Centrifugal turbo machine

Abstract

A centrifugal turbo machine (1) according to one embodiment comprises: an impeller (3); a diaphragm (4) that is disposed on the back side of the impeller (3); and a shroud (5) that is positioned around the impeller (3) and that forms a radial flow path (11) with the diaphragm (4). One of the diaphragm (4) and the shroud (5) is provided with a plurality of vanes (7) that are disposed in the radial flow path (11). In the other of the diaphragm (4) and the shroud (5), a plurality of independent grooves (8) into which the tips of the vanes (7) can be respectively inserted are formed. In each of the plurality of independent grooves (8), an elastic body (9) that abuts the tip of a corresponding vane (7) directly or via a metal plate is disposed.

Description

Centrifugal turbo machine

[0001] The present disclosure relates to a centrifugal turbo machine.

[0002] Conventionally, centrifugal turbo machines such as centrifugal compressors, centrifugal pumps, and radial turbines have been known. Centrifugal compressors and centrifugal pumps give work to a fluid to increase the pressure, and radial turbines recover power from a high-pressure fluid.

[0003] A centrifugal turbo machine includes an impeller, a diaphragm disposed on the back side of the impeller, and a shroud located around the impeller and forming a radial flow path between the diaphragm. A plurality of vanes disposed in the radial flow path are provided on the diaphragm or the shroud. The vanes are, for example, diffuser vanes in a centrifugal compressor and a centrifugal pump, and nozzle vanes in a radial turbine.

[0004] Generally, a certain gap is formed between the side without vanes of the diaphragm and the shroud and the vanes to prevent their contact due to thermal deformation. However, the gap causes a leakage flow that degrades the performance of the turbo machine.

[0005] For example, Patent Document 1 discloses a centrifugal compressor in which a recess into which the tip of each vane fits is formed in the side without vanes of the diaphragm and the shroud. In Patent Document 1, the diaphragm is called a "hub". In such a centrifugal compressor, the leakage flow through the gap between the side without vanes of the diaphragm and the shroud and the vanes is reduced.

[0006] Japanese Patent Application Laid-Open No. 2010-196705

[0007] When the centrifugal compressor structure described in Patent Document 1 is applied to turbomachinery operating at certain high or low temperatures, the aforementioned recess is set to a size that minimizes the clearance between the vane tip and the recess at around the design rating point. On the other hand, turbomachinery is often operated at partial load under conditions such as rotational speeds or pressure ratios lower than the design rating point. However, at such partial loads, the thermal balance, temperature distribution, or pressure balance changes significantly with respect to the design rating point, increasing the clearance between the vane tip and the recess. Therefore, the performance improvement effect due to the reduction of leakage flow is limited.

[0008] Therefore, the purpose of this disclosure is to provide a centrifugal turbomachinery that can exhibit performance improvement effects regardless of operating conditions such as design rating point or partial load.

[0009] This disclosure provides a centrifugal turbomachinery comprising, in a first aspect, an impeller, a diaphragm disposed on the rear side of the impeller, a shroud positioned around the impeller and forming a radial flow path between itself and the diaphragm, and a plurality of vanes provided on one of the diaphragm and the shroud and disposed within the radial flow path, wherein the other of the diaphragm and the shroud has a plurality of individual grooves into which the tips of the plurality of vanes can each enter, and elastic bodies are disposed within the plurality of individual grooves that contact the corresponding tips of the vanes directly or via metal plates.

[0010] This disclosure provides a centrifugal turbomachinery comprising: an impeller; a diaphragm disposed on the rear side of the impeller; a shroud located around the impeller and forming a radial flow path between itself and the diaphragm; and a plurality of vanes provided on one of the diaphragm and the shroud and disposed within the radial flow path, wherein an annular groove is formed in the other of the diaphragm and the shroud into which the tips of the plurality of vanes can enter, and an elastic body is disposed within the annular groove that contacts the tips of the plurality of vanes directly or via a metal plate.

[0011] According to this disclosure, a centrifugal turbomachinery is provided that can exhibit performance improvement effects regardless of operating conditions such as design rating point or partial load.

