DE102014012765A1 - Radial compressor stage - Google Patents

Abstract

A centrifugal compressor stage comprising a rotor (10) rotating with respect to a stator (12) and having a plurality of stator vanes (20) positioned downstream of the impeller (10) and having a plurality of stator vanes (20), and between Impeller (10) and the stator (12) has a Radseitenraum (28) is formed. Flow inlet edges (22) of the stator vanes (20) lie on a first circular contour, namely such that the flow inlet edges (22) of all the stator vanes (20) to the flow inlet edges (22) of the respective adjacent vanes (20) have an identical distance. Flow outlet edges (23) of the stator vanes (20) lie on a second circular contour, namely such that at at least one first circumferential position the flow outlet edge (23) of the respective stator side vane (20) to the flow outlet edge (23) of at least one adjacent vanes (20) has a different distance than at second circumferential positions.

Description

The invention relates to a radial compressor stage for a radial compressor according to the Oberbergriff of claim 1, 4 and 5 respectively.

From the DE 195 02 808 C2 is the basic structure of a centrifugal compressor with at least one radial compressor stage known. Thus, it is disclosed in this prior art that the or each radial compressor stage of a radial compressor comprises an impeller rotating with respect to a stator, the impeller comprising a hub and a plurality of rotor-side impeller blades. Each impeller vane of the impeller has a flow entrance edge and a flow exit edge, wherein a suction side, a pressure side, and an outer surface facing the stator extend between the flow entrance edge and the flow exit edge of each impeller vane, the outer surface of the respective impeller vane adjacent to the stator and sealing against the stator vane Stator is used. Such an impeller of a centrifugal compressor, in which the outer surfaces of the impeller blades indirectly adjacent to the stator, has no shroud and is also referred to as an open impeller. The impeller blades are positioned in an impeller flow passage delimited by the hub of the impeller and the stator.

Furthermore, it is from the DE 195 02 808 C2 It is known that the centrifugal compressor stage includes a diffuser positioned downstream of the impeller having a plurality of stator vanes. Each of the vanes of the diffuser has a flow inlet edge and a flow outlet edge, wherein a suction side and a pressure side extend between the flow inlet edge and the flow outlet edge of each guide vanes. The vanes are positioned in a diffuser flow channel defined by the stator.

From the DE 195 02 802 C2 can be seen that between the impeller and the stator of the radial compressor stage shown there is formed a so-called Radseitenraum, namely between a rear side of the impeller and the stator. This wheel side space is connected to an intermediate flow passage extending between the impeller flow passage and the diffuser flow passage.

Another radial compressor stage with such a Radseitenraum is from the DE 10 2007 019 264 A1 known.

From the EP 2 014 925 A1 is a radial compressor stage with a diffuser known, in which the angular distance of flow inlet edges of two adjacently arranged guide elements is different from the angular distance of flow inlet edges of two other adjacently arranged guide elements.

During operation of a radial compressor, the centrifugal compressor stages are exposed to mechanical stimuli and vibrations which can cause damage to the radial compressor stage, in particular to the rotor blades of the impeller of the radial compressor stage. Such mechanical excitations can be based on synchronous excitation mechanisms as well as on asynchronous excitation mechanisms.

In particular, three-dimensional and transient flow phenomena are generated by the interaction of rotating and stationary components. Under certain conditions, pressure fluctuations occur, which have a direction of rotation or of a direction opposite to that in the direction of rotation. The number and the circulation speed of these pressure fluctuations is arbitrary.

This phenomenon is the basis for asynchronous excitation of open impellers in centrifugal compressors. So far, no methods are known with the aid of which such asynchronous suggestions can be specifically counteracted to avoid a critical vibration excitation in particular of the impeller blades of the impeller.

There is therefore a need for a radial compressor stage for a radial compressor, in which in particular the impeller blades of the impeller are exposed to a low vibration excitation, in particular by such asynchronous excitations.

