TECHNICAL FIELD
[0001] The present disclosure relates to a compressor impeller and a method for manufacturing
the same.
BACKGROUND ART
[0002] Compressors such as a centrifugal compressor and an axial-flow compressor are configured
to apply kinetic energy to a fluid through rotation of a compressor impeller, and
convert the kinetic energy into pressure, thereby obtaining a highpressure fluid.
[0003] Such a compressor is provided with various features to meet the need to improve the
pressure ratio and the efficiency in a wide operational range.
[0004] JP2014-118916A discloses a centrifugal compressor for suppressing rotating stall. Rotating stall
is an unstable phenomenon in which a stalling region generated on a blade propagates
in the rotational direction from a blade to another blade at a speed lower than the
tip speed of the impeller during operation in a low flow-rate range.
[0005] When rotating stall occurs, continuous reduction of the flow rate may lead to occurrence
of surging of a flow accompanied by strong noise, where the compressor reaches its
operation limit. Thus, to expand the operation range in which the compressor can operate
stably, it is necessary to suppress rotating stall.
[0006] To suppress rotating stall, the compressor disclosed in
JP2014-118916A includes a suppressing member for suppressing development of vortices of a fluid
formed in the vicinity of a leading edge of a blade, disposed on the inner peripheral
surface of the casing or the outer peripheral surface of the rotational shaft of the
impeller at the upstream side of the blade leading edge of the impeller and configured
to rotate relatively to the blade.
SUMMARY
Problems to be Solved
[0008] To suppress rotating stall with the compressor disclosed in
JP2014-118916A, it is necessary to add a suppressing member configured to rotate relatively to the
blade, on the inner peripheral surface of the casing or the outer peripheral surface
of the impeller at the upstream side of the blade leading edge of the impeller. Thus,
the number of necessary parts increases and the configuration of the compressor becomes
complex.
[0009] The present invention was made in view of the above issue, and an object is to provide
a compressor impeller and a method for manufacturing the same, whereby it is possible
to suppress rotating stall with a simplified configuration.
Solution to the Problems
[0010]
- (1) A compressor impeller according to at least one embodiment of the present invention
includes: a hub; and a blade group including a plurality of blades arranged along
a circumferential direction on an outer peripheral surface of the hub, the blade group
being configured such that hub-side ends of leading edges of the respective blades
are aligned on the same circle. The plurality of blades include at least one first
blade and at least one second blade having a different shape from the at least one
first blade, and, when comparing a blade angle of a leading edge of the at least one
first blade to a blade angle of a leading edge of the at least one second blade at
the same position in a radial direction of the compressor impeller, the blade angle
of the leading edge of the at least one first blade is different from the blade angle
of the leading edge of the at least one second blade, at least in a partial range
in the radial direction of the compressor impeller.
In accordance with the invention, the number of the second blades in the blade group
is smaller than the number of the first blades in the blade group, and, when comparing
the blade angle of the leading edges of the first blades to the blade angle of the
leading edges of the second blades at the same position in the radial direction of
the compressor impeller, the blade angle of the leading edges of the second blades
is greater than the blade angle of the leading edges of the first blades at least
in a partial range in the radial direction of the compressor impeller.
With the compressor impeller described in the above (1), in the blade group configured
such that the hub-side ends of the leading edges align on the same circle, when comparing
the blade angle of the leading edge of the first blade to the blade angle of the leading
edge of the second blade at the same position with respect to the radial direction
of the compressor impeller, at least in a partial range in the radial direction of
the compressor impeller, the blade angle of the leading edge of the first blade is
different from the blade angle of the leading edge of the second blade. Accordingly,
for the plurality of blades arranged so that the hub-side ends of the leading edges
align on the same circle, it is possible to differentiate the stall characteristics
between the first blade and the second blade. Thus, as compared to a case where the
plurality of blades have a uniform shape, it is possible to impair uniform propagation
and development of rotating stall. Accordingly, it is possible to improve the characteristics
of the compressor at the low flow-rate side. Furthermore, it is unnecessary to provide
an additional suppressing member disclosed in the prior art (JP2014-118916), and thus it is possible to simplify the configuration compared to the prior art.
In addition, the blade angle of the leading edges of the relatively large number of
first blades is a relatively small blade angle taking into account the intake air
amount of the high-flow rate side, while the blade angle of the leading edges of the
relatively small number of second blades is a relatively large blade angle matched
to the small flow rate side (less likely to cause stalling even at a low flow rate).
Thus, it is possible to impair uniform propagation and development of rotating stall
while suppressing a decrease in the intake air amount of the compressor impeller.
- (2) In some embodiments, in the above compressor impeller (1), the at least one first
blade includes a plurality of first blades, the at least one second blade includes
a plurality of second blades, the number of the second blades in the blade group is
smaller than the number of the first blades in the blade group, and the plurality
of second blades include a pair of second blades between which the first blade is
not disposed.
With the above compressor impeller (2), the second blades relatively fewer than the
first blades and having different stalling characteristics from the first blades are
aligned continuously in the circumferential direction of the compressor impeller,
and thus it is possible to enhance the above effect to impair uniform propagation
and development of rotating stall.
- (3) In some embodiments, in the above compressor impeller (1) or (2), the blade angle
of the tip-side ends of the leading edges of the second blades is greater than the
blade angle of the tip-side ends of the leading edges of the first blades.
According to findings of the present inventors, rotating stall of the compressor impeller
is likely to occur in a region on the tip side of a blade. Thus, as in the above (3),
with the blade angle of the leading edges of the second blades on the tip side end
being greater than the blade angle of the leading edges of the first blades on the
tip side end as described above, it is possible to suppress rotating stall effectively.
- (4) In some embodiments, in the above compressor impeller (3), the blade angle of
the tip-side ends of the leading edges of the second blades is greater than the blade
angle of the tip-side ends of the leading edges of the first blades by five degrees
or more.
With the above compressor impeller (4), the effect in the above (3) can be exerted
to a greater extent.
- (5) In some embodiments, in the above compressor impeller (3) or (4), the blade angle
of hub-side ends of the leading edges of the second blades is equal to the blade angle
of hub-side ends of the leading edges of the first blades.
As described above, rotating stall of the compressor impeller is likely to occur in
the tip-side region of a blade. Thus, even if the angle of the leading edge of the
second blade at the hub-side end is greater than the blade angle of the leading edge
of the first blade at the hub-side end, the effect to suppress rotating stall is relatively
small. Furthermore, configuring the second blades to have a large blade angle matched
to the small flow-rate side in a broad range in the radial direction of the compressor
impeller may lead to a decrease in the intake air amount of the compressor impeller.