[0012] This is a cross-sectional view of a centrifugal turbomachinery according to the first embodiment. This is a front view of a portion of a diaphragm showing some of the vanes in cross-section. This is a cross-sectional view along the line III-III in Figure 2. This is a front view of a diaphragm showing the vanes in cross-section in a centrifugal turbomachinery according to the second embodiment. This is a cross-sectional view near the tip of one vane along the line V-V in Figure 4. This is a cross-sectional view near the tip of one vane in a modified example. This is a cross-sectional view near the tip of one vane in another modified example.

[0013] <First Embodiment> Figure 1 shows a centrifugal turbomachinery 1 according to one embodiment. The fluid used in the centrifugal turbomachinery 1 may be either a gas or a liquid. In this embodiment, the centrifugal turbomachinery 1 is a single-stage type, but the centrifugal turbomachinery 1 may be a multi-stage type.

[0014] The centrifugal turbomachinery 1 includes an impeller 3, a diaphragm 4 positioned on the back side of the impeller 3, and a shroud 5 positioned around the impeller 3 and forming a radial flow path 11 between itself and the diaphragm 4. In this embodiment, the centrifugal turbomachinery 1 includes a volute casing 6 that forms a volute chamber communicating with the radial flow path 11, but the volute chamber may be omitted.

[0015] The impeller 3 includes a hub 31 that expands in diameter from the front to the back, and a plurality of blades 32 provided on the outer circumferential surface of the hub 31. The impeller 3 is fixed to the rotating shaft 2, and a bearing 21 that rotatably supports the rotating shaft 2 is held in the diaphragm 4.

[0016] Multiple vanes 7 are arranged within the radial flow path 11. The vanes 7 are diffuser vanes if the centrifugal turbomachinery 1 is a centrifugal compressor or centrifugal pump, and nozzle vanes if the centrifugal turbomachinery 1 is a radial turbine.

[0017] As shown in Figure 2, the vanes 7 are arranged in a direction that creates a swirling flow from or to the impeller 3. In the illustrated example, each vane 7 has a shape that widens from the inner end on the impeller 3 side to the outer end on the opposite side of the impeller 3, but the shape of each vane 7 can be changed as appropriate.

[0018] In this embodiment, as shown in Figure 1, the vanes 7 are integrally provided with the shroud 5. On the other hand, the diaphragm 4 has the same number of individual grooves 8 as the vanes 7, into which the tips of each vane 7 can fit. As shown in Figure 2, the contour of each individual groove 8 is slightly larger than the contour of the vanes 7.

[0019] As shown in Figure 3, an elastic body 9 is arranged within each individual groove 8 so as to fill the groove 8. In this embodiment, each elastic body 9 is in direct contact with the tip of the corresponding vane 7. However, each elastic body 9 may be in contact with the tip of the corresponding vane 7 via a metal plate.

[0020] In this embodiment, the elastic body 9 is pre-formed into a shape similar to the individual groove 8 and inserted into the individual groove 8. Furthermore, each elastic body 9 tapers towards the bottom of the individual groove 8, and a gap is secured between the elastic body 9 and the side surface of the individual groove 8 to allow for the elastic body 9 to move when the vane 7 is inserted into the individual groove 8. Each elastic body 9 may be bonded to the bottom of the individual groove 8 with an adhesive, or it may be held in place within the individual groove 8 by the elastic force of the elastic body 9 in the width direction.

[0021] In this embodiment, the material of the elastic body 9 is rubber (thermosetting elastomer). Examples of rubber that can be used include silicone rubber, urethane rubber, and fluororubber. However, the material of the elastic body 9 may also be a thermoplastic elastomer. For example, the hardness (JIS K 6253) of the elastic body 9 is 60° to 80°.

