EP1607580A2 - Platform cooling of vanes in a gas turbine - Google Patents

Abstract

The platform cooler has cooling air outlet ducts (10) arranged at least in part in relation to the circumferential direction in a direction off-set by a certain angle. The angular position of the ducts in adjoining rows of ducts can be the same or different. The ducts can be off-set relative to each other in one and the same direction or in relation to adjacent rows.

Description

The invention relates to a platform cooling arrangement for the combustion chamber downstream vane ring a gas turbine, with at the periphery of the wall of the combustion chamber, the platforms and / or the wall of one between these arranged intermediate piece the respective wall in at least a continuous or discontinuous series or any other arrangement penetrating Kühlluftausblaskanälen, via the compressor of the gas turbine branched cooling air for film cooling to the Main gas flow surfaces of the platforms is passed.

The above-mentioned way of cooling the platforms of behind the annular gas outlet opening of the combustion chamber a gas turbine arranged vanes, the - limited by inner and outer platforms - one Form Leitschaufelkranz, for example, from DE 198 13 779 A1 known. It is about cooling air holes, in the region of the outlet opening in the combustion chamber wall or directly into the platforms or even in one interposed intermediate piece are introduced, From the compressor branched cooling air into the boundary layer blown in the hot gas stream. The injection of cooling air serves to lower the temperature of the combustion chamber discharged hot gas stream in one of the inner surfaces the platforms contacting the flow layer to the Platform material over the remaining uncooled Shield hot gas flow. In unprotected condition would be the platform material of such a high heat load exposed that the lifespan of the platforms of the Vanes significantly shortened. The usually in the field the annular outlet opening of the combustion chamber or near the front edge of the annularly arranged Platforms distributed around the circumference arranged Kühlluftausblasöffnungen However, because of the complicated Flow conditions in the near-wall area, and indeed due to the interaction between the hot gas flow and the blown cooling air, unable to blow the whole Inner surface of the platforms effective against the Shield or cool hot gas stream. Responsible this is a three-dimensional entrance boundary layer separation along a certain - variable - line on the surface of the platforms. To have a cooling effect in the largest possible area of the platform surfaces, that is, even in the field of three-dimensional To achieve secondary flow, DE 198 13 779 goes from a cooling air blowing called ballistic cooling in a direction corresponding to the radius, the means, in a limited by the turbine axis and the radius Level, under a relatively steep discharge angle to the turbine axis with high momentum ratios, at the Kühlluftausblas-openings forming the at least one row in Turbinenumfangsrichtung in from each other spaced groups are arranged, each on a range from the vane leading edge to the whose respective pressure side are limited towards. With the so-called "ballistic cooling" in each case the pressure side of the vanes restricted area should therefore also in the area behind the three-dimensional Entry boundary layer detachment lying platform surfaces reached by the cooling medium and cooled sufficiently become.

EP 0 615 055 A1, whose technical teaching is also based on the above-mentioned principle of film cooling or ballistic Cooling of the platforms is based on at least one, in contrast to that described in DE 198 13 779 A1 Solution not interrupted in the circumferential direction Series of blow-out channels, however, to achieve a certain mass flow distribution in the circumferential direction have different diameters to thereby as complete as possible cooling of the platform surface to effect. Also in this cooling arrangement agrees the direction of the exhaust channels, except one certain to penetrate the platform or the Combustion chamber wall required angle of attack, with the the turbine axis and the radius formed plane.

In fact, it succeeds with the cooling arrangements described above however, not due to the blown cooling air a high degree of mixing with the hot gas stream and too high a distance of the cooling air from the platform efficient use and beyond the film cooling also in all surface areas of the platforms, that is, also in the downstream boundary layer stripping area, to ensure sufficiently. Nevertheless, a certain hot gas shield the To reach platforms, it is necessary to have a relative use high proportion of cooling air and / or one Provide heat protection coating or more efficient and thus more cost-intensive form. In particular Cases can also be a complex cooling system for not be required in the hot gas flow areas, the as well as an increase in specific fuel consumption and the cost leads in like a movie cooling the vane passage.

The invention is based on the object, a platform cooling arrangement specify the type mentioned, the effective cooling of all main gas flow surfaces of the Platform guaranteed.

According to the invention, the object with a according to the Features of claim 1 trained platform cooling arrangement solved. From the dependent claims Advantageous developments and expedient refinements the invention.