Thus, with the blade angle of the leading edges of the second blades on the tip side
end being greater than the blade angle of the leading edges of the first blades on
the tip side end, and the blade angle of the leading edges of the second blades on
the hub-side end being equal to the blade angle of the leading edges of the first
blades on the hub-side end as in the above (5), it is possible to impair uniform propagation
and development of rotating stall while suppressing a decrease in the intake air amount
of the compressor impeller.
- (6) In some embodiments, in the above compressor impeller (5), when comparing the
blade angle of the leading edges of the first blades to the blade angle of the leading
edges of the second blades at the same position in the radial direction of the compressor
impeller, the blade angle of the leading edges of the second blades is greater than
the blade angle of the leading edges of the first blades in a range to the tip-side
ends from a predetermined position of not less than 50% of a blade height of the second
blades in the radial direction of the compressor impeller, and is equal to the blade
angle of the leading edges of the first blades in a range to the predetermined position
from the hub-side ends of the second blades in the radial direction of the compressor
impeller.
With the above compressor impeller (6), the effect in the above (5) can be exerted
to a greater extent.
- (7) In some embodiments, in the compressor impeller according to any one of the above
(1) to (6), the first blades and the second blades have different shapes only in an
upstream region of a reference position in an axial direction of the compressor impeller,
and have the same shape in a downstream region of the reference position in the axial
direction of the compressor impeller.
The curve of a blade and the blade angle of the trailing edge of a blade have a great
impact on the blade element performance, and thus the plurality of blades should have
a uniform shape on the trailing edge side. Thus, in the above compressor impeller
(7), the first blade and the second blade have different shapes only at the side of
the leading edge where the shape is likely to contribute to improvement of rotating
stall (the shape in the upstream region of the reference position in the axial direction
of the compressor impeller), and have the same shape at the side of the trailing edge
where the shape is less likely to contribute to improvement of rotating stall and
more likely to have an impact on the blade element performance (the shape in the downstream
region of the reference position in the axial direction of the compressor impeller).
Accordingly, it is possible to suppress rotating stall while suppressing a decrease
in the blade element performance, and thus it is possible to improve the performance
of the compressor impeller effectively.
- (8) In some embodiments, in the above compressor impeller (7), the reference position
is a position upstream of an intersection between a suction surface of the second
blade and a perpendicular line to the suction surface of the second blade from the
tip-side end of the leading edge of the blade next to the suction surface of the second
blade.
With the above compressor impeller (8), with the reference position described in the
above (7) being positioned upstream of the intersection in the axial direction of
the impeller (throat position of the second blade), it is possible to differentiate
the blade angle of the first blade from the blade angle of the second blade without
changing the throat width between the second blade and the blade next to the suction
surface of the second blade as described in the above (1) to (7). Thus, it is possible
to suppress rotating stall while suppressing a decrease in the intake air amount of
the compressor impeller.
- (9) A method for manufacturing the compressor impeller according to any one of the
above (1) to (8) includes: a first blade forming step of forming a plurality of first
blades having the same shape; and a second blade forming step of forming at least
one second blade by performing a bending process on a leading-edge side portion of
a part of the first blades formed in the first blade forming step.
[0011] According to the method for manufacturing a compressor impeller described in the
above (9), it is possible to form the second blade merely by performing a bending
process on the leading edge portion of only a part of the first blades after forming
a plurality of first blades having the same shape, and thereby it is possible to easily
manufacture the centrifugal compressor impeller described in any one of the above
(1) to (8).
Advantageous Effects
[0012] According to at least one embodiment of the present invention, provided is a compressor
impeller and a method for manufacturing the same, whereby it is possible to suppress
rotating stall with a simplified configuration.
BRIEF DESCRIPTION OF DRAWINGS
[0013]
FIG. 1 is an axial-directional view of a compressor impeller 100 (100A) according
to an embodiment.
FIG. 2 is a meridional cross-sectional view of a part of a compressor impeller 100
(100A) according to an embodiment, taken along the axial direction.
FIG. 3 is a schematic diagram for describing the shape of the first blade 12 and the
second blade 14.
FIG. 4 is a blade-row expanded view schematically showing the positional relationship
of the plurality of blades 4 on the tip side. In FIG. 4, the line indicating each
blade 4 is the camber line connecting the middle points of the suction surface and
the pressure surface of the blade 4.
FIG. 5 is a blade-row expanded view schematically showing the positional relationship
of the plurality of blades 4 on the hub side. In FIG. 5, the line indicating each
blade 4 is the camber line connecting the middle points of the suction surface and
the pressure surface of the blade 4.
FIG. 6 is a diagram schematically showing a rotating stall state in a comparative
embodiment. In FIG. 6, the line indicating each blade 4 is the camber line connecting
the middle points of the suction surface and the pressure surface of the blade 4.
FIG. 7 is a diagram schematically showing a rotating stall state in an embodiment.
In FIG. 7, the line indicating each blade 4 is the camber line connecting the middle
points of the suction surface and the pressure surface of the blade 4.
FIG. 8 is a view showing comparison of surge lines in an embodiment and a comparative
embodiment.
FIG. 9 is a schematic diagram for describing another example of the shape of the first
blade 12 and the second blade 14. In FIG. 4, the line indicating each blade 4 is the
camber line connecting the middle points of the suction surface and the pressure surface
of the blade 4.
FIG. 10 is an axial-directional view of a compressor impeller 100 (100B) according
to an embodiment.
FIG. 11 is a meridional cross-sectional view of a part of a compressor impeller 100
(100B) according to an embodiment, taken along the axial direction.
FIG. 12 is a blade-row expanded view schematically showing an example of the positional
relationship of a plurality of full blades 4f and a plurality of splitter blades 4s
on the tip side. In FIG. 12, the line indicating each blade 4 (4f, 4s) is the camber
line connecting the middle points of the suction surface and the pressure surface
of the blade 4.
FIG. 13 is a blade-row expanded view schematically showing an example of the positional
relationship of a plurality of full blades 4f and a plurality of splitter blades 4s
on the tip side. In FIG. 13, the line indicating each blade 4 (4f, 4s) is the camber
line connecting the middle points of the suction surface and the pressure surface
of the blade 4 (4f, 4s).
FIG. 14 is a blade-row expanded view schematically showing an example of the positional
relationship of a plurality of full blades 4f and a plurality of splitter blades 4s
on the tip side. In FIG. 14, the line indicating each blade 4 (4f, 4s) is the camber
line connecting the middle points of the suction surface and the pressure surface
of the blade 4 (4f, 4s).
FIG. 15 is a partial meridional cross-sectional view of a compressor impeller 100
according to an embodiment, taken along the axial direction.
DETAILED DESCRIPTION
[0014] Embodiments of the present invention will now be described in detail with reference
to the accompanying drawings. It is intended, however, that unless particularly identified,
dimensions, materials, shapes, relative positions and the like of components described
in the embodiments shall be interpreted as illustrative only and not intended to limit
the scope of the present invention, which is solely defined by the appended claims.
