Patent Grant
10626739
The present disclosure relates to a rotary machine.
In a rotary machine such as a compressor and a turbine, at least one of a stationary vane or a rotor blade may be configured as a variable blade that is revolvable about a pivot axis along the radial direction of a hub, to adjust the attack angle with respect to flow.
In a rotary machine provided with such a variable blade, if the variable blade is configured such that the hub-side end surface of the variable blade does not interfere with the blade-facing surface of the hub in the rotation range of the variable blade, clearance between the hub-side end surface of the variable blade and the blade-facing surface of the hub is likely to increase when the variable blade is revolved toward the close side (in a direction that the angle between the chord line of the variable blade and the axial direction of the hub increases). Furthermore, if the rotary machine is configured such that the tip-side end surface of the variable blade does not interfere with the blade-facing surface of the casing in the rotation range of the variable blade, clearance between the tip-side end surface of the variable blade and the blade-facing surface of the casing is likely to increase when the variable blade is revolved toward the open side (in a direction that the angle between the chord line of the variable blade and the axial direction of the hub decreases). As described above, if the clearance between the hub-side end surface of the variable blade and the blade-facing surface of the hub or the clearance between the tip-side end surface of the variable blade and the blade-facing surface of the casing increases, loss due to a leakage flow that passes through the clearance (hereinafter, referred to as clearance loss) increases, and the efficiency of the rotary machine may decrease.
Patent Document 1 discloses a rotary machine with a variable blade including a spherically-shaped hub-side end surface recessed outward in the radial direction of the hub and a hub including a blade-facing surface which has a spherically-shaped spherical region protruding outward in the radial direction of the hub, so that the clearance between the hub-side end surface of the variable blade and the blade-facing surface of the hub does not increase at rotation of the variable blade toward the closing side.
Patent Document 2 discloses a configuration in which a trench is formed on the inner surface of the casing that faces the tip-side end surface of the blade and the tip-side end surface of the blade protrudes into the groove, to suppress a decrease in the efficiency of the rotary machine device due to a leakage flow that passes through the clearance between the tip-side end surface of the blade and the blade-facing surface of the casing.
If the blade-facing surface of the hub has a spherically-shaped spherical region protruding outward in the radial direction of the hub like the rotary machine described in Patent Document 1, the spherical region protruding into a flow path obstructs the smooth flow of fluid in the flow path unless some measure is provided. As a result, an outward flow in the radial direction of the hub (secondary flow) is created, or separation or the like occurs downstream of the spherical region, which may lead to deterioration of the performance of the rotary machine.
Further, the blade of the rotary machine described in Patent Document 2 is supposed to be a fixed blade not having a pivot axis along the radial direction and not a variable blade. Thus, Patent Document 2 does not mention how to suppress an increase in the above described clearance loss at rotation of the variable blade.
In view of the above, an object of at least one embodiment of the present invention is to, in a rotary machine provided with a variable blade configured to be revolvable about a pivot axis along the radial direction of a hub, suppress an increase in clearance loss that accompanies rotation of a variable blade.
(1) A rotary machine according to at least one embodiment of the present invention comprises: a hub configured to be rotatable about a rotational center axis; a casing configured to cover the hub and forming a fluid flow passage between the casing and the hub; and a variable blade disposed in the fluid flow passage and configured to be revolvable about a pivot axis along a radial direction of the hub. The hub includes: a blade-facing hub portion including a first blade-facing surface facing a hub-side end surface of the variable blade; and an upstream hub portion disposed upstream of the blade-facing hub portion in an axial direction of the hub and having a first outer peripheral surface being adjacent to the first blade-facing surface in the axial direction. The casing includes: a blade-facing casing portion including a second blade-facing surface which faces a tip-side end surface of the variable blade; and an upstream casing portion disposed upstream of the blade-facing casing portion in the axial direction and having a first inner peripheral surface being adjacent to the second blade-facing surface in the axial direction. At least one of following condition (a) or (b) is satisfied:
Dr1<Dh1≤Dr2 (a)
Dc1≥Dt1>Dc2 (b)
where Dr1 is a distance between an upstream end of the first blade-facing surface and the rotational center axis of the hub (rotational axis direction of the rotary machine), Dh1 is a distance between an upstream end of a hub-side end surface of the variable blade and the rotational center axis of the hub when an angle formed between the axial direction of the hub and a chord line of the variable blade is maximum, Dr2 is a distance between a downstream end of the first outer peripheral surface and the rotational center axis of the hub, Dc1 is a distance between an upstream end of the second blade-facing surface and the rotational center axis of the hub, Dt1 is a distance between an upstream end of the tip-side end surface of the variable blade and the rotational center axis of the hub when the angle formed between the axial direction of the hub and the chord line of the variable blade is minimum, and Dc2 is a distance between a downstream end of the first inner peripheral surface and the rotational center axis of the hub.
