U.S. patent application number 13/380247 was filed with the patent office on 2012-05-31 for multi-stage radial turbine.
Invention is credited to Hirotaka Higashimori, Katsuki Yagi.
Application Number | 20120134797 13/380247 |
Document ID | / |
Family ID | 44195347 |
Filed Date | 2012-05-31 |
United States Patent
Application |
20120134797 |
Kind Code |
A1 |
Higashimori; Hirotaka ; et
al. |
May 31, 2012 |
MULTI-STAGE RADIAL TURBINE
Abstract
A multi-stage radial turbine that is capable of reducing the
number of bearings and of improving the conversion efficiency is
provided. Provided are a plurality of radial turbine rotor blades
(5) that are attached at intervals to a single rotating shaft (3);
a plurality of nozzles (19) that are individually installed on an
upstream side of each of the radial turbine rotor blades and that
accelerate a flow of fluid; a connecting channel portion (9) that
connects gas an outlet portion (23) of the radial turbine rotor
blade (5) on the front stage side and an upstream side of the
nozzle (19) on the rear stage side, the connecting channel portion
(9) being provided with a U-shaped bent portion (25) that deflects
outward in the radial direction the flow of fluid that is made to
flow out from the radial turbine rotor blade (5) in the shaft
direction; a vane portion having a plurality of deflecting vanes
(27) that deflect the flow of fluid inward in a rotation direction
(R) while guiding the flow of fluid from the U-shaped bent portion
(25) outward in the radial direction; and a return bent portion
(31) that deflects inward in the radial direction the flow that is
made to flow out from the vane portion (29) while swirling outward
in the radial direction.
Inventors: |
Higashimori; Hirotaka;
(Tokyo, JP) ; Yagi; Katsuki; (Tokyo, JP) |
Family ID: |
44195347 |
Appl. No.: |
13/380247 |
Filed: |
September 30, 2010 |
PCT Filed: |
September 30, 2010 |
PCT NO: |
PCT/JP2010/067065 |
371 Date: |
February 7, 2012 |
Current U.S.
Class: |
415/208.2 |
Current CPC
Class: |
F05D 2210/43 20130101;
F01D 1/06 20130101; F01D 13/02 20130101; F05D 2250/71 20130101;
F01D 9/06 20130101 |
Class at
Publication: |
415/208.2 |
International
Class: |
F01D 13/00 20060101
F01D013/00; F01D 9/04 20060101 F01D009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 2009 |
JP |
2009-292600 |
Claims
1. A multi-stage radial turbine comprising: a single rotating
shaft; a plurality of radial turbine rotor blades that are attached
at intervals to the rotating shaft and that cause a flow of fluid
that flows in from an outer peripheral side in a radial direction
to flow out in substantially a shaft direction; a plurality of
nozzles that are individually installed on an upstream side of each
of the radial turbine rotor blades and that accelerate the flow of
fluid in a rotation direction; a connecting channel portion that
connects an outlet portion of the radial turbine rotor blade on a
front stage side and an upstream side of the nozzle on a rear stage
side, the connecting channel portion being provided with a U-shaped
bent portion that deflects outward in the radial direction the flow
of fluid that is made to flow out from the radial turbine rotor
blade in the shaft direction; a vane portion having a plurality of
deflecting vanes that deflect the flow of fluid in the rotation
direction of the radial turbine rotor blades while guiding the flow
of fluid from the U-shaped bent portion outward in the radial
direction; and a return bent portion that deflects inward in the
radial direction the flow that flows out from the vane portion
while swirling outward in the radial direction.
2. A multi-stage radial turbine according to claim 1, wherein the
U-shaped bent portion is configured such that a downstream-portion
channel area at an end portion closer to the vane portion is made
smaller than an upstream-portion channel area at an end portion
closer to the radial turbine rotor blade.
3. A multi-stage turbine according to claim 2, wherein the
downstream-portion channel area is set to be equal to or less than
0.8 to 0.9 times the size of the upstream-portion channel area.
4. A multi-stage radial turbine according to claim 1, wherein the
deflecting vanes are configured to form involute curves.
5. A multi-stage radial turbine according to claim 2, wherein the
deflecting vanes are configured to form involute curves.
6. A multi-stage radial turbine according to claim 3, wherein the
deflecting vanes are configured to form involute curves.
Description
TECHNICAL FIELD
[0001] The present invention relates to a multi-stage radial
turbine.
BACKGROUND ART
[0002] A radial turbine has a configuration in which a plurality of
centrifugal blades are secured to a hub that is secured to a
rotating shaft, and air or gas, which is a working fluid that flows
inward from an outer peripheral side in the radial direction by
using the space between substantially parallel circular plates as a
flow channel, acts on the centrifugal blades, causing the hub to
rotate, and flows out in substantially a shaft direction.
