METHOD FOR THE ARRANGEMENT OF IMPINGEMENT COOLING HOLES AND EFFUSION HOLES IN A COMBUSTION CHAMBER WALL OF A GAS TURBINE

Abstract

A method for the arrangement of effusion holes and impingement cooling holes in a combustion chamber wall including: distribution of the effusion holes in the surface to be cooled in accordance with pattern, diameter and dimension selections made; distribution of the impingement cooling holes in accordance with pattern, diameter and dimension selections made; checking of the number of matches and their spacing from one another, taking into account the component and assembly tolerances; comparison with the permitted number and their minimum spacing; and, if quality requirements are not met, taking corrective actions, including selecting alternative diameters and patterns.

Description

This application claims priority to German Patent Application DE102012025375.3 filed Dec. 27, 2012, the entirety of which is incorporated by reference herein.

This invention relates to a method for the arrangement of effusion holes and impingement cooling holes in a combustion chamber wall of a gas turbine in accordance with the generic part of Claim 1. In detail, the invention relates to the arrangement and mutual assignment of the effusion holes and impingement cooling holes in the combustion chamber wail and in the combustion chamber tile fastened thereto. The invention also relates to a combustion chamber wall manufactured according to the method.

it is known from the state of the art to provide the combustion chamber wall and the tile carrier, respectively, with impingement cooling holes. Cooling air is passed through these impingement cooling holes onto the surface of the combustion chamber tile in order to cool it. The combustion chamber tile is cooled here by impingement cooling from the cold side of the combustion chamber tile. The combustion chamber tile is usually arranged at a distance from the combustion chamber wall, forming an interspace through which the cooling air exiting from the impingement cooling holes can move. In this way, that side of the combustion chamber tile facing away from the inner volume of the combustion chamber and referred to as the cold side is cooled.

By means of the effusion holes, cooling air flows through the combustion chamber tile and settles as a film onto the hot surface of the combustion chamber tile in order to cool it and shield it from the hot combustion gases.

WO 92/16798 A1 describes the design of a gas-turbine combustion chamber using metallic tiles fastened by means of stud bolts, which due to the combination of impingement and effusion cooling results in effective cooling and hence permits a reduction in cooling air consumption. The geometric relationship of the impingement holes to the effusion holes is not defined, and to each impingement cooling hole is assigned an effusion hole.

U.S. Pat. No. 6,237,344 B1 describes a two-layer impingement/effusion cooling system using two metal sheets which are kept a defined distance apart by bulges pressed in on the cold side. A 1:1 ratio of bulges and impingement cooling holes is stipulated here, since the bulges are intended to protect the impingement cooling jets from crossflow in the impingement cooling cavity. A geometric relationship between impingement holes and effusion holes is not described.

EP 1 104 871 81 describes the relationship of a large impingement cooling hole to a group of effusion holes, for example six effusion holes, equally spaced from a seventh, central effusion hole, where the impingement cooling jet inside the group hits the effusion wall. The impingement cooling holes are arranged in offset rows so that an equal distance from the surrounding impingement cooling holes is obtained and hence an equilateral triangle is formed between them, with one side of the triangle being aligned in the circumferential direction.

U.S. Pat. No. 5,758,504 A describes an impingement/effusion pattern in which the impingement cooling holes are arranged in equilateral rectangles on the combustion chamber wall, with a diagonal of the square being aligned in the circumferential direction. The effusion holes are arranged relative to the impingement cooling holes according to various principles (e.g. relative to the corners of the square, but not in the middle).

The state of the art shows design principles of cooling hole patterns which can be arranged in different ways and designs. For example, hopping patterns are known which can include two or more recesses. The state of the art also shows n-cornered basic cells, for example triangular or rectangular or square basic cells, where one side or diagonal of the basic cell is usually aligned in the circumferential direction or axial direction of the combustion chamber (relative to a center axis of the combustion chamber).

If the design does not specify a relationship of impingement holes and effusion holes, it is then possible for impingement cooling jets to directly match an effusion hole and therefore not impinge in the true sense on the combustion chamber wall, but flow off immediately through the effusion hole, so that no stagnation point forms on the combustion chamber wall. A high heat transfer at this point, and hence the superior cooling effect, are thus not achieved.

