EP1138878A2 - Flat freestanding gas turbine element - Google Patents

Abstract

The panel-shaped projecting component has a surface charged by hot gas, and bores for a coolant. At least one plenum chamber (30) is located next to the surface (2) charged by the hot gas, and the coolant passes through it in a convective flow. The coolant bores are formed as blow-out aperture, which extend from the plenum chamber and open into the hot gas-charged surface, thereby generating a coolant film. Plenum chambers and/or blow-out apertures are formed by an EDM process.

Description

Technical field

The invention relates to a plate-shaped, projecting component section of a Gas turbine or the like according to the preamble of claim 1.

State of the art

Such component sections can often be found where constructive Overhanging areas on main components, such as on Buckets, fasteners are provided or sealing elements, too between two neighboring components. Problematic are such overhanging component sections especially in thermally highly stressed Areas where hot gas is applied to the surface. It is often essential to provide cooling there.

EP 0 911 486 A2, from which the invention is based, describes a cooled one Known blade of a gas turbine, in which overhanging areas in the form of plate-shaped, cantilevered component sections are formed in the axial direction are attached in front of and behind the blade root to cover the hub area with the adjacent blade root areas of rotor blades to ensure. To cool this plate-shaped, cantilevered Component sections are provided cooling bores that are purely convective from cooling air be flowed through. The cooling holes run for example in the front overhanging component section in the circumferential direction and are from the main cooling air supply fed. Due to the high thermal load in this Area there are additional turbulence generators in the cooling holes, to improve heat transfer.

The rear, overhanging component section has a plurality of axially extending Cooling holes, which are also fed by the main cooling air supply. The cooling bores open axially at the end of the component section, so that the cooling medium escapes into the hot gas stream after flowing through the cooling channels.

Both component sections have in common that the one affected by the hot gas Surface is cooled purely by convection. The disadvantage here is that a lot of cooling air must be used to achieve the required cooling effect. This results in or worsens overall efficiency Use of expensive high temperature resistant materials required.

Presentation of the invention

The invention tries to avoid the disadvantages described. You are the Task based on a plate-shaped, projecting component section of a Specify gas turbine or the like of the type mentioned, the one allows more effective cooling of the surface exposed to hot gas and thus has an increased service life with a reduced cooling air requirement.

This is achieved according to the invention in that, in the case of a plate-shaped, projecting component section according to the preamble of claim 1 a plenum is provided, which is assigned exclusively to the component section, so that enables optimal cooling of the surface exposed to hot gas becomes. The plenum is immediately adjacent to the surface to be cooled arranged and is flowed through by the cooling medium convectively. Furthermore are the cooling bores are designed as blow-out openings which emanate from the plenum and open on the surface exposed to hot gas. So it is possible, a highly effective film cooling on the hot gas Realize surface, while the coolant consumption is kept extremely low can be. The reason is that the cooling air is initially convective flows through the cooling area and then by blowing out train highly effective cooling film.

Although basically extensive freedom of design with regard to the design of the plenary, it has proven to be advantageous if a single, continuous plenum is provided which largely completely the component section enforced. In this way, the surface exposed to hot gas evenly and without local interruption by, for example, partitions cooled, making it possible to achieve an unprecedented effective cooling effect is.

A number of preferred versions are based on the simple and inexpensive Realization of this cooling concept directed. The choice of the optimal shaping process for the plenary mainly depends on the manufacturing process from the actual component on which the plate-shaped, projecting section is to be provided. Other important aspects are those to be realized Geometry, as well as the manufacturing specifications.

In the case of the frequently encountered overhangs on turbine blades, it offers began to shape the plenum directly during the molding process. This is usually possible without much additional effort, whereby after Demould the plenum immediately and without the need for post-processing is formed.

Usually a multi-part core is used to create the desired geometry of the plenary. If necessary, side openings for Positioning of the core will be required afterwards, ie afterwards can be concluded from the shaping process.

As an alternative to this, it is also possible to pass the plenum through a recess in the component section to form, for example opposite to the one to be cooled Surface is open and therefore by a cover to be retrofitted can be locked. This eliminates the need to to provide a core for the formation of the plenum. The advantage of this variant lies in the possibility of making the geometry of the plenary largely revealing.

The cover can be attached using cost-effective connection methods, such as soldering or welding.

Finally, it is also possible to manufacture both the plenum and the blow-out openings using the EDM process. With the help of this method, the shape, size and arrangement of the blow-out openings in particular can be freely selected and implemented with the highest precision. The plenum as such can also be implemented exactly with this procedure. Lateral outlet openings, as required for the production of the plenum, can remain completely or partially open as additional outlet openings, depending on the design of the cooling concept. Otherwise, they are closed after the molding process.
The plenum is preferably connected via feed channels to a main plenum, which supplies the blade with cooling air. In this way, no direct connection to the cooling medium supply is required, which means that the design effort can be reduced.

Although the cooling concept described above is suitable for use with it is preferred that any thermally highly stressed components can be realized used on overhangs of turbine blades. On the one hand there are the thermal loads particularly high, on the other hand is in the immediate vicinity of the overhang mostly provided for a coolant supply anyway, whereby the cooling concept according to the invention is particularly easy to implement leaves.

Brief description of the drawing

Fig. 1

Überhang an einer Turbinenschaufel, perspektivische Ansicht von oben;

Fig. 2

Überhang gemäß Fig. 1, Ansicht von unten;

Fig. 3

Überhang an einer Turbinenschaufel gemäß einer ersten Ausführungsvariante, Ansicht von unten;

Fig.4

Kern zur Herstellung eines Plenums;

Fig. 5

Überhang an einer Turbinenschaufel gemäß einer zweiten Ausführungsvariante, Ansicht von unten.