[0003] Since it is possible to obtain a high expansion ratio with a
single stage, a radial turbine is generally employed with a
single-stage configuration.
[0004] In order to effectively utilize the energy of a working
fluid that shows a large heat drop at a high pressure ratio, it has
been proposed to utilize a multi-stage configuration in a radial
turbine, that is, to utilize the working fluid in series.
[0005] For example, as disclosed in Patent Literature 1, it has
been proposed to arrange a plurality of radial turbines in a row,
wherein a flow of fluid expelled from one radial turbine is
introduced into an inlet of the next radial turbine to recover the
energy of the working fluid. In this case, each radial turbine has
a shaft with a differing rotational speed, and work is performed by
using the rotation of the individual shafts.
CITATION LIST
Patent Literature
[0006] {PTL 1} Japanese Unexamined Patent Application, Publication
No. Sho 59-79096.
SUMMARY OF INVENTION
Technical Problem
[0007] With the disclosure in Patent Literature 1, because each
radial turbine has a rotating shaft, the numbers of bearings and
shaft seals increase. Because of this, bearing loss and leakage
loss increase; therefore, it has not been possible to efficiently
convert the energy of a high-pressure working fluid into rotational
motive power.
[0008] For example, when motive power is supplied for one
operation, a rotational force is transmitted from the individual
output shafts to a shaft for that operation by, for example,
employing gears; therefore, there is a problem in that the
structure thereof becomes large.
[0009] In light of the above-described circumstances, an object of
the present invention is to provide a multi-stage turbine that is
capable of reducing the number of bearings and of improving
conversion efficiency.
Solution to Problem
[0010] In order to solve the above-described problems, the present
invention employs the following solution.
[0011] Specifically, an aspect of the present invention is a
multi-stage radial turbine including a single rotating shaft; a
plurality of radial turbine rotor blades that are attached at
intervals to the rotating shaft and that cause a flow of fluid that
flows in from an outer peripheral side in a radial direction to
flow out in substantially a shaft direction; a plurality of nozzles
that are individually installed on an upstream side of each of the
radial turbine rotor blades and that accelerate the flow of fluid
in a rotation direction; a connecting channel portion that connects
an outlet portion of the radial turbine rotor blade on a front
stage side and an upstream side of the nozzle on a rear stage side,
the connecting channel portion being provided with a U-shaped bent
portion that deflects outward in the radial direction the flow of
fluid that is made to flow out from the radial turbine rotor blade
in the shaft direction; a vane portion having a plurality of
deflecting vanes that deflect the flow of fluid in the rotation
direction of the radial turbine rotor blades while guiding the flow
of fluid from the U-shaped bent portion outward in the radial
direction; and a return bent portion that deflects inward in the
radial direction the flow that flows out from the vane portion
while swirling outward in the radial direction.
[0012] With this aspect, the flow of fluid that flows in from the
outer peripheral side in the radial direction is accelerated in the
rotation direction by the nozzle and is introduced to the outer
peripheral portion of the radial turbine rotor blade. The fluid
that has been introduced to the radial turbine rotor blade is made
to flow out in the shaft direction from the radial turbine rotor
blade, passes through the U-shaped bent portion to be deflected
outward in the radial direction, and is subsequently deflected in
the rotation direction of the radial turbine rotor blade while
being guided outward in the radial direction with the deflecting
vanes when passing through the vane portion. The fluid that is made
to flow out from the vane portion while swirling outward in the
radial direction passes through the return bent portion to be
deflected inward in the radial direction and is made to flow into
the nozzle of the next stage from the outer peripheral side in the
radial direction. The flow of fluid repeatedly undergoes these
processes and is made to flow out in, for example, substantially
the shaft direction from the radial turbine rotor blade of the
final stage. Consequently, the rotation of each radial turbine
rotor blade is transmitted to the single rotating shaft, and the
rotating shaft is rotated.
[0013] Since the plurality of radial turbine rotor blades are
attached at intervals to the single rotating shaft in this way,
bearings and shaft seals need to be provided only for the single
rotating shaft, and, naturally, the numbers thereof can be reduced
as compared with a case in which a plurality of rotating shafts are
provided.
[0014] Therefore, because the bearing loss and the leakage loss can
be reduced, the energy of high-pressure working fluid can be
efficiently converted to a rotational motive force.
[0015] Furthermore, the structures of the radial turbine rotor
blades and the rotating shaft can be made similar to the
conventional structures, and it is possible to suppress an increase
in the size of the structure of the multi-stage radial turbine.
