U.S. patent application number 14/842397 was filed with the patent office on 2016-03-03 for radial compressor stage.
This patent application is currently assigned to MAN Diesel & Turbo SE. The applicant listed for this patent is Yves BIDAUT, Philipp JENNY, Thomas MOKULYS, Samuel SCHNEIDER, Christof SEEBASS-LINGGI. Invention is credited to Yves BIDAUT, Philipp JENNY, Thomas MOKULYS, Samuel SCHNEIDER, Christof SEEBASS-LINGGI.
Application Number | 20160061212 14/842397 |
Document ID | / |
Family ID | 54056112 |
Filed Date | 2016-03-03 |
United States Patent
Application |
20160061212 |
Kind Code |
A1 |
MOKULYS; Thomas ; et
al. |
March 3, 2016 |
RADIAL COMPRESSOR STAGE
Abstract
A radial compressor stage includes: an impeller, rotatable
relative to a stator, the impeller having multiple impeller blades
on a rotor side; a diffuser positioned in a flow direction
downstream of the impeller, the diffuser having multiple guide
blades on the stator side; an impeller side gap formed between the
impeller and the stator; and an intermediate flow channel extending
between the impeller and the diffuser. A gap is formed between an
outer edge of a downstream back side of the impeller and an
opposite inner edge of the stator, the gap being sealed via a seal
such that the seal seals the impeller side gap from the
intermediate flow channel.
Inventors: |
MOKULYS; Thomas; (Xanten,
DE) ; JENNY; Philipp; (Ennetbuergen, CH) ;
SEEBASS-LINGGI; Christof; (Wettingen, CH) ; BIDAUT;
Yves; (Reutlingen, CH) ; SCHNEIDER; Samuel;
(Zuerich, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MOKULYS; Thomas
JENNY; Philipp
SEEBASS-LINGGI; Christof
BIDAUT; Yves
SCHNEIDER; Samuel |
Xanten
Ennetbuergen
Wettingen
Reutlingen
Zuerich |
|
DE
CH
CH
CH
CH |
|
|
Assignee: |
MAN Diesel & Turbo SE
|
Family ID: |
54056112 |
Appl. No.: |
14/842397 |
Filed: |
September 1, 2015 |
Current U.S.
Class: |
415/173.1 ;
415/208.2; 415/211.2 |
Current CPC
Class: |
F05D 2250/283 20130101;
F04D 17/10 20130101; F04D 29/162 20130101; F04D 29/444 20130101;
F05D 2240/57 20130101; F04D 29/284 20130101; F05D 2250/611
20130101; F05D 2240/56 20130101 |
International
Class: |
F04D 29/16 20060101
F04D029/16; F04D 29/28 20060101 F04D029/28; F04D 29/44 20060101
F04D029/44; F04D 17/10 20060101 F04D017/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 2, 2014 |
DE |
DE 102014012764.8 |
Claims
1. A radial compressor stage comprising: an impeller (10), rotating
relative to a stator (12), the impeller (10) having multiple
impeller blades (11) on a rotor side; a diffuser (19) positioned in
a flow direction downstream of the impeller (10), the diffuser (19)
having multiple guide blades (20) on the stator side; an impeller
side gap (28) formed between the impeller (10) and the stator (12);
and an intermediate flow channel (26) extending between the
impeller (10) and the diffuser (19), wherein a gap (34) is formed
between an outer edge (35) of a downstream back side (27) of the
impeller (10) and an opposite inner edge (36) of the stator (12),
the gap (34) being sealed via a seal (37) such that the seal (37)
seals the impeller side gap (18) from the intermediate flow channel
(26).
2. The radial compressor stage according to claim 1, wherein the
seal (37) is supported by the stator (12) and is located opposite
the outer edge (35) of the downstream back side (27) of the
impeller (10).
3. A radial compressor stage comprising: an impeller (10),
rotatable relative to a stator (12), the impeller (10) having
multiple impeller blades (11) on a rotor side; a diffuser (19)
positioned in a flow direction downstream of the impeller (10), the
diffuser having multiple guide blades (20) on the stator side; and
an impeller side gap (28) formed between the impeller (10) and the
stator (12), wherein a gap (34) is formed between an outer edge
(35) of a downstream back side (27) of the impeller (10) and an
opposite inner edge (36) of the stator (12), the gap (34), seen in
a circumferential direction, has a varying gap dimension.