If a fixed relationship between impingement jets and effusion jets is specified in the design (e.g. the impingement cooling hole is always positioned on the wall at a distance x upstream on the symmetry lines between the two effusion holes through which air flows off again), then the design and also the production quality must likewise permit this, otherwise there is still a risk of placing an impingement cooling hole directly above an effusion hole and losing the impingement cooling effect. Experience has shown, however, that the total of component and assembly tolerances makes it difficult to correctly position a large number of holes, given all the possible differences of the components from one another.

The object underlying the present invention is to provide a method for the arrangement of effusion holes and impingement cooling holes, which while being simply designed and easily applicable, ensures operationally safe and dependable cooling of the combustion chamber tiles.

It is a particular object of the present invention to provide solution to the above problematics by the combination of the features of Claim 1.

It is thus provided in accordance with the invention that the patterns of effusion holes and impingement cooling holes are selected and then checked as to whether their mutual assignment meets the requirements. This procedure can in particular also be conducted with the aid of computers.

In accordance with the invention, a different ordering principle is used for the impingement cooling holes and for the effusion holes in such a way that the possibility of an impingement cooling hole directly matching an effusion hole is minimized, despite the component and assembly tolerances.

If an n-hopping pattern is used on the effusion side, such that the pattern is repeated after n rows or columns, then an m-sided basic cell is used on the impingement cooling side for distribution of the impingement cooling holes in such a way that the probability of placing an impingement cooling hole directly above an effusion hole is minimized, taking into account all component and assembly tolerances.

A basic cell is defined here such that a cooling air hole is provided in every corner of the basic cell.

The selected basic cell is then rotated in its edge length and in its alignment relative to the axial direction and to the circumferential direction such that the probability of overlapping is minimized despite the component and assembly tolerances. If the number of overlaps for the selected basic cell is still too high or if the matches are too close together, a basic cell with a higher or lower number of corners is selected and the optimization is repeated.

Axial direction is understood in accordance with the invention as being a direction parallel to the center plane of the combustion chamber and hence along the direction of flow through the combustion chamber.

The same method in accordance with the invention can also be used for an arrangement of the effusion holes in an n-cornered basic pattern.

These considerations result, in accordance with the invention, in the following method for determining the hole patterns for impingement holes and effusion holes, in which the input data from the cooling design, the total of the geometric surfaces of all effusion holes, the total of the surfaces of all impingement cooling holes and the surface to be cooled are assumed to be known or given:

• • 1.) Stipulation of the maximum permitted number of matches, where an impingement cooling hole axis matches an effusion hole center point at a distance y, and of the minimum spacing between the matches.
  • 2.) Selection of the pattern for the effusion holes.
  • 3.) Stipulation of the diameter of the effusion holes.
  • 4.) Calculation of the dimensions of the basic cell for the effusion holes, such that all holes provided fit into the surface to be cooled.
  • 5.) Distribution of the effusion holes in the surface to be cooled in accordance with the selections made under 2. and 3.
  • 6.) Selection of the pattern for the impingement cooling holes.
  • 7.) Stipulation of the diameter of the impingement cooling holes.
  • 8.) Calculation of the dimensions of the basic cell, such that all impingement cooling holes provided fit into the surface to be cooled.
  • 9.) Selection of the alignment of the basic cell for the impingement cooling holes.
  • 10.) Distribution of the impingement cooling holes in accordance with the selections made under 6. and 7.
  • 11.) Checking of the number of matches and their spacing from one another, taking into account the component and assembly tolerances.
  • 12.) Comparison with the permitted number and their minimum spacing.
  • 13.) If the quality requirements are not met:
    • a) First select another alignment of the basic cell of the impingement cooling holes and return to 10.
    • b) If this does not succeed, chose another diameter of the impingement cooling holes and return to 8.
    • c) If this does not succeed, chose another pattern and/or another basic cell of the impingement cooling holes and return to 6.
    • d) If this does not succeed, chose another effusion hole diameter and return to 4.
    • e) If this does not succeed, chose another effusion hole pattern and return to 3.
    • f) If this does not succeed, check the input data from the total of the geometric surfaces of all effusion holes, the total of the geometric surfaces of all impingement cooling holes and the surface to be cooled.
    • g) If this does not succeed, change the quality requirements.
  • 14. When the quality requirements have been met, then the final pattern has been found.

An advantageous and stable arrangement using the method in accordance with the invention is also characterized in that the number of effusion holes is not an even-numbered multiple of the number of impingement cooling holes.

The method in accordance with the invention for selecting a non-related pattern between impingement holes and effusion holes can be applied to impingement/effusion-cooled tiles, and also to other double-walled cooling arrangements, for example from two sheet metal layers.