[0016] In the above-described aspect, the U-shaped bent portion may
be configured such that a downstream-portion channel area at an end
portion closer to the vane portion is made smaller than an
upstream-portion channel area at an end portion closer to the
radial turbine rotor blade.
[0017] Since the U-shaped bent portion is configured in this way
such that the downstream-portion channel area at the end portion
closer to the vane portion is smaller than the upstream-portion
channel area at the end portion closer to the radial turbine rotor
blade, it is possible to accelerate the flow of fluid at the
U-shaped bent portion.
[0018] By doing so, it is possible to suppress flow separation due
to the influence of the low-flow-speed regions that may occur at
the outlet portions of the radial turbine rotor blade.
[0019] With the above-described configuration, it is preferable
that the downstream-portion channel area be set to be equal to or
less than 0.8 to 0.9 times the size of the upstream-portion channel
area.
[0020] The low-flow-speed regions that may occur at the outlet
portions of the radial turbine rotor blade generally occupy 10 to
20% of the channel area at the outlet portions of the radial
turbine rotor blade.
[0021] With this aspect, because the flow of fluid can be
accelerated at the U-shaped bent portion by at least 10 to 20%, it
is possible to alleviate the influence of this low-flow-speed
region portion.
[0022] In the above-described aspect, it is preferable that the
deflecting vanes be configured to form involute curves.
[0023] With this configuration, a change between the channel area
at the inlet portion between the deflecting vanes of the vane
portion and the channel area at the outlet portion thereof can be
reduced.
[0024] Accordingly, it is possible to reduce the loss due to
deceleration, and the loss due to deflection at the vane portion
can be reduced.
Advantageous Effects of Invention
[0025] With the present invention, because a plurality of radial
turbine rotor blades are attached at intervals to a single rotating
shaft, bearings and shaft seals need to be provided only for a
single rotating shaft, and, naturally, the numbers thereof can be
reduced as compared with a case in which a plurality of rotating
shafts are provided.
[0026] Therefore, because bearing loss and leakage loss can be
reduced, it is possible to efficiently convert the energy of a
high-pressure working fluid to rotational motive power.
[0027] Furthermore, structures of the radial turbine rotor blades
and the rotating shaft can be made similar to conventional
structures, and an increase in the size of structures of the
multi-stage radial turbine can be suppressed.
BRIEF DESCRIPTION OF DRAWINGS
[0028] FIG. 1 is a partial sectional view showing, in outline, the
configuration of a single-shaft multi-stage radial turbine
(multi-stage radial turbine) according an embodiment of the present
invention.
[0029] FIG. 2 is a sectional view taken along X-X in FIG. 1.
DESCRIPTION OF EMBODIMENTS
[0030] A single-shaft multi-stage radial turbine 1 according to an
embodiment of the present invention will be described below with
reference to FIGS. 1 and 2.
[0031] FIG. 1 is a partial sectional view, showing, in outline, the
configuration of the single-shaft multi-stage radial turbine 1.
FIG. 2 is a sectional view taken along X-X in FIG. 1.
[0032] The single-shaft multi-stage radial turbine 1 is provided
with a rotating shaft 3, a plurality of, for example, two, radial
turbine rotor blades 5, a casing 7, and a connecting flow channel
portion 9.
[0033] The rotating shaft 3 is supported on the casing 7 at one end
by a radial bearing (not shown), and the other end thereof is
supported by a radial bearing (not shown) and a thrust bearing (not
shown).
[0034] The plurality of radial turbine rotor blades 5 are attached
at intervals in a shaft direction L of the rotating shaft 3 and
make a flow of fluid that has flowed in from an outer peripheral
side in a radial direction K flow out substantially in the shaft
direction L.
[0035] The radial turbine rotor blades 5 are provided with hubs 11
that are secured to the rotating shaft 3, numerous centrifugal
blades 13 that are secured on surfaces of the hubs 11 at equal
intervals in the circumferential direction, and shrouds 15 that are
attached at tips of the centrifugal blades 13.
[0036] In the radial turbine rotor blades 5, gas channels through
which gas (working fluid) passes are defined by the hubs 11, the
centrifugal blades 13, and the shrouds 15. Portions of the gas
channels that are located away from the rotating shaft 3 serve as
gas inlet portions 21, and portions thereof closer to the rotating
shaft 3 serve as gas outlet portions (outlet portions) 23.
[0037] A doughnut-shaped inlet channel 17 is formed at a portion of
the casing 7 located on the outer peripheral side of the gas inlet
portions 21 in the radial direction K. The inlet channel 17 is
configured so that the gas flows inward in the radial direction K
from the outer side of the radial direction K.