4. The radial compressor stage according to claim 3, wherein the
inner edge (36) of the stator (12), seen in a circumferential
direction, has a wavelike contour.
5. The radial compressor stage according to claim 1, wherein the
guide blades (20) have flow inlet edges (22) on the stator side,
wherein the flow inlet edges (22) lie on a first circle contour
(29) such that the flow inlet edges (22) of all guide blades (20)
on the stator side have an identical distance from the flow inlet
edges (22) of the respective adjacent guide blades (20); and the
guide blades (20) have flow outlet edges (23) on the stator side,
wherein the flow outlet edges (23) lie on a second circle contour
(30), such that in at least one first circumferential position the
flow outlet edge (23) of the respective guide blade (20) on the
stator side has a distance to the flow outlet edge (23) that is
different from the distance to the flow outlet edge (23) of at
least one adjacent guide blade (20) in second circumferential
positions.
6. The radial compressor stage according to claim 5, wherein in the
second circumferential positions the respective guide blades (20)
on the stator side all have identical second stepping angles; and
in the, or each, first circumferential position the respective
guide blades (20) on the stator side has a first stepping angle
that deviates from the second stepping angle.
7. The radial compressor stage according to claim 6, wherein the
first stepping angle deviates from the second stepping angle by
.+-.10.degree..
8. The radial compressor stage according to claim 1, wherein at
least one guide blade (20) on the stator side has a curvature that
deviates from the other guide blades (20) on the stator side.
9. The radial compressor stage according to claim 1, further
comprising a plurality of diffuser flow channel sections (33) each
formed between adjacent guide blades (20) on the stator side,
wherein in at least one first circumferential position a diffuser
flow channel section (33) formed between adjacent guide blades (20)
on the stator side has a flow cross section that deviates relative
to the diffuser flow channel sections formed in second
circumferential positions.
10. The radial compressor stage according to claim 9, wherein
relative to the second circumferential positions in the, or each,
first circumferential position between the adjacent guide blades
(20) on the stator side at least one sidewall (31, 32) bounding the
diffuser flow channel section (33) is curved inwardly into the
diffuser flow channel section (33) so as to reduce the flow cross
section and/or curved outwardly into the stator (12) subject so as
to increase the flow cross section.
11. The radial compressor stage according to claim 6, wherein the
first stepping angle deviates from the second stepping angle by
.+-.7.degree..
12. The radial compressor stage according to claim 6, wherein the
first stepping angle deviates from the second stepping angle by
.+-.5.degree..
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a radial compressor stage for a
radial compressor.
[0003] 2. Description of the Related Art
[0004] From DE 195 02 808 C2 the fundamental construction of a
radial compressor having at least one radial compressor stage is
known. Accordingly, 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, wherein the impeller
comprises a hub and multiple impeller blades on the rotor side.
Each impeller blade of the impeller comprises a flow inlet edge and
a flow outlet edge, wherein between the flow inlet edge and the
flow outlet edge of each impeller blade a suction side, a pressure
side and an outer surface facing the stator extends, wherein the
outer surface of the respective impeller blade borders the stator
and serves for sealing relative to the stator. Such an impeller of
a radial compressor, in which the outer surfaces of the impeller
blades directly border the stator, does not comprise a shroud and
is also called an open impeller. The impeller blades are positioned
in an impeller flow channel that is bounded by the hub of the
impeller and the stator.
[0005] Furthermore it is known from DE 195 02 808 C2 that the
radial compressor stage comprises a diffuser positioned downstream
of the impeller, which comprises multiple guide blades on the
stator side. Each guide blade of the diffuser has a flow inlet edge
and a flow outlet edge, wherein between the flow inlet edge and the
flow outlet edge of each guide blade a suction side and a pressure
side extends. The guide blades are positioned in a diffuser flow
channel bounded by the stator.
[0006] From DE 195 02 802 C2 it is evident that between the
impeller and the stator of the radial compressor stage shown there,
a so-called impeller side gap is formed, namely between a back side
of the impeller and the stator. This impeller side gap is connected
to an intermediate flow channel that extends between the impeller
flow channel and the diffuser flow channel.
[0007] A further radial compressor stage with such an impeller side
gap is known from DE 10 2007 019 264 A1.
