JP2023150035A - Centrifugal rotary machine - Google Patents

Abstract

To provide a rotary machine capable of improving stability while avoiding performance deterioration.SOLUTION: A centrifugal rotary machine comprises: a rotational shaft that can rotate around an axial line; an impeller that has a disc fixed to the rotational shaft, a plurality of blades provided at intervals in a circumferential direction on a surface facing one side in the axial direction of the disc, and a cover covering the plurality of blades, and pumps working fluid introduced from one side in the axial direction to the outside in a radial direction; and a casing that covers the rotational shaft and the impeller, and defines a first flow path for introducing the working fluid and a second flow path for discharging the working fluid from the impeller, where a cover opposite surface, which is an inner peripheral surface of the casing that faces the outer peripheral surface of the cover, has a rough surface that is rougher than the outer peripheral surface of the cover.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to centrifugal rotating machines.

Generally, a centrifugal compressor as a centrifugal rotating machine has a rotor including a rotating shaft extending along an axis and an impeller provided on the rotating shaft, and a casing that covers the rotor. As the impeller, a type called a closed impeller is sometimes used. A closed impeller has a disk-shaped disk centered on an axis, a plurality of blades provided on one side of the disk, and a conical cover that covers the plurality of blades from one side. ing. A clearance (outer flow path) is provided between the outer peripheral surface of the cover and the inner peripheral surface of the casing.

When the centrifugal compressor is operated, fluid flows through the flow path defined by the blades. The fluid is compressed in the middle of flowing through the channel from the inlet side to the outlet side and becomes in a high pressure state. Here, since a higher pressure fluid flows on the outlet side of the channel than on the inlet side, the fluid also flows into the above-mentioned outer channel. In this way, when a large amount of fluid flows into the outer flow path, the compression efficiency of the centrifugal compressor decreases. Therefore, a technique is known in which a seal portion is provided on the inner circumferential surface of the casing to prevent fluid from flowing. For example, Patent Document 1 listed below discloses, as a specific example of the seal portion, a configuration in which a seal fin is provided on the inner circumferential surface of the casing on the inlet side of the impeller. Providing such sealing fins reduces fluid flowing into the outer flow path.

International Publication No. 2016/043090

By the way, in the above centrifugal compressor, the fluid flowing into the outer flow path has a swirl component. If the swirl component is large when displacement occurs in the rotor, a sinusoidal pressure distribution having a phase different from the clearance distribution is generated, and an excitation force in a direction perpendicular to the rotor displacement acts on the rotor. This excitation force may encourage the rotor to whirl around, resulting in a decrease in stability. Furthermore, it is desired that centrifugal compressors have lower excitation force and improved performance.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a rotating machine that can improve stability while avoiding performance deterioration.

In order to solve the above problems, a centrifugal rotating machine according to the present disclosure includes a rotating shaft rotatable around an axis, a disk fixed to the rotating shaft, and a surface of the disk facing one side in the axial direction that extends in a circumferential direction. an impeller having a plurality of blades provided at intervals between the blades and a cover that covers the plurality of blades, the impeller configured to force the working fluid introduced from one side in the axial direction outward in the radial direction; a casing that covers the impeller and defines a first flow path through which the working fluid is introduced, and a second flow path through which the working fluid pumped by the impeller flows; A cover facing surface, which is an inner circumferential surface of the casing facing each other, is a rough surface having a surface roughness greater than an outer circumferential surface of the cover.

A centrifugal rotating machine according to the present disclosure includes a rotating shaft rotatable around an axis, a disk fixed to the rotating shaft, and a surface of the disk facing one side in the axial direction provided at intervals in the circumferential direction. an impeller that has a plurality of blades and a cover that covers the plurality of blades and forces the working fluid introduced from one side in the axial direction radially outward; A casing that defines a first channel for introducing fluid and a second channel for discharging the working fluid from the impeller, and a cover-facing surface that is an inner circumferential surface of the casing that faces an outer circumferential surface of the cover. and a concavo-convex structural member.

According to the rotating machine of the present disclosure, stability can be improved while avoiding performance deterioration.