[0022] In the centrifugal turbomachinery 1 with the configuration described above, the elastic body 9 arranged in each individual groove 8 deforms in accordance with the positional change of the tip of the corresponding vane 7. Therefore, when thermal deformation occurs in the diaphragm 4 and shroud 5, or when the radial flow path 11 expands due to pressure, a gap is prevented from forming between the diaphragm 4 and the vane 7 where the vane 7 is not provided. Consequently, the centrifugal turbomachinery can exhibit performance improvement effects regardless of operating conditions such as the design rating point or partial load.

[0023] <Modification> The elastic body 9 does not necessarily need to be molded in advance into a shape similar to the individual grooves 8. For example, the elastic body 9 may be molded using the individual grooves 8 by pouring liquid silicone rubber that hardens at room temperature into the individual grooves 8 and allowing it to harden. In this case, the cross-sectional shape of the elastic body 9 will be the same as the cross-sectional shape of the individual grooves 8.

[0024] <Second Embodiment> Figure 4 shows a diaphragm 4 in a centrifugal turbomachinery according to the second embodiment. In this embodiment, an annular groove 8A centered on the rotation axis 2 is formed in the diaphragm 4, into which the tips of all the vanes 7 can enter. Furthermore, as shown in Figure 5, an elastic body 9A is arranged inside the annular groove 8A so as to fill the annular groove 8A. In this embodiment, the elastic body 9A is in direct contact with the tips of all the vanes 7.

[0025] The annular groove 8A has an inner surface located radially inward and an outer surface located radially outward. The diameter of the inner surface is smaller than the diameter of the circle passing through the inner end of the vane 7, and the diameter of the outer surface is larger than the diameter of the circle passing through the outer end of the vane 7.

[0026] Furthermore, in this embodiment, the elastic body 9A is pre-formed into a shape similar to the annular groove 8A and inserted into the annular groove 8A. Protrusions 81 that engage with the elastic body 9A are provided on both sides of the annular groove 8A, namely the inner and outer sides. The material of the elastic body 9A may be rubber (thermosetting elastomer) or a thermoplastic elastomer.

[0027] In this embodiment, the projections 81 protrude inward from the annular groove 8A along the surface of the diaphragm 4 facing the radial flow path 11. On the other hand, the pre-molded elastic body 9A has a ring portion with a width approximately equal to the distance between the projections 81, and a pair of hooks 91 protruding radially inward and radially outward from one end of the ring portion. When the elastic body 9A attempts to dislodge from the annular groove 8A, the hooks 91 engage with the projections 81, respectively.

[0028] In this embodiment, the elastic body 9A positioned within the annular groove 8A deforms in accordance with the positional changes of the tips of each vane 7. This prevents the formation of gaps between the diaphragm 4 and the vanes 7 when thermal deformation occurs in the diaphragm 4 and shroud 5, or when the radial flow path 11 expands due to pressure. Therefore, the centrifugal turbomachinery 1 can exhibit performance improvement effects regardless of operating conditions such as the design rating point or partial load.

[0029] Furthermore, since protrusions 81 are provided on both sides of the annular groove 8A, the elastic body 9A can be maintained within the annular groove 8A.

[0030] <Modification> The elastic body 9A does not necessarily need to be molded in advance into a shape similar to the annular groove 8A. For example, the elastic body 9A may be molded using the annular groove 8A by pouring liquid silicone rubber that hardens at room temperature into the annular groove 8A and allowing it to harden. In this case, as shown in Figure 6, the shape of the elastic body 9A will be the same as the cross-sectional shape of the annular groove 8A.

[0031] As shown in Figure 7, the elastic body 9A may contact the tips of all the vanes 7A via an annular metal plate 92 having the same width as the annular groove 8A. With this configuration, the elastic body 9A is prevented from coming into contact with the fluid flowing in the radial channel.

[0032] The metal plate 92 may be continuous in the circumferential direction, or it may be divided into multiple pieces arranged in the circumferential direction. If the metal plate 92 is divided into multiple pieces, the number of pieces can be appropriately selected as long as it is less than or equal to the number of vanes 7.

[0033] <Other Embodiments> This disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the gist of this disclosure.

