RU2575490C2 - Circular combustion wall with perfected cooling at primary bores and/or dilution bores level - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: multiple primary orifices are distributed in a circle to allow the passage of airflow recycled from circular wall cold side to hot side to create the air-fuel mix. Multiple primary orifices are distributed in a circle to allow the passage of airflow recycled from circular wall cold side to hot side to allow the air-fuel mix dilution. Multiple primary orifices are distributed in a circle to allow the passage of airflow recycled from circular wall cold side to hot side to allow the cooling air film formation along said circular wall. Cooling orifices are distributed in compliance with circular rows axially spaced apart. Geometrical axes of each said orifice are axially inclined in direction D of combustion gaseous products at the angle θ1 relative to perpendicular N to said circular wall. Said circular wall comprises additionally the multiple extra cooling orifices arranged, on one side, downstream of the primary orifices and, on opposite side, directly downstream of dilution orifices. Cooling orifices are distributed in compliance with circular rows axially spaced apart. Geometrical axes of each said extra orifice are located in the plane perpendicular to axial direction D and inclined at the angle θ2 relative to perpendicular N to said circular wall.

EFFECT: higher efficiency of cooling, lower costs, production time saving.

12 cl, 3 dwg

Description

Technical field

The present invention relates generally to the field of combustion chambers of gas turbine engines. In particular, it relates to an annular wall intended for a once-through or counter-current combustion chamber cooled by a process known as “multiperforation”.

Typically, an annular combustion chamber of a gas turbine engine is formed by an inner annular wall and an outer annular wall, which are connected upstream by a transverse wall forming the base of the chamber.

Each of the inner and outer annular walls is made with many different openings and openings, allowing the passage of air circulating around the combustion chamber into the latter.

Thus, openings called “primary” openings and “dilution” openings are formed in these annular walls to move air within the combustion chamber. The air using the primary openings for the passage helps to create an air-fuel mixture that is burned in the chamber, while the air coming from the dilution openings is intended to facilitate the dilution of this same air-fuel mixture.

The inner and outer annular walls are exposed to high temperatures of the gas resulting from the combustion of the air-fuel mixture.

To ensure their cooling, additional so-called multiperforation holes are also drilled through these annular walls on their entire surface. These multi-perforation openings, having an inclination at an angle of, as a rule, equal to 60 °, provide the possibility of the passage of air circulating outside the chamber into the latter to form films of cooling air along the walls.

However, in practice, it was noted that the area of the inner and outer annular walls, which is located directly behind the stream from each of the primary holes or dilution holes, in particular, due to the absence of holes formed as a result of using laser drilling technology, has a low cooling level with concomitant risk of cracking.

To solve this problem, US Pat. No. 6,145,319 proposes the implementation of vias in a wall zone located downstream of each of the primary and dilution apertures, wherein these vias have a smaller angle of inclination compared to the angle of inclination of the multi-perforation holes. However, provided that this is a localized treatment, this solution, unfortunately, is especially expensive and leads to a significant increase in the duration of the manufacture of walls.

Disclosure of invention

The present invention is to eliminate the above disadvantages and to develop an annular wall of the combustion chamber, which provides proper cooling of the areas located downstream directly from the primary holes and dilution holes.

To solve the problem, an annular wall of a combustion chamber of a gas turbine engine is proposed having a cold side and a hot side, wherein said annular wall contains:

- a plurality of primary openings distributed in accordance with the circumferential row to allow air circulating from the cold side of the annular wall to pass to the hot side to create an air-fuel mixture;

- a plurality of dilution holes distributed in accordance with the circumferential row to allow air circulating from the cold side of the annular wall to pass to the hot side to allow dilution of the air-fuel mixture; and

a plurality of cooling holes intended to allow air circulating from the cold side of said annular wall to pass to the hot side to form a film of cooling air along said annular wall, said cooling holes being distributed in accordance with a plurality of circumferential rows spaced apart from a friend defined in the axial direction, and the geometric axes of each of these cooling holes are inclined in the axial direction D of the pot and gaseous combustion products at an angle θ1 of inclination relative to the normal N to said annular wall;

characterized in that it further comprises a plurality of additional cooling holes located, on the one hand, upstream directly from said primary holes and, on the other hand, upstream directly from said dilution holes and distributed in accordance with a plurality of circumferential rows arranged at a distance from each other, defined in the axial direction,

while the geometric axis of each of these additional cooling holes are located in a plane perpendicular to the indicated axial direction D and are inclined at an angle θ2 of inclination relative to the normal N to the specified annular wall.

