WO2011077801A1

WO2011077801A1 - Multistage radial turbine

Info

Publication number: WO2011077801A1
Application number: PCT/JP2010/067065
Authority: WO
Inventors: 東森　弘高; 八木　克記
Original assignee: 三菱重工業株式会社
Priority date: 2009-12-24
Filing date: 2010-09-30
Publication date: 2011-06-30
Also published as: CN102472114A; RU2518703C2; JP2011132877A; EP2518280A1; RU2011152805A; EP2518280A4; US20120134797A1

Abstract

Provided is a multistage radial turbine wherein the number of bearings can be reduced to improve the conversion efficiency. The multistage radial turbine is provided with a plurality of radial turbine rotor blades (5) which are spaced and attached to a single rotary shaft (3), a plurality of nozzles (19), each of which is disposed upstream of each radial turbine rotor blade and accelerates flow of fluid in the rotational direction, and a connection passage portion (9) for connecting a gas outlet portion (23) of the former stage-side radial turbine rotor blades (5) to the upstream side of the latter stage-side nozzles (19). The connection passage portion (9) is provided with a U-shaped bending portion (25) for turning the flow of fluid discharged from the radial turbine rotor blades (5) in the axial direction, a vane portion (29) having a plurality of turning vanes (27) for turning the flow of fluid from the U-shaped bending portion (25) in the rotational direction (R) of the radial turbine rotor blades (5) while radially and outwardly introducing the flow, and a return bending portion (31) for radially and inwardly turning the flow of fluid discharged from the vane portion (29) while radially and outwardly swirling.

Description

Multistage radial turbine

The present invention relates to a multistage radial turbine.

In a radial turbine, a plurality of centrifugal blades are fixed to a hub fixed to a rotating shaft, and air or gas, which is a working fluid that flows inward from the outer peripheral side in the radial direction with a flow path between substantially parallel disks, is a centrifugal blade. The hub is rotated by acting on the structure and is substantially discharged in the axial direction.
A radial turbine may obtain a high expansion ratio in a single stage and is generally used in a single stage configuration.

In order to effectively use the energy of a working fluid having a large heat drop at a high pressure ratio, it has been proposed to use a radial turbine in a multistage configuration, that is, to use the working fluid in series.
For example, as shown in Patent Document 1, a plurality of radial turbines are arranged in parallel, and a fluid flow discharged from one radial turbine is introduced into the inlet of the next radial turbine to recover the energy of the working fluid. Proposed. This is because each radial turbine has a shaft with a different rotational speed, and the rotation of each shaft is used to work.

JP 59-79096 A

In what is shown in Patent Document 1, since there is a rotating shaft for each radial turbine, bearings and shaft seals increase. For this reason, since bearing loss and leakage loss become large, the energy of the high-pressure working fluid cannot be efficiently converted into rotational power.
For example, when power is supplied to one work, the rotational force is transmitted to each work shaft from each output shaft using, for example, a gear, so that there is a problem that the structure becomes large.

In view of such circumstances, an object of the present invention is to provide a multistage radial turbine capable of reducing the number of bearings and improving conversion efficiency.

In order to solve the above problems, the present invention employs the following means.
That is, according to one aspect of the present invention, there is provided a single rotating shaft and a plurality of radial turbine motions that are attached to the rotating shaft with a space therebetween and that flow out of the fluid flow flowing in from the radially outer side toward the substantially axial direction. A plurality of nozzles installed on the upstream side of each of the radial turbine rotor blades for accelerating the fluid flow in the rotational direction, an outlet portion of the radial turbine rotor blade on the front stage side, and an upstream side of the nozzle on the rear stage side A connection flow path portion that connects the fluid flow flowing in the axial direction from the radial turbine blade, and a U-shaped bend portion that turns outward in the radial direction; A vane portion having a plurality of turning vanes that turn in the rotational direction of the radial turbine rotor blade while guiding a fluid flow from the U-shaped bend portion radially outward, and radially outward from the vane portion. Swirl A return bend portion for deflecting the flow of reluctant outflow radially inward, a multi-stage radial turbine is provided.

