DE102019218911A1 - GUIDE VANE ARRANGEMENT FOR A FLOW MACHINE - Google Patents

Abstract

The present invention relates to a guide vane arrangement (20) for a turbomachine (1), with a guide vane blade (21) which has a pressure side surface (36) and a suction side surface (35), the guide vane blade (21) on a gas duct (42) limiting gas duct wall (22) is rotatably mounted about an axis of rotation (23), and wherein the axis of rotation (23) is arranged in a front section (30) of the guide vane blade (21) in relation to a flow around the guide vane blade (21) in the gas duct (42) is and in a rear section (31) a top surface (32) of the guide vane (21) with the gas duct wall (22) delimits a gap (33), the gap (33) viewed in a sectional plane (46) perpendicular to a skeleton line (45), from the pressure side surface (36) to the suction side surface (35) widens in such a way that it is driven by a gap flow (37) which is driven by a pressure gradient between the pressure side surface (36) and the suction side surface (35) ird, forms a diffuser (50).

Description

Technical area

The present invention relates to a guide vane arrangement with an adjustable guide vane blade for a turbomachine.

State of the art

The turbomachine can be, for example, a jet engine, e.g. B. a turbofan engine. Functionally, the turbomachine is divided into a compressor, combustion chamber and turbine. In the case of the jet engine, for example, air that is sucked in is compressed in the gas duct of the compressor and burned in the downstream combustion chamber with the added kerosene. The resulting hot gas, a mixture of combustion gas and air, flows through the downstream turbine and is expanded in the process. The turbine also extracts some of the energy from the hot gas in order to drive the compressor.

The present subject matter relates to an adjustable guide vane blade which is arranged on a gas duct wall so as to be rotatable about an axis of rotation and which delimits the gas duct radially in relation to the longitudinal axis of the turbomachine. In relation to the flow around the rotor blade, the axis of rotation is arranged in a front section thereof (it penetrates the guide blade). In a rear section of the guide vane blade, that is to say in an area at its rear edge, there is a gap between the gas duct wall and a top surface of the guide vane blade. Depending on which suspension point is considered, this top surface of the guide vane blade faces radially outwards (outer gas duct wall) or radially inwards (inner gas duct wall).

Presentation of the invention

The present invention is based on the technical problem of specifying an advantageous guide vane arrangement with an adjustable guide vane blade.

This is achieved according to the invention with the guide vane arrangement according to claim 1. In this case, the gap that the top surface of the guide vane blade delimits together with the gas duct wall is designed as a diffuser. This refers to a gap flow directed from the pressure side in the direction of the suction side, the gap widens in the direction of flow.

If there is flow around the guide vane blade in the gas duct (main flow), the gap flow occurs due to the pressure gradient between the pressure and suction side, and the flow under or over the guide vane blade in the axially rearward section. Interaction with the main flow can lead to mixing losses and the formation of a speed deficit. A negative axial velocity component of the gap flow can locally decelerate the main flow in the area of the partial gap. With the design according to the invention as a diffuser, the partial gap flow or its negative axial velocity component can be delayed, that is to say the intensity of the interaction with the main flow can be reduced. As a result, for example, the mixing losses can be reduced and a more homogeneous guide vane outflow can also be achieved.

Preferred embodiments can be found in the dependent claims and the entire disclosure, wherein in the representation of the features, a distinction is not always made in detail between device and method or use aspects; in any case, the disclosure is to be read implicitly with regard to all claim categories. Unless explicitly stated to the contrary, the specifications always relate both to the guide vane arrangement and to an axial compressor with such a guide vane arrangement, and also to corresponding aspects of the method and use.

The information “axial”, “radial” and “circumferential”, as well as the associated directions (axial direction etc.), relate in the context of this disclosure to the longitudinal axis of the turbo machine or compressor module, around which the rotor blade rings rotate during operation, for example. The information “vome” / “front” or “rear” / “rear” relate to the flow around the guide vane blade in the gas duct, ie to the main flow. Front means upstream, back means downstream. In order to prevent underflow or overflow of the guide vane blade in the axially front section, this can be arranged there on a rotary plate. The limitation of the turntable to the axially front section, as a result of which the gap arises axially at the rear, can be geometrically advantageous because of the correspondingly smaller size of the turntable, e.g. B. with regard to the staggering of circumferentially adjacent guide vane blades.

The diffuser effect of the gap results from an outflow cross-section that is larger in relation to the inflow cross-section. In a section perpendicular to the skeleton line of the airfoil, an edge of the pressure side surface facing the gas channel wall, together with the gas channel wall, delimits the inflow cross-section; the outflow cross-section is delimited by an edge of the suction side surface facing the gas channel wall together with the gas channel wall. The respective edge lies in or forms the transition between the respective side surface of the guide vane blade and the top surface. The gap width generally does not have to increase uniformly or continuously from the suction to the pressure side; for example, sections of constant width are also possible (see in detail below).