[0015] FIG. 1 is an axial-directional view of a compressor impeller 100 (100A) according
to an embodiment. FIG. 2 is a meridional cross-sectional view of a part of a compressor
impeller 100 (100A) shown in FIG. 1, taken along the axial direction.
[0016] As shown in FIGs. 1 and 2, the compressor impeller 100 includes a hub 2 and a blade
group 6 including a plurality of blades 4 arranged at intervals in the circumferential
direction on the outer peripheral surface 2a of the hub 2. In the blade group 6, the
blades 4 are aligned such that the hub-side ends 4A of the leading edges of the respective
blade 4 are on the same circle C centered at the rotational axis O of the compressor
impeller. The blade group 6 is configured such that the hub-side ends 4A of the plurality
of blades 4 are at the same position in the axial direction of the compressor impeller
100. The plurality of blades 4 includes at least one first blade 12, and at least
one second blade 14 having a different shape from the first blade 12.
[0017] FIG. 3 is a schematic diagram for describing the shape of the first blade 12 and
the second blade 14. FIG. 4 is a blade-row expanded view schematically showing the
positional relationship of the plurality of blades 4 on the tip side. FIG. 5 is a
blade-row expanded view schematically showing the positional relationship of the plurality
of blades 4 on the hub side.
[0018] In FIGs. 4 and 5, the horizontal axis represents the position 'rθ' in the circumferential
direction of the compressor impeller 100, and the vertical axis represents the distance
from the leading edge 12LE in the meridional direction 'm'. Herein, as shown in FIG.
15, the "meridional direction 'm'" refers to the direction along a line connecting
points at which the blade height ratio is the same, from the leading edge 12LE to
the trailing edge 12TE of the blade 4. Herein, "blade height ratio" is defined as
follows. First, as shown in FIG. 15, 'mh' refers to the meridional length from the
position of the leading edge 12LE to the position of the trailing edge TE at the hub-side
end of the blade 4, and 'mt' refers to the meridional length from the position of
the leading edge LE to the position of the trailing edge TE at the tip-side end of
the blade 4. Furthermore, provided that the position P and the position Q are such
positions that the ratio of the meridional length from the position of the leading
edge 12LE on the hub-side end of the blade 4 to the position P divided by the meridional
length 'mh' is equal to the ratio of the meridional length from the position of the
leading edge LE on the tip-side end of the blade 4 to the position Q divided by the
meridional length 'mh' (e.g. the position P and the position Q where both of the ratios
are 20%), the length of the segment connecting the position P and the position Q is
defined as the blade height 'h' at a meridional position (%). Further, the value y/h
obtained by dividing the distance y from the outer peripheral surface 2a of the hub
2 in the blade height direction along the segment by the blade height 'h' is defined
as the blade height ratio.
[0019] In FIGs. 3 and 4, when comparing the blade angle β1 of the leading edge LE of the
first blade 12 to the blade angle β2 of the leading edge 14LE of the second blade
14 at the same position 'r' with respect to the radial direction of the compressor
impeller 100, at least in a partial range w1 in the radial direction of the compressor
impeller 100, the blade angle β1 of the leading edge LE of the first blade 12 is different
from the blade angle β2 of the leading edge 14LE of the second blade 14. Herein, "blade
angle β" refers to the angle β (see FIG. 4, for instance) formed between the meridional
direction 'm' and the camber line at a blade height y/h, and is defined, using the
position 'm' in the meridional direction and the position 'rθ' in the circumferential
direction, by the following equation 1:
[0020] With the above configuration, for the plurality of blades 4 (see FIG. 1) arranged
so that the hub-side ends 4A of the leading edges align on the same circle, it is
possible to differentiate the stall characteristics between the first blade 12 and
the second blade 14. Thus, as compared to a case where the plurality of blades 4 have
a uniform shape, it is possible to impair uniform propagation and development of rotating
stall. Accordingly, it is possible to improve the characteristics of the compressor
at the low flow-rate side. Furthermore, it is unnecessary to provide an additional
suppressing member disclosed on the prior art (
JP2014-118916), and thus it is possible to simplify the configuration compared to the prior art.
[0021] In an embodiment, as shown in FIG. 1 for instance, the at least one first blade 12
includes a plurality of first blades 12, and the at least one second blade 14 includes
a plurality of second blades 14. The number of second blades 14 in the blade group
6 is smaller than the number of the first blades 12 in the blade group 6. Further,
as shown in FIGs. 1 and 4, the plurality of second blades 14 includes a pair of second
blades 14 between which the first blade 12 is not disposed in the circumferential
direction of the compressor impeller 100. In the exemplary embodiment shown in FIG.
1, the blade group 6 includes six blades 4, and the six blades 4 includes four first
blades 12 and two second blades 14. None of the first blades 12 is disposed between
the two second blades 14.
[0022] With the above configuration, the second blades 14 relatively fewer than the first
blades 12 and having different stalling characteristics from the first blades 12 are
aligned continuously in the circumferential direction of the compressor impeller 100,
and thus it is possible to enhance the above effect to impair uniform propagation
and development of rotating stall.
[0023] In an embodiment, as shown in FIGs. 3 and 4, when comparing the blade angle β1 of
the leading edge LE of the first blade 12 to the blade angle β2 of the leading edge
14LE of the second blade 14 at the same position 'r' with respect to the radial direction
of the compressor impeller 100, at least in the partial range w1 in the radial direction
of the compressor impeller 100, the blade angle β2 of the leading edge 14LE of the
second blade 14 is greater than the blade angle β1 of the leading edge 12LE of the
first blade 12.
[0024] With the above configuration, as compared to a comparative embodiment in which the
plurality of blades 4 have a uniform shape, that is, a case in which the plurality
of blades 4 includes only the first blades 12 (see FIG. 6), the leading edges LE of
the second blades 14 have the relatively large blade angle β2 matched to the small
flow-rate side (less likely to stall even at a small flow rate), and thereby stalling
is less likely to occur in the region A on the suction surface side of the second
blade 14, which makes it possible to impair propagation and development of rotating
stall effectively. Accordingly, as shown in FIG. 7, as compared to the above comparative
embodiment, it is possible to shift the surge line to the small flow-rate side and
expand the operational range at the small flow-rate side. Furthermore, the leading
edges 12LE of the relatively large number of first blades 12 have the relatively small
blade angle β1 taking account of the intake air amount at the high flow-rate side
in the range 21, and thereby it is possible to suppress a decrease in the intake air
amount of the compressor impeller 100. Thus, it is possible to suppress a decrease
in the intake air amount of the compressor impeller 100 while impairing uniform propagation
and development of rotating stall.