According to this aspect, the fluid flow flowing in from the radially outer peripheral side is accelerated in the rotational direction by the nozzle and introduced into the outer peripheral portion of the radial turbine rotor blade. The fluid introduced into the radial turbine blades flows axially out of the radial turbine blades, is turned radially outward through the U-shaped bend portion, and then, when passing through the vane portion, has a radius by the turning vane. It is turned in the rotational direction of the radial turbine rotor blade while being guided outward in the direction. The flow that flows out from the vane portion while turning outward in the radial direction is turned inward in the radial direction through the return bend portion, and flows into the next-stage nozzle from the outer peripheral side in the radial direction. The fluid flow repeats this and flows out from the radial turbine rotor blade at the final stage, for example, in a substantially axial direction. And rotation of each radial turbine rotor blade is transmitted to one rotating shaft, and a rotating shaft is rotated.
As described above, since the plurality of radial turbine rotor blades are attached to one rotary shaft with a space therebetween, the bearing and the shaft seal only need to be provided for one rotary shaft. The number can be reduced as compared with those having a plurality of rotating shafts.
Therefore, since the bearing loss and the leakage loss can be reduced, the energy of the high-pressure working fluid can be efficiently converted into rotational power.
Furthermore, the structure of the radial turbine rotor blade and the rotating shaft can be the same as the conventional structure, and the increase in the size of the structure of the multistage radial turbine can be suppressed.

In the above aspect, the U-shaped bend portion may be configured such that the downstream flow passage area at the vane portion side end is smaller than the upstream flow passage area at the radial turbine blade side end.

In this way, the U-shaped bend portion is configured such that the downstream flow passage area at the vane portion side end portion is smaller than the upstream flow passage area at the radial turbine rotor blade side end portion. The flow can be accelerated.
Thereby, the separation of the flow due to the influence of the low flow velocity region that may occur at the outlet portion of the radial turbine rotor blade can be suppressed.

In the above configuration, it is preferable that the downstream channel area is 0.8 to 0.9 times or less the upstream channel area.

The low flow velocity region that may occur at the outlet of the radial turbine blade generally occupies 10 to 20% of the flow path area of the outlet of the radial turbine blade.
According to this aspect, since the fluid flow can be accelerated by at least 10 to 20% in the U-shaped bend portion, the influence of the low-speed basin portion can be mitigated.

In the above aspect, it is preferable that the turning vane is configured as an involute curve.

If it does in this way, the change of the channel area in the entrance part between the turning vanes in a vane part and the channel area in an exit part can be made small.
Thereby, the loss by deceleration and the loss by turning can be reduced in a vane part.

According to the present invention, since the plurality of radial turbine rotor blades are attached to one rotary shaft with a space therebetween, the bearing and the shaft seal need only be provided for one rotary shaft. However, it can be reduced as compared with the one having a plurality of rotating shafts.
Therefore, since the bearing loss and the leakage loss can be reduced, the energy of the high-pressure working fluid can be efficiently converted into rotational power.
Furthermore, the structure of the radial turbine rotor blade and the rotating shaft can be the same as the conventional structure, and the increase in the size of the structure of the multistage radial turbine can be suppressed.

1 is a partial cross-sectional view showing a schematic configuration of a single-shaft multi-stage radial turbine (multi-stage radial turbine) according to an embodiment of the present invention. FIG. 2 is a sectional view taken along line XX in FIG.

Hereinafter, a single-shaft multistage radial turbine 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is a partial cross-sectional view showing a schematic configuration of a single-shaft multi-stage radial turbine 1. FIG. 2 is a sectional view taken along line XX of FIG.

The single-shaft multi-stage radial turbine 1 includes a rotating shaft 3, a plurality of, for example, two radial turbine blades 5, a casing 7, and a connection flow path portion 9.
One end of the rotary shaft 3 is supported on the casing 7 by a radial bearing (not shown), and the other end is supported by a radial bearing (not shown) and a thrust bearing (not shown).
The plurality of radial turbine blades 5 are attached at intervals in the axial direction L of the rotary shaft 3 and configured to flow out the fluid flow flowing in from the outer peripheral side in the radial direction K toward the substantially axial direction L. Yes.

The radial turbine rotor blade 5 includes a hub 11 fixed to the rotary shaft 3, centrifugal blades 13 fixed to the surface of the hub 11 at equal intervals in the circumferential direction, and a shroud attached to the tip of the centrifugal blade 13. 15 are provided.
In the radial turbine rotor blade 5, a gas passage through which gas (working fluid) passes is defined by the hub 11, the centrifugal blade 13, and the shroud 15. The side of the gas passage that is separated from the rotating shaft 3 is a gas inlet portion 21, and the rotating shaft 3 side is a gas outlet portion (outlet portion) 23.

An inlet flow path 17 having a donut shape is formed in the casing 7 on the outer peripheral side in the radial direction K of the gas inlet portion 21. The inlet channel 17 is configured such that gas flows along the radial direction K inward from the outside in the radial direction K.
A nozzle 19 having a blade shape for accelerating the gas flow in the rotational direction R is installed on the downstream side of the inlet channel 17, in other words, on the upstream side of the radial turbine rotor blade 5.

