WO2023246804A1

WO2023246804A1 - Turbine guide vane structure

Info

Publication number: WO2023246804A1
Application number: PCT/CN2023/101482
Authority: WO
Inventors: 洪辉; 鲍骐力; 张诗尧; 曹源; 谭智勇; 张屹尚
Original assignee: 中国航发商用航空发动机有限责任公司
Priority date: 2022-06-21
Filing date: 2023-06-20
Publication date: 2023-12-28
Also published as: CN117307258A

Abstract

A turbine guide vane structure, comprising a CMC component and a metal cover plate, the CMC component comprising an edge plate, and the edge plate being used for acting in concert with the metal cover plate; an axial force applying member is arranged between the edge plate and the metal cover plate, the axial force applying member being used for providing an axial pre-tightening force to the edge plate and the metal cover plate; at least a portion of an axial side surface of the edge plate comprises a notch, the notch comprising a first wall surface; at least part of the first wall surface is an inclined surface; an axial side surface of the metal cover plate acting in concert with said portion of the edge plate comprises a folding part used for acting in concert with the notch; the folding part comprises a side wall surface; the side wall surface is parallel to the first wall surface and is in surface-to-surface contact with the first wall surface. The turbine guide vane structure allows for keeping the metal component and the CMC component in close contact in an axial direction, thereby overcoming radial and axial expansion differences and guaranteeing installation stability.

Description

A turbine guide vane structure

Technical field

The present disclosure relates to the field of turbine guide vanes, and specifically to the field of CMC turbine guide vanes.

Background technique

As the requirements for thrust and efficiency of civil aviation engines continue to increase, the total engine inlet temperature also continues to rise. Under high-temperature take-off conditions, the gas temperature in front of the turbine has reached 1978K. Currently, for turbine stator parts, using traditional cooling technology and thermal barrier coating technology, the service temperature and performance of traditional high-temperature alloy materials are close to their limits, making it difficult to meet the design requirements of the next generation of advanced aeroengines.

Compared with traditional high-temperature alloys, Ceramic Matrix Composites (CMC) have the following advantages: (1) High temperature resistance: By improving the properties of fibers and matrix and combining the use of environmental coatings, CMC materials can withstand operating temperatures of 1650°C; (2) Corrosion resistance; (3) Low density: the density is about 1/4 to 1/3 of high-temperature alloys. Based on these advantages, applying CMC materials to turbine stator parts such as turbine guide blades can improve the performance of aeroengines in many aspects such as reducing the amount of cold air, increasing turbine temperature, and reducing NOx emissions, thereby meeting the needs of the next generation of advanced aeroengines.

At this stage, CMC components need to be used with metal materials. However, due to limitations in the preparation process, reinforced fiber toughness, matrix hardness and other reasons, CMC materials are difficult to form and process. Therefore, it is difficult to prepare components with complex shapes. Otherwise, it will bring great difficulties to the assembly and installation of CMC and metal structures. In addition, the thermal expansion coefficient of CMC materials is about 1/3 that of metal materials. When metal materials are assembled and used, it is easy to produce expansion differences in the radial and axial directions, which can lead to problems such as cold air leakage, vibration, and loss of restraint. CMC material has good high temperature resistance but low strength. When designing CMC turbine guide vanes, it is necessary to reduce the stress carried by the CMC structural part as much as possible. In addition, sufficient protection for metal parts needs to be provided in the same high temperature environment to ensure the reliability of the guide vane structure. sex.

public content

An object of the present disclosure is to provide a turbine guide vane structure that can effectively maintain close contact between metal components and CMC components in the axial direction and overcome the problem of axial expansion.

To achieve the above purpose, the turbine guide vane structure includes CMC components and metal cover plates. The CMC components It includes an edge plate, and the edge plate is used to cooperate with the metal cover plate. An axial force applying member is provided between the edge plate and the metal cover plate, and the axial force applying member is used to provide an axial preload force; at least part of the axial side of the edge plate includes a notch, and the The notch includes a first wall surface, at least part of the first wall surface is an inclined surface, and the axial side surface of the metal cover plate that cooperates with this part of the edge plate includes a folding portion for matching with the notch, and the folding portion It includes a side wall surface, which is parallel to the first wall surface and in surface contact with the first wall surface.