If the variable blade is configured such that the hub-side end surface of the variable blade does not interfere with the blade-facing surface of the hub in the rotation range of the variable blade, clearance between the hub-side end surface of the variable blade and the blade-facing surface of the hub (hereinafter, referred to as the hub-side clearance) is maximum when the angle formed between the chord line of the variable blade and the axial direction of the hub (hereinafter, referred to as blade angle) is maximum. Furthermore, if the rotary machine is configured such that the tip-side end surface of the variable blade does not interfere with the blade-facing surface of the casing in the rotation range of the variable blade, clearance between the tip-side end surface of the variable blade and the blade-facing surface of the casing (hereinafter, referred to as the tip-side clearance) is maximum when the blade angle is minimum. Herein, the blade angle being “maximum” and “minimum” refers to “maximum” and “minimum” in the rotation range used during operation of the rotary machine.
Thus, like the rotary machine described in the above (1), if at least one of the above condition (a) or (b) is satisfied, at least one of the hub-side clearance or the tip-side clearance is retracted from the mainstream of the fluid flow passage at the upstream end of the variable blade at any blade angle. Thus, it is possible to reduce clearance loss due to a leakage flow that passes through at least one of the hub-side clearance or the tip-side clearance.
Furthermore, with the above rotary machine (1), if at least one of Dr1<Dr2 (part of condition (a)) or Dc1>Dc2 (part of condition (b)) is satisfied, a step is formed between the first outer peripheral surface and the first blade-facing surface or between the first inner peripheral surface and the second blade-facing surface. This step generates a recirculation flow in at least one of the vicinity of the blade-facing surface of the hub or the vicinity of the blade-facing surface of the casing. This recirculation flow increases the virtual flow rate, and thus it is possible to suppress separation on the hub or the casing.
(2) In some embodiments, in the rotary machine described in the above (1), at least the above condition (a) is satisfied, and the first blade-facing surface is inclined so as to be away from the rotational center axis of the hub toward downstream.
Herein, whether separation occurs tends to depend on the flow rate in the vicinity of the leading edge of the blade. If the flow rate in the vicinity of the leading edge of the blade is set to be high, separation can be suppressed easily even if the flow rate is somewhat small in the vicinity of the trailing edge of the blade. A leakage flow passing through the hub-side clearance is created by the pressure difference between the pressure surface and the suction surface of the blade. Thus, if the clearance on the leading-edge side of the blade (upstream of the center of the chord line of the blade) with the maximum pressure difference is off the mainstream, it is possible to reduce the clearance loss effectively.
As described above, the need for the effect to reduce clearance loss and suppress separation is greater at the leading-edge side of the blade (upstream of the center of the chord line of the blade) and relatively smaller at the trailing-edge side.
Thus, on the trailing-edge side, the disadvantage from a decrease in the efficiency accompanying generation of a recirculation flow may outweigh the advantage of the effect to reduce clearance loss and suppress separation.
In this regard, with the above rotary machine (2), if the above condition (a) is satisfied, the upstream end of the hub-side clearance is retracted from the mainstream of the fluid flow passage at any blade angle. Thus, at the leading-edge side of the blade, it is possible to reduce clearance loss due at a leakage flow that passes through the hub-side clearance and suppress a decrease in separation by forming a recirculation flow.