[0025] In an embodiment, in FIGs. 3 and 4, the blade angle β2 of the tip side ends 14E of
the leading edges 14LE of the second blades 14 is greater than the blade angle β1
of the tip-side ends 12E of the leading edges 12LE of the first blades 12. Preferably,
the blade angle β2 of the tip side ends 14E of the leading edges 14LE of the second
blades 14 is greater than the blade angle β1 of the tip-side ends 12E of the leading
edges 12LE of the first blades 12 by 5 degrees or more.
[0026] According to findings of the present inventors, rotating stall of a compressor impeller
is likely to occur in a region on the tip side of the leading edge of a blade. Thus,
with the blade angle β2 of the tip side ends 14E of the leading edges 14LE of the
second blades 14 being greater than the blade angle β1 of the tip side ends 12E of
the leading edges 12LE of the first blades 12 as described above, it is possible to
suppress rotating stall effectively.
[0027] In an embodiment, in FIGs. 3 and 5, the blade angle β2 of the hub side ends 14A of
the leading edges 14LE of the second blades 14 is equal to the blade angle β1 of the
hub side ends 12A of the leading edges 12LE of the first blades 12.
[0028] As described above, rotating stall of a compressor impeller is likely to occur in
the tip-side region of a blade. Thus, even if the blade angle β2 of the leading edge
LE of the second blade 14 at the hub-side end 14A is greater than the blade angle
β1 of the leading edge 12LE of each blade 12 at the hub-side end 12A, the effect to
suppress rotating stall is relatively small. Furthermore, configuring the second blades
14 to have a large blade angle β2 matched to the small flow-rate side in a broad range
in the radial direction of the compressor impeller 100 may lead to a decrease in the
intake air amount of the compressor impeller 100.
[0029] Thus, with the blade angle β2 of the leading edges 14LE of the second blades 14 on
the tip side end 14E being greater than the blade angle β1 of the tip side ends 12E
of the leading edges 12LE of the first blades 12, and the blade angle of the leading
edges 14LE of the second blades 14 on the hub-side end 14E being equal to the blade
angle β1 of the hub-side ends 12A of the leading edges 12LE of the first blades 12,
it is possible to impair uniform propagation and development of rotating stall while
suppressing a decrease in the intake air amount of the compressor impeller 100.
[0030] In an embodiment, as shown in FIGs. 3 to 5, when comparing the blade angle β1 of
the leading edge LE of the first blade 12 to the blade angle β2 of the leading edge
14LE of the second blade 14 at the same position 'r' with respect to the radial direction
of the compressor impeller 100, the blade angle β2 of the leading edge 14LE of the
second blade 14 is greater than the blade angle β1 of the leading edge LE of the first
blade 12 in the range w1 from a predetermined position P1 of not less than 50% of
the blade height 'h' of the second blade 14 in the radial direction of the compressor
impeller 100 (e.g. a predetermined position of 70% to 80% of the blade height 'h'
of the second blade 14) to the tip side end 14E, and is equal to the blade angle β1
of the leading edge LE of the first blade 12 in the range w2 from the hub side end
14A of the second blade 14 in the radial direction of the compressor impeller 100
to the predetermined position P1.
[0031] As described above, rotating stall of a compressor impeller is likely to occur in
the tip-side region of the leading edge of a blade. Thus, even if the angle β2 of
the leading edge LE of the second blade 14 at the hub-side end is greater than the
blade angle β1 of the leading edge 12LE of the first blade at the hub-side end, the
effect to suppress rotating stall is relatively small. Furthermore, configuring the
second blades 14 so that the leading edges 14 have a large blade angle β2 matched
to the small flow-rate side in a broad range in the radial direction of the compressor
impeller 100 may lead to a decrease in the intake air amount of the compressor impeller
100.
[0032] Thus, with the blade angle β2 of the leading edge 14LE of the second blade 14 being
greater than the blade angle β1 of the leading edge LE of the first blade 12 in the
range w1 from the predetermined position P1 of not less than 50% of the blade height
h of the second blade 14 in the radial direction of the compressor impeller 100 to
the tip side end 14E, and being equal to the blade angle β1 of the leading edge LE
of the first blade 12 in the range w2 from the hub side end 14A of the second blade
14 in the radial direction of the compressor impeller 100 to the predetermined position
PI, it is possible to impair uniform propagation and development of the rotating stall
while suppressing a decrease in the intake air amount of the compressor impeller 100.
[0033] In an embodiment, as shown in FIGs. 3 and 4, the first blade 12 and the second blade
14 have different shapes only in the upstream region of the reference position P2
in the axial direction of the compressor impeller 100, and have the same shape in
the downstream region of the reference position P2 in the axial direction of the compressor
impeller 100.
[0034] The curve of a blade and the blade angle of the trailing edge of a blade have a great
impact on the blade element performance, and thus the plurality of blades 4 should
have a uniform shape on the trailing edge side. That is, preferably, the shape of
the blade 12 at the side of the trailing edge 12TE and the shape of the blade 14 at
the side of the trailing edge 14TE are the same. Thus, the first blade 12 and the
second blade 14 have different shapes only at the side of the leading edge where the
shape is likely to contribute to improvement of rotating stall (the shape in the upstream
region of the reference position P2 in the axial direction of the compressor impeller
100), and have the same shape at the side of the trailing edge where the shape is
less likely to contribute to improvement of rotating stall and more likely to have
an impact on the blade element performance (the shape in the downstream region of
the reference position P2 in the axial direction of the compressor impeller 100).
Accordingly, it is possible to suppress rotating stall while suppressing a decrease
in the blade element performance, and thus it is possible to improve the performance
of the compressor impeller 100 effectively.
[0035] In an embodiment, as shown in FIGs. 3 and 4 for instance, the above reference position
P2 is upstream of an intersection P3 (throat position of the second blade) between
the suction surface 14S of the second blade 2 and a perpendicular line to the suction
surface 14S of the second blade 14 from the tip-side end of the leading edge of the
blade 4 next to the suction surface 14S of the second blade 4 (the tip side end 12E
of the leading edge 12LE of the first blade 12 in the embodiment shown in the drawings).
[0036] With the reference position P2 being positioned upstream of the intersection P3 in
the axial direction of the impeller 100, it is possible to differentiate the blade
angle β1 of the first blade 12 from the blade angle β2 of the second blade 14 while
suppressing a change in the throat width S between the second blade 14 and the blade
4 next to the suction surface 14S of the second blade 14. Thus, it is possible to
suppress rotating stall while suppressing a decrease in the intake air amount of the
compressor impeller 100.
[0037] While the above described compressor impeller 100 can be manufactured by machining,
casting, or the like, the manufacturing method may include a first blade forming step
of forming the plurality of first blades 12 having the same shape, and a second blade
forming step of forming at least one second blade 14 by performing a bending process
only on a portion 12P (see FIG. 3) on the tip side and on the leading edge side of
a part of the first blades 12 formed in the first blade forming step so as to curve
smoothly toward the pressure surface side in an arc shape.