The essence of the invention consists in the arrangement at least part of the Kühlluftausblaskanäle in one of the one formed by the turbine axis and the radius Plane by an angle α deviating direction. In other words, that means the Kühlluftausblaskanäle slanted with respect to the circumferential direction are. By this of the usually straight alignment the Kühlluftausblaskanäle deviating angular arrangement and the corresponding Kühlluftstrahlrichtung to the platforms is surprisingly a diminished Mixing with the hot gas stream and a higher Concentration of the cooling air in the end wall area and from it resulting in a more effective cooling or a reduced Cooling air requirement reached. The oblique orientation the cooling air jets produces a vortex structure in which a reduced hot gas content is absorbed and the is also able to also the platform area behind the three-dimensional boundary layer detachment effectively and in all areas between the pressure side and the suction side to cool the adjacent vanes. By the reduced cooling air requirement and the improved cooling effect can both the effort required if necessary additional cooling measures as well as fuel consumption lowered emissions and improved emissions become.

According to the invention, at least part of the Kühlluftausblaskanäle adjusted obliquely to the circumferential direction. The means the size of the angle in which the neighboring ones Kühlluftausblaskanäle are aligned, may vary be and be partially 0 °.

The circumference of Kühlluftausblaskanälen in one or several discontinuous or continuous rows or even in regular or irregular groups or also individually as well as in variable form and Size be formed. Between the adjacent rows or in the same row or group of cooling air exhaust ducts The skew of the Kühlluftausblaskanäle can be different be.

In addition, the Kühlluftausblaskanäle in one and the same Row or with respect to the adjacent row be offset to each other.

The size and / or the shape of the cross section in and same row or with respect to the adjacent rows or in any other arrangement of cooling air exhaust ducts can be different.

Fig. 1

eine Teilansicht der Brennkammer einer Gasturbine mit an die Gasaustrittsöffnung unmittelbar angeschlossenem Leitschaufelsystem;

Fig. 2

eine Teilansicht der Brennkammer mit einem zwischen der Gasaustrittsöffnung und dem Leitschaufelsystem angeordneten Zwischenstück;

Fig. 3

eine Schnittansicht von jeweils zwei benachbarten, auf einer Plattform angebrachten Leitschaufeln mit einer Gruppe von jeder Leitschaufel zugeordneten, in unterschiedlicher Winkellage in der Plattform verlaufenden Kühlluftausblaskanälen; und

Fig. 4

eine geometrische Darstellung der in Bezug auf die Umfangsrichtung winkligen Anordnung der Kühlluftausblaskanäle.

An embodiment of the invention will be explained in more detail with reference to the drawing. Show it:

Fig. 1

a partial view of the combustion chamber of a gas turbine with directly connected to the gas outlet guide vane system;

Fig. 2

a partial view of the combustion chamber with an intermediate piece arranged between the gas outlet opening and the guide vane system;

Fig. 3

a sectional view of two adjacent, mounted on a platform vanes with a group of each guide vane associated, extending in different angular position in the platform Kühlluftausblaskanälen; and

Fig. 4

a geometric representation of the angle with respect to the circumferential direction arrangement of the Kühlluftausblaskanäle.

FIGS. 1 and 2 each show a vane 1, between an outer platform 2 and an inner Platform 3 is arranged. A plurality of guide vanes 1 with platforms 2, 3 forms a vane ring, the the annular gas outlet opening 5 of a combustion chamber 6 is connected downstream. The outer platforms 2 and the inner platforms 3 are shown in FIG. 1 immediately and As shown in FIG. 2 via an intermediate piece 7 with the wall 4 of Combustion chamber 6 connected or at the gas outlet opening 5 connected. A emerging from the gas outlet opening 5 Hot gas flow (arrow 8) is between the adjacent Guide vanes 1 and the platforms 2, 3 forwarded. To those due to the high gas temperature thermal loading of the blade and platform material to reduce, the vanes 1 and the platforms 2, 3 cooled. The cooling of the platforms, the object The present application is carried out with a Part of the branched off from the compressor (not shown), not used for the combustion process, Cooling air (arrow 9). For this purpose are close to the gas outlet 5, as shown in FIG. 1, in the outer platforms 2 and in the inner wall 4 of the combustion chamber 6 am Circumference distributed Kühlluftausblaskanäle 10 arranged. According to Fig. 2, the Kühlluftausblaskanäle 10 in the outer Wall 4 of the combustion chamber 6 and in a between the inner platform 3 and the inner wall of the combustion chamber 6 arranged intermediate piece 7 is formed. Regarding the respective arrangement of the Kühlluftausblas-channels 10 in the Platforms, the combustion chamber wall or the intermediate piece Other combinations are possible.

The Kühlluftausblaskanäle 10 are at the periphery of the inner or outer wall 4, the platforms 2, 3 or the intermediate piece 7 in at least one - continuous or discontinuous series (not shown) arranged and can - with several rows - in a line or be offset from each other. The cross-sectional area the Kühlluftausblaskanäle 10 is round or oval, but may also have a different shape.