While the specific search principle for the relationship of impingement cooling hole to effusion cooling hole does not completely rule out that the case may occur now and then of an impingement cooling hole blowing precisely into an effusion hole so that no impingement cooling effect is achieved, the distance between such failures in impingement cooling is maximized. It does not occur two times at directly adjacent points.

The impingement cooling effect is exploited to a high degree for wide component and assembly tolerances too, assuring a high cooling effect and as a result a long component service life. Due to the wide tolerances, the component costs are lowered and nevertheless a sturdy product is obtained.

In a favourable development of the invention, it is furthermore provided that at least on one part of the combustion chamber wall the impingement cooling holes are distributed according to a different rule than that for the effusion holes, where a fixed geometric relationship of impingement cooling holes and effusion holes is avoided.

The invention also relates to a combustion chamber wall designed using the method in accordance with the invention. It must be noted in particular here that at least on one part of the combustion chamber wall the impingement cooling holes are distributed according to a different rule than that for the effusion holes, while avoiding a fixed geometric relationship between the impingement cooling holes and the effusion cooling holes.

The present invention is described in the following in light of the accompanying drawing, showing an exemplary embodiment. In the drawing,

FIG. 1 shows a schematic representation of a gas-turbine engine in accordance with the present invention,

FIG. 2 shows a simplified schematic sectional view through a combustion chamber wall and combustion chamber tiles in accordance with the state of the art,

FIG. 3 shows an example in accordance with the state of the art, where the impingement and effusion holes and the impingement cooling holes are assigned in accordance with the design requirement,

FIG. 4 shows an arrangement, by analogy with the representation of FIG. 3, of the actual assignment of effusion holes and impingement cooling holes,

FIG. 5 shows an exemplary embodiment in accordance with the present invention of the design assignment by analogy with the representation of FIG. 3, and

FIG. 6 shows a representation, by analogy with FIG. 4, of the solution in accordance with the invention of the assignment of effusion holes and impingement cooling holes.

The gas-turbine engine 10 in accordance with FIG. 1 is a generally represented example of a turbomachine where the invention can be used. The engine 10 is of conventional design and includes in the flow direction, one behind the other, an air inlet 11, a fan 12 rotating inside a casing, an intermediate-pressure compressor 13, a high-pressure compressor 14, a combustion chamber 15, a high-pressure turbine 16, an intermediate-pressure turbine 17 and a low-pressure turbine 18 as well as an exhaust nozzle 19, all of which being arranged about a center engine axis 1.

The intermediate-pressure compressor 13 and the high-pressure compressor 14 each include several stages, of which each has an arrangement extending in the circumferential direction of fixed and stationary guide vanes 20, generally referred to as stator vanes and projecting radially inwards from the engine casing 21 in an annular flow duct through the compressors 13, 14. The compressors furthermore have an arrangement of compressor rotor blades 22 which project radially outwards from a rotatable drum or disk 26 linked to hubs 27 of the high-pressure turbine 16 or the intermediate-pressure turbine 17, respectively.

The turbine sections 16, 17, 18 have similar stages, including an arrangement of fixed stator vanes 23 projecting radially inwards from the casing 21 into the annular flow duct through the turbines 16, 17, 18, and a subsequent arrangement of turbine blades 24 projecting outwards from a rotatable hub 27. The compressor drum or compressor disk 26 and the blades 22 arranged thereon, as well as the turbine rotor hub 27 and the turbine rotor blades 24 arranged thereon rotate about the engine axis 1 during operation.

FIG. 2 shows a simplified sectional view according to the state of the art, showing a combustion chamber wall 29 provided with several impingement cooling holes 31. Combustion chamber tiles 30 provided with effusion holes 32 are arranged at a distance to the combustion chamber 29. The combustion chamber tiles 30 are fastened in the usual manner using bolts 33 to the combustion chamber wall 29 (tile carrier) such that an interspace 34 is obtained through which the cooling air can flow in the manner shown from the impingement cooling holes 31 to the effusion holes 32.

FIGS. 3 and 4 each show the assignment of impingement cooling holes 31 to effusion holes 32. The impingement cooling holes 31 are illustrated as stars while the effusion holes are shown as ellipses. This embodiment does not have to conform to the actual hole design; it was selected only to make the figures clear.

FIG. 3 shows a design arrangement provided according to a design drawing, where it can be seen that the impingement cooling holes 31 and the effusion holes 32 are arranged on a linear grid and are at an equal distance from one another in terms of their center points.

