U.S. patent application number 15/507544 was filed with the patent office on 2017-10-05 for radial compressor impeller and associated radial compressor.
This patent application is currently assigned to Siemens Aktiengesellschaft. The applicant listed for this patent is Siemens Aktiengesellschaft. Invention is credited to Werner Jonen.
Application Number | 20170284412 15/507544 |
Document ID | / |
Family ID | 54140466 |
Filed Date | 2017-10-05 |
United States Patent
Application |
20170284412 |
Kind Code |
A1 |
Jonen; Werner |
October 5, 2017 |
RADIAL COMPRESSOR IMPELLER AND ASSOCIATED RADIAL COMPRESSOR
Abstract
A radial compressor impeller having a wheel disc, a cover disc
arranged at a distance from the wheel disc, and blades arranged
therebetween and connecting the wheel disc and the cover disc. The
blades have an end portion, which is arranged at a distance from
the radial outer end of the wheel disc and the cover disc towards
the inside and has a reduced thickness with respect to an adjoining
section.
Inventors: |
Jonen; Werner; (Duisburg,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Siemens Aktiengesellschaft |
Munich |
|
DE |
|
|
Assignee: |
Siemens Aktiengesellschaft
Munich
DE
|
Family ID: |
54140466 |
Appl. No.: |
15/507544 |
Filed: |
September 16, 2015 |
PCT Filed: |
September 16, 2015 |
PCT NO: |
PCT/EP2015/071174 |
371 Date: |
February 28, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 17/10 20130101;
F04D 29/284 20130101; F04D 29/30 20130101; F05D 2240/304
20130101 |
International
Class: |
F04D 29/30 20060101
F04D029/30; F04D 17/10 20060101 F04D017/10; F04D 29/28 20060101
F04D029/28 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 22, 2014 |
DE |
10 2014 219 058.4 |
Claims
1.-11. (canceled)
12. A radial compressor impeller comprising: a wheel disk, a cover
disk spaced apart from said wheel disk, and blades arranged
therebetween and connecting the wheel disk and the cover disk and
which have an end portion, spaced apart inward from the radial
outer end of the wheel disk and the cover disk, wherein the end
portion has a reduced thickness compared with an adjoining portion,
wherein the end portions of the blades each have a rounded edge
either on the suction side or on the pressure side.
13. The radial compressor impeller as claimed in claim 12, wherein
the diameter of the blades is 1% to 15% less than the diameter d of
the wheel and/or cover disk.
14. The radial compressor impeller as claimed in claim 13, wherein
the rounded edge and the profile of the blade on the suction side
merge gradually into each other.
15. The radial compressor impeller as claimed in claim 14, wherein
the rounded edge has a radius R which corresponds at least
approximately to the equation R.apprxeq.a.d, where d is the
diameter of the cover disk and/or the wheel disk, and a is a factor
between 0.1 and 0.3.
16. The radial compressor impeller as claimed in claim 12, wherein
approximately one third of the width of the radial outer end of the
blades is designed to be approximately parallel to the outer
circumference of the wheel disk and/or the cover disk, and the
rounded edge of the suction side adjoins said one third of the
width.
17. The radial compressor impeller as claimed in claim 16, wherein
the rounded edge on the pressure side and the profile of the blade
on the pressure side merge gradually into each other.
18. The radial compressor impeller as claimed in claim 12, wherein
the rounded edge on the pressure side has a radius R which
corresponds at least approximately to the equation R.apprxeq.b.d,
where d is the diameter of the cover disk and/or the wheel disk,
and b is a factor between 0.1 and 0.3.
19. The radial compressor impeller as claimed in claim 18, wherein
approximately one third of the width of the radial outer end of the
blades is designed to be approximately parallel to the outer
circumference of the wheel disk and the cover disk, and in that the
rounded edge of the pressure side adjoins said third.
20. A radial compressor comprising a radial compressor impeller as
claimed in claim 12.
21. The radial compressor impeller as claimed in claim 15, wherein
a is a factor of 0.2.
22. The radial compressor impeller as claimed in claim 18, wherein
b is a factor of 0.2.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2015/071174 filed Sep. 16, 2015, and claims
the benefit thereof. The International Application claims the
benefit of German Application No. DE 102014219058.4 filed Sep 22,
2014. All of the applications are incorporated by reference herein
in their entirety.