Furthermore, with the above rotary machine (2), the first blade-facing surface is inclined so as to be away from the rotational center axis of the hub toward downstream, and thereby it is possible to suppress the disadvantage caused by the recirculation flow at the trailing-edge side.
(3) In some embodiments, in the rotary machine described in the above (1) or (2), at least the above condition (b) is satisfied, and the second blade-facing surface is inclined so as to be closer to the rotational center axis of the hub toward downstream.
As described above, the need for the effect to reduce clearance loss and suppress separation is greater at the leading-edge side of the blade (upstream of the center of the chord line of the blade) and relatively smaller at the trailing-edge side. Thus, on the trailing-edge side, the disadvantage from a decrease in the efficiency accompanying generation of a recirculation flow may outweigh the advantage of the effect to reduce clearance loss and suppress separation.
In this regard, with the above rotary machine (3), if the above condition (b) is satisfied, the upstream end of the tip-side clearance is retracted from the mainstream of the fluid flow passage at any blade angle. Thus, at the leading-edge side of the blade, it is possible to reduce clearance loss due to a leakage flow that passes through the tip-side clearance and suppress a decrease in separation by forming a recirculation flow.
Furthermore, with the above rotary machine (3), the second blade-facing surface is inclined so as to be closer to the rotational center axis of the hub toward downstream, and thereby it is possible to suppress the disadvantage caused by the recirculation flow at the trailing-edge side.
(4) In some embodiments, in the rotary machine according to any one of claims (1) to (3), the hub includes a downstream hub portion disposed downstream of the blade-facing hub portion in the axial direction of the hub. The downstream hub portion includes a second outer peripheral surface adjacent to the first blade-facing surface in the axial direction. An expression Dh2≤Dr3 is satisfied, where Dh2 is a distance between a downstream end of the hub-side end surface of the variable blade and the rotational center axis of the hub when the angle formed between the axial direction of the hub and the chord line of the variable blade is minimum, and Dr3 is a distance between an upstream end of the second outer peripheral surface and the rotational center axis of the hub.
With the above rotary machine (4), Dh2≤Dr3 is satisfied, and thereby the hub-side clearance is retracted from the mainstream of the fluid flow passage from the leading-edge side to the trailing-edge side when the blade angle is at its minimum.
As described above in the description on the above rotary machine (2), the need for the effect to reduce clearance loss is greater at the leading-edge side of the blade (upstream of the center of the chord line of the blade) and relatively smaller at the trailing-edge side of the blade. Thus, as with the above rotary machine (4), at the trailing-edge side of the blade, if the hub-side clearance is retracted from the mainstream of the fluid flow passage when the blade angle is minimum, it is possible to satisfy the need for the effect to reduce clearance loss to some extent.
(5) In some embodiments, in the rotary machine described in the above (4), the rotary machine satisfies an expression Dh3≤Dr3, where Dh3 is a distance between a downstream end of the hub-side end surface of the variable blade and the rotational center axis of the hub when the angle formed between the axial direction of the hub and the chord line of the variable blade is maximum, and Dr3 is a distance between an upstream end of the second outer peripheral surface and the rotational center axis of the hub.
With the above rotary machine (5), the entire region of the hub-side clearance is retracted from the mainstream of the fluid flow passage at any blade angle (regardless of the operational state of the rotary machine). Thus, it is possible to enjoy the effect to reduce clearance loss caused by a leakage flow that passes through the hub-side clearance at any blade angle.
(6) In some embodiments, in the rotary machine according to any one of claims (1) to (5), the casing includes a downstream casing portion disposed downstream of the blade-facing casing portion in the axial direction of the hub. The downstream casing portion includes a second inner peripheral surface adjacent to the second blade-facing surface in the axial direction. An expression Dt2≥Dc3 is satisfied, where Dt2 is a distance between a downstream end of the tip-side end surface of the variable blade and the rotational center axis of the hub when an angle formed between the axial direction of the hub and the chord line of the variable blade is maximum, and Dc3 is a distance between an upstream end of the second inner peripheral surface and the rotational center axis of the hub.