[0038] Accordingly, as compared to a case in which the first blade 12 and the second blade
14 are formed in separate steps, it is possible to form the second blades 14 by merely
performing a bending process on the first blades 12 formed via the first blade forming
step, and thus it is possible to manufacture the compressor impeller 100 easily.
[0039] Embodiments of the present invention were described in detail above, but the present
invention is not limited thereto, and various amendments and modifications may be
implemented.
[0040] For instance, in FIG. 4, the first blade 12 and the second blade 12 have different
shapes only in the upstream region of the reference position P2 in the axial direction
of the compressor impeller 100, and have the same shape in the downstream region of
the reference position P2 in the axial direction of the compressor impeller 100.
[0041] However, the present invention is not limited to this embodiment. As shown in FIG.
9 for instance, the second blade 14 may have a different shape from the first blade
12 in the entire range of the second blade 14 in the axial direction of the compressor
impeller 100. Also in this configuration, it is sufficient if, when comparing the
blade angle β1 of the leading edge 12LE of the first blade 12 to the blade angle β2
of the leading edge 14LE of the second blade 14 at the same position with respect
to the radial direction of the compressor impeller 100, at least in a partial range
w1 in the radial direction of the compressor impeller 100, the blade angle β1 of the
leading edge LE of the first blade 12 is different from the blade angle β2 of the
leading edge 14LE of the second blade 14. Thus, in terms of suppression of a decrease
in the intake air amount of the compressor impeller 100, it is possible to suppress
uniform propagation and development of rotating stall.
[0042] Nevertheless, in the embodiment shown in FIG. 4, it is possible to differentiate
the blade angle β1 of the first blade 12 from the blade angle β2 of the second blade
14 while suppressing a change in the throat width S between the second blade 14 and
the blade 4 next to the suction surface 14S of the second blade 14. Thus, the embodiment
shown in FIG. 4 is more preferable than the embodiment shown in FIG. 9.
[0043] Furthermore, in FIG. 1, the compressor impeller 100 includes a single blade group
6 (which includes a plurality of blades 4 arranged at intervals in the circumferential
direction on the outer peripheral surface 2a of the hub 2, and in which the blades
4 are aligned such that the hub-side ends 4A of the leading edges of the respective
blades 4 are on the same circle C centered at the rotational axis O of the compressor
impeller).
[0044] However, the present invention is not limited to this embodiment. As shown in FIGs.
10 and 11 for instance, the compressor impeller 100 may include a plurality of blade
groups. In the exemplary embodiment shown in FIG. 10, the compressor impeller 100
(100B) includes two blade groups: a full blade group 6f and a splitter blade group
6s.
[0045] The full blade group 6f includes a plurality of full blades 4f disposed at intervals
in the circumferential direction on the outer peripheral surface 2a of the hub 2.
The hub-side ends 4Af of the leading edges of the respective full blades 4f are aligned
on the same circle Cf centered at the rotational axis O of the compressor impeller.
[0046] The splitter blade group 6s includes a plurality of splitter blades 4s disposed at
intervals in the circumferential direction on the outer peripheral surface 2a of the
hub 2. The splitter blades 4s have a shorter blade length than the full blades 4f,
and each of the plurality of splitter blades 4s is disposed between two adjacent full
blades 4f. The hub-side ends 4As of the leading edges of the plurality of splitter
blades 4s are aligned on the same circle Cs centered at the rotational axis O of the
compressor impeller 100. Herein, the hub-side ends 4As of the leading edges of the
plurality of splitter blades 4s are disposed downstream of the hub-side ends 4Af of
the leading edges of the plurality of full blades 4f. That is, the circle Cs has a
greater radius than the circle Cf, and is positioned downstream of the circle Cf with
respect to the intake direction of the compressor impeller 100.
[0047] In the embodiment shown in FIG. 10, the invention according to the blade group 6
of the compressor impeller 100 (100A) described with reference to FIGs. 1 to 9 may
be applied only to the full blade group 6f as shown in FIG. 12, or only to the splitter
blade group 6s as shown in FIG. 13, or to both of the full blade group 6f and the
splitter blade group 6s as shown in FIG. 14.
[0048] In the embodiment shown in FIG. 12, the plurality of full blades 4f constituting
the full blade group 6f includes at least one first blade 12f, and at least one second
blade 14f having a different shape from the first blade 12f. Furthermore, when comparing
the blade angle β1f of the leading edge 12LEf of the first blade 12f to the blade
angle β2f of the leading edge 14LEf of the second blade 14f at the same position with
respect to the radial direction of the compressor impeller 100, at least in a partial
range (see the range w1 in FIG. 3) in the radial direction of the compressor impeller
100, the blade angle β1f of the leading edge 21LEf of the first blade 12f is different
from the blade angle β2f of the leading edge 14LEf of the second blade 14f.
[0049] Also with the above embodiment, for the plurality of full blades 4f arranged so that
the hub-side ends 4Af of the leading edges align on the same circle, it is possible
to differentiate the stall characteristics between the first blade 12f and the second
blade 14f. Thus, as compared to a case where the plurality of full blades 4f have
a uniform shape, it is possible to impair uniform propagation and development of rotating
stall. Accordingly, it is possible to improve the performance of the compressor at
the low flow-rate side. Furthermore, it is unnecessary to provide an additional suppressing
member disclosed in the prior art (
JP2014-118916), and thus it is possible to simplify the configuration compared to the prior art.
[0050] In the embodiment shown in FIG. 13, the plurality of splitter blades 4 constituting
the splitter blade group 6s includes at least one first blade 12s, and at least one
second blade 14s having a different shape from the first blade 12s. Furthermore, when
comparing the blade angle β1s of the leading edge 12LEs of the first blade 12s to
the blade angle β2s of the leading edge 14LEs of the second blade 14s at the same
position with respect to the radial direction of the compressor impeller 100, at least
in a partial range (see the range w1 in FIG. 3) in the radial direction of the compressor
impeller 100, the blade angle β1s of the leading edge 21LEs of the first blade 12s
is different from the blade angle β2s of the leading edge 14LEs of the second blade
14s.
[0051] Also with the above embodiment, for the plurality of splitter blades 4s arranged
so that the hub-side ends 4As of the leading edges align on the same circle, it is
possible to differentiate the stall characteristics between the first blade 12s and
the second blade 14s. Thus, as compared to a case where the plurality of splitter
blades 4s have a uniform shape, it is possible to impair uniform propagation and development
of rotating stall. Accordingly, it is possible to improve the characteristics of the
compressor at the low flow-rate side. Furthermore, it is unnecessary to provide an
additional suppressing member disclosed on the prior art, and thus it is simplify
the configuration compared to the prior art.