FIELD OF INVENTION
[0002] The invention relates to a radial compressor impeller with a
wheel disk, a cover disk spaced apart from said wheel disk, and
blades arranged therebetween and connecting the wheel disk and the
cover disk.
BACKGROUND OF INVENTION
[0003] Impellers of this type are used, for example, in compressors
or ventilators.
[0004] The wheel disk of such a radial compressor impeller has
blades which are, for example, milled from solid material, and a
cover disk is then fastened onto the blades, thereby forming the
radial compressor impeller.
[0005] A conventional radial compressor impeller is arranged on a
driven shaft. The radial compressor impeller is surrounded by a
housing and, as a result of the rotation of the radial compressor
impeller, a gas which flows axially into the space between the
wheel disk and cover disk can be accelerated radially and
circumferentially and consequently compressed. After it has passed
the radial compressor impeller, the flowing gas passes into a duct
of the housing.
[0006] The flow at the impeller outlet of a rotating radial
compressor impeller is coupled interactively with the flow at the
sides of the impeller. This interaction influences the performance,
in particular the achievable pressure increase and the efficiency
of a compressor stage. Pressure losses occur in the wake depression
in the region of the rotating trailing edge of an impeller blade
and this causes displacement and constriction effects in the flow
at the impeller outlet as a result of gas flowing from the sides of
the impeller into the impeller flow. The pressure increase of the
radial compressor impeller is thereby undesirably reduced.
[0007] These interactions between the flow at the impeller outlet
and the flow at the sides of the impeller are visualized by complex
3D flow simulations.
SUMMARY OF INVENTION
[0008] An object of the invention is therefore to provide a radial
compressor impeller which is designed such that a desired pressure
increase in a compressor stage occurs.
[0009] In order to achieve this object, in a radial compressor
impeller of the type mentioned at the beginning it is provided
according to the invention that the blades have an end portion,
spaced apart inward from the radial outer end of the wheel disk and
the cover disk, with a reduced thickness compared with an adjoining
portion.
[0010] In contrast to a conventional radial compressor impeller, in
which the blades extend as far as the outer circumference of the
wheel disk and cover disk, the blades of the radial compressor
impeller according to the invention are "shortened", i.e. they have
a shortened design and extend radially not as far as the outer end
of the wheel disk and cover disk but instead they have an end
portion which is offset or arranged radially inward from the outer
end. Furthermore, the radially outer end portions of the blades
also have a reduced thickness compared with the thickness of the
adjacent portion of the blades. The reduced thickness is here
advantageously provided only in the region of the end portion of
the blades, whereas the blades do not have a reduced thickness in
the adjoining portion. As a result of this adapted design of the
impeller outlet, the interaction of the impeller flow and the flow
at the sides of the impeller can be desirably influenced, and hence
the pressure increase in the compressor stage, at a specified
speed. Furthermore, mixture losses at the impeller outlet are
reduced, as a result of which the efficiency of the stage is
increased.
[0011] The "shortening" of the blades, i.e. their reduced diameter,
can be 1% to 15%, compared with the "unshortened" diameter d of the
wheel and/or cover disk.
[0012] A development of the invention provides that the end
portions of the blades in each case have a rounded edge on the
suction side. It has been noted that a thick blade trailing edge
causes clear pressure losses with correspondingly pronounced wake
depressions in the impeller downstream flow, and additionally
mixing takes place of the gas flowing through the radial compressor
impeller and the gas at the sides of the impeller.
[0013] The rounded edge and the profile of the blade on the suction
side advantageously gradual merge into each other. This means that
the rounded edge and the profile of the blade on the suction side,
i.e. the suction side contour, merge progressively into each other,
i.e. the rounded edge and the profile of the blade have the same
tangent at the point of contact.
[0014] In the radial compressor impeller according to the
invention, it is advantageous that the rounded edge has a radius R
which corresponds at least approximately to the equation
R.apprxeq.-a.d, where d is the diameter of the cover disk or the
wheel disk, and a is a factor between 0.1 and 0.3, which is
advantageously 0.2.
[0015] In a further embodiment of the invention it can be provided
that approximately one third of the width of the radial outer end
of the blades is designed to be approximately parallel to the outer
circumference of the wheel disk and the cover disk, and that the
rounded edge adjoins said third. Accordingly, the rounded edge does
not extend over the whole width of the radial outer end of the
blades and instead only over approximately two thirds of the width.