FIG. 1 is a schematic vertical cross-sectional view of a centrifugal compressor according to a first embodiment of the present disclosure. 1 is a schematic vertical sectional view showing main parts of a centrifugal compressor according to a first embodiment of the present disclosure. FIG. 2 is a schematic vertical sectional view showing main parts of a centrifugal compressor according to a second embodiment of the present disclosure. FIG. 3 is a perspective view of a unit lattice of a lattice structure as a concavo-convex structure member of a centrifugal compressor according to a second embodiment of the present disclosure. FIG. 3 is a perspective view of a metal foam material as an uneven structure member of a centrifugal compressor according to a second embodiment of the present disclosure.

<First embodiment>
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

<Basic configuration of centrifugal compressor>
As shown in FIG. 1, a centrifugal compressor 1 as a centrifugal rotating machine according to the present embodiment includes a rotating shaft 2, an impeller 10, a casing 30, and a seal portion 70. The centrifugal compressor 1 of this embodiment is a so-called single-shaft multi-stage centrifugal compressor that includes impellers 10 in multiple stages.

The rotating shaft 2 has a cylindrical shape extending in the direction of an axis O extending in the horizontal direction. The rotating shaft 2 is rotatably supported around the axis O by journal bearings 3 at a first end 2a side (one side in the axis O direction) and a second end 2b side (the other side in the axis O direction) in the axis O direction. has been done. The rotating shaft 2 has a first end 2 a supported by a thrust bearing 4 .

The impeller 10 is fitted onto the outer peripheral surface of the rotating shaft 2, and is provided in multiple stages at intervals in the direction of the axis O. These impellers 10 rotate together with the rotating shaft 2 about the axis O, thereby forcing the working fluid flowing in from one side in the direction of the axis O toward the outside in the radial direction.
The rotary shaft 2 and the impeller 10 constitute a rotor of the centrifugal compressor 1.

The casing 30 is a cylindrical member extending in the direction of the axis O, and accommodates the rotating shaft 2, the impeller 10, the journal bearing 3, etc. so as to cover them. The casing 30 rotatably supports the rotating shaft 2 via the journal bearing 3. This allows the impeller 10 attached to the rotating shaft 2 to rotate relative to the casing 30. The casing 30 has an introduction channel 31, a connection channel 32, and a discharge channel 33.

The introduction flow path 31 introduces working fluid from outside the casing 30 to the foremost impeller 10 disposed on one side in the axis O direction among the plurality of impellers 10 . The introduction channel 31 opens on the outer circumferential surface of the casing 30, and the opening serves as a suction port 31a for the working fluid. The introduction flow path 31 is connected to one side in the axis O direction of the impeller 10 at the frontmost stage at a radially inner portion.

The connection flow path 32 is a flow path that connects a pair of impellers 10 adjacent to each other in the direction of the axis O. The connection flow path 32 introduces the working fluid discharged radially outward from the impeller 10 on the front stage side to the impeller 10 on the rear stage side from one side in the axis O direction. The connection channel 32 has a diffuser channel 32a and a return channel 32b.
The diffuser flow path 32a is connected to the radially outer side of the impeller 10, and converts velocity energy into pressure energy while guiding the working fluid discharged radially outwardly from the impeller 10 radially outwardly. The return flow path 32b is connected to the radially outer side of the diffuser flow path 32a, and diverts the working fluid directed toward the radially outer side radially inward to guide it to the impeller 10 on the rear stage side.

The discharge flow path 33 discharges the working fluid discharged radially outward from the last stage impeller 10 disposed closest to the other side in the axis O direction among the plurality of impellers 10 to the outside of the casing 30 . The discharge passage 33 opens on the outer circumferential surface of the casing 30, and the opening serves as a discharge port 33a for the working fluid. The discharge passage 33 is connected to the radially outer side of the impeller 10 at the last stage at its radially inner portion.

