EP2428649A1 - Anti-swirl device in a leakage flow of a turbomachine - Google Patents

Abstract

The turbo machine has a rotor, which is pivoted around a rotational axis and a housing arranged around the rotor. The housing has a housing inner surface (14), which is formed relative to the rotor in a circumferential direction. A gap (18) is formed between the rotor and the housing inner surface.

Description

The invention relates to a turbomachine having a rotor rotatably mounted about a rotation axis and a housing arranged around the rotor, wherein the housing has a housing inner surface formed with respect to the rotor in a circumferential direction, wherein at least one gap is formed between the rotor and the housing inner surface, wherein a Number of radially extending vanes, each having a Leitschaufelfuß are attached to the housing and in the region of the housing inner surface a swirl crusher for reducing a twist of a leakage flow is arranged. It further relates to a power plant with such a turbomachine.

Turbomachines in the context of this invention are, for example, steam turbines, gas turbines or compressors, the invention preferably referring to steam turbines. Turbomachines are characterized by a flow medium. Hydraulic turbines, steam and gas turbines, wind turbines, centrifugal pumps and centrifugal compressors as well as propellers are summarized under the collective term "turbomachinery". All of these machines have in common that they serve the purpose of extracting energy from one fluid in order to drive another machine, or vice versa, to supply energy to a fluid in order to increase its pressure. In turbomachines, the energy conversion is indirect and preferably takes the path over the kinetic energy of the fluid. Such turbomachines are used, for example, in power generation in power plants.

In turbomachines, such. B. in steam turbines, flows during operation, a flow medium in a main flow direction, which corresponds substantially to the direction of the axis of rotation. The flow medium should ideally only through a so-called flow channel, which has so-called guide vanes and blades. Usually, the flow channel is formed of different successively arranged guide and moving blades, wherein the guide vanes are fixed to a Leitschaufelfuß to a housing of the turbomachine, while the blades are fixed to the rotor. The flow medium flows past the guide and moving blades through the flow channel, whereby the kinetic energy of the fluid is converted into rotational energy, which leads to a rotation of the rotor.

As movement of the rotor takes place in the housing, there are gaps between the housing inner surface and the rotor which should be made as small as possible. However, gaps can not be avoided, resulting in undesirable flow through the gaps. The undesirable flow results from the main flow, with a part branching off from the main flow and flowing through the gap. This gap flow can be referred to as a leakage flow, wherein the goal in any design of a turbomachine is to keep the leakage flow as low as possible. Therefore, various approaches exist to minimize the leakage flow. A first approach is to arrange so-called sealing lips between the rotating and fixed components. The sealing lips are arranged rotationally symmetrically on the rotor and stator and act as a barrier to the leakage flow. Thus, a leakage flow flowing substantially parallel to the main flow is decelerated.

The leakage flow, however, leads in turbomachinery to a further effect, which is undesirable. The leakage flow through the gaps can amplify or dampen existing rotor vibrations during operation, which occurs depending on the prevailing boundary conditions. This effect is referred to in fluid mechanics as Spalterregulation. Especially in steam turbine construction, this effect is referred to as Dampfanfachung. Since the branching off in the direction of the gap Flow medium portion having different directional components, in addition to the main direction component, which leads along the main flow channel also direction components are present, which are directed in the circumferential direction. This circumferentially directed leakage flow component is also referred to as a spin. The gap excitation or vaporization depends on the direction and magnitude of this twist of the leakage flow entering the gap. In general, the leakage flow in turbines has the effect that rather a fanning effect takes place instead of a damping.

This excitatory effect is disturbing and there are efforts to prevent this disorder. It is known to use swirl breakers in different designs. In this case, swirl breakers are understood as meaning components which form a barrier to the leakage flow flowing in the circumferential direction, which is referred to as a swirl. Alternatively or additionally, a brake fluid can be injected into the leakage flow in such a way that the twist is thereby minimized or prevented.

The swirl breakers are usually formed of individual components and incorporated in a suitable manner in the circumferential direction individually in the housing. This can require a high production cost, which leads to an increased production time.

The object of the invention is therefore to provide a turbomachine of the type mentioned above, which can be made quickly and at the same time technically particularly simple design.

This object is achieved according to the invention in that the swirl breaker is designed as a component which is fixed in a form-locking manner in a gap formed by two adjacent guide blade feet.

The invention is based on the consideration that a particularly simple and rapid production of a turbomachine would be possible if the individual swirl crushers could be used in a simple manner without special effort in the construction of the turbomachine. In particular, welding operations or similar complicated procedures should be omitted when introducing the individual swirl breaker. This can be achieved by fixing the swirl crushers in a form-fitting manner. In this case, the simplest possible structures should be used to fix the swirl crushers. This is achievable by suitably modifying the blade roots of adjacent vanes on the housing inner wall, e.g. B. by introducing appropriate wells, and the swirl breaker clamped between two adjacent Leitschaufelfüßen, d. H. be fixed positively.

By such an arrangement can now be distributed over the entire circumference swirl breakers, d. H. Advantageously, in each case a swirl breaker is positively fixed in a plurality of intermediate spaces formed from two adjoining vanes feet. This can be achieved in a simple manner in the entire circumferential direction sufficient suppression of the peripheral components of the leakage flow.