Exemplary embodiments of the invention are shown schematically. Show it:

Fig. 1

Overhang on a turbine blade, perspective view from above;

Fig. 2

Overhang according to Figure 1, bottom view.

Fig. 3

Overhang on a turbine blade according to a first embodiment, view from below;

Fig. 4

Core for the production of a plenum;

Fig. 5

Overhang on a turbine blade according to a second embodiment, view from below.

They are only the elements essential for understanding the invention shown and described.

Way of carrying out the invention

The concept according to the invention is based on a plate-shaped, cantilevered Component section explained in the form of an overhang 1, which is a component a platform 3 carrying a turbine blade 4 is formed. A surface 2 is thermally highly stressed, namely by one not shown here Hot gas jet. In this respect, the design variants described in more detail below designed in accordance.

In the embodiment shown in FIGS. 1 and 2 are on the overhang 1 four essentially parallel and spaced apart Pleni 10 available, which consistently enforce the overhang 1. You run immediately adjacent to the surface 2 and cool it in this area through a cooling medium, which is not shown in more detail and is passed through convectively. Blow-out openings 12 are also present, preferably in rows and arranged in association with the Pleni 10. They are based on Pleni 10 and open on the surface 2. In this way, the cooling medium from the Pleni 10 blown out through the blow-out openings 12 such that a coherent Forms cooling film. The surface 2 is thus optimally cooled.

As can be seen in particular from FIG. 2, the plenums 10 can be operated using EDM tools 19 are formed, drill the through holes in the overhang 1. This creates a connection to a main plenum 5 below the platform 3 manufactured, whereby the pleni 10 are fed with cooling air from this area.

Depending on the requirements, the plenums 10 can open on the side on the overhang 1, as shown in Fig. 1. In this case, cooling air is also discharged from the side blown out the overhang 1. However, it is equally possible to use Pleni 10 in to partially or completely close this area.

The cross-section of the individual plenums 10 can vary to match the local one To achieve a coordinated cooling effect when exposed to heat. This also applies to their number and distribution of their arrangement along the overhang 1. The same applies analogously for the cooling bores or blow-out openings 12, which for training of the cooling film are responsible.

The embodiment shown in Fig. 3 shows a plenum 30, the overhang 1 largely complete with regard to its longitudinal and transverse extension interspersed throughout. This enables a largely ideally evened out convective cooling of the surface 2 and also offers the possibility of the film cooling air bores (not shown here in detail) are distributed as desired to arrange.

The plenum 30 is again supplied by the main plenum 5. For this there are feed channels 6 provided that the connection between the main plenum 5 and the Establish plenum 30.

The plenum 30 and the feed channels 6 are in this case directly during the Casting process formed. A core 39 shown in FIG. 4 is used for this purpose, which specifies the shape of the plenum 30. There are also two feeder sections 38 provided to form the feed channels 6. With the help of this multi-part Kerns 38, 39 can easily include plenum 30 inclusive form the feed channels 6.

5 shows a recess 50 cast in the overhang 1, from which the cooling bores 52 depart. The actual plenum is then formed when the recess 50 is closed by a cover, not shown here becomes. The cover can consist of a simple plate that is on the overhang 1 is placed and soldered or welded there. So you can even complicated geometries due to a corresponding design of the recess 50 are implemented. Such geometries can, for example, on the Surface 2 arranged pins, ribs or turbulence generators (not shown).

As already mentioned at the beginning, the concept described above is not only limited to use on overhangs of turbine blades, rather can be used wherever plate-shaped, projecting component sections exposed to high thermal loads and therefore effective need to be cooled.

Reference list

1

Overhang

2nd

Hot gas side surface

3rd

platform

4th

Turbine blade

5

Main plenum

6

Dining channel

10th

Plenum, EDM drilling

12th

Film cooling hole, blow-out opening

19th

EDM tool

30th

plenum

38

Feeder section

39

core

50

deepening

52

Film cooling hole, blow-out opening

Claims (9)

Plate-shaped, projecting component section of a gas turbine or the like, with a surface exposed to hot gas and with cooling bores through which a cooling medium can flow, characterized in that at least one plenum (10; 30; 50) exclusively assigned to the component section (1) is provided, which is arranged directly adjacent to the surface (2) acted upon by hot gas and through which the cooling medium can flow through convectively, and that the cooling bores are designed as blow-out openings (12; 52) which start and leave the plenum (10; 30, 50) the surface exposed to hot gas (2) open, whereby a cooling film can be generated. Component section according to claim 1, characterized in that the plenum (30, 50) largely completely penetrates the component section (1). Component section according to claim 1 or 2, characterized in that the plenum (30, 50) is formed in the casting process. Component section according to claim 3, characterized in that the plenum (30; 50) is formed by means of a multi-part core (38; 39). Component section according to one of claims 1 to 4, characterized in that the plenum (30; 50) is formed by a recess (50) molded into the component section (1) and closed by a cover. Component section according to claim 5, characterized in that the cover is soldered or welded to the component section (1). Component section according to claim 1 or 2, characterized in that the plenum (10) and / or the blow-out openings (12) is / are produced using the EDM method. Component section according to one of the preceding claims, characterized in that the plenum (10; 30; 50) is connected to a main plenum (5) via feed channels (6). Component section according to one of the preceding claims in the form of a overhang (1) formed on a turbine blade (4).

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