Here, in the impeller 10 at the forefront stage, the introduction passage 31 becomes the first passage F1 (see FIG. 2) that introduces the working fluid into the impeller 10, and the diffuser passage 32a continuing downstream of the impeller 10 at the forefront stage is the first passage F1 (see FIG. 2). This becomes a second flow path F2 (see FIG. 2) through which the working fluid discharged from the impeller 10 flows.
Furthermore, in the impeller 10 at the last stage, the return passage 32b connected to the impeller 10 at the last stage becomes the first passage F1 for introducing the working fluid into the impeller 10, and the discharge passage 33 is used to forcefully feed the working fluid from the impeller 10. This becomes a second flow path F2 through which the working fluid flows.
Furthermore, in the impeller 10 between the impeller 10 at the front stage and the impeller 10 at the last stage, the return flow path 32b becomes the first flow path F1 that introduces the working fluid into the impeller 10, and the diffuser flow path 32a flows from the impeller 10 to the impeller 10. This becomes a second flow path F2 through which the working fluid to be pumped flows.

<Detailed configuration of impeller>
Next, the detailed configuration of the impeller 10 will be described with reference to FIG. 2. The impeller 10 is a so-called closed impeller having a disk 11, blades 12, and a cover 20.

<Disc>
The disk 11 is formed into a disk shape centered on the axis O. A through hole 11a is formed in the disk 11 in a circular shape centered on the axis O and penetrating in the direction of the axis O. The impeller 10 is integrally fixed to the rotating shaft 2 by fitting the inner peripheral surface of the through hole 11a into the outer peripheral surface of the rotating shaft 2.

The surface of the disk 11 facing the other side in the direction of the axis O is a disk back surface 11c having a planar shape orthogonal to the axis O. From one end of the through hole 11a in the axis O direction of the disk 11 to the radially outer end of the disk back surface 11c, there is a disk main surface that gradually extends radially outward from one axial side to the other side. 11b is formed. The disk main surface 11b has a portion on one side in the axis O direction facing outward in the radial direction, and gradually curves toward the other side in the axis O direction so as to face one side in the axis O direction. That is, the diameter of the disk main surface 11b gradually increases from one side toward the other side in the direction of the axis O. The disk main surface 11b has a concave curved shape.

<Disc>
A plurality of blades 12 are provided on the disk main surface 11b of the disk 11 at intervals in the circumferential direction of the axis O. Each blade 12 is curved toward the rear side in the rotational direction of the impeller 10 as it goes from the radially inner side to the radially outer side. Each blade 12 extends while forming a curved surface toward the front side in the direction of rotation.

<Cover>
The cover 20 covers the plurality of blades 12 from one side in the direction of the axis O. The cover 20 is provided facing the disk 11 so that the blade 12 is sandwiched between the cover 20 and the disk 11. The inner circumferential surface of the cover 20 (hereinafter referred to as the cover inner circumferential surface 21) is formed to gradually increase in diameter from one side toward the other side in the axis O direction. The cover inner circumferential surface 21 is curved similarly to the disk main surface 11b so as to correspond to the disk main surface 11b. An end of the blade 12 on the side opposite to the disk main surface 11b is fixed to the cover inner circumferential surface 21.

A flow path is formed between the cover inner circumferential surface 21, the disk main surface 11b, and the blade 12, and extends radially outward while curving backward in the rotational direction from one side to the other side in the axis O direction. There is.

<Detailed structure of casing>
Next, the detailed structure of the casing 30 will be explained with reference to FIG. 2. The casing 30 is an impeller housing space that accommodates the impeller 10 inside, between a first flow path F1 that introduces a working flow path into the impeller 10 and a second flow path F2 through which working fluid is pumped from the impeller 10. It has a section 40. A plurality of the impeller accommodating portions 40 are provided according to the number of the plurality of impellers 10.

A portion of the impeller 10 on the other side in the direction of the axis O in the impeller accommodating portion 40, which faces the disk back surface 11c, is a disk facing surface 50. The disk facing surface 50 is provided at a distance from the disk rear surface 11c.

<Cover facing surface>
A portion of the impeller accommodating portion 40 on one side in the direction of the axis O that faces the cover outer circumferential surface 22 of the impeller 10 is a cover facing surface 60 . The other end of the cover facing surface 60 in the direction of the axis O is connected to the second flow path F2 via the inlet step surface 67. The inlet step surface 67 has a cylindrical shape parallel to the axis O. One end of the cover facing surface 60 in the direction of the axis O is connected to the first flow path F1 via an outlet step surface 68. The exit step surface 68 has a planar shape that is perpendicular to the axis O and faces one side in the axis O direction.