In one or more embodiments, the contact length between the inclined surface and the side wall surface is greater than the difference between the expansion amount of the CMC component and the metal cover plate in the axial direction and the cosine of the inclination angle of the inclined surface. ratio.

In one or more embodiments, the notch further includes a second wall, at least part of the second wall is arranged parallel to the axial direction, the folded portion further includes a radial end, and the second wall is to separate the radial end from the CMC component.

In one or more embodiments, at least part of the circumferential side of the edge plate includes a notch, and the circumferential side of the metal cover plate that cooperates with the part of the edge plate includes a folded portion.

In one or more embodiments, at least part of said first wall is arranged parallel to the radial direction.

In one or more embodiments, the notch is provided on the suction side of the turbine guide vane structure.

In one or more embodiments, the notch is provided on the trailing edge side of the turbine guide vane structure.

In one or more embodiments, the turbine guide vane structure further includes a connecting rod that penetrates the CMC component and the metal cover plate, and the length variation of the axial force applying member at a temperature It is set to be greater than the difference in radial expansion of the connecting rod and the CMC component at the same temperature.

In one or more embodiments, at least part of the first wall surface and the side wall surface are arranged parallel to the radial direction, and the contact length of the first wall surface and the side wall surface is set to be larger than the connecting rod and the side wall surface. The difference in radial expansion of the CMC components.

In one or more embodiments, a circumferential seal is further included between the metal cover plate and the edge plate.

The above-mentioned turbine guide vane structure provides an axial rebound force by setting an axial force applying member, and also provides a side wall surface and a first wall surface that are in contact with each other at an inclined angle. The cooperation of the two enables the high-temperature alloy and CMC to remain in contact with each other after the expansion difference occurs. It can maintain contact in the axial direction, while ensuring that the axial force on the CMC blade is transmitted to the high-temperature alloy structure, effectively overcoming the radial and axial expansion differences between the metal and the CMC material after thermal expansion, and avoiding cold air leakage. , vibration, loss of restraint and other problems, ensuring the structural reliability of the guide vane.

Description of the drawings

The above and other features, properties and advantages of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which:

Figure 1 is a schematic structural diagram of a typical aeroengine.

Figure 2 is a schematic structural diagram of a typical turbine guide blade.

Figure 3 is an exploded view of an embodiment of a turbine guide vane.

Figure 4 is a front view of one embodiment of the turbine guide vane structure.

Figure 5 is a cross-sectional view of an embodiment of a turbine guide vane structure.

FIG. 6A is an enlarged view of position A in FIG. 4 .

FIG. 6B is an enlarged view of position B in FIG. 5 .

Figure 7 is a front view of another embodiment of a turbine guide vane structure.

FIG. 8 is an enlarged view of position C in FIG. 7 .

Symbol marking description

1. Nacelle

2. Fan

3. Compressor

4. Combustion chamber

5. Turbine

6. Edge plate

7. Folding part

8. Gap

9. Metal cover

10. Turbine guide vanes

11. Engine axis

12. CMC components

13. Upper cover

14. Lower support plate

15. Connecting rod

71. Side wall surface

72. Radial end

81. The first wall

82. Second wall

121. Upper edge plate

123. Lower edge plate

132. Installation holes

122. Leaf body

127. Circular seals

141. Boss

150. Axial force applying member

160. Nut

Detailed ways

The present disclosure will be further described below in conjunction with specific embodiments and drawings. More details are set forth in the following description in order to fully understand the present disclosure. However, the present disclosure can obviously be implemented in a variety of other ways that are different from this description. Those skilled in the art can make similar generalizations and deductions based on actual application conditions without violating the connotation of the present disclosure. Therefore, the protection scope of the present disclosure should not be limited by the content of the specific embodiments.

It should be noted that these and other subsequent drawings are only examples and are not drawn to equal scale, and should not be used to limit the scope of protection actually claimed by the present disclosure.

The typical structure of the engine can be understood with reference to Figure 1. It mainly includes nacelle 1, fan 2, compressor 3, combustion chamber 4, turbine 5 and other parts. Turbine 5 contains a certain number of turbine guide vanes 10 for Organize upstream airflow.

