EP2818724A1 - Fluid flow engine, casing treatment and method - Google Patents

Abstract

Disclosed is a turbomachine having at least one circulation structure (4), which has an annular space (22) with flow guide elements (26), which encompasses and is open to a main flow path (1), wherein a housing (2) of the turbomachine accommodates the circulation structure (4) in an axial parting plane (Ts) in a front housing portion (10) and a rear housing portion (12) is divided, and that the circulation structure (4) in an axial parting plane (Tz) in a front structural area (18) and in a rear structural region (2) is divided, a two-way divided in the axial direction of circulation structure and a method.

Description

The invention relates to a turbomachine having at least one circulation structure according to the preamble of patent claim 1, a circulation structure for a turbomachine and a method for introducing a circulation structure into a housing of a turbomachine.

Circulation structures or recirculation structures for turbomachines such as gas turbines and in particular their compressors are known as so-called "Casing Treatments" and "Hub Treatments". The primary purpose of the circulation structures is to increase an aerodynamically stable operating range of the compressor by optimizing a surge margin. An optimized surge margin allows higher compressor pressures and thus a higher compressor load. The faults responsible for a local stall and ultimately for pumping the compressor occur at the housing-side ends of the blades of one or more compressor stages or at the hub-side, radially inner ends of the vanes, since in these areas the aerodynamic load in the compressor is highest , The flow structures in the area of the blade ends are stabilized by the circulation structures.

A turbomachine having such a circulation structure is in DE102008010283A1 shown. The circulation structure is arranged in the compressor of the turbomachine, in particular of a gas turbine, and has an annular space which is oriented coaxially with the axis of rotation of a rotor of the turbomachine and is open to the main flow path. When viewed in the main flow direction of the main flow path, a plurality of chambers which can be flowed through in the axial direction are positioned upstream of the annular space. A turbomachine with an alternative circulation structure is in the EP1478828B1 shown. This circulation structure likewise has an annular space oriented coaxially to the axis of rotation of a rotor of the turbomachine and opened to the main flow path, in which, however, a multiplicity of flow guide elements are arranged.

The object of the invention is to provide a turbomachine having at least one circulation structure, which allows a simple introduction of the circulation structure in a housing of the turbomachine. Furthermore, it is an object of the invention to provide a circulation structure which can be easily incorporated into a housing of a turbomachine. It is another object of the invention to provide a method for easy introduction of a circulation structure in a housing of a turbomachine.

This object is achieved by a turbomachine having the features of patent claim 1, by a circulation structure having the features of patent claim 6 and by a method having the features of patent claim 8.

A turbomachine according to the invention has at least one circulation structure, which has an annular space with flow-guiding elements, which surrounds a main flow path and is open to it. According to the invention, a housing of the turbomachine for accommodating the circulation structure is divided in an axial parting plane into a front housing area and a rear housing area. In addition, the circulation structure is divided in an axial parting plane into a front structural region and in a rear structural region into an axial parting plane.

The division of the turbomachine housing for accommodating the circulation structure into at least two housing areas in combination with the division of the circulation structure into at least two structural areas simplifies the manufacture and introduction of the circulation structure. The front structural region and the rear structural region can thereby be formed by individual insert elements or insertion elements, lining segments or liners and the like, which are separate in the circumferential direction and can be assembled into a ring, or by annular segments closed in the circumferential direction. Likewise, the axial division of the turbomachine housing and the circulation structure enables, for example, the front structural region of the circulation structure to be introduced directly into the front housing region of the turbomachine, since alternative milling paths and tools can be inserted through the lateral access provided by the axial division. In this way, moreover, the circulation structure can be increased or made more compact. The terms "front" and "rear" refer in each case in the flow direction of a main flow path through the main stream.

The introduction of the circulation structure can also be simplified if the same axial separation plane of the housing in the mounted state is equal to the axial parting plane of the circulation structure. In order to avoid jamming of the circulation structure during assembly, the rear structural area in the mounted state can be set back slightly in relation to the parting planes, so that a minimum annular gap is formed between the structural areas in the installed state.

