EP3034944A1 - Gas turbine combustor with altered wall thickness - Google Patents

Abstract

The invention relates to a gas turbine combustor having at least one combustion chamber wall 6, 7 in which mixing air holes 5 are formed in a predetermined region which extends annularly relative to a central axis of the combustion chamber in a central region of the combustion chamber in that the combustion chamber wall 6, 7 has a greater thickness W in the annular region of the mixing air holes 5 than in the regions not provided with mixing air holes 5.

Description

The invention relates to a gas turbine combustor according to the preamble of claim 1.

In detail, the invention relates to a gas turbine combustor having at least one combustion chamber wall in which mixing air holes are formed in predetermined regions.

From the prior art, it is known to provide mixing air holes in combustion chamber walls of gas turbines, through which additional air is introduced into the combustion chamber interior.

The state of the art is on the EP 1 528 322 A2 , the EP 1 795 809 A2 or the US 2002/0116929 A1 directed.

Through the mixing air holes a significant weakening is introduced into the combustion chamber wall at a certain axial position. With increasing proportion of mixed air through better cooling and / or improved, firmer wall materials, it is possible to make the mixing air holes larger. As a result, the strength of the combustion chamber wall is increasingly weakened. This weakening results because one or two-layer combustion chamber walls are produced from sheets or castings of constant wall thickness. Due to these material weakenings, cracks result. The crack progression from mixed air hole to mixed air hole is an essential factor in the failure of combustion chamber walls. With increasing proportion of mixed air thus increases the risk of failure considerably.

The invention has for its object to provide a gas turbine combustor of the type mentioned above, which avoids the disadvantages of the prior art with a simple structure and simple, cost manufacturability and in particular in the area of the mixing air holes has sufficient strength.

According to the invention the object is achieved by the combination of features of claim 1, the dependent claims show further advantageous embodiments of the invention.

According to the invention, it is thus provided that the combustion chamber has a greater wall thickness in the area of the mixed air holes than in the areas not provided with mixed air holes.

The mixing air holes are arranged in a central region of the combustion chamber, based on the axial extent of the combustion chamber and in the circumferential direction of the combustion chamber. This annular peripheral region, in which the mixing air holes are arranged, is provided according to the invention with a greater wall thickness.

According to the invention, the load-bearing wall thickness of the combustion chamber wall is thus increased locally to the extent in which the cross section carrying the mixing air holes in the circumferential direction is removed. According to the invention, it is possible to use this solution both in single-layer and in two-layer combustion chamber walls. In the case of a two-layer combustion chamber wall, it is possible according to the invention to provide or to thicken only one layer, for example the load-bearing outer combustion-chamber wall or the hot, inner combustion-chamber wall or both.

In the solution according to the invention, there is thus the advantage that the stiffness of the combustion chamber wall no longer varies in the longitudinal direction, but is constant, in particular in the area of the mixing air holes, in particular compared with the areas in which no mixed air holes are formed. As a result, the external load distortions do not concentrate in the area provided with the mixed air holes. Furthermore, a gap, which may arise between the shingle (inner combustion chamber wall) and the shingle support (outer combustion chamber wall), becomes smaller due to the constant rigidity.

While in the constructions known from the prior art, a substantial failure mechanism is formed in the combustion chamber by the crack progress from mixed air hole to mixed air hole, by the inventive thickening or enlargement of the thickness of the combustion chamber wall, especially at the areas weakened by the mixed air holes, an increase of the stiffness and Strength of the combustion chamber wall. This makes it possible, the cracking and the Minimize crack propagation. This is done by a minimum cost of materials or a minimum increase in weight by the thickening of the combustion chamber wall.

The invention is applicable both to combustion chamber walls which are manufactured as a cast part, and to combustion chamber walls which are produced by means of a generative method (laser sintering, ALM, additive layer manufacturing). In combustor made of sheet metal, it is possible according to the invention to use specially contoured boards or to produce the thinner areas of the wall by ironing.

Similarly, the invention can also apply to combustor walls made of fiber reinforced ceramic (CMC). Here, the number of layers of ceramic fiber fabric or windings in the area of the mixed air holes is increased locally. This is associated with little additional effort, since the wall is basically constructed of several layers, only in the area of the mixed air holes, the number of layers of, for example, 12 increased to 20. The increase in wall thickness is more pronounced in CMC, since the wall temperature may be higher, so less cooling air must be used, and thus more air to be passed through the mixing holes, which increases their diameter beyond what is possible with a metallic construction. The layers can be inserted on the inside or outside or as additional intermediate layers with limited axial extent.