With the above rotary machine (6), Dt2≥Dc3 is satisfied, and thereby the tip-side clearance is retracted from the mainstream of the fluid flow passage when the blade angle is at its maximum.
As described above in the description on the above rotary machine (2), the need for the effect to reduce clearance loss is greater at the leading-edge side of the blade (upstream of the center of the chord line of the blade) and relatively smaller at the trailing-edge side of the blade. Thus, as with the above rotary machine (6), at the trailing-edge side of the blade, if the tip-side clearance is retracted from the mainstream of the fluid flow passage when the blade angle is maximum (during low-flow-rate operation of the rotary machine), it is possible to satisfy the need for the effect to reduce clearance loss to some extent.
(7) In some embodiments, in the rotary machine described in the above (3), the rotary machine satisfies an expression Dt3≥Dc3, where Dt3 is a distance between a downstream end of the tip-side end surface of the variable blade and the rotational center axis of the hub when the angle formed between the axial direction of the hub and the chord line of the variable blade is minimum, and Dc3 is a distance between an upstream end of the second inner peripheral surface and the rotational center axis of the hub.
With the above rotary machine (7), the entire region of the tip-side clearance is retracted from the mainstream of the fluid flow passage at any blade angle (regardless of the operational state of the rotary machine). Thus, it is possible to enjoy the effect to reduce clearance loss caused by a leakage flow that passes through the tip-side clearance at any blade angle.
According to at least one embodiment of the present invention, with a rotary machine provided with a variable blade configured to be revolvable about a pivot axis along the radial direction of a hub, it is possible to suppress an increase in clearance loss that accompanies rotation of the variable blade.
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly specified, 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.
For instance, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.
On the other hand, an expression such as “comprise”, “include”, “have”, “contain” and “constitute” are not intended to be exclusive of other components.
The axial-flow compressor 100 shown in
The rotor blades 8 are disposed in the fluid flow passage 4, and configured to be revolvable about the pivot axis O2 along the radial direction of the hub 2, thereby being capable of changing the angle α1 (see
The stationary vanes 10 are disposed in the fluid flow passage 4, and configured to be revolvable about the pivot axis O3 along the radial direction of the hub 2, thereby being capable of changing the angle α2 (see
When the hub 2 and the rotor blades 8 fixed to the hub 2 rotate about the rotational center axis O1, a fluid that flows from an inlet 7 of the casing 6 becomes compressed, and the compressed fluid flows out from an outlet 9 of the casing 6.
Next, with regard to the axial-flow compressor 100 shown in
In some embodiments, as shown in
Furthermore, the upstream hub portion 20, the blade-facing hub portion 16, and the downstream hub portion 32 may be formed integrally (of one piece), or may be formed separately (of separate members). Alternatively, at least one of the upstream hub portion 20, the blade-facing hub portion 16, or the downstream hub portion 32 may be formed of a plurality of members. For instance, as shown in
Furthermore, the upstream casing portion 30, the blade-facing casing portion 26, and the downstream casing portion 36 may be formed integrally (of one piece), or may be formed separately (of separate members). Alternatively, at least one of the upstream casing portion 30, the blade-facing casing portion 26, or the downstream casing portion 36 may be formed of a plurality of members. For instance, as shown in
In some embodiments, as shown in
Dr1<Dh1≤Dr2 (a)
Dc1≥Dt1>Dc2 (b)
Herein, as shown in
Next, the technical advantage of satisfying at least one of the condition (a) or (b) will be described with reference to
Accordingly, with the axial-flow compressor 100 shown in
Furthermore, with the axial-flow compressor 100 shown in
In some embodiments, shown in
Herein, whether separation occurs tends to depend on the flow rate in the vicinity of the leading edge of the rotor blade 8. If the flow rate in the vicinity of the leading edge of the rotor blade 8 is set to be high, separation can be suppressed easily even if the flow rate is somewhat small in the vicinity of the trailing edge of the rotor blade 8. Further, as shown in
As described above, the need for the effect to reduce clearance loss and suppress separation is greater at the leading-edge side of the rotor blade 8 and relatively smaller at the trailing-edge side. Thus, on the trailing-edge side, the disadvantage from a decrease in the efficiency accompanying generation of a recirculation flow may outweigh the advantage of the effect to reduce clearance loss and suppress separation.