[0008] From EP 2 014 925 A1 a radial compressor stage with a
diffuser is known, in which the angular spacing of flow inlet edges
of two guide elements arranged adjacent to one another differs from
the angular spacing of flow inlet edges of two other guide elements
arranged adjacent to one another.
[0009] During the operation of a radial compressor, the radial
compressor stages are exposed to mechanical excitations and
oscillations, which can cause damage to the radial compressor
stage, in particular to the impeller blades of the impeller of the
radial compressor stage. Such mechanical excitations can be based
on synchronous excitation mechanisms and on asynchronous excitation
mechanisms.
[0010] In particular, three-dimensional and unsteady flow phenomena
are generated through the interaction of rotating and stationary
components. Under certain conditions, pressure fluctuations develop
which have a character rotating in direction of rotation or in a
direction that is opposite to the direction of rotation. The number
and the rotating speed of these pressure fluctuations are
arbitrary.
[0011] This phenomenon is the basis of an asynchronous excitation
of open impellers in radial compressors. Up to now, no methods are
known that can specifically counteract such asynchronous
excitations in order to avoid a critical vibration excitation, in
particular of the impeller blades of the impeller.
[0012] 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 low vibration excitation in particular
through such asynchronous excitations.
SUMMARY OF THE INVENTION
[0013] Starting out from this, it is an object of the present
invention to create a radial compressor stage for a radial
compressor that fulfils the above requirements and accordingly is
exposed to a low vibration excitation in particular through such
asynchronous excitations.
[0014] According to a first aspect of the invention, this object is
solved through a radial compressor stage such that a gap, which is
formed between an outer edge of the downstream back side of the
impeller and an opposite edge of the stator, is sealed via a seal
in such a manner that the seal seals the impeller side gap from an
intermediate flow channel extending between the impeller and the
diffuser.
[0015] According to a second aspect of the invention, this object
is solved through a radial compressor stage such that a gap, which
is formed between an outer edge of a downstream back side of the
impeller and an opposite inner edge of the stator, seen in
circumferential direction, has a varying gap dimension.
[0016] With each of the two above aspects according to the
invention, asynchronous excitations of open impellers in radial
compressors can be easily and reliably counteracted, as a result of
which the vibration excitation in particular for the impeller
blades of the impeller of the radial compressor stage can be
reduced. The aspects according to the invention are alternatively
employed on a radial compressor stage.
[0017] The two above aspects according to the invention concern
measures that relate to the coupling of the impeller side gap to
the intermediate flow channel extending between the impeller flow
channel and the diffuser flow channel. The vibration excitation for
the impeller blades of the impeller of the radial compressor stage
can be reduced.
[0018] According to an advantageous further development of the
first and/or second aspect according to the invention it is
provided that the flow inlet edges of the guide blades of the
diffuser on the stator side lie on a first circle contour in such a
manner that the flow inlet edges of all guide blades on the stator
side have an identical spacing from the flow inlet edges of the
respective adjacent guide blades. The flow outlet edges of the
guide blades of the diffuser on the stator side lie on a second
circle contour in such a manner that in at least one first
circumferential position the flow outlet edge of the respective
guide blade on the stator side has a spacing from the flow outlet
edge of at least one adjacent guide blade other than in second
circumferential positions.
[0019] According to a further advantageous further development of
the first and/or second aspect according to the invention it is
provided that at least one guide blade of the diffuser on the
stator side has a curvature which deviates from the other guide
blades on the stator side.
[0020] According to a further advantageous development of the first
and/or second aspect of the invention it is provided that in at
least one first circumferential position a diffuser flow channel
section formed between adjacent guide blades of the diffuser on the
stator side has a flow cross section that deviates with respect to
the diffuser flow channel sections formed in second circumferential
positions.
[0021] The above advantageous further developments of the first
and/or second aspect according to the invention relate to measures
for the design configuration of the diffuser.
[0022] Particularly preferred is a radial compressor stage on which
one of the aspects according to the invention, which relate to the
coupling of the impeller side gap to the intermediate flow channel,
combined with at least one of the advantageous further
developments, which relate to the configuration of the diffuser,
are employed.