[0038] An airfoil nozzle 19 that accelerates a gas flow in a
rotation direction R is installed on the downstream side of the
inlet channel 17, in other words, on an upstream side of the radial
turbine rotor blade 5.
[0039] The connecting channel portion 9 is a channel provided in
the casing 7 that connect the gas outlet portions 23 of the radial
turbine rotor blade 5 on a front-stage side and an upstream side of
the nozzle 19 on a rear-stage side.
[0040] The connecting channel portion 9 is provided with a U-shaped
bent portion 25 that deflects a gas flow that has flowed out in the
shaft direction L from the radial turbine rotor blade 5 outward in
the radial direction K, a vane portion 29 that has a plurality of
deflecting vanes 27 that deflect the gas flow from the U-shaped
bent portion 25 in the rotation direction R of the radial turbine
rotor blades 5, while guiding the gas flow outward in the radial
direction K, and a return bent portion 31 that deflects inward in
the radial direction K the gas that flows out from the vane portion
29 while swirling outward in the radial direction K.
[0041] A downstream-portion channel area A2 at an end portion of
the U-shaped bent portion 25 closer to the vane portion 29 is set
to have at most 0.8 to 0.9 times the area of an upstream-portion
channel area A1 at an end portion closer to the radial turbine
rotor blade 5. In other words, the downstream-portion channel area
A2 is made smaller than the upstream-portion channel area A1.
[0042] This ratio is determined in consideration of low-flow-speed
regions T that occur at least at the outlet portions of the radial
turbine rotor blade 5. The low-speed regions T generally occur so
as to occupy 10 to 20% of an outlet-portion channel area, that is,
the upstream-portion channel area A1, of the radial turbine rotor
blade 5.
[0043] Although it is preferable that the downstream-portion
channel area A2 be smaller than the upstream-portion channel area
A1, it may be made substantially equal in size or larger, depending
of the usage circumstances.
[0044] As shown in FIG. 2, the deflecting vanes 27 of the vane
portions 29 are configured so as to form involute curves.
[0045] The amount of change between a channel area A3 at an inlet
portion between the deflecting vanes 27 of the vane portion 29 and
a channel area A4 at an outlet portion thereof can be made
considerably smaller as compared with the amount of change between
a channel area A5 at an inlet portion between deflecting vanes 33,
which linearly expand as shown with two-dot chain lines in FIG. 2,
and a channel area A6 at an outlet portion thereof.
[0046] Although it is preferable that the deflecting vanes 27 form
the involute curves, they are not limited thereto, and they may be
appropriately shaped.
[0047] The operation of the single-shaft multi-stage radial turbine
1 according to this embodiment, configured as above, will now be
described.
[0048] A gas flow G1 that is supplied from a gas source (not shown)
to the inlet channel 17 of a first stage passes through the inlet
channel 17 and flows inward in the radial direction K into the
nozzle 19 from the outer peripheral side in the radial direction
K.
[0049] The nozzle 19 accelerates this gas flow G1 in the
circumferential direction R and supplies it to the gas inlet
portions 21 located at an outer peripheral portion of the radial
turbine rotor blade 5.
[0050] The gas that has been introduced to the radial turbine rotor
blade 5 is expanded when passing through the gas channel defined by
the hub 11, the centrifugal blades 13, and the shroud 15. The
centrifugal blades 13 are pushed by means of this expansion and
move in the rotation direction R. Since the hub 11 is rotationally
moved in the rotation direction R due to this movement of the
centrifugal blades 13, the rotating shaft 3 is rotated.
[0051] The gas flow that has flowed out in the shaft direction L
from the gas outlet portions 23 of the radial turbine rotor blade
passes through the U-shaped bent portion 25 and is deflected
outward in the radial direction K.
[0052] At this time, because the downstream-portion channel area A2
of the U-shaped bent portion 25 is set to be at most 0.8 to 0.9
times the area of the upstream-portion channel area A1, the gas
flow that passes through the U-shaped bent portion 25 is
accelerated by at least 10 to 20%, corresponding to the reduction
of the channel area, for example.
[0053] Although the low-speed regions T that occupy 10 to 20% of
the channel area generally occur in front of and behind the gas
outlet portions 23 of the radial turbine rotor blade 5, because at
least a corresponding level of acceleration occurs at the U-shaped
bent portion 25, it is possible to substantially eliminate the
low-speed regions T. In other words, the influence of the
low-flow-speed regions T can be alleviated.