The radial outer end of the blades is designed to be parallel to
the outer circumference of the wheel disk and the cover disk, or
alternatively can also be designed as a tangent.
[0016] It is also within the scope of the invention that the end
portions of the blades in each case have a rounded edge on the
pressure side. Similarly or contrary to the rounded edge on the
suction side, the pressure side thus has a rounded edge.
Accordingly, the aerodynamic properties of the radial compressor
impeller according to the invention can be influenced in a targeted
fashion by modifying the profile on the suction side and/or the
pressure side. Usually either the suction side or the pressure side
is rounded, because both effects counteract each other.
[0017] On the pressure side too it is advantageous that the rounded
edge and the profile of the blade merge gradually into each other,
i.e. the tangents are identical at the contact point.
[0018] In the radial compressor impeller according to the
invention, the rounded edge can have a radius R which corresponds
at least approximately to the equation R.apprxeq.b.d, where d is
the diameter of the cover disk or the wheel disk, and b is a factor
between 0.1 and 0.3, which is advantageously 0.2.
[0019] A variant of the radial compressor impeller according to the
invention provides that approximately one third of the width of the
radial outer end of the blades is designed to be approximately
parallel to the outer circumference of the wheel disk and the cover
disk, and that the rounded edge adjoins said third.
[0020] Additionally, the invention relates to a radial compressor
which has a radial compressor impeller of the type described which
is accommodated in a housing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The invention is described in detail below with the aid of
exemplary embodiments and with reference to the drawings. The
drawings are schematic representations in which:
[0022] FIG. 1 shows a view in section of a detail of a radial
compressor impeller according to the invention;
[0023] FIG. 2 shows a cross-section through the blade shown in FIG.
1, along the line II-II;
[0024] FIG. 3 shows a similar view in section to that in FIG. 2
according to a further exemplary embodiment;
[0025] FIG. 4 shows a detail from FIG. 3 in the region of the end
portion of the blade;
[0026] FIG. 5 shows a similar view in section of the blade to that
in FIG. 2 according to a further exemplary embodiment; and
[0027] FIG. 6 shows a detail of the blade shown in FIG. 5 in the
region of the end portion of the blade.
DETAILED DESCRIPTION OF INVENTION
[0028] The view in section in FIG. 1 shows part of a radial
compressor impeller 1 which comprises a wheel disk 2 which is
fastened on a shaft (not shown). The radial compressor impeller 1
additionally comprises a cover disk 3 spaced apart from the wheel
disk 2. Blades 4, arranged distributed around the circumference,
are arranged in the space between the wheel disk 2 and the cover
disk 3. The radial compressor impeller 1 is surrounded externally
by a housing 5 which is shown only partially in FIG. 1. When the
radial compressor impeller 1, fastened on a shaft, is set in
rotation, a gas which flows in axially in the direction shown by an
arrow 6 can be accelerated and hence compressed radially and
circumferentially. The gas passes over the radial compressor
impeller 1 and flows into a flow duct 7 formed in the housing
5.
[0029] FIG. 2 is a view in section of the radial compressor
impeller 1 in FIG. 1 along the line II-II. In FIG. 2, only the
section through the blade 4 and a part of the wheel disk 2 is
shown, which is designed integrally with the blade 4. The blade 4
has an aerodynamic profile and comprises a suction side 8 and a
pressure side 9. The blade 4 has an approximately uniform thickness
over its length.
[0030] It can be seen in FIG. 2 that the blade 4 has an end portion
10 which is spaced apart inward from the radial outer end 11 of the
wheel disk 2 and from the cover disk 3 arranged approximately
parallel thereto. Accordingly, the blade 4 has a shortened radially
outer end, compared with a conventional blade. The shortened blade
end, which can be produced for example by machining, in particular
by boring, effects a reduction in the pressure increase of the
radial compressor impeller 1. A radial compressor impeller can
thus, for example after a bench test has been performed, be
modified by boring in such a way that a predetermined pressure
increase is obtained. As part of the production of a new radial
compressor impeller, the end portion of the blade can of course
also be formed directly, as shown in FIG. 2, i.e. with an end
portion spaced apart from the outer end of the wheel disk. On the
other hand, a pre-existing radial compressor impeller can be
machined as described by boring in order to shorten the blades in
the impeller outlet region.