The inflow cross-section can, for. B. be chosen so that it corresponds to a minimum possible gap width for manufacturing reasons or due to thermal restrictions. With the design as a diffuser, the amount of fluid flowing through the gap is not changed, but this is delayed on the suction side (which results in the reduced interaction). From the change in width related to the gap flow, it can be seen that the “diffuser effect” relates to a subsonic flow.

In a preferred embodiment, the outflow cross section is at least 1.2 times the inflow cross section, particularly preferably at least 1.3 times. Advantageous upper limits can, for example, be at most twice or 1.9 times the inflow cross-section.

According to a preferred embodiment, the gas duct wall at least partially forms the diffuser, that is to say, viewed in section, it is shaped with an indentation.

This can overall have the shape of a bead or groove and be introduced into the housing wall facing the top surface of the guide vane blade.

In a preferred embodiment, the top surface of the guide vane blade at least partially forms the diffuser. The edge of the suction side surface is raised compared to the edge of the pressure side surface, either radially outwards (gap on the inner gas duct wall) or radially inwards (gap on the outer gas duct wall). The “raised” edge of the suction side surface, viewed in the sectional plane, can be spaced from a straight line which is perpendicular to the pressure side surface and touches the edge of the pressure side surface, that is, it can be offset into the gas channel.

In general, the diffuser design by means of the top surface can be used on its own or in combination with the arched gas duct wall. An advantage of the top surface design can result, for example, in that the diffuser can then depend less on the adjustment angle of the guide vane blade. In general, the diffuser-like widening gap or an above-specified ratio of outflow and inflow cross-section is preferably in any case at the design operating point (Aerodynamic Design Point, ADP), e.g. B. in the case of an aircraft engine under cruise condition.

The gap flow can increase in particular when the compressor is throttled and lead to a strong radial flow redistribution of the guide vane outflow, which can have a negative effect on the aerodynamic stability and the efficiency of the downstream rotor blade. Due to the generally circular hub or housing contour, the mean gap width and thus the partial gap flow can increase with increasing adjustment compared to the nominal position. With the structuring of the diffuser on the top surface side, the intensity of the gap flow and thus its interaction with the main flow can be reduced even with large adjustment angles.

According to a preferred embodiment, the cover surface forming the diffuser, viewed in section, has a straight course, at least in sections. The top surface can extend in a straight line as a whole, that is to say from the pressure side to the suction side surface, but on the other hand it can also have a straight course only in sections.

According to a preferred embodiment, the top surface has a convex and / or a concave curvature, at least in sections. It can in turn extend as a whole, that is to say from edge to edge, with the corresponding curvature (convex or concave), but on the other hand the corresponding curvature can also only be present in one section. In particular, combinations with a straight course into the pressure and / or suction side surface are also possible.

A combination of concave and convex curvature can be preferred, with a section of concave curvature particularly preferably following a section of convex curvature (based on the gap flow). This can furthermore be combined with a linear extension in sections, between the concave and convex section and / or at the inflow and / or outflow cross-section. In general terms, the top surface, viewed in section, can have a freely formed contour or a contour running with inflection points, for example in order to influence or optimize the outflow vector.

So far, reference has primarily been made to the contour or shape of the gap in the section, i.e. in the section plane perpendicular to the skeleton line. In relation to a length of the gap taken along the skeleton line, the configuration as a diffuser is present in a preferred configuration over at least 60%, 70% or 80% of the gap length. The gap can also form a diffuser over its entire length (100%), but upper limits can also be 95% or 90%, for example. For example, the diffuser can be formed in the entire adjustment range or only in part thereof.

If the diffuser is realized via a correspondingly shaped top surface, its shape can e.g. B. take place after the blade production, for example by machining. The guide vane can then also be manufactured conventionally, e.g. B. by casting. On the other hand, however, generative production is also possible, that is to say a layer-by-layer construction from a previously shapeless or shape-neutral material, for example in a powder bed process. Here, the contour of the top surface can already be taken into account in the course of building what z. B. can enable particularly complex geometries (freeform).

The invention also relates to a compressor module with a guide vane arrangement disclosed in the present case, and also relates to a turbo-engine or an aircraft engine with such a compressor module.

Figure list

In the following, the invention is explained in more detail on the basis of exemplary embodiments, with the individual features in the context of the independent claims also being essential to the invention in other combinations, and furthermore no individual distinction is made between the different claim categories.