In this way, the clearance between the cover facing surface 60 provided between the first flow path F1 and the second flow path F2 and the outer peripheral surface of the impeller 10 is the outer circumferential surface of the impeller 10 that connects the first flow path F1 and the second flow path F2. It is designated as flow path F3. One end of the outer flow path F3 in the axis O direction communicates with the first flow path F1. The other end of the outer flow path F3 in the axis O direction communicates with the second flow path F2. The pressure of the working fluid flowing through the second flow path F2 is higher than the pressure of the working fluid flowing through the first flow path F1. Therefore, an operating flow path flows through the outer flow path F3 from the second flow path F2 side toward the first flow path F1 side, that is, from the other side in the axis O direction to the one side in the axis O direction.

The cover facing surface 60 has a first surface 61 , a second surface 62 , a third surface 63 , and a fourth surface 64 .
The first surface 61 is the part of the cover facing surface 60 closest to the second flow path F2, that is, the part closest to the upstream side of the working fluid flowing through the outer flow path F3. The first surface 61 is connected to the entrance step surface 67 at the other end in the direction of the axis O. The first surface 61 extends in the shape of a conical surface whose diameter decreases radially inward toward one side in the axis O direction.

The second surface 62 is connected to the downstream side of the first surface 61. The second surface 62 has a cylindrical shape centered on the axis O. The other end of the second surface 62 in the direction of the axis O is connected to the first surface 61 .
The third surface 63 extends radially inward from the downstream end of the second surface 62. The third surface 63 has a planar shape that is perpendicular to the axis O and faces the other side in the direction of the axis O.

The fourth surface 64 is connected to the radially inner end of the third surface 63. The fourth surface 64 has a cylindrical shape centered on the axis O. The fourth surface 64 has an upstream end, which is the other end in the direction of the axis O, connected to a radially inner end of the third surface 63 . The downstream end of the fourth surface 64, which is one end in the direction of the axis O, is connected to the radially outer end of the outlet step surface 68.

<Seal part>
The seal portion 70 is provided in the outer flow path F3, and seals the working fluid flowing through the outer flow path F3 from leaking from the second flow path F2 side to the first flow path F1 side. The seal portion 70 includes a seal ring 71 and a plurality of fins 72.

The seal ring 71 is a cylindrical member centered on the axis O. The outer peripheral surface of the seal ring 71 is fixed to the fourth surface 64 of the cover-facing surface 60 of the casing 30 .
The fins 72 are provided so as to protrude radially inward from the inner peripheral surface of the seal ring 71 and extend in the circumferential direction. The radially inner end of the fin 72 faces the cover outer circumferential surface 22 of the cover 20 with a slight gap therebetween. A plurality of fins 72 are provided at intervals in the direction of the axis O.

<Detailed structure of cover facing surface and cover outer peripheral surface>
Here, at least a portion of the cover-facing surface 60 of the casing 30 is a rough surface having an uneven structure with a surface roughness greater than that of the outer circumferential surface 22 of the cover. That is, the surface texture of the cover facing surface 60 is formed to be rougher than the surface texture of the cover outer peripheral surface 22.
In particular, in this embodiment, the first surface 61 and the second surface 62, which are located upstream of the seal portion 70 on the cover facing surface 60 and radially opposed to the cover outer peripheral surface 22, are located on the cover outer peripheral surface 60. The surface has a rough surface roughness greater than that of surface 22.

The surface roughness of the rough surface of the cover facing surface 60 is, for example, 10 μm to 1000 μm in maximum height (Rmax), preferably 20 μm to 500 μm, more preferably 30 μm to 200 μm, still more preferably 50 μm to 150 μm, and optimally 100 μm (0 μm). .1 mm) is set to a value of 80 μm to 120 μm.

On the other hand, the surface roughness of the cover outer circumferential surface 22 and the third surface 63 and fourth surface 64, which are the non-roughened portions of the cover facing surface 60, is set to a value smaller than the above value. The surface roughness of these surfaces is set, for example, at a maximum height (Rmax) of 10 μm to 40 μm, preferably 20 μm to 30 μm, more preferably 25 μm.