In one embodiment, the flow guide elements are formed in the front structural area, which is inserted into the front housing area. In this embodiment, the front structure portion is composed of a plurality of insert segments circumferentially partitioned from each other and made separately from the front housing portion. Alternatively, the front structural portion is a single circumferentially closed ring member made separately from the front housing portion. The separate production of the front housing portion and the front structural area, the production of the flow guide can be simplified.

In an alternative embodiment, the flow guide elements are introduced directly into the front housing area. This eliminates the need for separate insert or insertion segments or on a separate ring member for forming the front structural area, which in principle fewer parts must be mounted. In addition, the weight of the turbomachine or its housing is reduced by the integral design of the front structural area in the front housing area.

Preferably, the rear structural portion is an integral front body portion of a trim member inserted into the rear housing portion. The cladding element may consist of a plurality of individual circumferentially divided cladding segments, which together form a closed ring, or be a single cladding ring. The body portion may include a holding portion of the trim member for attaching the trim element to the rear Be housing area, so that no additional sections must be attached to the cladding element or its segments. The separate production of the rear housing portion and the rear portion of the structure, the production of the flow guide can be simplified. Preferably, the cladding element carries a squish or enlacing covering which extends over the cladding element in the circumferential direction and forms a closed ring, so that a blade-tip-side flow around a blade row opposite the cladding element is prevented.

A circulation structure according to the invention for a turbomachine has a structural housing which is divided in an axial parting plane into a front structural area and into a rear structural area. The at least two-part design of the circulation structure simplifies their manufacture and in particular their integration into a turbomachine housing.

The effect of the circulation structure can be improved if it has flow guidance elements in the front structural area. The flow guide elements can have different lateral spacings from one another, different geometries and / or different positions relative to each other. The flow guide elements can thus have variable circumferential positioning and geometries or courses, whereby the circulation structure can be adjusted specifically to the particular application.

In a method according to the invention for introducing a circulation structure into a housing of a turbomachine, a housing of the turbomachine is provided, which is divided in an axial parting plane into a front housing area and into a rear housing area. Then, a front structural portion of the circulation structure is inserted in the front housing portion, and a rear structural portion of the circulation structure is inserted in the rear housing portion. Subsequently, the housing areas are joined in the parting plane.

The method allows a simple by the axial separation of the turbomachine housing in the region of the circulation structure and the axial separation of the circulation structure Introducing and in particular an optimal alignment of the circulation structure. In this case, introduction means both an insertion of structural regions of the circulation structure produced separately from the turbomachine housing and an integral design of the structural regions in the turbomachine housing, for example by means of a milling process.

Preferably, in the front structural area, air passages between flow guide elements are worked out in each case in a single processing run. By this measure, the production time of the circulation structure is reduced compared to known production periods. An exemplary tool is a end mill. The tool guide is preferably chosen such that flow characteristics of the flow guide elements remain unaffected or virtually unaffected.

The rear structural area can be turned off, for example. At this time, the rear structure portion is integrally formed in the rear housing portion, whereby fewer parts have to be mounted. In addition, if the front structural area is worked out directly in the front housing area, for example by means of milling operations, virtually only the housing areas are to be mounted.

To set, for example, different or reduced transition radii of the flow guide from the bottom of the air ducts they can be edited separately after Fräse the air channels. This can be done, for example, by means of an alternative end mill with a reduced milling radius compared with the end mill used to form the air channels.

Other advantageous embodiments of the invention are the subject of further subclaims.

Figur 1

einen Längsschnitt durch eine Strömungsmaschine im Bereich einer Zirkulationsstruktur,

Figur 2

eine Werkzeugführung zur Ausbildung einer alternativen Zirkulationsstruktur,

Figuren 3, 4 und 5

verschiedene Ausbildungen von Strömungsleitelementen im vorderen Strukturbereich der Zirkulationsstruktur,

Figuren 6 und 7

beispielhafte Werkzeugführungen zur Ausbildung der Strömungsleitelemente mit kleinen Übergangsradien, und

Figuren 8 und 9

Werkzeugführungen bei einem einteiligen Strömungsmaschinengehäuse im Bereich der Zirkulationsstruktur.

