Centrifugal turbo machine

Abstract

To provide a centrifugal turbo machine that can exert a performance improvement effect regardless of operation conditions such as a design rated point and a partial load.SOLUTION: A centrifugal turbo machine 1 includes: an impeller 3; a hub 5 arranged on the back side of the impeller 3; and a shroud 6 located around the impeller 3, and forming a radial flow passage 11 between itself and the hub 5. In one of the hub 5 and the shroud 6, a plurality of vanes 8 arranged in the radial flow passage 11 is provided. In the other of the hub 5 and the shroud 6, a plurality of depressions 51 in which tips of the vanes 8 are fitted respectively is formed. In the respective depressions 51, seals 9 for sealing gaps between bottoms of the depressions 51 and the tips of the corresponding vanes 8, and deforming by following dimensional changes between the bottoms of the depressions 51 and the tips of the vanes 8 are arranged.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to centrifugal turbomachines. [Background technology]

[0002] Conventionally, centrifugal turbomachines such as centrifugal compressors, centrifugal pumps, radial turbines, etc. have been known. The centrifugal compressors and centrifugal pumps apply work to a fluid to increase its pressure, and the radial turbines recover power from the high-pressure fluid.

[0003] A centrifugal turbomachine includes an impeller, a hub disposed on the rear side of the impeller, and a shroud disposed around the impeller and forming a radial flow passage between the hub and the impeller. The hub or the shroud is provided with a plurality of vanes disposed in the radial flow passage. The vanes are, for example, diffuser vanes in centrifugal compressors and centrifugal pumps, and nozzle vanes in radial turbines.

[0004] Generally, a certain amount of clearance is provided between the vanes and the hub or shroud that does not have the vanes in order to prevent contact between them due to thermal deformation, but the clearance causes leakage flow that deteriorates the performance of the turbomachine.

[0005] For example, Patent Document 1 discloses a centrifugal compressor in which a recess into which the tip of a vane fits is formed on the side of the hub or shroud on which the vane is not provided. The recess is called a "recess" in Patent Document 1. In this type of centrifugal compressor, leakage flow through a gap between the side of the hub or shroud on which the vane is not provided and the vane is reduced. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-196705 A Summary of the Invention [Problem to be solved by the invention]

[0007] When the structure of the centrifugal compressor of Patent Document 1 is applied to a turbomachine that operates at a relatively high or low temperature, the above-mentioned recess is set to a size that minimizes the clearance between the tip of the vane and the recess at around the design rated point. Meanwhile, turbomachines are often operated at partial load under conditions such as a lower rotation speed and a lower pressure ratio than the design rated point. However, at such partial loads, the heat balance and temperature distribution change significantly from the design rated point, and the clearance between the tip of the vane and the recess increases. For this reason, the performance improvement effect by reducing the leakage flow is limited.

[0008] Therefore, an object of the present disclosure is to provide a centrifugal turbomachine that can achieve a performance improvement effect regardless of an operating state such as a design rated point or a partial load. [Means for solving the problem]

[0009] The present disclosure provides a centrifugal turbomachine comprising: an impeller; a hub arranged on a rear side of the impeller; a shroud positioned around the impeller and forming a radial flow passage between the hub and the shroud; and a plurality of vanes arranged in the radial flow passage provided on one of the hub and the shroud, wherein a plurality of recesses are formed on the other of the hub and the shroud into which tips of the plurality of vanes respectively fit, and a seal is arranged within each recess, which seals between the bottom of the recess and the tip of the corresponding vane and deforms in response to a dimensional change between the bottom of the recess and the tip of the vane. Effect of the Invention

[0010] According to the present disclosure, a centrifugal turbomachine is provided that can achieve performance improvement effects regardless of operating conditions such as a design rated point or partial load. [Brief description of the drawings]

[0011] [Figure 1]1 is a cross-sectional view of a centrifugal turbomachine according to an embodiment; [Diagram 2] FIG. 2 is a cross-sectional view of one vane. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 1 shows a centrifugal turbomachine 1 according to one embodiment. The fluid used in the centrifugal turbomachine 1 may be either a gas or a liquid. In this embodiment, the centrifugal turbomachine 1 is a single-stage type, but the centrifugal turbomachine 1 may be a multi-stage type.

[0013] The centrifugal turbomachine 1 includes an impeller 3, a hub 5 disposed on the rear side of the impeller 3, and a shroud 6 positioned around the impeller 3 and forming a radial flow passage 11 between the impeller 3 and the hub 5. In this embodiment, the centrifugal turbomachine 1 includes a volute casing 7 forming a volute chamber communicating with the radial flow passage 11, but the volute chamber may be omitted.

[0014] The impeller 3 includes a hub 31 whose diameter increases 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 a rotating shaft 2, and a bearing 4 that rotatably supports the rotating shaft 2 is held by a hub 5.