[0031] FIGS. 3 and 4 show a further exemplary embodiment of a
radial compressor impeller, wherein--similarly to FIG. 2--only a
cross-section through a blade is shown, and in FIG. 4 a detail of
the view in FIG. 3.
[0032] The blade 12 shown in FIG. 3 corresponds in principle to the
blade 4 shown in FIG. 2. In particular, the blade 12 has an end
portion 13 which is spaced apart inward from the radial outer end
of the wheel disk 2. As can be seen best in the enlarged view in
FIG. 4, the end portion 13 of the blade 12 has a rounded edge 14 on
the suction side 8. The rounded edge 14 and the profile of the
blade 12 on the suction side 8 merge gradually into each other, and
at this point the tangential condition is fulfilled, i.e. the edge
14 and the edge of the profile of the blade 12 have the same
tangent at the contact point.
[0033] The rounded edge 14 is a segment of a circle with a radius R
which corresponds to approximately 0.2 times the diameter d of the
wheel disk 2.
[0034] It can be seen in FIG. 4 that approximately one third of the
(unrounded) width of the radial outer end portion 13 of the blade
12 is designed to be approximately parallel to the outer
circumference of the wheel disk 2, and that the rounded edge 14
adjoins said third. The outer edge of the end portion 13 and the
rounded edge 14 enclose an angle which is somewhat greater than
90.degree..
[0035] The end portion 13 having the rounded edge 14 can be formed
directly during the production of the blade 12 or the wheel disk 12
formed integrally with the blades, or alternatively the end portion
13 can also be produced subsequently by shaping a conventional
blade on a lathe. The production of the rounded edge 14 can thus be
viewed as "rounding off", i.e. the edge usually present at this
point is provided with a radius.
[0036] FIGS. 5 and 6 show a further exemplary embodiment of a
radial compressor impeller in the region of a blade, wherein FIG. 5
shows a similar view to that in FIGS. 2 and 3, and FIG. 6 shows an
enlarged detail of the blade shown in FIG. 5.
[0037] The blade 15 shown in FIGS. 5 and 6 has, in conformity with
the exemplary embodiment shown in FIG. 2, an end portion 16 which
is spaced apart from the radial outer end
[0038] 11 of the wheel disk 2. The end portion 16 of the
"shortened" blade 15 has a rounded edge 17 on the pressure side 9.
As can best be seen in FIG. 6, the rounded edge 17 and the outer
contour of the blade 15 on the pressure side 9 merge gradually into
each other. The tangential condition is fulfilled at the contact
point.
[0039] It is moreover shown in FIG. 6 that the rounded edge 17
takes the form of a segment of a circle, the radius of which
corresponds to approximately 0.2 times the diameter d of the wheel
disk 2. In other embodiments, a different radius can be provided
and this can be, for example, between 0.15 d and 0.25 d.
[0040] Approximately one third of the width of the radial end
portion 16 of the blade 15 is designed so that it is parallel to
the outer circumference of the wheel disk 2, and the rounded edge
17, which thus extends over approximately two thirds of the
(notional) width, adjoins said third.
[0041] A conventional radial compressor impeller can be machined by
boring the radial end portion of the blades and by rounding off on
the pressure side in such a way that the radial compressor impeller
shown in FIGS. 5 and 6 results. On the other hand, the shape of the
blade 15 shown in FIGS. 5 and 6 can be formed, during the
production of a new radial compressor impeller, directly by milling
or a different manufacturing method.
[0042] The different methods shown in the exemplary embodiments for
influencing the flow conditions cause a reduction in pressure
losses and reduction or prevention of undesired mixing of fluid in
the region of the sides of the impeller with fluid in the region of
the impeller outlet. In this way, the efficiency of the impeller
stage is increased. The measures shown in the different described
exemplary embodiments can also be combined with each other. In
order to obtain a radial compressor impeller with defined
properties, the modifications performed in the region of the end
portion of the blades can also be modified. For example, a rounded
edge can be provided on both the suction side and the pressure
side. Additionally, the remaining length of the blades in the
radial direction or the distance from the outer edge of the wheel
disk can also be adapted.
[0043] Although the invention has been illustrated and described in
detail via the preferred exemplary embodiments, the invention is
not limited by the disclosed examples and other variations can be
derived by a person skilled in the art without going beyond the
protective scope of the invention.
* * * * *