[0023] Other objects and features of the present invention will
become apparent from the following detailed description considered
in conjunction with the accompanying drawings. It is to be
understood, however, that the drawings are designed solely for
purposes of illustration and not as a definition of the limits of
the invention, for which reference should be made to the appended
claims. It should be further understood that the drawings are not
necessarily drawn to scale and that, unless otherwise indicated,
they are merely intended to conceptually illustrate the structures
and procedures described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Preferred further developments of the invention are obtained
from the following description. Exemplary embodiments of the
invention are explained in more detail with the help of the
drawings without being restricted to this. In the drawings:
[0025] FIG. 1: shows a meridional section of a radial compressor
stage according to the invention according to a first aspect of the
invention;
[0026] FIG. 2: shows a meridional section of a further radial
compressor stage according to the invention according to the first
aspect of the invention;
[0027] FIG. 3: shows a meridional section of a radial compressor
stage according to the invention according to a second aspect of
the invention;
[0028] FIG. 4: shows an axial section through the radial compressor
stage of FIG. 3;
[0029] FIG. 5: shows an axial section through a radial compressor
stage for illustrating a first advantageous further development of
the first and/or second aspect according to the invention;
[0030] FIG. 6: shows an axial section through a radial compressor
stage for illustrating a second advantageous further development of
the first and/or second aspect according to the invention; and
[0031] FIG. 7: shows a meridional section through a radial
compressor stage for illustrating a third advantageous further
development of the first and/or second aspect according to the
invention.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0032] The present invention relates to a radial compressor with at
least one radial compressor stage.
[0033] FIG. 1 shows a detail of a radial compressor stage according
to the invention in meridional section according to a first aspect
of the invention.
[0034] The radial compressor stage of FIG. 1 comprises an impeller
10 with multiple impeller blades 11 on the rotor side. The impeller
10 rotates relative to the stator 12. The stator 12 can be a
housing or a stator ring or the like. The impeller blades 11 are
positioned in an impeller flow channel 13 which is bounded by a hub
contour 14 on the rotor side and a stator contour 15. Each impeller
blade 12 comprises a flow inlet edge 16 and a flow outlet edge 17.
Between the flow inlet edge 16 and the flow outlet edge 17 of each
impeller blade 11 a pressure side, a suction side and radially
outside on the impeller blade 11 an outer surface 18 of the
respective impeller blade 11 facing the stator 12 extends. The
outer surface 18 of the impeller blade 11 borders the stator 12 and
serves for sealing relative to the stator 12. Such an impeller 10,
in the case of which the outer surfaces 18 of the impeller blades
11 indirectly border the stator 12, does not have a shroud and is
also called an open impeller.
[0035] According to FIG. 1, a diffuser 19 on the stator side is
positioned downstream of the impeller 10. The diffuser 19 comprises
multiple guide blades 20 on the stator side. The guide blades 20 of
the diffuser 19 on the stator side are positioned in a diffuser
flow channel 21 bounded by the stator 12, wherein each of the guide
blades 20 of the diffuser 19 on the stator side comprises a flow
inlet edge 22 and a flow outlet edge 23. Between the flow inlet
edge 22 and the flow outlet edge 23 of the respective guide blade
20 on the stator side a suction side 24 and a pressure side 25 of
the respective guide blade extends. (See FIG. 5.)
[0036] Between the impeller flow channel 13, in which the impeller
blades 11 of the impeller 10 on the rotor side are positioned, and
the diffuser flow channel 21, in which the guide blades 20 of the
diffuser 19 on the stator side are positioned, an intermediate flow
channel 26 extends, via which medium compressed in the radial
compressor stage starting out from the impeller 10 can flow in the
direction of the diffuser 16. According to FIG. 1, an impeller side
gap 28 is formed between a back side 27 of the impeller 10 and the
stator 12, wherein this impeller side gap 28 according to FIG. 1 is
coupled to the intermediate flow channel 26 via a gap 34.
[0037] The details of a radial compressor stage described above
making reference to FIG. 1 count among the prior art. The invention
now relates to such details of a radial compressor stage with the
help of which the danger of unsteady flow phenomena, which can lead
to an asynchronous excitation of the open impellers, can be
reduced.
[0038] According to a first aspect of the invention (see FIG. 1, 2)
it is proposed that the gap 34, which is formed between an outer
edge 35 of the downstream back side 27 of the impeller 10 and an
opposite inner edge 36 of the stator 12, and via which the impeller
side gap 28 is coupled to the intermediate flow channel 26, is
sealed via a seal 37.