Proceeding from this, the present invention has the object to provide a radial compressor stage for a centrifugal compressor, which meets the above requirements and therefore a low vibration excitation is exposed in particular by such asynchronous excitations.

This object is achieved according to a first aspect of the invention by a radial compressor stage according to claim 1. Thereafter, the flow inlet edges of the stator vanes of the diffuser lie on a first circular contour, namely such that the flow inlet edges of all the stator vanes have an identical distance to the flow inlet edges of the respective adjacent vanes. The flow outlet edges of the stator-side guide vanes of the diffuser lie on a second circular contour, namely such that at at least one first circumferential position, the flow outlet edge of the respective stator-side vane to the flow outlet edge of at least one adjacent vanes has a different distance than at second circumferential positions.

According to a second aspect of the invention, this object is achieved by a radial compressor stage according to claim 4. After this, at least one stator-side guide vane of the diffuser has a curvature deviating from the other stator-side guide vanes.

According to a third aspect of the invention, this object is achieved by a radial compressor stage according to claim 5. Hereinafter, at least a first circumferential position, a diffuser flow channel section formed between adjacent stator-side guide vanes of the diffuser has a flow cross-section deviating from the diffuser flow channel sections formed at second circumferential positions.

With any of the above aspects of the invention, asynchronous excitations of open wheels in radial compressors can be easily and reliably counteracted, whereby the vibration excitation can be reduced in particular for the impeller blades of the impeller of the radial compressor stage.

In this case, the above aspects of the invention can be used either alone or preferably in combination of several such inventive aspects of a radial compressor stage.

The above aspects of the invention all relate to structural design of the diffuser.

Preferred embodiments of the invention will become apparent from the dependent claims and the description below. Embodiments of the invention will be described, without being limited thereto, with reference to the drawings. Showing:

1 a meridional section through a radial compressor stage according to the invention according to a first aspect of the invention;

2 : An axial section through the radial compressor stage of 1 ;

3 : An axial section through a radial compressor stage according to a second aspect of the invention; and

4 FIG. 2: A meridional section through a radial compressor stage according to the invention according to a third aspect of the invention. FIG.

The present invention relates to a centrifugal compressor with at least one radial compressor stage.

1 shows a detail of a radial compressor stage according to the invention in meridional section according to a first aspect of the invention, wherein 2 an axial section through the radial compressor stage of 1 shows.

The radial compressor stage of 1 has an impeller 10 with several rotor-side impeller blades 11 on. The impeller 10 rotates with respect to a stator 12 , At the stator 12 it may be a housing or a stator ring or the like. The impeller blades 11 are in an impeller flow channel 13 positioned by a rotor-side hub contour 14 and a stator contour 15 limited. Every impeller blade 11 has a flow inlet edge 16 and a flow exit edge 17 on. Between the flow inlet edge 16 and the flow exit edge 17 every impeller blade 11 extends a pressure side, a suction side and radially outward on the impeller blade 11 one the stator 12 facing outer surface 18 the respective impeller blade 11 , The outer surface 18 the impeller blade 11 adjoins the stator 12 and serves to seal against the stator 12 , Such an impeller 10 in which the outer surfaces 18 the impeller blades 11 indirectly to the stator 12 border, has no shroud and is also referred to as an open impeller.

According to 1 is downstream of the impeller 10 a stator-side diffuser 19 positioned. The diffuser 19 includes a plurality of stator vanes 20 , The stator-side vanes 20 of the diffuser 19 are in one of the stator 12 limited diffuser flow channel 21 positioned, wherein each of the stator vanes 20 of the diffuser 19 a flow entry edge 22 and a flow exit edge 23 includes. Between the flow inlet edge 22 and the flow exit edge 23 the respective stator-side vane 20 extends a suction side 24 and a print page 25 the respective vane.