[0015] A plurality of vanes 8 are arranged in the radial flow passage 11. The vanes 8 are diffuser vanes when the centrifugal turbomachine 1 is a centrifugal compressor and a centrifugal pump, and are nozzle vanes when the centrifugal turbomachine 1 is a radial turbine.

[0016] In this embodiment, the vanes 8 are provided integrally with the shroud 6. The hub 5 is formed with a plurality of recesses 51 into which the tips of the vanes 8 are fitted. Further, a seal 9 is disposed in each recess 51 to provide a seal between the bottom of the recess 51 and the tip of the corresponding vane 8.

[0017] As shown in Fig. 2, the contour of the recess 51 is slightly larger than the contour of the vane 8. The vane 8 has a shape that widens from one end on the impeller 3 side toward the other end opposite the impeller 3. On the other hand, the seal 9 has a constant width and is disposed along the center line 81 of the corresponding vane 8. In Fig. 2, the center line 81 is a straight line, but the center line 81 may be a curved line.

[0018] The seal 9 deforms in response to a dimensional change between the bottom of the recess 51 and the corresponding tip of the vane 8. In this embodiment, the seal 9 is a brush seal including a base 91 and brush bristles 92 embedded in the base 91, as shown in Fig. 3. The base 91 is fixed to the bottom of the recess 51 with an adhesive or the like, and the brush bristles 92 are pressed against the tip surface of the vane 8 in an elastically deformed state. For example, the brush bristles 92 may be metal wire or carbon fiber.

[0019] However, the seal 9 may be an elastically deformable gap seal made of resin, in other words, a strip made of resin. For example, the resin may be nylon.

[0020] As described above, in the centrifugal turbomachine 1 of this embodiment, the seals 9 arranged in each recess 51 deform in response to the dimensional change between the bottom of the recess 51 and the tip of the vane 8, so that when thermal deformation occurs in the hub 5 and the shroud 6, a gap is prevented from being formed between the hub 5 where the vane 8 is not provided and the vane 8. Therefore, the performance improvement effect of the centrifugal turbomachine 1 can be achieved regardless of the operating state such as the design rated point or partial load.

[0021] <Modification> The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0022] For example, contrary to the above embodiment, the vane 8 may be integrally provided on the hub 5, and the recess 51 may be formed in the shroud 6. With this configuration, when the hub 5 and the shroud 6 are thermally deformed, it is possible to prevent a gap from being formed between the vane 8 and the shroud 6 where the vane 8 is not provided.

[0023] <Summary> In a first aspect, the present disclosure provides a centrifugal turbomachine comprising: an impeller; a hub arranged on a rear side of the impeller; a shroud positioned around the impeller and forming a radial flow passage between the hub and the shroud; and a plurality of vanes arranged in the radial flow passage provided on one of the hub and the shroud, wherein a plurality of recesses are formed on the other of the hub and the shroud into which tips of the vanes respectively fit, and a seal is arranged within each recess, which seals between the bottom of the recess and the tip of the corresponding vane and deforms in response to a dimensional change between the bottom of the recess and the tip of the vane.

[0024] According to the above-mentioned configuration, the seals arranged in each recess deform in response to the dimensional change between the bottom of the recess and the tip of the vane, so that when thermal deformation occurs in the hub and the shroud, a gap is prevented from being formed between the vane and the one of the hub and the shroud where the vane is not provided, and therefore the performance improvement effect of the centrifugal turbomachine can be achieved regardless of the operating state such as the design rated point or partial load.

[0025] As a second aspect, in the first aspect, for example, the seal may be disposed along the centerline of the corresponding vane.

[0026] As a third aspect, in the first or second aspect, for example, the seal may be a brush seal or an elastically deformable resin gap seal. [Explanation of symbols]

[0027] 1. Centrifugal turbomachinery 11 Radial flow passage 3 Impeller 5 Hub 51 Depression 6. Shroud 8 Vane 81 Center line 9 Seal

Claims

1. An impeller, A hub disposed on a rear side of the impeller; A shroud is disposed around the impeller and defines a radial flow passage between the shroud and the hub. a plurality of vanes disposed in the radial flow passage on one of the hub and the shroud; a plurality of recesses into which tips of the plurality of vanes are fitted are formed in the other of the hub and the shroud, A centrifugal turbomachine, wherein a seal is disposed within each recess to seal between a bottom of the recess and a tip of a corresponding vane, the seal deforming in response to a dimensional change between the bottom of the recess and the tip of the vane.

2. The centrifugal turbomachine of claim 1 , wherein the seal is disposed along a centerline of a corresponding vane.

3. 3. The centrifugal turbomachine according to claim 1, wherein the seal is a brush seal or an elastically deformable resin gap seal.

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