In this regard, with the axial-flow compressor 100 shown in
In some embodiments, as shown in
As described above, the need for the effect to reduce clearance loss and suppress separation is greater at the leading-edge side of the rotor blade 8 and relatively smaller at the trailing-edge side. Thus, on the trailing-edge side, the disadvantage from a decrease in the efficiency accompanying generation of a recirculation flow may outweigh the advantage of the effect to reduce clearance loss and suppress separation.
In this regard, with the axial-flow compressor 100 shown in
In some embodiments, as shown in
Herein, Dh2 is the distance between the downstream end 12b of the hub-side end surface 12 of the rotor blade 8 and the rotational center axis O1 of the hub 2 when the blade angle of the rotor blade 8 is at its minimum, and Dr3 is the distance between the upstream end 34a of the second outer peripheral surface 34 and the rotational center axis O1 of the hub 2.
With this configuration, Dh2≤Dr3 is satisfied, and thereby the hub-side clearance Ch is retracted from the mainstream of the fluid flow passage 4 from the leading-edge side to the trailing-edge side when the blade angle is at its minimum.
As described above, the need for the effect to reduce clearance loss is greater at the leading-edge side of the rotor blade 8 (upstream of the center of the chord line of the rotor blade 8) and relatively smaller at the trailing-edge side of the rotor blade 8. Thus, as with the axial-flow compressor 100 shown in
In some embodiments, as shown in
Herein, Dh3 is the distance between the downstream end 12b of the hub-side end surface 12 of the rotor blade 8 and the rotational center axis O1 of the hub 2 when the blade angle is at its maximum, and Dr3 is the distance between the upstream end 34a of the second outer peripheral surface 34 and the rotational center axis O1 of the hub 2.
With this configuration, the entire region of the hub-side clearance Ch is retracted from the mainstream of the fluid flow passage 4 at any blade angle. Thus, it is possible to enjoy the effect to reduce clearance loss caused by a leakage flow that passes through the hub-side clearance Ch at any blade angle.
In some embodiments, as shown in
Herein, Dt2 is the distance between the downstream end 22b on the tip-side end surface 22 of the rotor blade 8 and the rotational center axis O1 of the hub 2 when the blade angle is at its maximum, and Dc3 is the distance between the upstream end 38a of the second inner peripheral surface 38 and the rotational center axis O1 of the hub 2.
With this configuration, Dt2≥Dc3 is satisfied, and thereby the tip-side clearance Ct is retracted from the mainstream of the fluid flow passage 4 when the blade angle is at its maximum.
As described above, the need for the effect to reduce clearance loss is greater at the leading-edge side of the rotor blade 8 and relatively smaller at the trailing-edge side of the rotor blade 8. Thus, as with the axial-flow compressor 100 shown in
In some embodiments, as shown in
Herein, Dt3 is the distance between the downstream end 22b of the tip-side end surface 22 of the rotor blade 8 and the rotational center axis O1 of the hub 2 when the blade angle is at its minimum, and Dc3 is the distance between the upstream end 38a of the second inner peripheral surface 38 and the rotational center axis O1 of the hub 2.
With this configuration, the entire region of the tip-side clearance Ct is retracted from the mainstream of the fluid flow passage 4 at any blade angle. Thus, it is possible to enjoy the effect to reduce clearance loss caused by a leakage flow that passes through the tip-side clearance Ch at any blade angle.
In some embodiments, the axial-flow compressor 100 may satisfy Dt3<Dc3 as shown in
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.
For instance, while the relationship between the shape of the rotor blade 8 and the shape of the hub 2 or the casing 6 is described in the above embodiments, this relationship can be applied to the relationship between the shape of the stationary vane 10 and the shape of the hub 2 or the casing 6.