Between the flow channel 13 in which the rotor-side impeller blades 11 of the impeller 10 are positioned, and the diffuser flow channel 21 in which the stator-side vanes 20 of the diffuser 19 are positioned, an intermediate flow channel extends 26 , over which in the centrifugal compressor stage compressed medium starting from the impeller 10 towards the diffuser 19 can flow. According to 1 is between a back 27 of the impeller 10 and the stator 12 a wheel side room 28 formed, with this Radseitenraum 28 according to 1 with the Between flow channel 26 over a gap 34 is coupled.

The above with reference to 1 and 2 described details of a radial compressor stage are state of the art.

The invention now relates to such details of a centrifugal compressor stage, with the help of which the risk of transient flow phenomena, which can lead to an asynchronous excitation of the open wheels, can be reduced.

According to a first aspect of the invention, with reference to 1 and 2 will be described below, are all flow inlet edges 22 all stator-side vanes 20 of the diffuser 19 on a first circle contour 29 ,

Here are the flow inlet edges 22 the stator-side vanes 20 of the diffuser 19 such on the first circle contour 29 in that the flow entry edges 22 all stator-side vanes 20 to the flow entry edges 22 the respective adjacent vanes 20 have an identical distance. The flow inlet edges 22 in the circumferential direction of the diffuser flow channel 21 seen side by side positioned vanes 20 of the diffuser 19 are therefore equally distributed in the circumferential direction, so that therefore all flow inlet edges 22 that are on the first circle contour 29 lie, to adjacent flow entry edges 22 have identical circumferential distances.

According to the first aspect of the invention is further provided that the flow outlet edges 23 the stator-side vanes 20 of the diffuser 19 on a second circular contour 30 lie.

Here are the flow outlet edges 23 the stator-side vanes 20 of the diffuser 19 such on the second circle contour 30 in that at least a first circumferential position of the diffuser flow channel 21 the flow outlet edge 23 the respective stator-side vane positioned there 20 to the flow exit edge of at least one adjacent vane 20 has a different distance than at second circumferential positions of the diffuser flow channel 21 ,

In the area of the flow outlet edges 23 is therefore in the circumferential direction of the diffuser flow channel 21 seen no uniform distribution of the flow outlet edges 23 provided, but preferably at the first circumferential positions, the uniform distribution of the flow outlet edges 23 all on the second circle contour 30 lifted, so as to reduce the risk of unsteady flow phenomena, which can lead to an asynchronous excitation of the open wheels.

According to the first aspect of the invention, it is possible in a first extreme case that exclusively at a single circumferential position of the diffuser flow channel 21 the corresponding flow outlet edge 23 another distance to the respective adjacent flow outlet edges 23 has, however, that on the other circumferential positions, the flow outlet edges 23 are equally distributed in terms of their circumferential positions.

Likewise, it is possible according to the first aspect of the invention in a second extreme case that at all circumferential positions of the diffuser flow channel 21 the flow outlet edges 23 to the respective adjacent flow outlet edges 23 each have different distances.

At the second circumferential positions of the diffuser flow channel 21 have the respective stator-side vanes 20 of the diffuser 19 preferably all identical second graduation angles.

The stator vanes positioned at the or each first circumferential position 20 however, preferably have a first stagger angle which deviates from the second stagger angle, in particular by ± 10 °, preferably by ± 7 °, more preferably by ± 5 °, most preferably by ± 3 °.

According to the first aspect of the present invention, it is therefore proposed to reduce the risk of unsteady flow phenomena, which can lead to an asynchronous excitation of the open wheels, the flow outlet edges 23 selected stator-side vanes 20 of the diffuser 19 in the circumferential direction, preferably with suspension or interruption of the otherwise in the circumferential direction of the Diffusorströmungskanals 21 seen equally distributed flow outlet edges 23 ,

In an extreme case, the flow outlet edges 23 all stator-side vanes 20 of the diffuser 19 to the respective adjacent flow outlet edges 23 have different distances.

As 2 can be removed, a flow outlet edge 23 '' (see dashed line of in 2 right vane) in the direction of the pressure side 25 the respective adjacent vane 20 or a flow outlet edge 23 ' (see dashed line of in 2 left vane) in the direction of the suction side 24 the respective adjacent vane 20 be shifted in the circumferential direction, in such a way that still all flow outlet edges 23 on the second circle contour 30 lie.