In the following preferred embodiments of the invention will be explained in more detail with reference to schematic representations. Show it:

FIG. 1

a longitudinal section through a turbomachine in the region of a circulation structure,

FIG. 2

a tool guide for forming an alternative circulation structure,

FIGS. 3, 4 and 5

various embodiments of flow guide elements in the front structural region of the circulation structure,

FIGS. 6 and 7

exemplary tool guides for forming the flow guide with small transition radii, and

FIGS. 8 and 9

Tool guides in a one-piece turbomachine housing in the region of the circulation structure.

In FIG. 1 is a longitudinal section through a main flow path or flow channel 1 of a turbomachine in the region of its stator 2 shown. In particular, in FIG. 1 a section through a introduced into the stator 2 circulation structure 4 is shown. The flow channel 1 is from a main flow as shown in FIG FIG. 1 flows through from left to right. The turbomachine is, for example, a gas turbine and in particular an aircraft engine. The stator housing 2 forms a partial housing of the turbomachine and is preferably a compressor of the turbomachine.

In the in FIG. 1 shown region of the turbomachine in the flow channel 1 is an adjustable in the stator housing 2 mounted vane ring 6 and a rotor associated blade row 8. With reference to the main flow direction, the vane ring 6 is arranged in front of the blade row 8 or the blade row 8 behind the blade ring 6.

The stator housing 2 is subdivided into a front housing area 10 and into a rear housing area 12 for receiving the circulation structure 4 in an axial dividing plane Ts. The housing portions 10, 12 are each one with the flow channel 1 and the axial Dividing plane Ts open front annular recess 14 and rear annular recess 16 is provided. The ring extensions 14, 16 are arranged in the axial direction or flow direction opposite to each other and together form an approximately U-shaped annular recess.

The circulation structure 4 is divided into a front structural area 18 and a rear structural area 20 in an axial dividing plane Tz. The axial parting plane Tz is positioned in such a way that it lies on the axial parting plane Ts of the stator housing 2 in the mounted state shown. In the assembled state, the dividing planes Ts, Tz are thus identical or congruent. In order to avoid jamming of the circulation structure 4 during assembly and to thermal expansion compensation between the circulation structure 4 and the housing 2, the rear structure area 20 is slightly recessed in the mounted state with respect to the parting planes Ts, Tz, such that FIG. 1 shown in the assembled state, a minimum annular gap 21 is formed between the structural areas. Of course, the rear structure portion 20 may be led to the parting planes Ts, Tz and the front structure portion 18 opposite to the parting planes Ts, Tz reset to form the annular gap 21.

The circulation structure 4 defines an annular space 22 which surrounds the flow channel 1 in the radial direction and is open to it. Preferably, the circulation structure 4 is oriented coaxially with the axis of rotation of the rotor.

In the illustrated embodiment, the front structural portion 18 is formed as an insert member 24 inserted into the front annular recess 14, in which a plurality of circumferentially spaced apart flow directing members 26 are positioned. The insert element 24 is in the embodiment shown, a circumferentially closed ring segment. However, it may also consist of a plurality of circumferentially separated and in the assembled state forming a closed ring segments. The flow guide elements 26 have a blade-like profile and are in the circumferential direction via individual approximately in the axial direction extending air channels 28 (s. FIGS. 3 to 7 ) Figures spaced apart.

The rear structural region 20 is designed to be circumferentially symmetrical and, in the exemplary embodiment shown, has a peripheral groove facing the flow guide elements 26. The structural region 20 is integrated in a cladding element 30, which in the embodiment shown consists of a plurality of cladding segments which are separated from one another in the circumferential direction and form a closed ring in the mounted state. Alternatively, the trim element 30 is a single circumferentially closed ring element. In order to prevent a blade tip-side flow around the blade row 8, the cladding element 30 is provided on its the blade row 8 side facing with a circumferential Anstreifbelag 32.