The connection channel 9 is a channel dug in the casing 7 and connects the gas outlet 23 of the radial turbine rotor blade 5 on the upstream side and the upstream side of the nozzle 19 on the downstream side.
In the connecting flow path portion 9, the gas flow flowing out in the axial direction L from the radial turbine rotor blade 5 is converted to a U-shaped bend portion 25 that turns outward in the radial direction K, and a gas flow from the U-shaped bend portion 25. And a vane portion 29 having a plurality of turning vanes 27 that turn in the rotation direction R of the radial turbine rotor blade 5, and flows out from the vane portion 29 while turning outward in the radial direction K. And a return bend portion 31 for turning the gas inward in the radial direction K.

The downstream flow area A2 at the end on the vane section 29 side in the U-shaped bend section 25 is 0.8 to 0.9 times or less the upstream flow area A1 at the end on the radial turbine blade 5 side. Yes. That is, the downstream flow path area A2 is smaller than the upstream flow path area A1.
This ratio is determined in consideration of at least the size of the low flow velocity region T generated at the outlet of the radial turbine rotor blade 5. The low speed region T is generally generated so as to occupy 10 to 20% of the outlet flow path area of the radial turbine rotor blade 5, that is, the upstream flow path area A1.
The downstream flow passage area A2 is preferably smaller than the upstream flow passage area A1, but may be substantially equal or larger depending on the use situation.

The turning vane 27 of the vane portion 29 is configured to form an involute-shaped curve, as shown in FIG.
In the vane portion 29, the amount of change between the flow passage area A3 at the inlet portion between the turning vanes 27 and the flow passage area A4 at the outlet portion is between the turning vanes 33 expanding linearly as shown by the two-dot chain line in FIG. The amount of change between the channel area A5 at the inlet portion and the channel area A6 at the outlet portion can be significantly reduced.
The turning vane 27 preferably forms an involute curve, but is not limited thereto and may be appropriately shaped.

The operation of the single-shaft multi-stage radial turbine 1 according to the present embodiment configured as described above will be described.
A gas flow G1 supplied from a gas source (not shown) to the first-stage inlet channel 17 flows into the nozzle 19 in the radial direction K from the outer peripheral side in the radial direction K toward the inner side through the inlet channel 17.
The nozzle 19 accelerates the gas flow G 1 in the circumferential direction R and supplies the gas flow G 1 to the gas inlet portion 21 located on the outer peripheral portion of the radial turbine rotor blade 5.

The gas introduced into the radial turbine rotor blade 5 is expanded when passing through a gas passage defined by the hub 11, the centrifugal blade 13, and the shroud 15. With this expansion, the centrifugal blade 13 is pushed and moves in the rotation direction R. Since the hub 11 rotates in the rotation direction R due to the movement of the centrifugal blade 13, the rotating shaft 3 rotates.
The gas flow flowing out in the axial direction L from the gas outlet portion 23 of the radial turbine rotor blade passes through the U-shaped bend portion 25 and is turned outward in the radial direction K.

At this time, since the downstream flow passage area A2 of the U-shaped bend portion 25 is 0.8 to 0.9 times or less of the upstream flow passage area A1, the gas flow through the U-shaped bend portion 25 is reduced. Is accelerated by, for example, 10 to 20% or more in response to the reduction of the channel area.
A low-speed region T, which generally occupies 10 to 20% of the flow path area, is generated at the front and rear positions of the gas outlet 23 of the radial turbine rotor blade 5, but at least a corresponding amount is accelerated by the U-shaped bend 25. Therefore, the low speed region T can be substantially eliminated. In other words, the influence of the low-speed basin T portion can be mitigated.

Since the influence of the low speed region T can be mitigated in this way, the flow separation is caused by the curvature of the surface of the shroud 15 on the downstream side by the accumulation of the low flow velocity region T generated at the gas outlet 23 of the radial turbine rotor blade 5. Occurrence can be suppressed.
Further, when the downstream flow area A2 can be made smaller than 0.8 to 0.9 times the upstream flow area A1, it is more difficult to peel off, so the curvature of each part is made smaller. be able to.
Thereby, since the total axial length of the multistage configuration can be particularly shortened, the overall length of the single-shaft radial turbine 1 can be shortened, and the single-shaft radial turbine 1 can be configured in a small size.