• 1 ein Mantelstromtriebwerk in einem schematischen Schnitt;
• 2 eine Leitschaufelanordnung mit einer verstellbaren Leitschaufel auf einem Drehteller in einer Schrägansicht;
• 3 eine verstellbare Leitschaufel in einer Umlaufprojektion;
• 4 einen Tangentialschnitt durch das Leitschaufelblatt gemäß 3 zur Illustration einer Spaltströmung;
• 5 eine erste Möglichkeit zur Ausbildung eines Diffusors durch eine Deckflächenkonturierung;
• 6 eine zweite Möglichkeit zur Ausbildung eines Diffusors durch eine Deckflächenkonturierung;
• 7 eine dritte Möglichkeit zur Ausbildung eines Diffusors durch eine Deckflächenkonturierung;
• 8 eine Möglichkeit zur Ausbildung eines Diffusors durch kombinierte Deckflächen- und Gaskanalwandkonturierung.

Shows in detail

• 1 a turbofan engine in a schematic section;
• 2 a guide vane arrangement with an adjustable guide vane on a turntable in an oblique view;
• 3rd an adjustable guide vane in an orbital projection;
• 4th a tangential section through the guide vane according to FIG 3rd to illustrate a gap flow;
• 5 a first possibility for the formation of a diffuser by means of a top surface contouring;
• 6th a second possibility for the formation of a diffuser by means of a top surface contouring;
• 7th a third possibility of forming a diffuser by means of a top surface contouring;
• 8th a possibility for the formation of a diffuser through combined top surface and gas duct wall contouring.

Preferred embodiment of the invention

1 shows a turbomachine 1 in section, specifically a jet engine (turbofan engine). The turbo machine 1 is functionally divided into compressors 1a , Combustion chamber 1b and turbine 1c . Both the compressor 1a as well as the turbine 1c are each made up of several modules, the compressor 1a in the present case from a low-pressure laa and a high-pressure compressor 1ab . Each compressor laa, 1ab is in turn made up of several stages; each stage is usually composed of a rotor blade ring and a guide blade ring. The compressor is in operation 1a based on a longitudinal axis 2 axially from the compressor gas 3rd , in this case air, flows through, in a compressor gas duct 4th . The compressor gas is thereby 3rd compressed, in the combustion chamber 1b kerosene is then mixed in and this mixture is burned.

2 shows a vane arrangement 20th with a guide vane 21 attached to a gas duct wall 22nd is arranged. The guide vane 21 is around an axis of rotation 23 rotatably mounted, it sits on a turntable 24 that is in a recess 25th in the gas duct wall 22nd is used. The axis of rotation 23 is in an axially forward section 30th of the guide vane 21 arranged, this sits on the turntable 24 . An axially posterior section 31 protrudes backwards, between the gas duct wall 22nd and the corresponding top surface 32 of the guide vane 21 there is a gap 33 .

Due to the pressure gradient, it forms through the gap during operation 33 a gap flow 37 which can already be disadvantageous in itself (compare 4th in detail). Furthermore, there may be an interaction with other secondary flow effects, such as, for example, the flow through the turntable 27 , a corner vortex 28 (Corner detachment) or the horseshoe vortex 29 .

Like the schematic circumferential projection according to 3rd illustrated is the guide vane blade 21 both on the radially inner gas duct wall 22.1 as well as on the radially outer gas duct wall 22.2 accordingly rotatably mounted, there is a gap radially on the inside 33.1 and a gap radially on the outside 33.2 . The present article can have both the radially inner top surface 32.1 as well as the radially outer top surface 32.2 affect.

As in 4th Illustrates the the vane blade 21 shows in a tangential section, arises due to the pressure gradient between the suction side surface 35 and the print face 36 of the guide vane 21 the gap flow 37 through the gap 33 a. This flows under or over the guide vane blade 21 essentially orthogonal to the skeleton line 45 , there is an interaction with the main flow on the suction side 38 . The gap flow 37 has one against the mainstream here 38 Directed axial speed component, which can result in severe mixing losses and a local speed deficit. This can lead to a loss of efficiency and to a radial redistribution of the flow, which is harmful, for example, for rows of blades located downstream. It can also be a blockage area 39 form.

To prevent this, the top surface is 32 of the guide vane 21 contoured, it forms a diffuser 50 . How out 5 one can see an inflow cross-section 51 through which the gap flow 37 in the gap 33 flows in, smaller than an outflow cross-section 52 . The outflow cross-section 52 makes about 1.5 times the inflow cross-section 51 out. The gap flow is experienced by the widening flow cross-section 37 a delay, which on the suction side is the intensity of the interaction with the main flow 38 decreased.

With the variant according to 5 has the top surface 32 in the to the skeleton line 45 vertical cutting plane 46 (compare 4th ) considers a straight line. In contrast, shows 6th a top surface 32 that have a concave curvature 60 has (in the same cutting plane 46 considered). With the variant according to 7th is the top surface 32 with a convex curvature 70 Combinations of convex and concave curvature in sections are also possible (not shown), compare the introduction to the description in detail.