From Figures 1 and 2 it can be seen that the Kühlluftausblaskanäle 10 - according to the prior art in conventional Way - in one of the turbine axis x and the Radius r (Fig. 4) formed inclined plane are. The figure 3 makes it clear that the Kühlluftausblaskanäle 10 but also in another, from the r, x-plane deviating plane (Θ-plane of FIG. 5) are aligned obliquely, so that from the Kühlluftausblaskanälen 10 exiting cooling air jets (Arrow 11) in one of the r, x-plane by the angle α deviating direction on the surface of the platforms 2, 3 run, that is, with respect to the circumferential direction (Arrow 15) are aligned at an angle. Based on these Cooling air jet 11 is in cooperation with the hot gas stream 8 from the combustion chamber a vortex structure formed, on the one hand, the mixing of the cooling air jets 11 minimized with the hot gas stream 8 and the others covering the entire platform surface with Cooling air, that is, also in the area 12 of the three-dimensional Boundary layer separation downstream of the boundary layer separation line 13 and in particular in the suction side 14 of the vanes 1 adjacent area ensures. This is associated with a reduction in the cooling air requirement and thus an improvement of the emission values, because a larger amount of air for combustion to Available. Optionally, the heat protection coating account for the platform surfaces, so that the corresponding costs are reduced. Optionally, a complex cooling system for dispensed with the acted upon by the hot gas flow surfaces or cooling the passage through the Guide vane can be avoided, so ultimately the specific fuel consumption and the costs are lowered can be.

The angular position of the Kühlluftausblaskanäle 10 can in each case adjacent rows of Kühlluftausblaskanälen be the same or different. It is beyond that also conceivable that the Kühlluftausblaskanäle 10, as in Fig. 3 indicated, in one and the same - continuous or discontinuous - series (or arrangement) in one in the circumferential direction 15 of the platforms 1, 2, the intermediate piece 7 or the wall 4 of the combustion chamber. 6 related different angles α1, α2 to a Angle α = 0 are arranged.

LIST OF REFERENCE NUMBERS

1

vane

2

outer platform

3

inner platform

4

inner / outer wall of 6

5

Gas outlet

6

combustion chamber

7

connecting piece

8th

Hot gas stream

9

cooling air

10

Kühlluftausblaskanal

11

Cooling air jet

12

Area of boundary layer separation

13

Boundary layer separation line

14

Suction side v. 1

15

circumferentially

X

turbine axis

r

radius

α ₁ , α ₂

Discharge angle in the circumferential direction. (to the r, x-level)

Claims (9)

Platform cooling arrangement for the combustion chamber downstream vane ring of a gas turbine, with at the periphery of the wall of the combustion chamber, the platforms or an intermediate piece between the respective wall in at least one continuous or discontinuous row or other arbitrary arrangement penetrating Kühlluftausblaskanälen, branched off from the compressor of the gas turbine Cooling air for film cooling is directed to the main gas flow surfaces of the platform, characterized in that the Kühlluftausblaskanäle (10) with respect to the circumferential direction (15) at least a part in a by a certain angle (α ₁ , α ₂ ) angled direction are arranged. Platform cooling arrangement according to claim 1, characterized in that the angular position of the Kühlluftausblaskanäle (10) in adjacent rows of Kühlluftausblaskanälen is the same or different. Platform cooling arrangement according to claim 1, characterized in that the angular position of the Kühlluftausblaskanäle (10) in one and the same row is the same or different. Platform cooling arrangement according to claim 1, characterized in that the angular position of the Kühlluftausblaskanäle (10) in the arbitrary arrangement of Kühlluftausblaskanälen (10) is the same or different. Platform cooling arrangement according to claim 2, 3 or 4, characterized in that at different angular positions of the angle α in one and the same row is partially or in one of a plurality of rows total 0 °. Platform cooling arrangement according to claim 1, characterized in that the Kühlluftausblaskanäle (10) in one and the same row or with respect to each adjacent rows are arranged offset from one another. Platform cooling arrangement according to one of claims 1 to 5, characterized in that the Kühlluftausblaskanäle (10) have variable cross-sectional shapes and / or - sizes. Platform cooling arrangement according to claim 7, characterized in that the Kühlluftausblaskanäle (10) in one and the same array or with respect to adjacent rows of different cross-sectional shapes and / or sizes. Platform cooling arrangement according to claim 1, characterized in that Hauptgasstromflächen the platforms a single Kühlluftausblaskanal (10) is provided.

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