In certain Mischluftlochmustern in a double-walled combustion chamber, it is also advantageous to have no narrow web between narrow mixing air holes between the mixing air holes, but to provide the two closely adjacent mixing holes in the shingle through a single opening in the cold combustion chamber wall with air. The shingle can be thickened by eliminating the bridge to the outside. This can also be done in the form of a rib on the cold side of the shingle, which then protrudes through the opening in the cold combustion chamber wall.

In any case, an increase in the thickness of the combustion chamber wall takes place so that the mixing air holes do not reduce the rigidity of the combustion chamber wall.

Fig. 1

eine schematische Darstellung eines Gasturbinentriebwerks gemäß der vorliegenden Erfindung,

Fig. 2

eine Längs-Schnittansicht einer Brennkammer gemäß dem Stand der Technik,

Fig. 3

eine schematische Ansicht der Anordnung von Mischluftlöchern gemäß dem Stand der Technik,

Fig. 4

eine Ansicht, analog Fig. 3, einer erfindungsgemäßen Anordnung von Mischluftlöchern,

Fig. 5

eine schematische Seitenansicht einer Brennkammer analog Fig. 2, eines ersten Ausführungsbeispiels der Erfindung, und

Fig. 6

eine Ansicht, analog Fig. 5, eines weiteren Ausführungsbeispiels der Erfindung.

In the following the invention will be described by means of embodiments in conjunction with the drawing. Showing:

Fig. 1

a schematic representation of a gas turbine engine according to the present invention,

Fig. 2

a longitudinal sectional view of a combustion chamber according to the prior art,

Fig. 3

a schematic view of the arrangement of mixed air holes according to the prior art,

Fig. 4

a view, analog Fig. 3 , an arrangement according to the invention of mixed air holes,

Fig. 5

a schematic side view of a combustion chamber analog Fig. 2 , A first embodiment of the invention, and

Fig. 6

a view, analog Fig. 5 , Another embodiment of the invention.

The gas turbine engine 110 according to Fig. 1 is a generalized example of a turbomachine, in which the invention can be applied. The engine 110 is formed in a conventional manner and comprises in succession an air inlet 111, a fan 112 circulating in a housing, a medium pressure compressor 113, a high pressure compressor 114, a combustion chamber 115, a high pressure turbine 116, a medium pressure turbine 117 and a low pressure turbine 118 and a Exhaust nozzle 119, which are all arranged around a central engine center axis 101.

The intermediate pressure compressor 113 and the high pressure compressor 114 each include a plurality of stages, each of which includes a circumferentially extending array of fixed stationary vanes 120, commonly referred to as stator vanes, which are radially inwardly of the engine casing 121 in an annular manner Flow channel through the compressors 113, 114 protrude. The compressors further include an array of compressor blades 122 projecting radially outward from a rotatable drum or disk 125 coupled to hubs 126 of high pressure turbine 116 and intermediate pressure turbine 117, respectively.

The turbine sections 116, 117, 118 have similar stages, comprising an array of fixed vanes 123 projecting radially inward from the housing 121 into the annular flow passage through the turbines 116, 117, 118, and a downstream array of turbine blades 124, projecting outwardly from a rotatable hub 126. The compressor drum or compressor disk 125 and the vanes 122 disposed thereon and the turbine rotor hub 126 and turbine blades 124 disposed thereon rotate about the engine centerline 101 during operation.

The Fig. 2 shows a longitudinal sectional view of a known from the prior art combustion chamber wall in an enlarged view. In this case, a combustion chamber 1 is shown with a central axis 9, which comprises a combustion chamber head 3, a base plate 8 and a heat shield 2. A burner seal is provided with the reference numeral 4. The combustion chamber 1 has an outer cold combustion chamber wall 7, to which an inner, hot combustion chamber wall 6 is attached. For supplying mixed air mixing air holes 5 are provided. The presentation of impingement cooling holes and effusion holes has been omitted for clarity.

The inner combustion chamber wall 6 is provided with bolts 13, which are designed as threaded bolts and are screwed by means of nuts 14. The storage of the combustion chamber 1 via Brennkammerflansche 12 and 11 Brennkammeraufhängungen.

Prior art combustor walls made of sheet metal typically have a constant thickness in the range of 0.9 to 1.6 mm, while combustor walls made as castings have wall thicknesses of between 1.2 and 2.5 mm have.

The 3 and 4 show in a schematic side view of a combustion chamber wall, the arrangement of mixed air holes. The Fig. 3 shows, for example, the assignment of mixed air holes, as they are known from the prior art. It will be understood that the change in wall thickness, and hence rigidity, of the combustion chamber wall will depend on the arrangement and pattern of the mixing air holes. In particular, the axial distance and the circumferential distance of the mixed air holes must be taken into account. Furthermore, the respective diameters of the mixed air holes play a role.