[0039] Accordingly, the seal 37 seals the impeller side gap 28 from
the intermediate flow channel 26 running between the impeller 10
and the diffuser 19. For this purpose, a honeycomb-shaped seal 37
is employed in the exemplary embodiment of FIG. 1, which is
supported by the stator 12 and is located opposite the outer edge
35 of the downstream back side 27 of the impeller 10. Through such
sealing of the gap 34 and thus of the impeller side gap 28 relative
to the intermediate flow channel 26 the danger of unsteady flow
phenomena, which can lead to an asynchronous excitation of the open
impellers, can be reduced.
[0040] FIG. 2 shows a configuration of a radial compressor stage
according to the first aspect of the present invention, which
differs from the exemplary embodiment of FIG. 1 by the specific
configuration of the seal 37. Accordingly, no honeycomb seal is
employed in FIG. 2. Rather, the seal in the exemplary embodiment of
FIG. 2 is designed as a lip-type seal, with which accordingly a
sealing lip 38 comes to lie against the outer edge 35 of the
downstream back side 27 of the impeller 10. This sealing element 37
of FIG. 2 can, for example, be a wiping seal or touch seal or a
brush seal.
[0041] A radial compressor stage according to a second aspect of
the invention is shown in FIGS. 3 and 4. According to the second
aspect of the invention it is proposed that the gap 34, via which
the impeller side gap 28 is coupled to the intermediate flow
channel 26, seen in circumferential direction, has a varying gap
dimension. To this end, the inner edge 36' of the stator 12 located
opposite the outer edge 35 of the downstream back side 27 of the
impeller 10 is contoured wavelike according to the dashed line
course of FIG. 4, so that accordingly seen in circumferential
direction the spacing between the inner edge 36' of the stator 12
and of the outer edge 35 of the downstream back side 27 of the
impeller 10 is not constant, but rather variable.
[0042] Through the wavelike contour of the inner edge 36' of the
stator 12, this gap dimension of the gap 34 that is variable in
circumferential direction preferentially varies steadily, i.e., not
step-like.
[0043] The above measures according to the first aspect of the
invention and according to the second aspect of the invention are
alternatives. Thus, these measures are not employed in combination
with one another.
[0044] According to a first advantageous further development of the
first aspect and/or second aspect of the invention it is provided
(see FIG. 5) that all flow inlet edges 22 of all guide blades 20 of
the diffuser 19 on the stator side lie on a first circle contour
29.
[0045] Here, the flow inlet edges 22 of the guide blades 20 of the
diffuser 19 on the stator side lie on the first circle contour 29
such that the flow inlet edges 22 of all guide blades 20 on the
stator side have an identical spacing from the flow inlet edges 22
of the respective adjacent guide blades 20. The flow inlet edges 22
of the guide blades 20 of the diffuser 19 located seen in
circumferential direction of the diffuser flow channel 21 next to
one another are accordingly evenly distributed seen in
circumferential direction, so that accordingly all flow inlet edges
22, which lie on the first circle contour 29, have identical
circumferential distances to adjacent flow inlet edges 22.
[0046] According to the first advantageous further development of
the first aspect and/or second aspect of the invention it is
provided, furthermore, that the flow outlet edges 23 of the guide
blades 20 of the diffuser 19 on the stator side lie on a second
circle contour 30.
[0047] Here, the flow outlet edges 23 of the guide blades 20 of the
diffuser 19 on the stator side lie on the second circle contour 30
such that, in at least one first circumferential position of the
diffuser flow channel 21, the flow outlet edge 23 of the respective
guide blade 20 on the stator side positioned there has a distance
from the flow outlet edge of at least one adjacent guide blade 20
other than in second circumferential positions of the diffuser flow
channel 21.
[0048] Accordingly, in the region of the flow outlet edges 23, no
equal distribution of the flow outlet edges 23 is provided seen in
circumferential direction of the diffuser flow channel 21. On the
contrary, the equal distribution of the flow outlet edges 23, which
all lie on the second circle contour 30, is preferentially
cancelled in the first circumferential positions in order to
thereby reduce the risk of unsteady flow phenomena, which can lead
to an asynchronous excitation of the open impellers.
[0049] According to the first advantageous further development of
the first aspect and/or second aspect of the invention it is
possible in a first extreme case that the corresponding flow outlet
edge 23 in a single circumferential position of the diffuser flow
channel 21 has another distance from the respective adjacent flow
outlet edges 23, that by contrast in the other circumferential
positions the flow outlet edges 23 with respect to their
circumferential positions are equally distributed.
