodiment of the invention, the orientation of the outer CMC layers arranged in the stack construction concept runs in the direction of the heat flow and thereby advantageously increases the heat conduction from the hot surface to the tubes through which cooling medium flows.

There is no leakage of the cooling medium through the use of ceramic or metallic tubes.

The cooling system proposed here for the first time allows efficient cooling of the trailing edge of a guide or moving blade, in addition to the known impingement cooling.

According to an advantageous embodiment of the invention, the wrap stack construction concept described here for the first time is provided with robust thermal insulation layers and / or corrosion protection layers such as the so-called thermal barrier coating “TBC” coatings and / or with the so-called environmental barrier coating “EBC”. Coatings can be combined.

• 1 zeigt eine schematische Darstellung einer Leit- oder Laufschaufel einer Turbine, die als CMC-Formkörper 1 gemäß dem WrapStack-Aufbaukonzept, also mit innenliegendem Wrap- und außen umgebenden Stack-CMC-Teilelement, aufgebaut ist. Zu erkennen sind dabei erste Hohlräume 2a, 2b und zweite Hohlräume 3a bis 3x, in denen Kühlmedium geführt wird.

The invention is explained in more detail below with reference to figures which show an advantageous embodiment of the invention:

• 1 shows a schematic representation of a guide or rotor blade of a turbine, the CMC molded body 1 in accordance with the WrapStack assembly concept, i.e. with an internal wrap and a surrounding stack CMC sub-element. The first cavities can be seen 2a . 2 B and second cavities 3a to 3x in which cooling medium is carried.

Two inner WRAP-CMC sub-elements can be seen 5a and 5b that of an outer STACK-CMC sub-element the CMC laminate layers 6a . 6b . 6c . 6d ... are comprehensive, surrounded.

At the trailing edge are the second cavities 3b to 3x Arranged close to the surface, so that an effective "near wall cooling" cooling structure is generated.

In the second cavities 3a to 3x are partially or in all stabilizers or placeholders, such as the tubes 4 introduced. This will make the CMC molded body 1 conferred further stability, fixed the dimension of the cooling structure and / or avoided leakage of the cooling structure at the fixed points.

In the embodiment of the invention shown here, the first cavities for guiding the cooling medium can be produced by subsequent drilling. This is how the holes are made 3a . 3b . 3c .... these holes 3a . 3b . 3c ... up to 3x through tubes 4 that are inserted into the holes stabilized.

The cooling structure proposed here is particularly suitable for CMC molded parts in areas with a large wall thickness, such as, for example, ribs or the trailing edge of a guide or moving blade.

The holes 3a to 3x in the outer STACK-CMC sub-element of the molded body, in particular in areas with a large wall thickness of the CMC molded body 1 , with tubes 4 lined, which guide the cooling air and prevent leakage.

Through the openings 3a to 3x , whether lined with stabilizers 4 or not, cooling medium flows, for example cooling air, for effective cooling in the area of the ribs and the trailing edge, also called “trailing edge”.

In areas of the WrapStack CMC molded body 1 shown here with a small wall thickness, such as, for example, at the leading edge of the guide or moving blade, one or more first cavities are used 2a . 2 B .. cooled as impingement cooling.

2 shows in detail the arrangement of the second cavities 3a in the area of a rib the running or guide vane. It is important that the second cavities, for example the cooling air bores, are positioned according to their optimal thermal effect and lined with tubes.

The same CMC shaped body can be seen as in 1 , but only a partial section at the leading edge. The stack CMC sub-element with the layers is shown 6e and 6f , as well as the wrap CMC sub-element 5a and the cavity 2a leading to the first cavities 2 counts which are formed by recess during lamination. These first cavities are preferably provided in areas of the CMC molded body with a small wall thickness, that is to say, for example, at the leading edge for impact cooling. Between the first two cavities 2a and 2 B of the CMC molded body 1 there is a rib in the embodiment shown here 8th that the two cavities 2a and 2 B separates from each other. In the area of the rib 8th cooling structure according to the invention, in the case of two bores, is provided.

The two holes 3a and 3b are in 2 shown again in detail below. The openings of the tubes can be seen 4 that act as a placeholder and / or stabilizer in the second cavities 3a . 3b are introduced. The course of the second cavities in the interior of the second CMC sub-element realized in the stack construction concept can be recognized by dashed lines.

The invention for the first time discloses the principle of a two-component cooling system, comprising impingement cooling with relatively large, first cavities and a finely chased second cooling structure with relatively small second cavities, the cooling structure with smaller cavities, especially in areas of large wall thickness of the CMC molded body is provided and vice versa.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 102018201555 [0005, 0007, 0008]

Claims (15)

Shaped body made of ceramic fiber composite material "CMC", which, according to the wrap stack construction concept, has at least one internal CMC sub-element designed in the wrap construction and at least one external CMC sub-element designed in the stack construction, with a cooling system for guiding one Cooling medium first cavities and second cavities are provided. Shaped body after Claim 1 , wherein the first cavities are provided in the wrap CMC sub-element of the molded body. Shaped body according to one of the preceding Claims 1 or 2 , wherein the second cavities are provided in the stack CMC sub-element of the molded body. Shaped body according to one of the preceding claims, wherein the first cavities can be formed by cutouts when laminating the first wrap element. Shaped body according to one of the preceding claims, wherein the second cavities in the second stack CMC sub-element can be formed by subsequent processing. Shaped body according to one of the Claims 1 or 2 , wherein the second cavities in the second stack CMC sub-element can be produced by subsequent drilling. Shaped body according to one of the preceding claims, wherein the first cavities are provided in regions of the CMC shaped body with a thin wall thickness. Shaped body according to one of the preceding claims, wherein the first cavities are provided, for example, at the leading edge of a rotor or guide blade of a turbine. Shaped body according to one of the preceding claims, wherein the second cavities are provided in regions of the CMC shaped body with a large wall thickness. Shaped body according to one of the preceding claims, wherein the second cavities are provided, for example, on the trailing edge of a rotor or guide vane. Shaped body according to one of the preceding claims, wherein placeholders and / or stabilizers are at least partially provided in the second cavities. Shaped body according to one of the preceding claims, tubes being provided in the second cavities as placeholders and / or stabilizers. Shaped body according to one of the preceding Claims 11 or 12 , wherein the placeholders and / or stabilizers are made of a material whose thermal expansion coefficient is matched to that of the prepreg CMC laminate layer molded body at the point. Shaped body according to one of the preceding claims, wherein the CMC material is silicon carbide-based or metal oxide-based. Shaped body according to one of the preceding claims, wherein the cooling medium used in the cooling system is air.

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