The rough surface of the cover facing surface 60 can be realized, for example, by the following methods (1) to (3).
(1) Omission of finishing process in cutting When manufacturing the impeller 10 and casing 30 by cutting, after forming the cover outer circumferential surface 22 of the impeller 10 and the cover facing surface 60 of the casing 30 by rough machining, Of the surface 22 and the cover facing surface 60, only the cover outer circumferential surface 22 is finished. As a result, the outer peripheral surface of the impeller 10 can be made into a smooth finished surface, while the cover facing surface 60 can be made into a rough surface by rough processing.

(2) Omission of finishing process in casting When the casing 30 is formed by casting, finishing on the cover facing surface 60 is omitted. Thereby, the cover facing surface 60 becomes a cast surface, and the above-mentioned rough surface can be realized. Regardless of whether the impeller 10 is manufactured by cutting or casting, the cover outer circumferential surface 22 is made to have a smooth finished surface by finishing.

(3) Uneven processing on the cover facing surface 60 After the cover facing surface 60 and the cover outer circumferential surface 22 are manufactured to have the same surface roughness, only the cover facing surface 60 is subjected to uneven processing. As a result, the cover facing surface 60 can be made into a rough textured surface. Examples of the uneven processing include a method of creating impact marks such as shot peening, and a method of damaging the surface with a file or other tools. On the other hand, the outer circumferential surface 22 of the cover is a non-textured surface that is not subjected to any uneven processing after finishing. In the case of the method of damaging with a file or other tools, it can be easily applied to the existing centrifugal compressor 1.

<Effect>
The working fluid flowing through the outer flow path F3 from the second flow path F2 side toward the first flow path F1 side has a swirl component due to rotational pressure feeding of the impeller 10. If this swirl component is large, a sinusoidal pressure distribution having a phase different from the clearance distribution between the impeller 10 and the casing 30 occurs when the rotor is displaced. Due to this pressure distribution, an excitation force acts on the impeller 10 in a direction perpendicular to the displacement of the rotor. If this excitation force promotes whirling of the rotor, rotational stability may be impaired and stable operation may not be possible.

In contrast, in this embodiment, the swirl component of the working fluid can be reduced, so rotational stability can be maintained. That is, the working fluid flowing into the outer flow path F3 from the second flow path F2 comes into contact with the cover-facing surface 60 of the casing 30 while proceeding toward the first flow path F1. In particular, centrifugal force is applied to the working fluid due to the contribution of the swirl component of the working fluid. Therefore, the working fluid flows not to the cover outer circumferential surface 22 on the radially inner side but to the cover facing surface 60 on the radially outer side.

At this time, in this embodiment, since the cover-facing surface 60 of the casing 30 is a rough surface, the swirl component can be reduced. That is, when the swirl component of the working fluid flowing through the outer flow path F3 comes into contact with the cover facing surface 60, the velocity loss becomes large due to the viscosity with the rough surface of the cover facing surface 60. In other words, the energy of the swirl component is dissipated as frictional energy with the rough surface of the cover facing surface 60. As a result, the swirl component of the working fluid in the outer flow path F3 can be reduced, and the generation of excitation force against the cover 20 of the impeller 10 can be suppressed. As a result, whirling of the rotating shaft 2 can be suppressed, and stable operation can be continued.

Note that, for example, a method may also be considered in which the working fluid in the second flow path F2, where the pressure of the working fluid is high, is bled into the outer flow path F3 in a direction that cancels out the swirl component. In this case, although the swirl component can be reduced, a portion of the high-pressure working fluid is consumed, so the performance of the centrifugal compressor 1 is degraded. In this embodiment, by making the cover facing surface 60 a rough surface, swirl can be reduced without suffering from such disadvantages.

On the other hand, the outer peripheral surface of the cover 20 is not a rough surface, but is a smoother surface than the cover facing surface 60. Therefore, it is less susceptible to the influence of the viscosity of the working fluid flowing through the outer flow path F3. Therefore, the occurrence of rotation loss of the impeller 10 due to the fluid can be suppressed. As a result, it becomes possible to perform stable operation while maintaining performance.