The presence of additional cooling holes located obliquely in the plane perpendicular to the direction of flow of the gaseous products of combustion, the flow directly behind the primary holes and dilution holes and next to the primary holes and dilution holes, provides effective cooling compared to classical axial multiperforation, in which these holes prevents the formation of an air film, and thus does not change the flow in the primary zone.

The annular wall preferably comprises, at the level of the transition zone formed downstream of the plurality of rows of additional holes, at least two rows of holes in which the geometric axes of each of these holes are inclined relative to a plane perpendicular to the indicated axial direction D at an angle of inclination, defined as different for each of these two rows.

In accordance with another embodiment, the annular wall of the combustion chamber of a gas turbine engine having a cold side and a hot side may also comprise:

- a plurality of primary holes or dilution holes distributed in accordance with the circumferential row to allow air circulating from the cold side of the annular wall to pass to the hot side, respectively, to create an air-fuel mixture or to dilute the air-fuel mixture; and

a plurality of cooling holes intended to allow air circulating from the cold side of said annular wall to pass to the hot side to form a film of cooling air along said annular wall, said cooling holes being distributed in accordance with a plurality of circumferential rows spaced apart from a friend defined in the axial direction, and the geometric axes of each of these cooling holes are inclined in the axial direction D of the pot and gaseous combustion products at an angle θ1 of inclination relative to the normal N to said annular wall;

characterized in that it further comprises a plurality of additional cooling holes located downstream directly from said primary holes or dilution holes and distributed in accordance with a plurality of circumferential rows spaced apart from one another, defined in the axial direction,

while the geometric axis of each of these additional cooling holes are located in a plane perpendicular to the specified axial direction D, and are inclined at an angle θ2 of inclination relative to the normal N to the specified annular wall,

and the fact that it additionally contains at the level of the transition zone formed downstream from the specified set of rows of additional holes at least two rows of holes in which the geometric axes of each of these holes are inclined relative to a plane perpendicular to the indicated axial direction D at an angle slope, defined as different for each of these two rows.

Due to smoothing of flows, this transitional zone of rotationally axial multi-perforation provides a decrease in the temperature gradient in the zone of initiation of cracks. The average temperature profile at the outlet of the chamber improves due to the resulting more efficient mixture.

According to a preferred embodiment of the invention, said inclination angle θ2 of said additional holes relative to the normal N to said annular wall is identical to the inclination angle θ1 of said cooling holes.

The diameter d2 of said additional holes is preferably identical to the diameter d1 of said cooling holes, and the pitch p2 of said additional holes is preferably identical to the pitch p1 of said cooling holes, and said additional holes may preferably have a higher density directly behind the primary holes and dilution holes.

In the case where the annular wall contains these two rows of holes, the indicated inclination angles are 30 ° and 60 °, respectively. These two rows of holes in this case are either two rows of additional holes located downstream directly from the row of cooling holes, or two rows of cooling holes located downstream directly from the row of additional holes, or a series of additional holes and an adjacent row of cooling holes .

In the case where the annular wall contains several rows of holes, these inclination angles are evenly distributed between 0 ° and 90 °.

The inclination direction of these additional openings is preferably limited by the direction of flow of the air-fuel mixture upstream of said combustion chamber.

Another objective of the present invention is to provide a combustion chamber and a gas turbine engine (having a combustion chamber) comprising an annular wall, as previously defined.

Brief Description of the Drawings

Other features and advantages of the present invention will become apparent from the following description, provided with reference to the attached drawings, which illustrate an embodiment without any limiting character.

 In the figures:

- FIG. 1 is a longitudinal section of a combustion chamber of a gas turbine engine in its environment;

- FIG. 2 is a partial and expanded view of one of the annular walls of the combustion chamber of FIG. 1 in accordance with one embodiment of the invention; and

- FIG. 3 is a partial perspective view of a portion of the annular wall of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates in its environment a combustion chamber 10 for a gas turbine engine. Such a gas turbine engine contains, in particular, a compression section (not shown) in which air is compressed before it is injected under pressure into the casing 12 of the chamber, then into the combustion chamber 10 installed inside the casing 12. Compressed air is introduced into the combustion chamber and mixed with the fuel before burning. Gases resulting from this combustion are directed to a high pressure turbine 14 located at the exit of the combustion chamber.

The combustion chamber is an annular type chamber. It is formed by an inner annular wall 16 and an outer annular wall 18, which are connected upstream by a transverse wall 20 forming the base of the chamber. It can be straight-through, as illustrated, or counter-current. In this case, the return elbow, which can also be cooled by means of numerous drilled holes, is located between the combustion chamber and the turbine distributor.