Next, the gas flow is turned in the rotation direction R of the radial turbine rotor blade 5 while being guided outward in the radial direction K by the turning vane 27 when passing through the vane portion 29.
At this time, since the turning vane 27 is configured to form an involute-shaped curve, the amount of change between the flow passage area A3 at the inlet portion and the flow passage area A4 at the outlet portion between the turning vanes 27 is small. It has been made smaller. Thereby, in the vane part 29, the loss by the deceleration of a gas flow and the loss by turning can be reduced.
Furthermore, by adjusting the angle of the turning vane 27, the flow angle at the inlet of the downstream nozzle 19 can be adjusted. For example, if the flow angle at the inlet of the nozzle 19 is adjusted to be 40 to 50 degrees from the circumferential direction, the inlet collision loss of the nozzle 19 can be reduced.

The flow flowing out from the vane portion 29 while turning outward in the radial direction K is turned inward in the radial direction K through the return bend portion 31 and flows into the inlet channel 17 of the next stage from the outer peripheral side in the radial direction K. It is done.
The gas flow G 2 supplied from the return bend portion 31 flows into the nozzle 19 in the radial direction K from the outer peripheral side in the radial direction K toward the inner side through the inlet channel 17.
The nozzle 19 accelerates the gas flow G 2 in the circumferential direction R and supplies the gas flow G 2 to the gas inlet portion 21 located on the outer peripheral portion of the radial turbine rotor blade 5.

The gas introduced into the radial turbine rotor blade 5 is expanded when passing through a gas passage defined by the hub 11, the centrifugal blade 13, and the shroud 15. With this expansion, the centrifugal blade 13 is pushed and moves in the rotation direction R. Since the hub 11 rotates in the rotation direction R due to the movement of the centrifugal blade 13, the rotating shaft 3 rotates.
The gas flow flowing out in the axial direction L from the gas outlet 23 of the radial turbine rotor blade is discharged out of the uniaxial radial turbine 1 through a discharge passage (not shown).

As described above, since the plurality of radial turbine blades 5 are attached to the single rotating shaft 3 at intervals, it is sufficient that the bearing and the shaft seal are provided for the single rotating shaft 3. Of course, it can be reduced as compared with the one having a plurality of rotating shafts.
Therefore, since the bearing loss and the leakage loss can be reduced, the energy of the high-pressure working fluid can be efficiently converted into rotational power. Moreover, the heat drop can be converted into rotational power with a set of single-shaft radial turbines.
Furthermore, the structure of the radial turbine rotor blade 5 and the rotary shaft 3 can be the same as that of the conventional structure, and the size of the single-shaft multi-stage radial turbine 1 can be suppressed from being increased.

The present invention is not limited to the embodiment described above, and various modifications may be made without departing from the spirit of the present invention.
For example, in this embodiment, the radial turbine rotor blade 5 has two stages, but it may have three or more stages. In this case, the adjacent radial turbine rotor blades 5 are connected to each other by the connection flow path portions 9.

DESCRIPTION OF SYMBOLS 1 Single-shaft radial turbine 3 Rotating shaft 5 Radial turbine rotor blade 9 Connection flow path part 19 Nozzle 25 U-shaped bend part 27 Turning vane 29 Vane part 31 Return bend part A1 Upstream flow area A2 Downstream flow area K Radial direction L Axial direction R Rotation direction

Claims

One rotating shaft,
A plurality of radial turbine rotor blades attached to the rotating shaft at intervals and flowing out the fluid flow flowing in from the radially outer peripheral side substantially in the axial direction;
A plurality of nozzles, each installed upstream of each radial turbine blade, for accelerating fluid flow in the rotational direction;
A connecting flow path portion connecting the outlet portion of the radial turbine rotor blade on the front stage side and the upstream side of the nozzle on the rear stage side, and
In the connection flow path portion, a fluid flow that flows out in the axial direction from the radial turbine rotor blade, a U-shaped bend portion that turns outward in the radial direction, and
A vane portion having a plurality of turning vanes that turn in the rotational direction of the radial turbine blade while guiding the fluid flow from the U-shaped bend portion radially outward;
A multi-stage radial turbine comprising: a return bend portion that turns a flow that flows out from the vane portion in a radial direction while turning outward in the radial direction.
2. The multistage radial according to claim 1, wherein the U-shaped bend portion is configured such that a downstream flow passage area of the vane portion side end portion is smaller than an upstream flow passage area of the radial turbine blade side end portion. Turbine.
The multi-stage radial turbine according to claim 2, wherein the downstream flow path area is 0.8 to 0.9 times or less of the upstream flow path area.
The multi-stage radial turbine according to any one of claims 1 to 3, wherein the turning vanes are configured in an involute curve.