Further, in the working fluid flowing through the outer flow path F3, the swirl component that acts as an excitation force is particularly noticeable on the inlet side of the outer flow path F3, which is upstream of the seal portion 70. Therefore, as in the present embodiment, only the first surface 61 and the second surface 62, which are the portions of the cover facing surface 60 on the other side in the axis O direction than the seal portion 70, are made rough, thereby effectively creating a swirl. components can be reduced.

In the first embodiment, the rough surface of the cover facing surface 60 may have a spline shape extending in the direction of the axis O. That is, a configuration may be adopted in which convex portions and concave portions are alternately arranged in parallel in the circumferential direction and extend in the direction of the axis O. Thereby, the uneven structure functions as an obstacle to the swirl component circulating in the circumferential direction. Therefore, the swirl component can be reduced more effectively.
<Second embodiment>
Next, a second embodiment of the present invention will be described using FIG. 3. In the second embodiment, the same reference numerals are given to the same components as in the first embodiment, and detailed description thereof will be omitted.
In the second embodiment, instead of making the cover-facing surface 60 of the casing 30 a rough surface, an uneven structure member 80 is provided on the cover-facing surface 60 to reduce the swirl component.

That is, of the cover outer peripheral surface 22 and the cover facing surface 60, the uneven structure member 80 is provided only on the first surface 61 and the second surface 62 of the cover facing surface 60 over the entire first surface 61 and second surface 62. It is provided.
The uneven structure member 80 has at least a surface facing inward in the radial direction that is a rough surface formed of a fine uneven structure. On the other hand, the outer circumferential surface 22 of the cover is a smooth finished surface, similar to the embodiment.

As the uneven structure member 80, for example, a lattice structure 90 formed by combining a large number of unit lattices 91 shown in FIG. 4 can be employed. The unit lattice 91 as an example in FIG. 4 has a triangular pyramid shape with each side formed by combining a plurality of rods 91a. The unit lattice 91 is not limited to this structure, and various three-dimensional lattices can be employed. The fine lattice structure 90 can be easily realized using additive manufacturing.

Further, as the uneven structure member 80, a foamed metal material 100 shown in FIG. 5, for example, can be employed. The metal foam material 100 is a structure made of metal that has a large amount of microscopic spaces filled with gas. As a material for such a metal foam material 100, for example, aluminum or steel can be used. The surface of the metal foam material 100 has an uneven structure formed over the entire area based on the fine spaces created by the gas.

Also in the second embodiment, as in the first embodiment, the unevenness on the surface of the uneven structure member 80 can reduce the swirl component from the working fluid flowing through the outer flow path F3.
By using a relatively low-strength free-cutting material such as a lattice structure 90 or a foamed metal material 100 as the uneven structure member 80, even if the cover 20 of the impeller 10 comes into contact with the casing 30, Damage to the impeller 10 can be avoided.
Further, since the structure for reducing the swirl component can be realized by simply attaching the uneven structure member 80 separately, it can be easily applied to the existing centrifugal compressor 1.

<Other embodiments>
Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and can be modified as appropriate without departing from the technical idea of the invention.

In the embodiment, an example has been described in which only the first surface 61 and the second surface 62 of the cover facing surface 60 are roughened or the uneven structure member 80 is provided only on these surfaces. However, the invention is not limited thereto, and the present invention may be applied to other parts of the cover facing surface 60, ie, the third surface 63 and the fourth surface 64. Further, the present invention may be applied to at least one of the first surface 61 and the second surface 62, or only a portion of the first surface 61 and the second surface 62.

For example, in the embodiment, an example in which the present invention is applied to the centrifugal compressor 1 has been described, but the present invention is not limited to this and may be applied to other centrifugal rotating machines.

<Additional notes>
The centrifugal rotating machine described in each embodiment can be understood, for example, as follows.