[0052] In the embodiment shown in FIG. 14, the plurality of full blades 4f constituting
the full blade group 6f includes at least one first blade 12f, and at least one second
blade 14f having a different shape from the first blade 12f. Furthermore, when comparing
the blade angle β1f of the leading edge 12LE of the first blade 12f to the blade angle
β2f of the leading edge 14LEf of the second blade 14f at the same position with respect
to the radial direction of the compressor impeller 100, at least in a partial range
(see the range w1 in FIG. 3) in the radial direction of the compressor impeller 100,
the blade angle β1f of the leading edge 21LEf of the first blade 12f is different
from the blade angle β2f of the leading edge 14LEf of the second blade 14f. Furthermore,
the plurality of splitter blades 4s constituting the splitter blade group 6s includes
at least one first blade 12s, and at least one second blade 14s having a different
shape from the first blade 12s. Furthermore, when comparing the blade angle β1s of
the leading edge 12LEs of the first blade 12s to the blade angle β2s of the leading
edge 14LEs of the second blade 14s at the same position with respect to the radial
direction of the compressor impeller 100, at least in a partial range (see the range
w1 in FIG. 3) in the radial direction of the compressor impeller 100, the blade angle
β1s of the leading edge 21LEs of the first blade 12s is different from the blade angle
β2s of the leading edge 14LEs of the second blade 14s.
[0053] Also with the above embodiment, for the plurality of full blades 4f arranged so that
the hub-side ends 4Af of the leading edges align on the same circle, it is possible
to differentiate the stall characteristics between the first blade 12f and the second
blade 14f. Thus, as compared to a case where the plurality of full blades 4f have
a uniform shape, it is possible to impair uniform propagation and development of rotating
stall. Furthermore, for the plurality of splitter blades 4s arranged so that the hub-side
ends 4As of the leading edges align on the same circle, it is possible to differentiate
the stall characteristics between the first blade 12s and the second blade 14s. Thus,
as compared to a case where the plurality of splitter blades 4s have a uniform shape,
it is possible to impair uniform propagation and development of rotating stall. Accordingly,
it is possible to improve the performance of the compressor at the low flow-rate side.
Furthermore, it is unnecessary to provide an additional suppressing member disclosed
in the prior art, and thus it is to simplify the configuration compared to the prior
art.
[0054] While a centrifugal compressor is described as an example in the above embodiment,
the present invention is not limited to a centrifugal compressor and may be applied
to an axial-flow compressor or a mixed-flow compressor, for instance.
Description of Reference Numerals
[0055]
- 2
- Hub
- 2a
- Outer peripheral surface
- 4
- Blade
- 4A
- Hub-side end
- 4f
- Full blade
- 4s
- Splitter blade
- 6
- Blade group
- 6f
- Full blade group
- 6s
- Splitter blade group
- 12
- Second blade
- 12LE
- Leading edge
- 12E
- Tip-side end of leading edge
- 12A
- Hub-side end of leading edge
- 12P
- Portion
- 14
- Second blade
- 14LE
- Leading edge
- 14E
- Tip-side end of leading edge
- 14A
- Hub-side end of leading edge
- 14S
- Suction surface
- 100
- Impeller
- C, Cf, Cs
- Circle
- L
- Perpendicular line
- O
- Rotational axis
- P1
- Predetermined position
- P2
- Reference position
- P3
- Intersection
- w1, w2
- Range
- r, z
- Position
1. A compressor impeller (100, 100A), comprising:
a hub (2); and
a blade group (6) including a plurality of blades (4) arranged along a circumferential
direction on an outer peripheral surface of the hub (2), the blade group (6) being
configured such that hub-side ends of leading edges of the respective blades (4) are
aligned on the same circle, wherein the plurality of blades (4) include at least one
first blade (12) and at least one second blade (14) having a different shape from
the at least one first blade (12), and
wherein, when comparing a blade angle of a leading edge (12LE), which is the angle
formed between a meridional direction (m) and the camber line of the blade at a certain
blade height, of the at least one first blade (12) to a blade angle of a leading edge
(14LE) of the at least one second blade (14) at the same position in a radial direction
of the compressor impeller (100, 100A), the blade angle of the leading edge (12LE)
of the at least one first blade (12) is different from the blade angle of the leading
edge (14LE) of the at least one second blade (14), at least in a partial range in
the radial direction of the compressor impeller (100, 100A);
wherein the number of the second blades (14) in the blade group (6) is smaller than
the number of the first blades (12) in the blade group (6), and
wherein, when comparing the blade angle of the leading edges (12LE) of the first blades
(12) to the blade angle of the leading edges (14LE) of the second blades (14) at the
same position in the radial direction of the compressor impeller (100, 100A), the
blade angle of the leading edges (14LE) of the second blades (14) is greater than
the blade angle of the leading edges (12LE) of the first blades (12) at least in a
partial range in the radial direction of the compressor impeller (100, 100A).
2. The compressor impeller (100, 100A) according to claim 1,
wherein the at least one first blade (12) includes a plurality of first blades (12),
wherein the at least one second blade (14) includes a plurality of second blades (14),
and wherein the plurality of second blades (14) include a pair of second blades (14)
between which the first blade (12) is not disposed.
3. The compressor impeller (100, 100A) according to claim 1 or 2,
wherein the blade angle of tip-side ends (14E) of the leading edges (14LE) of the
second blades (14) is greater than the blade angle of tip-side ends (12E) of the leading
edges (12LE) of the first blades (12).
4. The compressor impeller (100, 100A) according to claim 3,
wherein the blade angle of the tip-side ends (14E) of the leading edges (14LE) of
the second blades (14) is greater than the blade angle of the tip-side ends (12E)
of the leading edges (12LE) of the first blades (12) by five degrees or more.
5. The compressor impeller (100, 100A) according to claim 3 or 4,
wherein the blade angle of hub-side ends (14A) of the leading edges (14LE) of the
second blades (14) is equal to the blade angle of hub-side ends (12A) of the leading
edges (12LE) of the first blades (12).
6. The compressor impeller (100, 100A) according to claim 5,
wherein, when comparing the blade angle of the leading edges (12LE) of the first blades
(12) to the blade angle of the leading edges (14LE) of the second blades (14) at the
same position in the radial direction of the compressor impeller (100, 100A),
the blade angle of the leading edges (14LE) of the second blades (14) is greater than
the blade angle of the leading edges (12LE) of the first blades (12) in a range to
the tip-side ends (12E) from a predetermined position of not less than 50% of a blade
height of the second blades (14) in the radial direction of the compressor impeller
(100, 100A), and is equal to the blade angle of the leading edges (12LE) of the first
blades (12) in a range to the predetermined position from the hub-side ends (14A)
of the second blades (14) in the radial direction of the compressor impeller (100,
100A).