This corresponds to a change in the staggering angle of the stator-side guide vanes 20 of the diffuser 19 at selected circumferential positions. At selected second circumferential positions of the diffuser 19 have the respective stator-side vanes 20 about different graduation angles.

Those selected vanes 20 , compared to the other stator vanes 20 have a different staggering angle, are characterized in that their stagger angle in particular by ± 10 °, more preferably by ± 5 °, of the stagger angles of the other vanes 20 of the diffuser 19 differs.

By the above measures of the first aspect of the present invention, at defined circumferential positions at non-uniform circumferential distances, a slightly higher or a somewhat lower load from the guide vanes 20 of the diffuser 19 be imprinted. The danger of unsteady flow phenomena, which can lead to an asynchronous excitation of the open wheels, can thus be reduced.

According to a second aspect of the invention (see 3 ) is proposed to reduce the risk of unsteady flow phenomena, which can lead to an asynchronous excitation of the open wheels, that both on the first circle contour 29 positioned flow entry edges 22 the stator-side vanes 20 of the diffuser 19 as well as on the second circle contour 30 positioned flow outlet edges 23 the stator-side vanes 20 of the diffuser 19 are equally distributed in the circumferential direction, ie each having identical circumferential distances.

According to the second aspect of the invention, however, has at least one stator vane 20 of the diffuser 19 between the flow inlet edge 22 and the flow exit edge 23 a different curvature, namely a suction side 24 ' and a print page 25 ' with respect to the other vanes 20 deviating curvature. This is in 3 by the dashed curve for the middle vane 20 shown.

According to the second aspect of the invention, it is possible in a first extreme case that only a single stator vane 20 of the diffuser 19 has a different curvature, however, that all other stator vanes 20 of the diffuser 19 have identical curvatures.

Likewise, according to the second aspect of the invention, in a second extreme case, it is possible to apply to all stator vane 20 of the diffuser 19 have different curvatures.

It is preferred to use the first aspect of the invention and the second aspect of the invention in combination with one another to reduce the risk of transient flow phenomena that can lead to asynchronous excitation of the open wheels on the centrifugal compressor stage.

A third aspect of the present invention will be described below with reference to FIG 4 discussed.

According to the third aspect of the invention, in order to reduce the risk of unsteady flow phenomena which may lead to asynchronous excitation of the open wheels, it is proposed to provide at least a first circumferential position of the diffuser flow channel 21 one between adjacent stator vanes 20 of the diffuser 19 formed diffuser flow channel section 33 to change such that it has a different flow cross-section with respect to the diffuser flow channel sections formed at second circumferential positions.

So can 4 be taken that at a first circumferential position of the diffuser 19 between adjacent stator vanes 20 the respective diffuser flow channel section 33 has a reduced flow cross-section, namely, characterized in that the respective diffuser flow channel section 33 limiting, stator side walls 31 . 32 while reducing the flow area of the respective diffuser flow channel section 33 are curved inwards. It should be pointed out that only one of these stator-side, the respective diffuser flow channel section 33 bounding sidewalls 31 . 32 into the respective diffuser flow channel section 33 can be arched into it. It is likewise possible to widen the respective diffuser flow channel section with respect to its flow cross section at selected circumferential positions, in which case at least one of these side walls 31 . 32 out into the stator 12 is arched into it.

According to the third aspect, it is possible in a first extreme case that exclusively at a single circumferential position of the diffuser flow channel 21 the corresponding diffuser flow channel section 33 has a different flow cross-section that, however, all other diffuser flow channel sections 33 have identical flow cross sections.

Likewise, according to the third aspect of the invention, in a second extreme case it is possible that at all circumferential positions of the diffuser flow channel 21 the diffuser flow channel sections 33 each have different flow cross-sections.