(1) A centrifugal rotating machine 1 according to a first aspect includes a rotating shaft 2 rotatable around an axis O, a disk 11 fixed to the rotating shaft 2, and a disk 11 facing one side in the direction of the axis O. It has a plurality of blades 12 provided on the surface at intervals in the circumferential direction, and a cover 20 that covers the plurality of blades 12, and forces the working fluid introduced from one side in the direction of the axis O to the outside in the radial direction. a casing that covers the rotating shaft 2 and the impeller 10 and defines a first flow path F1 through which the working fluid is introduced and a second flow path F2 through which the working fluid pumped by the impeller 10 flows. 30, and a cover facing surface 60, which is an inner peripheral surface of the casing 30 that faces the outer peripheral surface of the cover 20 via a clearance, is a rough surface having a surface roughness greater than that of the outer peripheral surface of the cover 20. has been done.

As a result, when the swirl component of the working fluid flowing through the clearance comes into contact with the cover-facing surface 60 of the casing 30, the velocity loss increases due to the viscosity of the swirl component with the rough surface of the cover-facing surface 60. As a result, the swirl component of the working fluid can be reduced, and the excitation force can be reduced.
On the other hand, since the outer circumferential surface of the cover 20 is not roughened, it is not easily affected by the viscosity of the working fluid flowing through the clearance. Therefore, it is possible to suppress rotation loss caused by the fluid.

(2) The centrifugal rotating machine 1 according to the second aspect is provided in a part of the cover facing surface 60 in the axis O direction to seal between the cover facing surface 60 and the outer peripheral surface of the cover 20. The centrifugal rotating machine 1 according to (1), further comprising a sealing part 70, wherein of the cover facing surface 60, only a region on the other side in the axis O direction than the sealing part 70 is the rough surface. be.

The swirl component that acts as an excitation force is particularly noticeable on the working fluid inlet side of the clearance, which is a portion on the other side in the axis O direction than the seal portion 70. Therefore, by making the cover facing surface 60 at the other side in the axis O direction than the seal portion 70 a rough surface, the swirl component can be effectively reduced.

(3) The centrifugal rotating machine 1 according to the third aspect is configured as described in (1) or (2), wherein the rough surface is a rough-machined surface, and the outer circumferential surface of the cover 20 is a finished surface. This is a centrifugal rotating machine 1.

When the casing 30 is formed by cutting, the cover-facing surface 60 of the casing 30 is purposely made into a rough-machined surface without finishing, while the outer peripheral surface of the cover 20 is finished, thereby improving performance while suppressing excitation force. It can be maintained.

(4) The centrifugal rotating machine 1 according to the fourth aspect is provided as described in (1) or (2), wherein the rough surface is a cast surface, and the outer peripheral surface of the cover 20 is a finished surface. This is a centrifugal rotating machine 1.

When the casing 30 is cast, the cover-facing surface 60 of the casing 30 is purposely made into a cast surface without finishing, while the outer peripheral surface of the cover 20 is finished to maintain performance while suppressing the excitation force. be able to.

(5) The centrifugal rotating machine 1 according to a fifth aspect is as described in (1) or (2), wherein the rough surface is a textured surface, and the outer circumferential surface of the cover 20 is a non-textured surface. This is a centrifugal rotating machine 1.

By forming a textured surface by processing only the cover-facing surface 60 of the casing 30, performance can be maintained while suppressing the excitation force.

(6) A centrifugal rotating machine 1 according to a sixth aspect includes a rotating shaft 2 rotatable around an axis O, a disk 11 fixed to the rotating shaft 2, and a disk 11 facing one side in the direction of the axis O. It has a plurality of blades 12 provided on the surface at intervals in the circumferential direction, and a cover 20 that covers the plurality of blades 12, and forces the working fluid introduced from one side in the direction of the axis O to the outside in the radial direction. a casing that covers the rotating shaft 2 and the impeller 10 and defines a first flow path F1 through which the working fluid is introduced and a second flow path F2 through which the working fluid pumped by the impeller 10 flows. 30, and an uneven structure member 80 provided only on the cover facing surface 60 of the outer peripheral surface of the cover 20 and the cover facing surface 60 which is the inner peripheral surface of the casing 30 facing the outer peripheral surface of the cover 20. and.