Mit

• W_max: maximale Wandstärke
• W₀: nominale Wandstärke
• A: Abstand der Lochmitten benachbarter Löcher
• Sr. Summe der Lochradien benachbarten Löcher
• C: Wirkfaktor 0,7..1,3: vom Konstrukteur zu wählen, basierend auf früheren Erfahrungen. Dieser Faktor kann für unterschiedliche Anwendungen (je nach Erfahrung) andere Werte annehmen.

The greater thickness (W) of the combustion chamber (6, 7) is formed with a wall thickness, wherein the maximum wall thickness is calculated according to the following equation: $${\mathrm{W}}_{\mathrm{Max}}=C*\sqrt{\left(\mathit{A}-\mathit{S}\mathit{r}\right)/A}*{\mathrm{W}}_0$$

With

• W _max : maximum wall thickness
• W ₀ : nominal wall thickness
• A : Distance of the hole centers of adjacent holes
• Sr. Sum of hole radii adjacent holes
• C: Effective factor 0.7..1.3: to be chosen by the designer based on previous experience. This factor can take different values for different applications (depending on experience).

• Unterschreitet die verbleibende Stegbreite zwischen benachbarten Mischluftlöchern die Summe der Durchmesser der beiden Mischluftlöcher um mehr als 20%, so wird die Wandstärke um mindestens 27% erhöht.

Thus, for example, for an effective factor = 1, the following handling instruction results:

• If the remaining web width between adjacent mixed air holes exceeds the sum of the diameters of the two mixed air holes by more than 20%, the wall thickness is increased by at least 27%.

If the remaining web width between adjacent mixing air holes undershoots the mean value of the diameters of the two mixing air holes, the wall thickness is increased substantially by 41%.

If the remaining web width between adjacent mixing air holes undershoots the mean value of the radii of the two mixed air holes, the wall thickness is increased substantially by 73%.

It is irrelevant whether the smallest web width occurs between the mixed air holes of one row or between the mixed air holes of adjacent rows. This only determines the axial position of the maximum wall thickness. If the smallest web width lies between the mixed air holes of a row, then the maximum of the wall thickness lies at the axial position of the axes of the mixed air hole row. If the minimum land width lies between mixed air holes of adjacent rows of mixed air holes, then the maximum wall thickness between the central axes of the two rows of mixing air holes is substantially midway between the rows.

The axial extent of the thickening for a mixed air hole row is substantially limited to the range between a hole diameter upstream and a hole diameter downstream.

The axial extent of the thickening for two rows of mixed air holes is limited to the range between a hole diameter of the upstream mixed air hole row upstream and a hole diameter of the downstream mixed air hole row downstream.

If different mixing air hole diameters are present in a row, then the largest diameter of the respective row of holes applies to these limitations.

To simplify manufacture, the wall thickness may be increased in a ramp in front of the thickness-determining ligament, followed by a region of constantly high wall thickness in the area of the mixing air holes and a ramp back to a lesser wall thickness, which then substantially until shortly before the end of the combustion chamber is maintained. Here, the substantially constant wall thickness before the mixing air hole row need not be identical to the substantially constant wall thickness downstream thereof. As a result, the transitions in the wall thickness are fluent designed to avoid voltage spikes by cross-sectional jumps.

According to the invention, for example, it is possible to increase the sheet thickness of the outer, cold combustion chamber wall 7 from 1.2 mm to 1.6 mm, while the thickness of a formed as a casting, inner, hot combustion chamber wall 6 in the mixing air holes of 1.4 mm 2 mm is increased. Thus, it is possible in known patterns or arrangements of mixing air holes 5 by a thickening of the wall thickness to achieve a change in stiffness so that the occurring without the thickening weakening of the wall is compensated.

The Fig. 4 illustrates a possible embodiment according to the invention, in which the two Mischluftlochreihen are substantially approximated in the circumferential direction or almost overlap. Without an increase in the wall thickness, as provided by the invention, the weakening of the combustion chamber wall would be further increased. According to the invention thus takes place in this area a greater thickening, as it follows in connection with the Fig. 5 and 6 is described. For example, a sheet thickness of a combustion chamber wall can be increased from 1.2 mm to 1.8 mm. The wall thickness of a casting of 1.4 mm can be increased according to the invention, for example in the region of the intersection of the mixed air holes to 2.5 mm.