In particular, the rear structural portion 20 is formed by an integral front body portion 34 of the trim member 30 which is inserted into the stator rear annular extension 16. Specifically, the body portion 34 is a holding portion for attaching the trim member 30 to the rear housing portion 12. The body portion 34 has a downstream retaining ring 36 adapted for mounting the trim member 30 in an upstream and in the rear housing portion 12 introduced annular retaining groove 38 engages positively.

In FIG. 2 a tool guide for forming a circulation structure 4 is shown, which is integrally incorporated into a two-part stator housing 2. Die Statorgehäuse 2 sind in der Figur 2 dargestellt. The stator housing 2 is as described above in FIG FIG. 1 in a front housing portion 10 and in a rear housing portion 12 in two parts. In the front housing area 10, a front structural area 18 of the circulation structure 4 and in the rear housing area 12 a rear structural area 20 of the circulation structure 4 are arranged.

As in FIG. 2 As shown, the flow guide elements 26 are introduced into the front housing area 10 by means of a milling tool 40, for example a milling cutter. The tool guide is such that between the flow guide 26 formed air channels 28 (s. FIGS. 3 to 5 ) are produced in each case in a single machining operation. Accordingly, the end mill 40 has a milling width which corresponds to a circumferential spacing of the flow guide elements 26 from each other.

The rear umsymmetrische structural area 20 is also formed in this embodiment by means of the end mill 40 in the stator housing 2, and in particular in the rear housing portion 12. Alternatively, the rear structural portion 20 may be pre-rotated in the rear housing portion 12 prior to milling with the end mill 40, or may only be rotated (see FIG. FIG. 9 ).

As in FIG. 3 The flow guide elements 26 or the air channels 28 formed between the flow guide elements 26 can have a uniform circumferential positioning. In particular, the air channels 28 then have a uniform concave basic contour 42, a uniform angle of incidence α in the circumferential direction, a uniform radial height h and a uniform circumferential width b _L. The flow guide 26 have a constant circumferential width b _s with a uniform circumferential positioning. The width bs corresponds to the width of the end mill 40.

As in FIG. 4 However, the flow guide 26 may also have a varying width b _S1 , b _S2 , the air guide channels, however, have a uniform width b _L , so that both the flow guide 26 and the air channels 28 have a variable circumferential positioning.

As shown in FIG. 5 In addition, the angle of attack α ₁ , α _{2 of} the air channels 28 and / or the radial height h ₁ , h _{2 of} the air channels 28 can vary.

In all prescribed embodiments of the FIGS. 2 to 5 is the same, that for the introduction of the circulation structure 4 in the stator housing 2, first the stator housing 2 in an axial dividing plane Ts in a front housing portion 10 and in a rear housing portion 12 is divided. Thereafter, the front structural portion 18 of the circulation structure 4 is inserted into the front housing portion 10 and the rear structural portion 20 of the circulation structure 4 is inserted into the rear housing portion 12. Subsequently, the front housing portion 10 and the rear housing portion 12 are joined. The formation of the air channels 28 and thus the flow guide 26 is preferably carried out in each case in a single machining operation.

In the FIGS. 6 and 7 the embodiment of current-conducting elements 26 is shown, whose transition radius _{r r has been} reworked to the base contour 42 of the air-conducting channels 28. In the embodiments of the FIGS. 6 and 7 the transition radii _r r are reduced compared to the original transition radius r _u .

The formation of the reduced transition radii r _r is preferably carried out by means of alternative end mills 44, which have a reduced cutting radius and a reduced milling width compared to the original end mill 40. As in FIG. 6 The reduced cutter 44 may be shown in overlapping tracks or as shown in FIG FIG. 7 shown to be guided in adjacent tracks. In addition, as in FIG. 6 shown, the reduced cutter 44 are driven into different depths between the flow guide 26, so that in addition to a reduction of the transition radii _{r r} also the basic contour 42 is changed to itself. As in FIG. 6 By way of example, a quasi-flat basic contour 42 can thus be created, which extends almost tangentially to the circumferential direction. As in FIG. 7 By way of example, it is thus also possible to provide a quasi-flat basic contour 42 which extends obliquely to the circumferential direction.