[0050] It is likewise possible according to the first advantageous
further development of the first aspect and/or second aspect of the
invention in a second extreme case that in all circumferential
positions of the diffuser flow channel 21 the flow outlet edges 23
have different distances in each case from the respective adjacent
flow outlet edges 23.
[0051] In the second circumferential positions of the diffuser flow
channel 21, the respective guide blades 20 of the diffuser 19 on
the stator side preferentially all have identical, second stepping
angles.
[0052] The guide blades 20 on the stator side positioned in the, or
each, first circumferential position by contrast preferentially
have a first stepping angle, which deviates from the second
stepping angle, in particular by plus minus .+-.10.degree.,
preferably by plus minus .+-.7.degree., particularly preferably by
.+-.5.degree., most preferably by .+-.3.degree..
[0053] According to the first advantageous further development of
the first aspect and/or second aspect of the invention it is
accordingly proposed for reducing the danger of unsteady flow
phenomena, which can lead to an asynchronous excitation of the open
impellers, to reposition the flow outlet edges 23 of selected guide
blades 20 of the diffuser 19 on the stator side in circumferential
direction, preferentially subject to cancelling or interrupting the
flow outlet edges 23 which, seen in the circumferential direction
of the diffuser flow channel 21, are otherwise equally
distributed.
[0054] In an extreme case, the flow outlet edges 23 of all guide
blades 20 of the diffuser 19 on the stator side can have different
distances from the respective adjacent flow outlet edges 23.
[0055] As is evident in FIG. 5, a flow outlet edge 23'' (see dashed
line course of the in FIG. 5 right guide blade) in the direction of
the pressure side 25 of the respective adjacent guide blade 20 or a
flow outlet edge 23' (see dashed line course of the in FIG. 5 left
guide blade) can be relocated in circumferential direction in the
direction of the suction side 24 of the respective adjacent guide
blade 20 in such a manner that all flow outlet edges 23 as before
still lie on the second circle contour 30.
[0056] This corresponds to a change of the stepping angle of the
guide blades 20 of the diffuser 19 on the stator side in selected
circumferential positions. In selected second circumferential
positions of the diffuser 19, the respective guide blades 20 on the
stator side have deviating stepping angles.
[0057] Those selected guide blades 20 which, compared with the
remaining guide blades 20 on the stator side, have a different
stepping angle are characterized in that their stepping angle
deviates in particular by .+-.10.degree., and particularly
preferably by .+-.5.degree. from the stepping angles of the
remaining guide blades 20 of the diffuser 19.
[0058] Through the above measures of the first advantageous further
development of the first aspect and/or second aspect of the
invention, a slightly higher or a slightly lower loading can be
imposed on the guide blades 20 of the diffuser 19 in defined
circumferential positions at uneven circumferential distances. The
danger of unsteady flow phenomena, which can lead to an
asynchronous excitation of the open impellers, can thereby be
further reduced.
[0059] According to a second advantageous further development of
the first aspect and/or second aspect of the invention (see FIG.
6), it is proposed for reducing the danger of unsteady flow
phenomena, which can lead to an asynchronous excitation of the open
impellers, that both the flow inlet edges 22 of the guide blades 20
of the diffuser 19 on the stator side positioned on the first
circle contour 29 as well as the flow outlet edges 23 of the guide
blades 20 of the diffuser 19 on the stator side positioned on the
second circle contour 30 are equally distributed, i.e., in each
case have identical circumferential distances.
[0060] According to the second advantageous further development of
the first aspect and/or second aspect of the invention, however, at
least one guide blade 20 of the diffuser 19 on the stator side has
a deviating curvature between the flow inlet edge 22 and the flow
outlet edge 23, namely a suction side 24' and a pressure side 25'
with a curvature deviating relative to the other guide blades 20.
This is shown in FIG. 6 by the dashed line course for the middle
guide blade 20.
[0061] According to the second advantageous further development of
the first aspect and/or second aspect of the invention, it is
possible in a first extreme case that exclusively a single guide
blade 20 of the diffuser 19 on the stator side has a deviating
curvature, that by contrast all other guide blades 20 of the
diffuser 19 on the stator side have identical curvatures.
[0062] According to the second advantageous further development of
the first aspect and/or second aspect of the invention, it is
likewise possible in a second extreme case that all guide blades 20
of the diffuser 19 on the stator side have curvatures that deviate
from one another.