[0054] Because the influence of the low-speed regions T can be
alleviated in this way, by concentrating the low-flow-speed regions
T that occur at the gas outlet portions 23 of the radial turbine
rotor blade 5, it is possible suppress the occurrence of flow
separation by means of the curvature of a surface of the shroud 15
on the downstream side.
[0055] Furthermore, in the case in which the downstream-portion
channel area A2 can be made smaller than 0.8 to 0.9 times the area
of the upstream-portion channel area A1, it is possible to further
suppress flow separation; therefore, the curvatures of individual
portions can be reduced further.
[0056] By doing so, the total shaft length of the multi-stage
configuration in particular can be made shorter; therefore, the
total length of the single-shaft radial turbine 1 can be made
shorter, and the single-shaft radial turbine 1 can be made more
compact.
[0057] When the gas flow subsequently passes through the vane
portion 29, it is deflected in the rotation direction R of the
radial turbine rotor blade 5 while being guided outward in the
radial direction K by the deflecting vanes 27.
[0058] At this time, because the deflecting vanes 27 are configured
to form involute curves, the amount of change between the channel
area A3 at the inlet portion between the deflecting vanes 27 and
the channel area A4 at the outlet portion thereof is made small.
Accordingly, at the vane portion 29, it is possible to reduce the
loss due to deceleration of the gas flow and the loss due to
deflection.
[0059] Furthermore, by adjusting the angles of the deflecting vanes
27, a flow angle at the inlet of the nozzle 19 on the downstream
side can be adjusted. For example, if the flow angle at the inlet
of the nozzle 19 is adjusted to be 40 to 50 degrees in the
circumferential direction, the inlet-collision loss at the nozzle
19 can be reduced.
[0060] The flow that flows out from the vane portion 29 outward in
the radial direction K while swirling passes through the return
bent portion 31, is deflected inward in the radial direction K, and
is made to flow into the inlet channel 17 of the next stage from
the outer peripheral side in the radial direction K.
[0061] A gas flow G2 supplied from the return bent portion 31
passes through the inlet channel 17 and flows into the nozzle 19
inward in the radial direction K from the outer peripheral side in
the radial direction K.
[0062] The nozzle 19 accelerates this gas flow G2 in the
circumferential direction R and supplies it to the gas inlet
portions 21 located at the outer peripheral portion of the radial
turbine rotor blade 5.
[0063] The gas that is introduced to the radial turbine rotor blade
5 is expanded when passing through the gas channel defined by the
hub 11, the centrifugal blades 13, and the shroud 15. The
centrifugal blades 13 are pushed by means of this expansion and
move in the rotation direction R. Since the hub 11 is rotationally
moved in the rotation direction R due to this movement of the
centrifugal blades 13, the rotating shaft 3 is rotated.
[0064] The gas flow that has flowed out in the shaft direction L
from the gas outlet portions 23 of the radial turbine rotor blade
passes through a discharge channel (not shown) and is discharged to
the exterior of the single-shaft radial turbine 1.
[0065] Since the plurality of radial turbine rotor blades 5 are
attached at intervals to the single rotating shaft 3 in this way,
bearings and shaft seals need to be provided only for the single
rotating shaft 3, and, naturally, the numbers thereof can be
reduced as compared with a case in which a plurality of rotating
shafts are provided.
[0066] Therefore, because bearing loss and leakage loss can be
reduced, the energy of high-pressure working fluid can efficiently
be converted to a rotational motive force. Moreover, the heat drop
thereof can be converted to a rotational motive force with one
single-shaft radial turbine.
[0067] Furthermore, together with the fact that the structures of
the radial turbine rotor blades 5 and the rotating shaft 3 can be
made similar to the conventional structures, it is possible to
suppress an increase in the size of the structures in the
single-shaft radial turbine 1.
[0068] The present invention is not limited to the above-described
embodiment, various modifications may be made within a range that
does not depart form the spirit of the present invention.
[0069] For example, although two stages of the radial turbine rotor
blades 5 are employed in this embodiment, this may be changed to
three stages or greater. In this case, the radial turbine rotor
blades 5 that are adjacent to each other are connected with the
connecting channel portions 9.
REFERENCE SIGNS LIST
[0070] 1 single-shaft radial turbine [0071] 3 rotating shaft [0072]
5 radial turbine rotor blade [0073] 9 connecting channel portion
[0074] 19 nozzle [0075] 25 U-shaped bent portion [0076] 27
deflection vane [0077] 29 vane portion [0078] 31 return bent
portion [0079] A1 upstream-portion channel area [0080] A2
downstream-portion channel area [0081] K radial direction [0082] L
shaft direction [0083] R rotation direction
* * * * *