As mentioned, the invention can be used both with single-walled and two-walled combustion chambers. In the case of a single-walled combustion chamber, for example, the wall thickness of the metal sheet in the area of the mixed air holes is increased or the adjacent area not provided with mixed air holes is reduced in its cross-section by ironing pressures. By Abstreckdrücken a move away from standardized sheet thicknesses to a adapted to the local requirements wall thickness. By means of ironing produced components with locally adapted wall thickness are cheaper to produce than components which are joined from several sheets, forgings or castings. In a multilayer wall construction of the combustion chamber wall, which is produced for example as a cassette or by joining laminated sheets, it is possible according to the invention to adapt the wall thickness in the region of the mixing air holes analogously to the local requirements.

The Fig. 5 shows a sectional view of a combustion chamber analogous to Fig. 2 , In Fig. 2 is in the upper part of the figure as a diagram the wall thickness W over the length of the Combustion chamber wall applied. It follows that the combustion chamber wall has a constant wall thickness W over its entire length. In comparison, the in Fig. 5 shown embodiment in the area of the mixing air holes 5, a thickening of the wall and thus a greater wall thickness provided, as can be seen from the diagram in the upper half of the figure Fig. 5 results.

The Fig. 5 shows in the sectional view of a construction in which both the outer, cold combustion chamber wall 7, and the inner, hot combustion chamber wall 8 are formed thickened. As a result, the decrease in the available with respect to the strength of the cross-section of the two combustion chamber walls 7, 8 is compensated by the thickening.

The Fig. 6 shows a further embodiment in a representation analog Fig. 5 , It can be seen that in addition to the in Fig. 5 provided thickening or increasing the wall thickness in the area between the mixing air holes 5 and in the region of their overlap (s Fig. 4 ) a further increase in wall thickness or wall thickness occurs. This results in particular from the diagram in the upper half of the representation of Fig. 6 ,

LIST OF REFERENCE NUMBERS

1

combustion chamber

2

heat shield

3

bulkhead

4

Brenner seal

5

mixed air

6

inner, hot combustion chamber wall / segment / shingles

7

outer, cold combustion chamber wall

8th

baseplate

9

central axis

10

sealing lip

11

combustion chamber suspension

12

Brennkammerflansch

13

bolt

14

mother

101

Engine centerline axis

110

Gas turbine engine / core engine

111

air intake

112

fan

113

Medium pressure compressor (compressor)

114

High pressure compressor

115

combustion chamber

116

High-pressure turbine

117

Intermediate pressure turbine

118

Low-pressure turbine

119

exhaust nozzle

120

vanes

121

Engine casing

122

Compressor blades

123

vanes

124

turbine blades

125

Compressor drum or disc

126

Turbinenrotornabe

127

outlet cone

W

Wall thickness / wall thickness

Claims (9)

Gas turbine combustor having at least one combustion chamber wall (6, 7), in which in a predetermined region which extends annularly relative to a center axis of the combustion chamber in a central region of the combustion chamber, mixed air holes (5) are formed, characterized in that the combustion chamber wall (6, 7) has a greater thickness (W) in the annular region of the mixing air holes (5) than in the regions not provided with mixing air holes (5). Gas turbine combustor according to claim 1, characterized in that the combustion chamber wall (6, 7) in all areas, in particular in the longitudinal direction, based on the flow direction of the combustion chamber (1), has a substantially constant rigidity. Gas turbine combustor according to claim 1 or 2, characterized in that the greater thickness (W) of the combustion chamber (6, 7) is formed with a wall thickness, wherein the maximum wall thickness is calculated according to the following equation: $${\mathrm{W}}_{\mathrm{Max}}=C*\sqrt{\left(\mathit{A}-\mathit{S}\mathit{r}\right)/A}*{\mathrm{W}}_0$$

W _max · maximum wall thickness W ₀ : nominal wall thickness A : Distance of the hole centers of adjacent holes Sr. Sum of the hole radii adjacent holes C: active factor 0.7..1.3 Gas turbine combustor according to one of claims 1 to 3, characterized in that the combustion chamber wall (6, 7) is formed in a single layer. Gas turbine combustor according to one of claims 1 to 3, characterized in that the combustion chamber wall (6, 7) is formed in two layers and at least one of the combustion chamber walls (6, 7) in the region of the mixing air holes (5) is provided with a greater wall thickness. Gas turbine combustor according to one of claims 1 to 5, characterized in that the combustion chamber wall (6, 7) is made as a cast part. Gas turbine combustor according to one of claims 1 to 5, characterized in that the combustion chamber wall (6, 7) is manufactured by means of a generative method. Gas turbine combustor according to one of claims 1 to 5, characterized in that the combustion chamber wall (6, 7) is made of contoured sheet materials. Gas turbine combustor according to one of claims 1 to 5, characterized in that the combustion chamber wall (6, 7) is made of a fiber-reinforced ceramic material.

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