7. The compressor impeller (100, 100A) according to any one of claims 3 to 6,
wherein the first blades (12) and the second blades (14) have different shapes only
in an upstream region of a reference position in an axial direction of the compressor
impeller (100, 100A), and have the same shape in a downstream region of the reference
position in the axial direction of the compressor impeller (100, 100A).
8. The compressor impeller (100, 100A) according to claim 7,
wherein the reference position is a position upstream of an intersection between a
suction surface (14S) of the second blade (14) and a perpendicular line to the suction
surface of the second blade (14) from the tip-side end (14E) of the leading edge (14LE)
of the blade next to the suction surface of the second blade (14).
9. A method for manufacturing the compressor impeller (100, 100A) according to any one
of claims 1 to 8, comprising:
a first blade (12) forming step of forming a plurality of first blades (12) having
the same shape; and
a second blade (14) forming step of forming at least one second blade (14) by performing
a bending process on a leading-edge side portion (12P) of a part of the first blades
(12) formed in the first blade (12) forming step.
1. Verdichterlaufrad (100, 100A), umfassend:
eine Nabe (2); und
eine Schaufelgruppe (6), die eine Vielzahl von Schaufeln (4) einschließt, die entlang
einer Umfangsrichtung an einer Außenumfangsfläche der Nabe (2) angeordnet ist, wobei
die Schaufelgruppe (6) so ausgebildet ist, dass nabenseitige Enden von Vorderkanten
der entsprechenden Schaufeln (4) auf demselben Kreis ausgerichtet sind, wobei die
Vielzahl von Schaufeln (4) zumindest eine erste Schaufel (12) und zumindest eine zweite
Schaufel (14) aufweisend eine andere Form als die zumindest eine erste Schaufel (12)
einschließt, und
wobei, wenn ein Schaufelwinkel einer Vorderkante (12LE), der der Winkel ist, der zwischen
einer meridionalen Richtung (m) und der Wölbungslinie der Schaufel bei einer bestimmten
Schaufelhöhe gebildet ist, der zumindest einen ersten Schaufel (12) mit einem Schaufelwinkel
einer Vorderkante (14LE) der zumindest einen zweiten Schaufel (14) an derselben Position
in einer radialen Richtung des Verdichterlaufrades (100, 100A) verglichen wird, der
Schaufelwinkel der Vorderkante (12LE) der zumindest einen ersten Schaufel (12) sich
von dem Schaufelwinkel der Vorderkante (14LE) der zumindest einen zweiten Schaufel
(14) zumindest in einem Teilbereich in der radialen Richtung des Verdichterlaufrades
(100, 100A) unterscheidet;
wobei die Anzahl der zweiten Schaufeln (14) in der Schaufelgruppe (6) kleiner als
die Anzahl der ersten Schaufeln (12) in der Schaufelgruppe (6) ist, und
wobei, wenn der Schaufelwinkel der Vorderkanten (12LE) der ersten Schaufeln (12) mit
dem Schaufelwinkel der Vorderkanten (14LE) der zweiten Schaufeln (14) an derselben
Position in der radialen Richtung des Verdichterlaufrades (100, 100A) verglichen wird,
der Schaufelwinkel der Vorderkanten (14LE) der zweiten Schaufeln (14) zumindest in
einem Teilbereich in der radialen Richtung des Verdichterlaufrades (100, 100A) größer
ist als der Schaufelwinkel der Vorderkanten (12LE) der ersten Schaufeln (12).
2. Verdichterlaufrad (100, 100A) nach Anspruch 1,
wobei die zumindest eine erste Schaufel (12) eine Vielzahl von ersten Schaufeln (12)
einschließt,
wobei die zumindest eine zweite Schaufel (14) eine Vielzahl von zweiten Schaufeln
(14) einschließt, und
wobei die Vielzahl von zweiten Schaufeln (14) ein Paar von zweiten Schaufeln (14)
einschließt, zwischen welchen die erste Schaufel (12) nicht angeordnet ist.
3. Verdichterlaufrad (100, 100A) nach Anspruch 1 oder 2,
wobei der Schaufelwinkel von spitzenseitigen Enden (14E) der Vorderkanten (14LE) der
zweiten Schaufeln (14) größer ist als der Schaufelwinkel von spitzenseitigen Enden
(12E) der Vorderkanten (12LE) der ersten Schaufeln (12).
4. Verdichterlaufrad (100, 100A) nach Anspruch 3,
wobei der Schaufelwinkel der spitzenseitigen Enden (14E) der Vorderkanten (14LE) der
zweiten Schaufeln (14) um fünf Grad oder mehr größer ist als der Schaufelwinkel der
spitzenseitigen Enden (12E) der Vorderkanten (12LE) der ersten Schaufeln (12).
5. Verdichterlaufrad (100, 100A) nach Anspruch 3 oder 4,
wobei der Schaufelwinkel von nabenseitigen Enden (14A) der Vorderkanten (14LE) der
zweiten Schaufeln (14) gleich dem Schaufelwinkel von nabenseitigen Enden (12A) der
Vorderkanten (12LE) der ersten Schaufeln (12) ist.
6. Verdichterlaufrad (100, 100A) nach Anspruch 5,
wobei, wenn der Schaufelwinkel der Vorderkanten (12LE) der ersten Schaufeln (12) an
derselben Position in der radialen Richtung des Verdichterlaufrades (100, 100A) mit
dem Schaufelwinkel der Vorderkanten (14LE) der zweiten Schaufeln (14) verglichen wird,
der Schaufelwinkel der Vorderkanten (14LE) der zweiten Schaufeln (14) in einem Bereich
zu den spitzenseitigen Enden (12E) von einer vorbestimmten Position von nicht weniger
als 50% einer Schaufelhöhe der zweiten Schaufeln (14) in der radialen Richtung des
Verdichterlaufrades (100, 100A) größer ist als der Schaufelwinkel der Vorderkanten
(12LE) der ersten Schaufeln (12) und in einem Bereich zu der vorbestimmten Position
von den nabenseitigen Enden (14A) der zweiten Schaufeln (14) in der radialen Richtung
des Verdichterlaufrades (100, 100A) gleich dem Schaufelwinkel der Vorderkanten (12LE)
der ersten Schaufeln (12) ist.
7. Verdichterlaufrad (100, 100A) nach einem der Ansprüche 3 bis 6,
wobei die ersten Schaufeln (12) und die zweiten Schaufeln (14) nur in einer stromaufwärts
liegenden Region einer Referenzposition in einer Axialrichtung des Verdichterlaufrades
(100, 100A) verschiedene Formen aufweisen und dieselbe Form in einer stromabwärts
liegenden Region der Referenzposition in der Axialrichtung des Verdichterlaufrades
(100, 100A) aufweisen.