The annular inner 16 and outer 18 walls extend along the longitudinal axis with a slight slope relative to the longitudinal axis 22 of the gas turbine engine. The base 20 of the chamber is made with many holes 20A, in which the fuel nozzles 24 are installed.

The casing 12 of the chamber, which is formed by the inner envelope part 12a and the outer envelope part 12b, forms, together with the combustion chamber 10, annular spaces 26 into which compressed air is supplied for burning, diluting and cooling the chamber.

Each of the annular inner 16 and outer 18 walls has a cold side 16a, 18a located on the side of the annular space 26 in which compressed air circulates, and a hot side 16b, 18b facing the inside of the combustion chamber (Fig. 3).

The combustion chamber 10 is divided into a zone called the “primary” (or combustion zone) and a zone called the “secondary” (or dilution zone) located upstream of the previous zone (“downstream” means the relative axial direction of the gas flow resulting from the combustion of the air-fuel mixture inside the combustion chamber and shown as arrows D).

Air that is supplied to the primary zone of the combustion chamber is introduced through the circumferential row of primary openings 28 formed in the annular inner 16 and outer 18 chamber walls along the entire circumference of these annular walls. These primary openings have a downstream edge aligned along the same line 28A. As for the air entering the secondary zone of the chamber, it passes through a plurality of dilution holes 30, also formed on the annular inner 16 and outer 18 walls along the entire circumference of these annular walls. These dilution holes 30 are aligned in accordance with the circumferential row, which is axially offset further downstream of the rows of primary holes 28, and the dilution holes 30 can have different diameters, in particular when alternating large and small holes. In the configuration illustrated in FIG. 2, these dilution holes with different diameters, however, have a flow-back edge aligned with the same line 30A.

To cool the annular inner 16 and outer 18 walls of the combustion chamber, which are exposed to high temperatures from the side of the gaseous products of combustion, a plurality of cooling holes 32 are made (illustrated in FIGS. 2 and 3).

These holes 32, which provide cooling of the walls 16, 18 by multiperforation, are distributed in accordance with a plurality of circumferential rows located at a distance from each other defined in the axial direction. These rows of multiperforation openings cover the entire surface of the annular walls of the chamber, with the exception of certain zones forming the subject of the invention, precisely bounded and located between the line 28A, 30A, which forms the upstream transition axis and the downstream transition axis, shifted axially further down the axis flow relative to a given axis, upstream, and located either essentially in front of the dilution holes (for the upstream axis 28B), or essentially in front of the exit plane of the chamber (for the back along flow axis 30V).

The number and diameter d1 of the cooling holes 32 are identical in each of the rows. The pitch p1 between two holes of the same row is constant and may be identical or non-identical for all rows. In addition, adjacent rows of cooling holes are swept so that holes 32 can be staggered as shown in FIG. 2.

As illustrated in FIG. 3, cooling holes 32 typically have a tilt angle θ1 with respect to the normal N to the annular wall 16, 18 in which they are made. This tilt angle θ1 allows air passing through these openings to form an air film along the hot side 16b, 18b of the annular wall. Compared to non-inclined openings, it provides an increase in the surface of the annular wall, which is cooled. In addition, the inclination of the cooling holes 32 at an angle θ1 is directed so that the resulting air film spreads in the direction of the flow of gaseous products of combustion inside the chamber (shown by arrow D).

As an example, for an annular wall 16, 18 formed of a metal or ceramic material and having a thickness of 0.6 to 3.5 mm, the diameter d1 of the cooling holes 32 may be 0.3 to 1 mm, the pitch p1 may be from 1 to 10 mm, and the angle θ1 of their inclination can be from + 30 ° to + 70 °, usually + 60 °. As a comparison, for an annular wall having the same characteristics, the primary holes 28 and dilution holes 30 have a diameter of about 4-20 mm.

In accordance with the invention, each annular wall 16, 18 of the combustion chamber comprises a plurality of downstream directly from the primary openings 28 and dilution openings 30 distributed in accordance with several circumferential rows, typically at least 5 rows in the area from the upstream transition axes 28A, 30A to the downstream transition axis 28B, 30B, additional cooling holes 34. However, in comparison with the previous cooling holes, which provide an air film spreading in the axial direction D, the air film created by these additional holes spreads in the perpendicular direction due to their location in the plane perpendicular to the axial direction D of the flow of gaseous products of combustion. This multiperforation, performed in a direction perpendicular to the axis of the gas turbine engine (in the description this will be called rotational / circular multiperforation, in contrast to axial multiperforation of cooling holes), provides closer openings for primary holes or dilution holes and increases the efficiency of the air-fuel mixture.