As shown in FIG. 2 , the turbine guide vane 10 is provided in the high-temperature turbine component of the gas turbine engine, and is used to rectify the upstream high-temperature and high-pressure gas and output it to the downstream. The turbine guide vanes 10 are generally installed on the casing, and together with the casing form a stator. As the total engine inlet temperature continues to rise, the gas temperature in front of the turbine is higher under high-temperature take-off conditions. Nowadays, the turbine guide vane 10 can be made of ceramic matrix composites (Ceramic Matrix Composites, CMC) and metal parts are made together, including CMC part 12 and metal cover 9. The metal cover 9 includes an upper cover 13 and a lower supporting plate 14; the CMC component 12 includes an edge plate 6, which includes an upper edge plate 121 and a lower edge plate 123. The edge plate 6 is used to cooperate with the metal cover plate 9 to complete the assembly between the CMC components and the metal components.

However, the thermal expansion coefficients of the CMC component 12 and the metal cover plate 9 are quite different. Therefore, under high temperature operating conditions, the turbine guide vanes will produce a certain expansion difference in the axial and radial directions, which will cause cold air leakage, vibration, and loss of restraint. And other issues. In addition, the strength of CMC materials is lower than that of metal materials, but it can withstand higher temperatures. Therefore, the turbine guide vane structure must take into account the strength and temperature resistance properties of both CMC materials and metal materials to ensure the reliability of the guide vane structure. sex.

The disclosed turbine guide vane structure can alleviate the thermal mismatch problem in the axial direction, and can also take into account the strength and temperature resistance characteristics of CMC materials and metal materials to ensure the reliability of the guide vane structure.

As shown in FIGS. 2 and 3 , the turbine guide vane 10 includes a CMC component 12 and a metal cover plate 9 . The metal cover plate 9 includes an upper cover plate 13 and a lower supporting plate 14 . It should be noted that in the coordinate axes shown in Figures 2 and 3, the X direction represents the axial direction, such as the extension direction shown by the engine axis 11; the Y direction represents the radial direction of the turbine. It can be understood that in FIG. 3 , for the unit blade, the Z direction that is perpendicular to both the X direction and the Y direction represents the circumferential direction. The axial side refers to the surface along the two ends of the X-axis, that is, the left and right direction in Figure 3; the circumferential side refers to the surface along the two ends of the Z-axis, which is the front-to-back direction in Figure 3.

The upper cover 13 , the lower supporting plate 14 and the CMC component 12 are connected by connecting rods 15 . The CMC component 12 includes an upper edge plate 121 , a lower edge plate 123 and an airfoil 122 connecting the upper edge plate 121 and the lower edge plate 123 . The upper edge plate 121, the lower edge plate 123 and the blade body 122 can be made in one piece, that is, the fibers are continuous; or they can be prepared separately and then assembled into an integral structure, that is, the fibers are discontinuous. During operation, the upper and lower edge plates of the CMC and the CMC blade body 122 form a flow channel, which is in contact with high-temperature gas and isolates other metal parts from direct contact with the gas, thus playing a protective role.

The upper edge plate 121 cooperates with the upper cover plate 13, the lower edge plate 123 cooperates with the lower supporting plate 14, the connecting rod 15 passes through the upper cover plate 13, the CMC component 12 and the lower supporting plate 14, and is tightened through the nut 160 at one end. force to realize the connection constraints between the CMC component 12, the upper cover plate 13 and the lower supporting plate 14. The upper cover 13 is connected to the external casing through the hook mounting edge 131 and the mounting hole 132 to secure the turbine guide vane 10 .

Continuing to refer to FIGS. 3 to 5 , it can be understood that in the turbine guide vane structure of the present disclosure, an axial force applying member 150 is provided between the edge plate 6 and the metal cover plate 9 , and the axial force applying member 150 is used to provide axial predetermination. Tightening force, such as elastic parts such as springs, or force-applying parts made of shape memory alloys, rely on the pseudo-elasticity of shape memory alloys (pseudoelasticity), applying an axial preload force to the edge plate 6 and the metal cover plate 9 through thermal expansion at high temperatures. At least part of the axial side of the edge plate 6 includes a notch 8. The notch 8 includes a first wall 81. At least part of the first wall 81 is a slope. The axial side of the metal cover 9 that cooperates with this part of the edge plate 6 includes a folded portion. 7. The folded portion 7 is used to cooperate with the notch 8. The folded portion 7 includes a side wall surface 71 which is parallel to the first wall surface 81 and in surface contact with the first wall surface 81 .