With the variant according to 8th becomes the diffuser 50 on the one hand from the contoured top surface 32 formed, which in this case analogous to the variant according to 6th is shaped. Furthermore, there is also the gas duct wall 22nd structured, namely with an indentation 80 intended. This forms the diffuser 50 together with the contoured top surface 32 , so increases the delay caused by the gap flow 37 in the gap 33 learns.

List of reference symbols

1

Turbo machine

1a

compressor

1aa

Low pressure compressor

1ab

High pressure compressor

1b

Combustion chamber

1c

turbine

2

Longitudinal axis

3

Compressor gas

4th

Compressor gas duct

20th

Guide vane assembly

21

Guide vane

22nd

Gas duct wall

22.1

inner gas duct wall

22.2

outer gas duct wall

23

Axis of rotation

24

Turntable

25th

Recess

27

Turntable flow

28

Corner vortex

29

Horseshoe vortex

30th

Axially anterior section

31

Axially posterior section

32

Deck area

32.1

inner top surface

32.2

outer top surface

33

gap

33.1

inner gap

33.2

outer gap

35

Suction side surface

35.1

Edge

36

Print face

36.1

Edge

37

Gap flow

38

Mainstream

39

Blockage area

45

Skeleton line

46

Cutting plane

50

Diffuser

51

Inflow cross-section

52

Outflow cross-section

60

Concave curvature

70

Convex curvature

80

Bulge

Claims (13)

Guide vane arrangement (20) for a turbomachine (1), with a guide vane blade (21) which has a pressure side surface (36) and a suction side surface (35) and is disposed in a gas channel (42), wherein the guide vane blade (21) is mounted rotatably about an axis of rotation (23), and wherein the axis of rotation (23) is based on a flow around the guide vane blade (21) in the gas channel (42) in a front section (30) of the guide vane blade (21) is arranged and in a rear section (31) a top surface (32) of the guide vane blade (21) delimits a gap (33) with a gas duct wall (22) delimiting the gas duct (42), wherein the gap (33) is viewed in a sectional plane (46) which is perpendicular to a skeleton line (45) of the guide vane blade (21), in at least one adjustment position of the guide vane blade (21) or the adjustment guide vane from the pressure side surface (36) the suction side surface (35) expands in such a way that it forms a diffuser (50) for a gap flow (37) which is driven by a pressure gradient between the pressure side surface (36) and the suction side surface (35). Guide vane arrangement (20) according to Claim 1 , in which an outflow cross-section (52), viewed in the sectional plane (46), delimits an edge (35.1) of the suction side surface (35) facing the gas channel wall (22) together with the gas channel wall (22), at least 1.2 times one The inflow cross-section (51) is defined by an edge (36.1) of the pressure side surface (36) facing the gas channel wall (22) together with the gas channel wall (22). Guide vane arrangement (20) according to Claim 2 , in which the outflow cross-section (52), viewed in the sectional plane (46), is at most twice the inflow cross-section (51). Guide vane arrangement (20) according to one of the preceding claims, in which the gas duct wall (22) at least partially forms the diffuser (50), the gas duct wall (22), viewed in the sectional plane (46), is thus formed with an indentation (80). Guide vane arrangement (20) according to one of the preceding claims, in which the top surface (32) of the guide vane blade (21) at least partially forms the diffuser (50), that is to say an edge (35.1) facing the gas duct wall (22) when viewed in the cutting plane (46) the suction side surface (35) is raised compared to an edge (36.1) of the pressure side surface (36) facing the gas duct wall (22). Guide vane arrangement (20) according to Claim 5 , in which the top surface (32) of the guide vane blade (21), viewed in the sectional plane (46), has a straight course, at least in sections. Guide vane arrangement (20) according to Claim 5 or 6th , in which the top surface (32) of the guide vane blade (21), viewed in the sectional plane (46), has a convex curvature (70) at least in sections. Guide vane arrangement (20) according to one of the Claims 5 to 7th , in which the top surface (32) of the guide vane blade (21), viewed in the sectional plane (46), has a concave curvature (60) at least in sections. Guide vane assembly (20) according to the Claims 7 and 8th , in which the top surface (32) of the guide vane (21), viewed in the plane of section (46), is shaped in such a way that, based on the gap flow (37), a section with the concave curvature (60) on a section with the convex curvature (70 ) follows. Guide vane arrangement (20) according to one of the preceding claims, in which the gap (33) forms the diffuser (50) over at least 60% of a gap length taken along the skeleton line (45) of the guide vane blade (21). Guide vane arrangement (20) according to one of the preceding claims, in which the diffuser (50) is formed in the entire adjustment range or is formed only in part thereof. Compressor module (1aa, 1ab) with a guide vane arrangement (20) according to one of the preceding claims. Turbomachine (1), in particular aircraft engine, with a guide vane arrangement (20) according to one of the Claims 1 to 10 or a compressor module (1aa, 1ab) Claim 11 .

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