Additional holes 34 from the same row have the same diameter d2, preferably identical to the diameter d1 of the cooling holes 32, are arranged with a constant pitch p2, which may be identical or not identical to the pitch p1 between the cooling holes 32, and have an inclination angle θ2, preferably identical the angle θ1 of the inclination of the cooling holes 32, but the inclination is made in a perpendicular plane. However, despite the fact that these characteristics are still within the ranges of values defined above, these characteristics of the additional holes 34 could essentially differ from the characteristics of the cooling holes 32, i.e., the angle of inclination θ2 of the additional holes from one and of the same row relative to the normal N to the annular wall 16, 18 may differ from the angle θ1 of the inclination of the cooling holes, and the diameter d2 of the additional holes from the same row may differ from the diameter d1 of the cooling holes 32.

However, in accordance with the need for preferred cooling, the additional holes 34 located behind the row of primary holes 28 may also preferably have characteristics in terms of inclination, diameter or pitch, different from the characteristics of the additional holes located next to the holes 30 dilution, and, in in particular, within the same zone, a difference in diameter d2 and pitch p2 can be provided to make this cooling more intense in parts with the highest thermal stresses li, i.e., those located downstream of the primary holes and the large dilution holes, when the latter are formed by alternating large and small holes, as illustrated in FIG. 2.

The introduction of circular / circular multiperforation between the row of primary holes and the row of dilution holes prevents the formation of cracks downstream of the primary holes 28 by limiting the increase in temperature gradient. Since the multiperforation upstream of the dilution holes 30 from the upstream transition axis 28B is an axial type perforation, it is necessary to provide a transition zone formed, for example, of two rows in which each of the additional cooling holes 34 is located in a plane having the inclination in one row by an angle of 30 ° and in the other row by an angle of 60 ° relative to the axial direction D, while the remaining parameters, in particular, diameter d2, pitch p2 and angle θ2 n clone these additional holes in these ramps remain unchanged.

Similarly, at the chamber exit, more precisely, starting from the upstream transition axis 30B of the transition (Fig. 2), the introduction of axial multiperforation corresponds to the local level of circular rotation so as not to lose the output power provided by the combustion chamber for the high pressure turbine (TuHP). In a preferred manner, it is also desirable to provide a transition zone of rotationally axial multiperforation for smoothing flows in order to reduce the temperature gradient in the zone of initiation of cracks. The average temperature profile at the outlet of the chamber improves due to the resulting more efficient mixture. This transition zone, for example, can be made in the form of two rows of additional cooling holes, each of which is located in a plane having an inclination in one row at an angle of 30 ° and in the other row at an angle of 60 ° relative to the axial direction D, while the remaining parameters, in particular the diameter d2, pitch p2 and the angle θ2 of the inclination of the additional holes in these inclined planes remain unchanged. In the case of a counterflow combustion chamber, this zone starting from axis 30B cannot exist or cannot be made in the return elbow.

Obviously, if the transition zone has been described at the level of rotational / circular multiperforation, there is no problem placing it at the level of axial multiperforation or even positioning it between a series of axial multiperforations with an inclination at an angle of 30 ° and a series of rotational / circular multiperforations with an inclination at a angle of 60 °. Similarly, this transition zone may contain more than two rows, with the angle of inclination of the holes in this case being evenly distributed between 0 ° (axial multiperforation) and 90 ° (circular / circular multiperforation). For example, with three rows, the angle of inclination of the holes will be respectively 22.5 °, 45 ° and 67.5 °.

When using the invention, the flow in the primary zone does not change, and the circular motion does not affect the orientation of the dilution jets, and the exclusion of the thermal barrier provides a gain in terms of mass and, accordingly, cost. It is also obvious that in order to preserve the flow directions in the high-pressure distributor (HPD) and to avoid aerodynamic separation, and to maintain the output power of the high-pressure turbine, the direction of drilling of rotational / circular multiperforation is determined by the flow direction of the aerodynamic profiles of the high-pressure distributor (HPD) behind the combustion chamber.