At least part of the first wall surface 81 on the axial side is set as an inclined surface, that is, a certain angle a is formed with respect to the X direction. The first wall surface 81 and the side wall surface 71 can generate component forces in both the radial and axial directions. , that is, the component force along the Y direction and the component force along the X direction. Under the action of the axial force applying member 150, the inclined first wall surface 81 and the side wall surface 71 can always ensure close contact in the axial direction. Since the axial force applying member 150 is in a compressed state during initial installation, it is compressed to provide a radial preload force. After thermal expansion, due to the large thermal expansion coefficient of the metal, the deformation of the metal cover plate is greater than that of the CMC part in both the radial and axial directions. At this time, the axial force applying member 150 such as the elastic member generates a certain compression restoring force, which first offsets the gap in the radial direction caused by the expansion difference, and also generates movement in the axial direction with the help of the design of the inclined surface, so that the first wall 81 The two inclined surfaces of the side wall surface 71 are in close contact with each other. The mutual displacement of the two inclined surfaces of the side wall surface 71 and the first wall surface 81 can simultaneously offset the gap caused in the axial direction, overcome the axial expansion difference to a certain extent, and ensure the installation The stability and sealing performance alleviate the thermal mismatch problem in the axial direction.

The axial force applying member 150 can be disposed on the same side in the radial direction as the notch 8, as shown in Figure 3; it can also be disposed on different sides, as shown in Figure 7. The notch 8 can be provided on both sides of the axial direction at the same time, or can be provided on only one side of the axial direction, so as to achieve the effect of alleviating the axial expansion difference. As in the embodiment shown in FIG. 7 , the axial force applying member 150 continuously applies an upward rebound force to the CMC component. When thermal expansion occurs, the rebound force can compensate for the expansion difference between the CMC component and the metal component. With the first wall surface 81 and the side wall surface 71 located on the axial side that are tilted, compensation in the axial direction can be achieved, thereby simultaneously reducing the effects of expansion differences in the axial and radial directions.

In some embodiments, the notch 8 is provided on the trailing edge side of the turbine guide vane structure. As shown in FIG. 7 , the right F area represents the blade leading edge, and the left T area represents the blade trailing edge. The pressure at the blade leading edge is greater than the blade trailing edge, and the airflow will flow from the F area to the T area. In one embodiment, the notch 8 and the folded portion 7 are only provided on the trailing edge side of the turbine guide vane, that is, the side of the blade close to the T area, so that with the help of air pressure, the parts located on the CMC component 12 will be moved under the action of aerodynamic force. The force is transmitted to the metal parts through face-to-face contact, and the force on the CMC parts is transferred to the metal parts, thereby reducing the self-stress on the CMC parts and alleviating the expansion difference at the same time. It also ensures that the strength of CMC components always meets the requirements.

In some embodiments, in order to ensure that the upper edge plate 121 and the upper cover plate 13 do not separate during operation, the contact length between the inclined surface and the side wall surface 71 needs to meet a certain length. Referring to Figure 6A, it is understood that the contact length between the inclined surface and the side wall surface 71 needs to be continuously greater than the ratio of the difference between the expansion amount of the CMC component 12 and the metal cover plate in the axial direction to the cosine of the inclination angle a of the inclined surface, that is, L1· cos(a)>ΔLx, where L1 is the contact length of the contact surface, and ΔLx is the difference in expansion amount between the upper cover plate 13 and the upper edge plate 121 in the axial direction, that is, the X direction, at a certain high temperature, thereby ensuring that When the engine is running, the upper edge plate 121 and the upper cover plate 13 always rely on the cooperation of the inclined surfaces to ensure the connection between the metal parts and the CMC parts.

In some embodiments, as shown in FIG. 3 , the notch 8 further includes a second wall 82 , the folded portion 7 further includes a radial end 72 , and the second wall 82 is used to separate the radial end. End 72 and CMC component 12 . Since the CMC material is more resistant to high temperatures than metal materials, the second wall 82 can prevent the radial end 72 of the metal folding portion 7 from directly contacting the high-temperature gas near the CMC blade 122 , thereby effectively protecting the metal components. , to prevent it from being damaged by high temperatures.