Furthermore, to suppress an increase in the hub-side clearance or the tip-side clearance when changing the blade angle, spherical machining as described in Patent Document 1 may be applied to the hub-side end surface 12, the first blade-facing surface 14, the tip-side end surface 22, and the second blade-facing surface 24 if needed.
Furthermore, the present invention can be applied to a rotary machine such as a boiler axial-flow fan, a blast-furnace axial-flow blower, a gas turbine compressor, and various turbines.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/080170 | 10/27/2015 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/072844 | 5/4/2017 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 835836 | Schulz | Nov 1906 | A |
| 2651496 | Buckland | Sep 1953 | A |
| 2963268 | Paulson | Dec 1960 | A |
| 3701536 | Matthews | Oct 1972 | A |
| 3885886 | Richter | May 1975 | A |
| 3990810 | Amos | Nov 1976 | A |
| 3992127 | Booher, Jr. | Nov 1976 | A |
| 4013377 | Amos | Mar 1977 | A |
| 4150915 | Karstensen | Apr 1979 | A |
| 4278398 | Hull | Jul 1981 | A |
| 4732538 | Wollenweber | Mar 1988 | A |
| 4738586 | Harter | Apr 1988 | A |
| 4861228 | Todman | Aug 1989 | A |
| 4884820 | Jackson | Dec 1989 | A |
| 5297931 | Yapp | Mar 1994 | A |
| 5489186 | Yapp | Feb 1996 | A |
| 6350102 | Bailey | Feb 2002 | B1 |
| 6602049 | Caubet | Aug 2003 | B2 |
| 6709231 | Schipani | Mar 2004 | B2 |
| 8360712 | Deo | Jan 2013 | B2 |
| 8439634 | Liang | May 2013 | B1 |
| 8668445 | Crespo | Mar 2014 | B2 |
| 9533485 | Marshall | Jan 2017 | B2 |
| 9638212 | Marshall | May 2017 | B2 |
| 9708914 | Fulayter | Jul 2017 | B2 |
| 20020061249 | Caubet | May 2002 | A1 |
| 20040240990 | Rockley | Dec 2004 | A1 |
| 20050091849 | Brooks | May 2005 | A1 |
| 20050220610 | Ghasripoor | Oct 2005 | A1 |
| 20070289286 | Bauer | Dec 2007 | A1 |
| 20110070074 | Schabowski | Mar 2011 | A1 |
| 20110299977 | Memmer | Dec 2011 | A1 |
| 20120248704 | Fennell | Oct 2012 | A1 |
| 20130084168 | Babu | Apr 2013 | A1 |
| 20130236298 | Chouhan | Sep 2013 | A1 |
| 20130312249 | Buchal | Nov 2013 | A1 |
| 20140255188 | Fulayter | Sep 2014 | A1 |
| 20150003972 | Lim | Jan 2015 | A1 |
| 20150037145 | Casavant | Feb 2015 | A1 |
| 20160010560 | Dierksmeier | Jan 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 30-818 | Feb 1955 | JP |
| 53-162407 | May 1976 | JP |
| 57-117799 | Jan 1981 | JP |
| 58-183898 | Oct 1983 | JP |
| 59-73600 | May 1984 | JP |
| 3-13498 | Feb 1991 | JP |
| 7-26904 | Jan 1995 | JP |
| 2007-321721 | Dec 2007 | JP |
| Entry |
|---|
| JP-026904A—Machine Translation (Year: 1993). |
| Office Action dated Dec. 26, 2018 in corresponding Chinese Application No. 201580081804.1. |
| English Translation of Written Opinion of the International Searching Authority of PCT/JP2015/080170 dated Jan. 26, 2016. |
| International Search Report of PCT/JP2015/080170 dated Jan. 26, 2016. |
| Office Action dated May 26, 2017 issued in corresponding JP Application No. 2014-167695 with Translation. |
| Number | Date | Country | |
|---|---|---|---|
| 20180073376 A1 | Mar 2018 | US |