[0063] It is preferable to employ on the radial compressor stage
the above first advantageous further development and the above
second advantageous further development combined with the first
aspect or the second aspect of the invention to reduce the danger
of unsteady flow phenomena which can lead to an asynchronous
excitation of the open impellers.
[0064] A third advantageous further development of the first aspect
and/or second aspect of the invention is discussed in the following
making reference to FIG. 7.
[0065] According to the third advantageous further development of
the first aspect and/or second aspect of the invention, it is
proposed, for reducing the danger of unsteady flow phenomena, which
can lead to an asynchronous excitation of the open impellers, to
change a diffuser flow channel section 33 formed between adjacent
guide blades 20 of the diffuser 19 on the stator side in at least
one first circumferential position of the diffuser flow channel 21
such that the same compared with the diffuser flow channel sections
formed in second circumferential positions has a deviating flow
cross section.
[0066] Accordingly it is evident from FIG. 7 that in a first
circumferential position of the diffuser 19 between adjacent guide
blades 20 on the stator side the respective diffuser flow channel
section 33 has a reduced flow cross section, namely because of the
fact that sidewalls 31, 32 on the stator side bounding the
respective diffuser flow channel section 33 are curved towards the
inside subject to reducing the flow cross section of the respective
diffuser flow channel section 33. Even merely one of these
sidewalls 31, 32 on the stator side bounding the respective
diffuser flow channel section 33 can be curved into the respective
diffuser flow channel section 33. It is likewise possible in
selected circumferential positions to widen the respective diffuser
flow channel section with respect to its flow cross section,
whereby at least one of these sidewalls 31, 32 is then curved
outwardly into the stator 12.
[0067] According to the third advantageous further development of
the first aspect and/or second aspect of the invention, it is
possible in a first extreme case that exclusively in a single
circumferential position of the diffuser flow channel 21 the
corresponding diffuser flow channel section 33 has a deviating flow
cross section, but by contrast all other diffuser flow channel
sections 33 have identical flow cross sections. According to the
third advantageous further development of the first aspect and/or
second aspect of the invention it is likewise possible in a second
extreme case that in all circumferential positions of the diffuser
flow channel 21 the diffuser flow channel sections 33 each have
different flow cross sections.
[0068] The measures of the third advantageous further development
can be employed combined with the measures of the first
advantageous further development and/or the measures of the second
advantageous further development combined with the first or the
second aspect of the invention. Preferably, the measures of all
three advantageous further developments are employed on a radial
compressor stage combined with the first aspect or the second
aspect.
[0069] Thus, while there have been shown and described and pointed
out fundamental novel features of the invention as applied to a
preferred embodiment thereof, it will be understood that various
omissions and substitutions and changes in the form and details of
the devices illustrated, and in their operation, may be made by
those skilled in the art without departing from the spirit of the
invention. For example, it is expressly intended that all
combinations of those elements and/or method steps which perform
substantially the same function in substantially the same way to
achieve the same results are within the scope of the invention.
Moreover, it should be recognized that structures and/or elements
and/or method steps shown and/or described in connection with any
disclosed form or embodiment of the invention may be incorporated
in any other disclosed or described or suggested form or embodiment
as a general matter of design choice. It is the intention,
therefore, to be limited only as indicated by the scope of the
claims appended hereto.
LIST OF REFERENCE NUMBERS
[0070] 10 Impeller [0071] 11 Impeller blade [0072] 12 Stator [0073]
13 Impeller flow channel [0074] 14 Hub contour [0075] 15 Stator
contour [0076] 16 Flow inlet edge [0077] 17 Flow outlet edge [0078]
18 Outer surface [0079] 19 Diffuser [0080] 20 Guide blade [0081] 21
Diffuser flow channel [0082] 22 Flow inlet edge [0083] 23 Flow
outlet edge [0084] 24 Suction side [0085] 25 Pressure side [0086]
26 Intermediate flow channel [0087] 27 Back side [0088] 28 Impeller
side gap [0089] 29 Circle contour [0090] 30 Circle contour [0091]
31 Sidewall [0092] 32 Sidewall [0093] 33 Diffuser flow channel
section [0094] 34 Gap [0095] 35 Outer edge [0096] 36 Inner edge
[0097] 37 Seal [0098] 38 Sealing lip
* * * * *