Advantageously, the respective intermediate space is formed by recesses which are introduced into the respectively adjacent guide blade feet. The guide blade feet thus have recesses which serve as a fit for the swirl breaker to be introduced.

To suppress the circumferential components of the swirl breaker should establish a barrier in a substantially radial-axial plane of the turbomachine. Since the spaces between the vanes feet are extended in this plane, a particularly simple, flat design results by the respective swirl breaker advantageously as is designed substantially in the radial-axial plane extending component.

In an advantageous embodiment, the respective swirl breaker is designed as a sheet metal. This allows a particularly simple and inexpensive design. Additionally or alternatively, the respective swirl breaker can advantageously be made of one piece of material, ie. H. made of one piece or piece of sheet metal. If necessary, such a swirl breaker can be used as a standard component in all gaps between the rotor and the housing inner wall. This also simplifies the manufacture and assembly.

The vanes feet after installation make a positive connection for the respective swirl breaker in the circumferential direction. In order to ensure a positive connection in the axial direction, the swirl breaker advantageously has a section extending in the radial direction, which is fixed in a form-fitting manner in a groove of the housing.

In an advantageous embodiment of the respective swirl breaker is fixed with a clearance fit, d. H. the nominal size of the swirl breaker is slightly less than that of the space between the vanes feet. This will ensure that the flow of force passes over the sides of the vanes feet.

In a further or alternative embodiment, the respective swirl crusher has a bead, so that it elastically deforms during installation of the guide vanes. He is then secured in the circumferential direction against tilting. A profiling of the sheet by means of a bead can also serve to achieve a stiffening against the attacking flow forces.

Since the leakage flow sometimes has a wide variety of directional components, it depends greatly on the boundary conditions, which form of the swirl breaker is suitable. Such is for example a swirl breaker wall is conceivable which has rounded corners, has a triangular shape or has further geometric shapes. For a particularly simple influencing of the flow of the free-standing in the flow part of the swirl breaker with respect to the jammed between two blade roots area can be arranged at an angle, ie, the swirl crusher is advantageously bent at a shallow angle in the circumferential direction. The orientation of the swirl breaker is then independent of the orientation of the blade roots.

In an advantageous embodiment, such a turbomachine is used in a power plant.

The advantages achieved by the invention are in particular that a particularly simple and cost-effective installation of the swirl crusher in a turbomachine is made possible by a swirl crusher, which is positively fixed between two vanes feet. The swirl breaker is a standard component that can be used in the same way on all gaps between the rotor and the housing of a turbine. The standard component can simply be formed from a sheet which is placed in a suitable recess on the side of a blade root. Thus, a subsequent replacement is particularly simple and inexpensive possible. At the same time a particularly high efficiency of the turbomachine is achieved by effective spin suppression.

FIG 1

eine Dampfturbine als Ausführungsbeispiel für eine Strömungsmaschine,

FIG 2

einen Ausschnitt aus einer Strömungsmaschine,

FIG 3

eine Ansicht eines Drallbrechers in Umfangsrichtung,

FIG 4

eine Ansicht des Drallbrechers in axialer Richtung, und

FIG 5

eine Ansicht des Drallbrechers in radialer Richtung.

An embodiment of the invention will be explained in more detail with reference to a drawing. Show:

FIG. 1

a steam turbine as an exemplary embodiment of a turbomachine,

FIG. 2

a section of a turbomachine,

FIG. 3

a view of a swirl breaker in the circumferential direction,

FIG. 4

a view of the swirl breaker in the axial direction, and

FIG. 5

a view of the swirl breaker in the radial direction.

Identical parts are provided with the same reference numerals in all figures. The terms radial, axial and circumferential direction also refer in the following to the system of the turbomachine, wherein the direction designation "axially" refers to the axis of rotation.

The FIG. 1 shows a turbomachine 1, here as an embodiment of a steam turbine. Further examples of a turbomachine are a gas turbine or a compressor. The steam turbine comprises an outer housing 2, which is designed as a pot housing. The pot construction is merely exemplary, the invention can also be used in turbines of other designs. To outer housing 2, a lid 3 is arranged with fastening means. Within the outer housing 2, an inner housing 4 is arranged. The inner housing 4 has guide vanes 5. For the sake of clarity is in the FIG. 1 only one vane provided with the reference numeral 5. Furthermore, the steam turbine 1 has an inflow opening 6 through which steam flows as a flow medium during operation. The flow medium flows through a flow channel 7 past the guide vanes 5. Within the inner housing 4, a rotor 8 is rotatably mounted about a rotation axis 9. The rotor 8 comprises rotor blades arranged on the rotor surface 10. For the sake of clarity is in the FIG. 1 only one blade provided with the reference numeral 10.

The rotor 8 further comprises a thrust balance piston 11, which is commonly used in high pressure turbine parts with a usual for this type blading. The steam flowing through the steam turbine 1 gives its energy to the Rotor 8 from, resulting in a rotation of the rotor 8. The rotation of the rotor 8 is used, for example, to drive generators or pumps.