[0034] For example, contrary to the above embodiment, the vanes 7 may be integrally provided with the diaphragm 4, and individual grooves 8 or annular grooves 8A may be formed in the shroud 5. With this configuration, when thermal deformation occurs in the diaphragm 4 and shroud 5, it is prevented that a gap will be formed between the shroud 5, where the vanes 7 are not provided, and the vanes 7.

[0035] <Summary> In a first aspect, the present disclosure provides a centrifugal turbomachinery comprising: an impeller; a diaphragm disposed on the rear side of the impeller; a shroud located around the impeller and forming a radial flow path between itself and the diaphragm; and a plurality of vanes provided on one of the diaphragm and the shroud and disposed within the radial flow path, wherein the other of the diaphragm and the shroud has a plurality of individual grooves into which the tips of the plurality of vanes can each enter, and elastic bodies are disposed within the plurality of individual grooves that contact the corresponding vane tips directly or via metal plates.

[0036] According to the above configuration, the elastic body placed in each individual groove deforms in accordance with the positional change of the tip of the corresponding vane. This prevents the formation of a gap between the vane-less side of the diaphragm and shroud and the vane itself when thermal deformation occurs in the diaphragm and shroud or when the radial flow path expands due to pressure. Therefore, the centrifugal turbomachinery can achieve improved performance regardless of operating conditions such as design rating point or partial load.

[0037] In a second aspect, the present disclosure provides a centrifugal turbomachinery comprising: an impeller; a diaphragm disposed on the rear side of the impeller; a shroud located around the impeller and forming a radial flow path between itself and the diaphragm; and a plurality of vanes provided on one of the diaphragm and the shroud and disposed within the radial flow path, wherein an annular groove is formed in the other of the diaphragm and the shroud into which the tips of the plurality of vanes can enter, and an elastic body is disposed within the annular groove that contacts the tips of the plurality of vanes directly or via a metal plate.

[0038] According to the above configuration, the elastic body placed in the annular groove deforms in accordance with the positional changes of the tips of each vane. This prevents the formation of a gap between the vane-less side of the diaphragm and shroud and the vane itself when thermal deformation occurs in the diaphragm and shroud or when the radial flow path expands due to pressure. Therefore, the centrifugal turbomachinery can achieve improved performance regardless of operating conditions such as design rating point or partial load.

[0039] In a third embodiment, as in the second embodiment, projections that engage with the elastic body may be provided on both sides of the annular groove. With this configuration, the elastic body can be maintained within the annular groove.

[0040] In a fourth embodiment, in any of the first to third embodiments, for example, the material of the elastic body may be rubber.

[0041] 1. Centrifugal turbomachinery 11. Radial flow path 3. Impeller 4. Diaphragm 5. Shroud 7. Vanes 8. Individual grooves 8A. Annular groove 81. Projection 9, 9A. Elastic body

Claims

1. A centrifugal turbomachine comprising: an impeller; a diaphragm disposed on the rear side of the impeller; a shroud positioned around the impeller and forming a radial flow path between it and the diaphragm; and a plurality of vanes provided on one of the diaphragm and the shroud and disposed within the radial flow path, wherein the other of the diaphragm and the shroud has a plurality of individual grooves into which the tips of the plurality of vanes can each enter, and elastic bodies are disposed within the plurality of individual grooves that contact the corresponding tips of the vanes directly or via metal plates.

2. A centrifugal turbomachine comprising: an impeller; a diaphragm disposed on the rear side of the impeller; a shroud positioned around the impeller and forming a radial flow path between it and the diaphragm; and a plurality of vanes provided on one of the diaphragm and the shroud and disposed within the radial flow path, wherein an annular groove is formed in the other of the diaphragm and the shroud into which the tips of the plurality of vanes can enter, and an elastic body is disposed within the annular groove that contacts the tips of the plurality of vanes directly or via a metal plate.

3. The centrifugal turbomachinery according to claim 2, wherein projections that engage with the elastic body are provided on both sides of the annular groove.

4. The centrifugal turbomachinery according to any one of claims 1 to 3, wherein the material of the elastic body is rubber.

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