The measures of the third aspect can be used in combination with the measures of the first aspect and / or the measures of the second aspect. The measures of the third aspect are preferably used in combination with the measures of the first aspect and with the measures of the second aspect on a radial compressor stage.

LIST OF REFERENCE NUMBERS

10

Wheel

11

impeller blade

12

stator

13

Impeller flow channel

14

hub contour

15

stator contour

16

Flow inlet edge

17

Flow outlet edge

18

outer surface

19

diffuser

20

vane

21

Diffuser flow channel

22

Flow inlet edge

23

Flow outlet edge

24

suction

25

pressure side

26

Between flow channel

27

back

28

wheel side

29

circular contour

30

circular contour

31

Side wall

32

Side wall

33

Diffuser flow channel section

34

gap

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19502808 C2 [0002, 0003]
• DE 19502802 C2 [0004]
• DE 102007019264 A1 [0005]
• EP 2014925 A1 [0006]

Claims (6)

Radial compressor stage, the one opposite a stator ( 12 ) rotating impeller ( 10 ) with a plurality of rotor-side impeller blades ( 11 ) and one downstream of the impeller ( 10 ) positioned diffuser ( 19 ) with a plurality of stator-side vanes ( 20 ), and wherein between the impeller ( 10 ) and the stator ( 12 ) a Radseitenraum ( 28 ) is formed, characterized in that flow inlet edges ( 22 ) of the stator-side vanes ( 20 ) on a first circular contour ( 29 ), namely such that the flow entry edges ( 22 ) of all stator-side vanes ( 20 ) to the flow entry edges ( 22 ) of the respective adjacent guide vanes ( 20 ) have an identical distance; Flow outlet edges ( 23 ) of the stator-side vanes ( 20 ) on a second circular contour ( 30 ), namely such that at at least one first circumferential position the flow outlet edge ( 23 ) of the respective stator-side vane ( 20 ) to the flow exit edge ( 23 ) at least one adjacent guide vanes ( 20 ) has a different distance than at second circumferential positions. Radial compressor stage according to claim 1, characterized in that at the second circumferential positions the respective stator-side guide vanes ( 20 ) all have identical second stagger angles; and at the or each first circumferential position, the respective stator-side vanes ( 20 ) has a first stagger angle that deviates from the second stagger angle. Radial compressor stage according to claim 2, characterized in that, the first grading angle deviates from the second grading angle by ± 10 °, preferably by ± 7 °, particularly preferably by ± 5 °. Radial compressor stage, the one opposite a stator ( 12 ) rotating impeller ( 10 ) with a plurality of rotor-side impeller blades ( 11 ) and one downstream of the impeller ( 10 ) positioned diffuser ( 19 ) with a plurality of stator-side vanes ( 20 ), and wherein between the impeller ( 10 ) and the stator ( 12 ) a Radseitenraum ( 28 ), characterized in that at least one stator vane ( 20 ) one of the other stator-side vanes ( 20 ) has a different curvature. Radial compressor stage, the one opposite a stator ( 12 ) rotating impeller ( 10 ) with a plurality of rotor-side impeller blades ( 11 ) and one downstream of the impeller ( 10 ) positioned diffuser ( 19 ) with a plurality of stator-side vanes ( 20 ), and wherein between the impeller ( 10 ) and the stator ( 12 ) a Radseitenraum ( 28 ), characterized in that at at least one first circumferential position a between adjacent stator-side vanes ( 20 ) formed diffuser flow channel section ( 33 ) has a flow cross section deviating from the diffuser flow channel sections formed at second circumferential positions. Radial compressor stage according to claim 5, characterized in that opposite to the second circumferential positions at the or each first circumferential position between the adjacent stator-side vanes ( 20 ) at least one of the diffuser flow channel section ( 33 ) limiting sidewall ( 31 . 32 ) while reducing the flow area inwardly into the diffuser flow channel section (FIG. 33 ) and / or under enlargement of the flow cross-section to the outside in the stator ( 12 ) is arched into it.

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