Based on the above embodiment, at least part of the second wall surface 82 is arranged parallel to the axial direction, that is, the second wall surface 82 is parallel to the X-axis direction, so as to play a buffering and protective role. It can be understood that the second wall surface 82 can also be configured as other angled inclined surfaces that can play a buffering and protective role.

In addition, at least part of the circumferential side of the edge plate 6 may also include a notch 8', and the circumferential side of the metal component mated with this part of the edge plate may include a folded portion 7'. As shown in Figures 3 and 5, the notch 8' also includes a first wall surface 81', the folded portion 7' includes a side wall surface 71', and the first wall surface 81' and the side wall surface 71' are in face-to-face contact.

In some embodiments, at least part of the first wall 81 is arranged parallel to the radial direction, that is, parallel to the Y direction. As shown in the notch 8' on the lower edge plate 123 in Figure 3, the first wall surface 81' is parallel to the Y direction, and the side wall surface 71' parallel to the first wall surface 81 is also parallel to the Y direction. Continuing to refer to FIG. 5 , the side wall surface 71 ′ of the folded portion 7 ′ located on the circumferential side of the upper cover plate 13 or the lower supporting plate 14 is also parallel to the Y-axis direction, and is located on the upper edge plate 121 or the lower edge plate. The first wall surface 81' of the notch 8' on the circumferential side of 123 fits, and is arranged in a radial direction to help achieve better transmission of force.

At this time, in order to ensure that the CMC component and the metal component do not separate from each other, based on the above embodiment, the contact surface length L2 of the first wall surface 81' and the side wall surface 71' is continuously larger than the diameter of the connecting rod 15 and the CMC component 12. The difference in expansion amount. As shown in Figure 6B, L2>ΔLy, ΔLy is the relationship between the connecting rod 15 and the CMC component 12 at high temperature. The difference in expansion in the radial direction. If the above formula is satisfied, it can be ensured that the CMC component 12 and the metal cover plate 9 always maintain contact in the radial direction without separation at high temperatures.

Continuing to refer to Figure 5, the area P located on the left side of the turbine guide vane structure is the pressure surface side, and the area S located on the right side of the turbine guide vane structure is the suction surface side. Since the working air pressure on the pressure surface is higher than the suction surface, therefore, In one embodiment, the notch 8' and the folded portion 7' are provided on the suction side of the turbine guide vane structure, so that under the action of aerodynamic force, the CMC component 12 can also be close to the high temperature in the circumferential direction, that is, in the circumferential direction. Alloy ensures that the hoop force can be transmitted to the high-temperature alloy structure, thereby ensuring the reliability of the guide vane structure.

In one embodiment, the radial length change of the axial force applying member 150 at a temperature is greater than the difference in radial extension of the connecting rod 15 and the CMC component 12 at the same temperature. The axial force applying member 150 can be an elastic member made of high-temperature alloy or ceramic material, such as a spring, a disc spring, etc.; it can also be a specific material with a thermal expansion coefficient greater than the thermal expansion coefficient of the connecting rod 15, such as an elastic member made of a shape memory alloy. force parts. The axial force applying member 150 can maintain close contact between the CMC component 12 and the metal cover 9 through elastic recovery or thermal expansion properties at high temperatures. The axial force applying member 150 can resume elongation or thermal expansion at high temperature. By selecting a spring with appropriate parameters or a material with an appropriate thermal expansion coefficient, its length change ΔLs at high temperature is greater than that of the connecting rod 15 and CMC components at the same temperature. The difference in radial extension of 12, that is, ΔLs>ΔLy, ensures that the CMC upper edge plate 121 and the axial force applying member 150, and the CMC lower edge plate 123 and the metal lower supporting plate 14 can always maintain close contact assembly. ΔLy is the difference between the radial expansion amounts of the connecting rod 15 and the CMC component 12 at a certain high temperature. Therefore, through the cooperation of elastic parts and oblique contact surfaces, the CMC material and the high-temperature alloy always maintain close contact under high temperature conditions, while overcoming the radial and axial expansion differences, ensuring installation stability.