8. Verdichterlaufrad (100, 100A) nach Anspruch 7,
wobei die Referenzposition eine Position stromaufwärts eines Schnittpunkts zwischen
einer Ansaugfläche (14S) der zweiten Schaufel (14) und einer senkrechten Linie zur
Ansaugfläche der zweiten Schaufel (14) von dem spitzenseitigen Ende (14E) der Vorderkante
(14LE) der Schaufel neben der Saugfläche der zweiten Schaufel (14) ist.
9. Verfahren zum Herstellen des Verdichterlaufrades (100, 100A) nach einem der Ansprüche
1 bis 8, umfassend:
einen Bildungsschritt einer ersten Schaufel (12) zum Bilden einer Vielzahl von ersten
Schaufeln (12), die dieselbe Form aufweisen; und
einen Bildungsschritt einer zweiten Schaufel (14) zum Bilden zumindest einer zweiten
Schaufel (14) durch Durchführen eines Biegeprozesses an einem vorderkantenseitigen
Abschnitt (12P) eines Teils der ersten Schaufeln (12), die im Bildungsschritt einer
ersten Schaufel (12) gebildet wurden.
1. Rouet centrifuge (100, 100A), comprenant :
un moyeu (2) ; et
un groupe d'aubes (6) incluant une pluralité d'aubes (4) agencés le long d'une direction
circonférentielle sur une surface périphérique extérieure du moyeu (2), le groupe
d'aubes (6) étant configuré de telle sorte que des extrémités côté moyeu de bords
d'attaque des aubes (4) respectives sont alignées sur le même cercle, dans lequel
la pluralité d'aubes (4) incluent au moins une première aube (12) et au moins une
deuxième aube (14) ayant une forme différente de l'au moins une première aube (12),
et
dans lequel, quand on compare un angle d'aube d'un bord d'attaque (12LE), qui est
l'angle formé entre une direction méridionale (m) et la ligne de cambrure de l'aube
à une certaine hauteur d'aube, de l'au moins une première aube (12) à un angle d'aube
d'un bord d'attaque (14LE) de l'au moins une deuxième aube (14) dans la même position
dans une direction radiale du rouet centrifuge (100, 100A), l'angle d'aube du bord
d'attaque (12LE) de l'au moins une première aube (12) est différent de l'angle d'aube
du bord d'attaque (14LE) de l'au moins une deuxième aube (14), au moins dans une plage
partielle dans la direction radiale du rouet centrifuge (100, 100A) ;
dans lequel le nombre des deuxièmes aubes (14) du groupe d'aubes (6) est inférieur
au nombre des premières aubes (12) du groupe d'aubes (6), et
dans lequel, quand on compare l'angle d'aube des bords d'attaque (12LE) des premières
aubes (12) à l'angle d'aube des bords d'attaque (14LE) des deuxièmes aubes (14) dans
la même position dans la direction radiale du rouet centrifuge (100, 100A), l'angle
d'aube des bords d'attaque (14LE) des deuxièmes aubes (14) est différent de l'angle
d'aube des bords d'attaque (12LE) des premières aubes (12) au moins dans une plage
partielle dans la direction radiale du rouet centrifuge (100, 100A).
2. Rouet centrifuge (100, 100A) selon la revendication 1,
dans lequel l'au moins une première aube (12) inclut une pluralité de premières aubes
(12),
dans lequel l'au moins une deuxième aube (14) inclut une pluralité de deuxièmes aubes
(14), et
dans lequel la pluralité de deuxièmes aubes (14) inclut une paire de deuxièmes aubes
(14) entre lesquelles la première aube (12) n'est pas disposée.
3. Rouet centrifuge (100, 100A) selon la revendication 1 ou 2,
dans lequel l'angle d'aube d'extrémités côté pointe (14E) des bords d'attaque (14LE)
des deuxièmes aubes (14) est supérieur à l'angle d'aube d'extrémités côté pointe (12E)
des bords d'attaque (12LE) des premières aubes (12).
4. Rouet centrifuge (100, 100A) selon la revendication 3,
dans lequel l'angle d'aube des extrémités côté pointe (14E) des bords d'attaque (14LE)
des deuxièmes aubes (14) est supérieur à l'angle d'aube des extrémités côté pointe
(12E) des bords d'attaque (12LE) des premières aubes (12) de cinq degrés ou plus.
5. Rouet centrifuge (100, 100A) selon la revendication 3 ou 4,
dans lequel l'angle d'aube d'extrémités côté moyeu (14A) des bords d'attaque (14LE)
des deuxièmes aubes (14) est égal à l'angle d'aube d'extrémités côté moyeu (12A) des
bords d'attaque (12LE) des premières aubes (12).
6. Rouet centrifuge (100, 100A) selon la revendication 5,
dans lequel, quand on compare l'angle d'aube des bords d'attaque (12LE) des premières
aubes (12) à l'angle d'aube des bords d'attaque (14LE) des deuxièmes aubes (14) dans
la même position dans la direction radiale du rouet centrifuge (100, 100A),
l'angle d'aube des bords d'attaque (14LE) des deuxièmes aubes (14) est supérieur à
l'angle d'aube des bords d'attaque (12LE) des premières aubes (12) dans une plage
jusqu'aux extrémités côté pointe (12E) depuis une position prédéterminée de pas plus
de 50% d'une hauteur d'aube des deuxièmes aubes (14) dans la direction radiale du
rouet centrifuge (100, 100A), et est égal à l'angle d'aube des bords d'attaque (12LE)
des premières aubes (12) dans une plage jusqu'à la position prédéterminée depuis les
extrémités côté moyeu (14A) des deuxièmes aubes (14) dans la direction radiale du
rouet centrifuge (100, 100A).
7. Rouet centrifuge (100, 100A) selon l'une quelconque des revendications 3 à 6,
dans lequel les premières aubes (12) et les deuxièmes aubes (14) ont des formes différentes
uniquement dans une région amont d'une position de référence dans une direction axiale
du rouet centrifuge (100, 100A), et ont la même forme dans une région aval de la position
de référence dans la direction axiale du rouet centrifuge (100, 100A).
8. Rouet centrifuge (100, 100A) selon la revendication 7,
dans lequel la position de référence est une position en amont d'une intersection
entre une surface d'aspiration (14S) de la deuxième aube (14) et une ligne perpendiculaire
à la surface d'aspiration de la deuxième aube (14) depuis l'extrémité côté pointe
(14E) du bord d'attaque (14LE) de l'aube à côté de la surface d'aspiration de la deuxième
aube (14).
9. Procédé pour fabriquer le rouet centrifuge (100, 100A) selon l'une quelconque des
revendications 1 à 8, comprenant :
une étape de formation de première aube (12) de formation d'une pluralité de premières
aubes (12) ayant la même forme ; et
une étape de formation de deuxième aube (14) de formation d'au moins une deuxième
aube (14) en réalisant un processus de cintrage sur une partie côté bord d'attaque
(12P) d'une partie des premières aubes (12) formées lors de l'étape de formation de
première aube (12).