Claims (12)

1. An annular wall (16, 18) of a combustion chamber of a gas turbine engine having a cold side (16a, 18a) and a hot side (16b, 18b), wherein said annular wall comprises:
- a plurality of primary openings (28) distributed in accordance with the circumferential row to allow air circulating from the cold side (16a, 18a) of said annular wall to the hot side (16b, 18b) to create an air-fuel mixture;
- a plurality of dilution holes (30) distributed in accordance with the circumferential row to allow air circulating from the cold side (16a, 18a) of said annular wall to the hot side (16b, 18b) to allow dilution of the air-fuel mixture; and
- a plurality of cooling holes (32) designed to allow air circulating from the cold side (16a, 18a) of said annular wall to the hot side (16b, 18b) to form a cooling air film along said annular wall, said holes cooling are distributed in accordance with many circumferential rows located at a distance from each other, determined in the axial direction, and the geometric axis of each of these cooling holes are inclined axially on D systematic way flow of gaseous combustion products at an angle θ1 relative to the normal N to said annular wall;
characterized in that it further comprises a plurality of additional cooling holes (34) located, on the one hand, downstream directly from said primary holes and, on the other hand, downstream directly from said dilution holes and distributed in accordance with a plurality of circumferential rows located at a distance from each other, defined in the axial direction,
the geometric axes of each of these additional cooling holes are located in a plane perpendicular to the indicated axial direction D and are inclined at an angle θ2 relative to the normal N to the specified annular wall. 2. The wall according to claim 1, characterized in that said inclination angle θ2 of said additional holes relative to the normal N to said annular wall is identical to the inclination angle θ1 of said cooling holes. 3. The wall according to claim 1 or 2, characterized in that the diameter d2 of said additional holes is identical to the diameter d1 of said cooling holes, and the step p2 of said additional holes is identical to the step p1 of said cooling holes. 4. The wall according to claim 1, characterized in that the said additional holes have a high density flow arrangement directly behind the primary holes and dilution holes. 5. The wall according to claim 1, characterized in that it further
contains in place of the transition zone (28B, 30B), formed upstream behind the specified set of rows of additional holes, at least two rows of holes in which the geometric axis of each of these holes are inclined relative to the plane perpendicular to the specified axial direction D, at an angle defined as different for each of these two rows. 6. An annular wall (16, 18) of a combustion chamber of a gas turbine engine having a cold side (16a, 18a) and a hot side (16b, 18b), wherein said annular wall comprises:
- a plurality of primary holes (28) or dilution holes (30) distributed in accordance with the circumferential row to allow air circulating from the cold side (16a, 18a) of said annular wall to the hot side (16b, 18b), respectively, to create air-fuel mixture or to ensure dilution of the air-fuel mixture; and
- a plurality of cooling holes (32) designed to allow air circulating from the cold side (16a, 18a) of said annular wall to the hot side (16b, 18b) to form a cooling air film along said annular wall, said holes cooling are distributed in accordance with many circumferential rows located at a distance from each other, determined in the axial direction, and the geometric axis of each of these cooling holes are inclined in the axial direction the direction D of the flow of gaseous products of combustion at an angle θ1 relative to the normal N to the specified annular wall;
characterized in that it further comprises a plurality of additional cooling holes (34) located downstream of said primary holes or dilution holes and distributed in accordance with a plurality of circumferential rows spaced apart from one another, defined in the axial direction,
while the geometric axis of each of these additional cooling holes are located in a plane perpendicular to the indicated axial direction D and are inclined by an angle θ2 relative to the normal N to the specified annular wall,
wherein said annular wall further comprises, in place of the transition zone (28B, 30B) formed upstream behind said plurality of rows of additional holes, at least two rows of holes in which the geometric axes of each of said holes are inclined relative to a plane perpendicular to said axial direction D, at an angle of inclination defined as different for each of these two rows. 7. The wall according to claim 5 or 6, characterized in that it contains two rows of holes, and the indicated inclination angles are 30 ° and 60 °, respectively. 8. The wall according to claim 7, characterized in that said two rows of holes are two rows of additional holes located downstream directly from the row of cooling holes, two rows of cooling holes located downstream directly from the row of additional holes, or even a number of additional holes and an adjacent row of cooling holes. 9. The wall according to claim 5 or 6, characterized in that it comprises several rows of holes, and said inclination angles are evenly distributed between 0 ° and 90 °. 10. The wall according to claim 1, characterized in that the direction of inclination of these additional holes is limited by the direction of flow of the air-fuel mixture in the stream behind the specified combustion chamber. 11. The combustion chamber (10) of a gas turbine engine, comprising at least one annular wall (16, 18) according to claim 1. 12. A gas turbine engine containing a combustion chamber (10) having at least one annular wall (16, 18) according to claim 1.

Images