In some embodiments, a circumferential seal 127 is further included between the metal cover plate and the edge plate. For example, in Figure 7, when the lower edge plate 123 and the lower supporting plate 14 are also matched with the boss 141, the circumferential seal 127 is disposed in the groove opened by the boss 141 and the lower edge plate 123 for Block the airflow path to avoid gas leakage.

The above-mentioned turbine guide vane structure can ensure close axial contact between CMC components and metal components by configuring inclined side walls and first wall surfaces. It can also use pressure differences to transfer forces through surface contact to minimize CMC. Partially bear the stress; in addition, by setting up the second wall, the metal components are effectively protected from direct impact of high temperatures and the stability of the structure is improved.

It should be noted that the use of words such as "first" and "second" in the above introduction to define parts is only to facilitate the distinction between corresponding parts. Unless otherwise stated, the above words have no special meaning. The meaning does not represent the primary or secondary meaning, and therefore cannot be understood as limiting the scope of protection of this application.

At the same time, this application uses specific words to describe the embodiments of the application. For example, "one embodiment", "an embodiment", and/or "some embodiments" means a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that “one embodiment” or “an embodiment” or “an alternative embodiment” mentioned twice or more at different places in this specification does not necessarily refer to the same embodiment. . In addition, certain features, structures or characteristics in one or more embodiments of the present application may be appropriately combined.

Although the present disclosure is disclosed above in terms of preferred embodiments, this is not intended to limit the present disclosure. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, any modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present disclosure that do not deviate from the technical solution of the present disclosure shall fall within the protection scope defined by the claims of the present disclosure.

Claims

A turbine guide vane structure includes a CMC component (12) and a metal cover plate (9). The CMC component includes an edge plate (6), and the edge plate (6) is used to communicate with the metal cover plate (9). Cooperation is characterized by,

An axial force applying member (150) is provided between the edge plate (6) and the metal cover plate (9). The axial force applying member (150) is used to apply force to the edge plate (6) and the metal cover plate (9). The metal cover (9) provides axial preload;

At least part of the axial side of the edge plate (6) includes a notch (8), the notch (8) includes a first wall surface (81), and at least part of the first wall surface (81) is a slope,

The axial side of the metal cover plate (9) that cooperates with the partial edge plate includes a folded portion (7) for matching with the notch (8). The folded portion (7) includes a side wall surface ( 71), the side wall surface (71) is parallel to the first wall surface (81) and in surface contact with the first wall surface (81).
The turbine guide vane structure according to claim 1, characterized in that the contact length between the inclined surface and the side wall surface (71) is greater than the axial length between the CMC component (12) and the metal cover plate (9). The ratio of the difference in expansion amount in the direction to the cosine of the inclination angle of the inclined plane.
The turbine guide vane structure according to claim 1, wherein the notch (8) further includes a second wall surface (82), the folded portion (7) further includes a radial end (72), and the The second wall (82) is used to separate the radial end (72) from the CMC component (12).
The turbine guide vane structure according to claim 1, characterized in that at least part of the circumferential side surface of the edge plate (6) includes a notch (8'), and the metal cover plate (9) mated with this part of the edge plate ) includes a folded portion (7') on its circumferential side.
The turbine guide vane structure according to claim 1 or 4, characterized in that at least part of the first wall surface (81) is arranged parallel to the radial direction.
The turbine guide vane structure according to claim 4, characterized in that the notch (8') is provided on the suction surface side of the turbine guide vane structure.
The turbine guide vane structure according to claim 1, characterized in that the notch (8) is provided on the trailing edge side of the turbine guide vane structure.
The turbine guide vane structure according to claim 5, characterized in that the turbine guide vane structure further includes a connecting rod (15), and the connecting rod (15) penetrates the CMC component (12) and the metal cover plate (9), the length change of the axial force applying member (150) at a temperature is set to be greater than the difference in radial expansion of the connecting rod (15) and the CMC component (12) at the same temperature. .
The turbine guide vane structure according to claim 8, characterized in that at least part of the first wall surface (81) and the side wall surface (71) are arranged parallel to the radial direction, and the first wall surface (81) The contact length with the side wall surface (71) is set to be greater than the difference in radial expansion amounts of the connecting rod (15) and the CMC component (12).
The turbine guide vane structure according to claim 1, characterized in that a circumferential seal (127) is further included between the metal cover plate (9) and the edge plate (6).