FIG. 4 shows the arrangement according to FIG. 3 in the actual embodiment with component tolerances and assembly tolerances. It can be seen here that the impingement cooling holes 31 are displaced relative to the arrangement of the effusion holes 32 such that the impingement cooling holes 31 partially overlap the effusion holes 32, with the result that sufficient impingement cooling cannot take place. Furthermore, the flow through the effusion holes 32 is altered by the directly impinging cooling air.

FIG. 5 shows an exemplary embodiment in accordance with the invention as per the inventive method. The result of this is that the impingement cooling holes 31 are provided in an arrangement differing from the even arrangement of the effusion holes 32. In accordance with the invention, they are assigned such that in the actual arrangement shown in FIG. 6, with the component tolerance and the assembly tolerance taken into consideration, all or almost all impingement cooling holes 31 are placed such that the airflow impinges not at all or only negligibly on the effusion holes 32. This results in the advantages described in accordance with the invention, so that dependable and operationally safe cooling is assured.

LIST OF REFERENCE NUMERALS

• 1 Engine axis
• 10 Gas-turbine engine/core engine
• 11 Air inlet
• 12 Fan
• 13 Intermediate-pressure compressor (compressor)
• 14 High-pressure compressor
• 15 Combustion chamber
• 16 High-pressure turbine
• 17 Intermediate-pressure turbine
• 18 Low-pressure turbine
• 19 Exhaust nozzle
• 20 Guide vanes
• 21 Engine casing
• 22 Compressor rotor blades
• 23 Stator vanes
• 24 Turbine blades
• 26 Compressor drum or disk
• 27 Turbine rotor hub
• 28 Exhaust cone
• 29 Combustion chamber wall
• 30 Combustion chamber tile
• 31 Impingement cooling hole
• 32 Effusion hole
• 33 Bolt
• 34 Interspace

Claims

1. Method for the arrangement of effusion holes and impingement cooling holes in a combustion chamber wall and in combustion chamber tiles of a gas turbine, with the combustion chamber having a combustion chamber wall provided with impingement cooling holes and combustion chamber tiles, which are arranged at a distance from the combustion chamber wall and provided with effusion holes, characterized in that the method includes the following process steps: 1.) Stipulation of the maximum permitted number of matches, where an impingement pooling hole axis matches an effusion hole center point at a distance y, and of the minimum spacing between the matches.2.) Selection of the pattern for the effusion holes.3.) Stipulation of the diameter of the effusion holes.4.) Calculation of the dimensions of the basic cell for the effusion holes, such that all holes provided fit into the surface to be cooled.5.) Distribution of the effusion holes in the surface to be cooled in accordance with the selections made under 2. and 3.6.) Selection of the pattern for the impingement cooling holes.7.) Stipulation of the diameter of the impingement cooling holes.8.) Calculation of the dimensions of the basic cell, such that all impingement cooling holes provided fit into the surface to be cooled.9.) Selection of the alignment of the basic cell for the impingement cooling holes.10.) Distribution of the impingement cooling holes in accordance with the selections made under 6. and 7.11.) Checking of the number of matches and their spacing from one another, taking into account the component and assembly tolerances.12.) Comparison with the permitted number and their minimum spacing.13.) If the quality requirements are not met: a) First select another alignment of the basic cell of the impingement cooling holes and return to 10.b) If this does not succeed, chose another diameter of the impingement cooling holes and return to 8.c) If this does not succeed, chose another pattern and/or another basic cell of the impingement cooling holes and return to 6.d) If this does not succeed, chose another effusion hole diameter and return to 4.e) If this does not succeed, chose another effusion hole pattern and return to 3.f) If this does not succeed, check the input data from the total of the geometric surfaces of all effusion holes, the total of the geometric surfaces of all impingement cooling holes and the surface to be cooled.g) If this does not succeed. change the quality requirements.

2. Combustion chamber wall of a gas turbine, which at least on one part of the combustion chamber wall is provided with a two-layer cooling system and designed in accordance with the method of claim 1.

3. Combustion chamber wall in accordance with claim 2, characterized in that at least on one part of the combustion chamber wall the impingement cooling holes are distributed according to a different rule than that for the effusion holes, while avoiding a fixed geometric relationship between the impingement cooling holes and the effusion holes.

4. Combustion chamber wall in accordance with claim 3, characterized in that at least on one part of the combustion chamber wall no even-numbered multiples of the number of impingement cooling holes are provided for the number of effusion holes.