As a result, when the swirl component of the working fluid flowing through the clearance comes into contact with the uneven structure member 80 provided on the cover-facing surface 60 of the casing 30, the velocity loss due to viscosity increases. As a result, the swirl component of the working fluid can be reduced, and the excitation force can be reduced.
On the other hand, since the uneven structure member 80 is not provided on the outer peripheral surface of the cover 20, it is less susceptible to the influence of the viscosity of the working fluid flowing through the clearance. Therefore, it is possible to suppress rotation loss caused by the fluid.

(7) The centrifugal rotating machine 1 according to a seventh aspect is the centrifugal rotating machine 1 according to (7), wherein the uneven structure member 80 is a lattice structure 90 in which a plurality of three-dimensional unit lattices 91 are combined. be.

Thereby, the swirl component can be appropriately reduced.

(8) A centrifugal rotating machine 1 according to an eighth aspect is the centrifugal rotating machine 1 according to (7), wherein the uneven structure member 80 is a foamed metal material 100.

This also makes it possible to appropriately reduce the swirl component.

1 Compressor 2 Rotating shaft 2a First end 2b Second end 3 Journal bearing 4 Thrust bearing 10 Impeller 11 Disk 11a Through hole 11b Disk main surface 11c Disk back surface 12 Blade 20 Cover 21 Cover inner peripheral surface 22 Cover outer peripheral surface 30 Casing 31 Introduction channel 31a Suction port 32 Connection channel 32a Diffuser channel 32b Return channel 33 Discharge channel 33a Discharge port 40 Impeller housing section 50 Disk facing surface 60 Cover facing surface 61 First surface 62 Second surface 63 Third Surface 64 Fourth surface 67 Inlet step surface 68 Outlet step surface 70 Seal portion 71 Seal ring 72 Fin 80 Concave-convex structure member 90 Lattice structure 91 Unit lattice 91a Bar material 100 Foam metal material O Axis line F1 First flow path F2 Second flow path F3 Outer flow path

Claims (8)

A rotating shaft that can rotate around the axis,
A disk fixed to the rotating shaft, a plurality of blades provided at intervals in the circumferential direction on a surface of the disk facing one side in the axial direction, and a cover that covers the plurality of blades, an impeller that pumps working fluid introduced from one side radially outward;
a casing that covers the rotating shaft and the impeller and defines a first flow path for introducing the working fluid into the impeller and a second flow path for discharging the working fluid from the impeller;
Equipped with
A centrifugal rotating machine, wherein a cover facing surface, which is an inner circumferential surface of the casing that faces an outer circumferential surface of the cover with a clearance therebetween, is a rough surface having a surface roughness greater than that of the outer circumferential surface of the cover. further comprising a seal portion provided on a portion of the cover facing surface in the axial direction to seal between the cover facing surface and the outer circumferential surface of the cover;
The centrifugal rotating machine according to claim 1, wherein only a region of the cover facing surface on the other side in the axial direction of the seal portion is the rough surface. The rough surface is a roughly processed surface,
The centrifugal rotating machine according to claim 1 or 2, wherein the outer peripheral surface of the cover is a finished surface. The rough surface is a cast surface,
The centrifugal rotating machine according to claim 1 or 2, wherein the outer peripheral surface of the cover is a finished surface. The rough surface is a textured surface,
The centrifugal rotating machine according to claim 1 or 2, wherein the outer peripheral surface of the cover is a non-roughened surface. A rotating shaft that can rotate around the axis,
A disk fixed to the rotating shaft, a plurality of blades provided at intervals in the circumferential direction on a surface of the disk facing one side in the axial direction, and a cover that covers the plurality of blades, an impeller that pumps working fluid introduced from one side radially outward;
a casing that covers the rotating shaft and the impeller and defines a first flow path through which the working fluid is introduced, and a second flow path through which the working fluid pumped by the impeller flows;
an uneven structure member provided only on the cover-facing surface of the outer circumferential surface of the cover and the cover-facing surface that is the inner circumferential surface of the casing that faces the outer circumferential surface of the cover;
A centrifugal rotating machine equipped with The centrifugal rotating machine according to claim 6, wherein the uneven structure member is a lattice structure formed by combining a plurality of three-dimensional unit lattices. The centrifugal rotating machine according to claim 6, wherein the uneven structure member is a foamed metal material.

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