In FIG. 8 a tool guide for introducing a circulation structure 4 is shown in a one-piece stator housing 2 of a turbomachine. The circulation structure 4 has a front asymmetric structure region 18 with a plurality of flow guide elements 26 and a rear circumferentially symmetric structure region 20. The circulation structure 4 is introduced into the stator housing 2 directly by means of a mechanical treatment. Preferably, the air channels 28 between the flow guide 26, as in the FIGS. 2 to 5 described, each worked out in a single processing. In addition, the rear structural area 20 can be machined out of the stator housing 2 by a corresponding milling guide.

As shown in FIG. 9 For example, the rear structural area 20 may be preprocessed in a turning operation as indicated by gap 46. Of course, the rear structural portion 20 can also be rotated completely.

Disclosed is a turbomachine having at least one circulation structure, which has an annular space with flow guide elements, which surrounds a main flow path and is open to it, wherein a housing of the flow machine for receiving the circulation structure is divided in an axial parting plane into a front housing area and a rear housing area, and that the circulation structure is divided in an axial parting plane into a front structural region and a rear structural region, an axially divided two-part circulation structure, and a method.

LIST OF REFERENCE NUMBERS

1

Flow channel / main flow path

2

Stator housing / housing

4

circulation structure

6

vane ring

8th

Blade row

10

front housing area

12

rear housing area

14

front ring recess

16

rear ring recess

18

front structural area

20

rear structure area

21

annular gap

22

annulus

24

insert element

26

flow guide

28

air duct

30

cladding element

32

abradable

34

Body section / holding section

36

retaining ring

38

retaining groove

40

milling tool

42

basic contour

44

milling cutter

46

gap

ts

axial parting plane stator housing

tz

axial parting plane Circulation structure

α, α ₁ , α ₂

angle of attack

h, h ₁ , h ₂

height

b _l

Wide air duct

b _s , b _S1 , b _S2

Wide flow guide

r _u

original transition radius

r _r

reduced transition radius

Claims (11)

Turbomachine with at least one circulation structure (4), which has an annular space (22) with flow guide elements (26), which surrounds a main flow path (1) and is open to this, characterized in that a housing (2) of the turbomachine for receiving the circulation structure (4) in an axial parting plane (Ts) in a front housing portion (10) and a rear housing portion (12) is divided, and that the circulation structure (4) in an axial parting plane (Tz) in a front structural area (18) and in a rear structure portion (20) is divided. Turbomachine according to claim 1, wherein the axial separation plane (Ts) of the housing (2) in the assembled state is equal to the axial parting plane (Tz) of the circulation structure (4). Turbomachine according to claim 1 or 2, wherein the flow guide elements (26) in the front structural region (18) are formed and this is inserted into the front housing portion (10). Turbomachine according to claim 1 or 2, wherein the flow guide elements (26) are introduced directly into the front housing portion (10). Turbomachine according to one of the preceding claims, wherein the rear structural region (20) is an integral front body portion (34) of a cladding element (30) inserted into the rear housing region (12). Circulation structure for a turbomachine, comprising a structural housing which is divided in an axial parting plane (Tz) into a front structural area (18) and into a rear structural area (20). Circulation structure according to claim 6, wherein flow guide elements (26) in the front structural region (18) have different lateral spacings from one another and / or positions relative to each other. Method for introducing a circulation structure (4) into a housing (2) of a turbomachine, comprising the steps of: - Providing a housing (2) of the turbomachine, which is divided in an axial parting plane (Ts) in a front housing portion (10) and in a rear housing portion (12), - Introducing a front structure portion (18) in the front housing portion (10) and introducing a rear structure portion (20) in the rear housing portion (12), and - Add the housing portions (10, 12) in the parting plane (Ts). The method of claim 8, wherein in the front structural region (18) air channels (28) between flow guide elements (26) are worked out in each case a single machining operation. A method according to claim 8 or 9, wherein the rear structural portion (20) is turned out. The method of claim 8, 9 or 10, wherein after the formation of the flow guide elements (26) transition radii (r _u , r _r ) are processed.

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