In the FIG. 2 is a section of a turbomachine shown. The FIG. 2 shows a portion of a blade 10. The blade 10 has a shroud 12 on. Opposite the shroud 12, the housing inner surface 14 of a portion of the inner housing 4 is shown. The inner housing 4 has sealing lips 16, which are arranged rotationally symmetrically in the circumferential direction. Between the housing inner surface 14 and a surface of the shroud 12 of the blade 10, a gap 18 is formed. A flow of the flow medium through this gap 18 represents a loss that should be prevented or minimized.

The majority of the flow medium flows along the main flow, essentially along the axis of rotation 9. In the case of conical flow channels, the main flow direction does not necessarily run exactly along the axes of rotation 9. A comparatively small proportion of the main flow 16 branches off in the radial direction towards the gap 18. In addition to a radial flow component, the leakage flow also has a flow component which takes place in the circumferential direction, ie in FIG. 2 out of the picture plane or into it. To minimize this flow component of the leakage flow formed in the circumferential direction, a swirl breaker 20 is mounted in the region of the housing inner surface 14.

For a particularly simple construction of the turbomachine 1, the swirl breaker 20 is designed as a one-piece standard component made of sheet metal, which is fixed in a form-fitting manner between two guide blade feet 22 of two guide vanes 5. For this purpose, corresponding recesses or depressions are introduced into the guide blade feet 22, which serve as a fit for the swirl breakers 20. In FIG. 2 only one swirl breaker 20 is shown, but these are distributed rotationally symmetrically over the entire circumference of the turbomachine 1. In this case, the swirl breaker 20 extends in its surface substantially in the radial-axial plane. The swirl breaker 20 has a radially extending portion 26 which engages the guide vane groove 28. Thus, both in the circumferential direction by the guide vanes 5 and in the axial direction by the Leitschaufelnut 28 a positive connection and thus secure hold of the swirl breaker 20 is ensured. The dimensions of the swirl breaker 20 are chosen for a clearance fit. The swirl crusher further has a ground edge 29 facing the shroud 12 in the installed state. This is to prevent that in the case of a touch, not the entire side surface of the swirl breaker 20 touches the shroud 12 and excessively damaged.

In the FIG. 3 is a view of the swirl breaker 20 in the circumferential direction. The swirl breaker 20 has a bead 30 which extends initially in the radial direction over the radial section 26, and then over the remaining axial section. This serves on the one hand to stiffen the component, on the other hand, the swirl crusher 20 can be elastically deformed during installation so that it is secured against tilting. FIG. 4 shows a corresponding view of the swirl breaker 20 in the axial direction. FIG. 5 shows the swirl breaker 20 from the radial direction, wherein a bend of the swirl breaker 20 at the base of the radial portion 26 can be seen. Here, the swirl breaker 20 is bent at a flat angle about a bending axis 32 running in the radial direction. Thus, the orientation of the projecting into the gap 18 portion of the swirl breaker 20 regardless of the installation situation of the vanes 5 are attached to the respective flow conditions. The proposed here swirl breaker is a standard component, which allows a particularly simple and inexpensive construction of a turbomachine 1.

Claims (11)

Turbomachine having a rotor (8) rotatably mounted about a rotation axis (9) and a housing (4, 2) arranged around the rotor (8),
the housing (4, 2) having a housing inner surface (14) formed in a circumferential direction with respect to the rotor (8),
wherein at least one gap (18) is formed between the rotor (8) and the housing inner surface (14),
wherein a number of radially extending vanes (24) each having a vane root (22) are secured to the housing and a swirler (20) for reducing a twist of a leakage flow is disposed in the region of the housing interior surface (14);
wherein the swirl breaker (20) is designed as a component fixed in a form-locking manner in a gap formed by two adjacent guide blade feet (22). Turbomachine (1) according to claim 1,
wherein in each case a swirl breaker (20) is positively fixed in a plurality of intermediate spaces formed from in each case two adjacent guide blade feet (22). Turbomachine (1) according to claim 1 or 2,
wherein in each of the two adjacent guide blade feet (22) recesses are introduced and the respective intermediate space is formed substantially by the recesses. Turbomachine (1) according to one of the preceding claims,
wherein the respective swirl breaker (20) is designed as a component extending substantially in the radial-axial plane. Turbomachine (1) according to one of the preceding claims,
wherein the respective swirl breaker (20) is designed as a sheet metal. Turbomachine (1) according to one of the preceding claims,
wherein the respective swirl breaker (20) is material integral. Turbomachine (1) according to one of the preceding claims,
wherein the respective swirl crusher (20) has a radially extending portion which is positively fixed in a groove (28) of the housing (4, 2). Turbomachine (1) according to one of the preceding claims,
wherein the respective swirl breaker (20) is fixed with clearance fit. Turbomachine (1) according to one of the preceding claims,
wherein the respective swirl crusher (20) has a bead (30). Turbomachine (1) according to one of the preceding claims,
wherein the respective swirl breaker (20) is bent at a slight angle in the circumferential direction. Power plant with a turbomachine (1) according to one of the preceding claims.

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