CN116538135A

CN116538135A - Impeller and rotary machine

Info

Publication number: CN116538135A
Application number: CN202211741635.8A
Authority: CN
Inventors: 前田聪; 佐野岳志; 深尾伸次; 中川笃; 松本圭介; 宫川和芳
Original assignee: Waseda University; Mitsubishi Heavy Industries Ltd
Current assignee: Waseda University; Mitsubishi Heavy Industries Ltd
Priority date: 2022-02-03
Filing date: 2022-12-29
Publication date: 2023-08-04
Also published as: US20230243364A1; DE102023200705A1; JP2023113428A

Abstract

In an impeller and a rotary machine, pressure pulsation is suppressed by reducing pressure fluctuation at an outflow port. The impeller is provided with: a hub having a circular plate shape centered on the axis; a shroud disposed opposite to the hub in the direction of the axis; and a plurality of blades arranged at intervals in the circumferential direction between the hub and the shroud, the radial shapes of the impellers being different in the circumferential direction.

Description

Impeller and rotary machine

Technical Field

The present disclosure relates to impellers and rotary machines.

Background

As a rotary machine, there is a centrifugal compressor in which an impeller is housed. Centrifugal compressors impart pressure energy and velocity energy to a fluid by rotating an impeller. As an impeller suitable for a centrifugal compressor, there is a closed impeller in which a plurality of blades are arranged between a hub and a shroud. As the closed impeller, for example, there is a closed impeller described in the following patent document.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 3299638

A typical closed impeller is provided with a flow path that is spiral from an inflow port located on the center side toward an outflow port located on the outer peripheral portion. The flow path is radially provided, so that the flow path area is rapidly enlarged toward the outer peripheral portion, and the fluid is easily peeled off, and loss is easily generated. Therefore, it is considered that the abrupt expansion of the passage area is suppressed by gradually increasing the thickness of the vane from the inflow port toward the outflow port. However, if the thickness of the vane is gradually increased from the inlet port toward the outlet port, the plurality of outlet ports are circumferentially interrupted by an amount corresponding to the thickness of the vane. In this way, there is a problem that the pressure of the fluid ejected from each outlet port in the outer peripheral portion fluctuates in the circumferential direction, and pressure pulsation occurs.

Disclosure of Invention

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide an impeller and a rotary machine that suppress the occurrence of pressure pulsation by reducing pressure fluctuation at an outflow port.

An impeller of the present disclosure for achieving the above object is provided with: a hub having a circular plate shape centered on the axis; a shroud disposed opposite to the hub in a direction of the axis; and a plurality of blades arranged at intervals in the circumferential direction between the hub and the shroud, wherein the radial shapes of the impellers are different in the circumferential direction.

In addition, the rotary machine of the present disclosure has the impeller.

Effects of the invention

According to the impeller and the rotary machine of the present disclosure, the occurrence of pressure pulsation can be suppressed by reducing pressure fluctuation at the outflow port.

Drawings

Fig. 1 is a cross-sectional view showing a main part of a rotary machine to which an impeller of the present embodiment is applied.

Fig. 2 is a front view showing the impeller.

Fig. 3 is a cross-sectional view taken at a position in a view III in fig. 2 showing a meridian plane shape of an upper half of the impeller of the present embodiment.

Fig. 4 is a cross-sectional view at a position in view IV in fig. 2 showing a meridian plane shape of an upper half of the impeller of the present embodiment.

Fig. 5 is a cross-sectional view taken at a position V in fig. 2 showing the shape of the meridian plane of the upper half of the impeller of the present embodiment.

Fig. 6 is a cross-sectional view taken at a position in view VI in fig. 2 showing the shape of the meridian plane of the upper half of the impeller of the present embodiment.

Fig. 7 is a main part side view of an impeller showing an outflow port of the impeller of the present embodiment.

Fig. 8 is a schematic view showing a blade shape on the hub side in the impeller.

Fig. 9 is a schematic view showing the shape of the blades at the intermediate portion between the hub and the shroud in the impeller.

Fig. 10 is a schematic view showing the shape of the vane on the shroud side in the impeller.

Fig. 11 is a main part side view of an impeller showing an outflow port of the impeller of the first modification.

Fig. 12 is a main part side view of an impeller showing an outflow port of the impeller of the second modification.

Fig. 13 is a side view of a main portion of an impeller showing an outflow port of the impeller according to the third modification.

Reference numerals illustrate:

centrifugal compressor (rotary machine);

a housing;

a rotating shaft;

13. impellers 13A, 13B, 13C;

first space part;

second space;

inflow pathway;

discharge passage;

hub;

a shield;

33. 33A, 33B, 33C, 33D;

34. impeller flow paths;

through holes;

major face;

the opposing face;

44. an inflow opening;

45. the outflow opening.

Detailed Description

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The present disclosure is not limited to the embodiment, and includes a configuration in which the embodiments are combined when there are a plurality of embodiments. The constituent elements of the embodiment include those that can be easily understood by those skilled in the art, those that are substantially the same, and those that are so-called equivalent ranges.

Embodiment(s)

< centrifugal compressor >

Fig. 1 is a cross-sectional view showing a meridian plane shape of an upper half of an impeller applied to a rotary machine. In this embodiment, a centrifugal compressor is used as a rotary machine.

As shown in fig. 1, the centrifugal compressor 10 includes a casing 11, a rotary shaft 12, and an impeller 13. The centrifugal compressor 10 imparts pressure energy and speed energy to a working fluid (liquid, gas, or the like) by rotating the impeller 13.

The housing 11 accommodates a part of the rotation shaft 12 and the impeller 13. The housing 11 has a cylindrical shape long in the extending direction of the axis O of the rotary shaft 12 (hereinafter referred to as the axis direction Da). The housing 11 is provided with a first space portion 21 having a cylindrical shape along the axis direction Da, and a second space portion 22 having a disk shape expanding in a direction orthogonal to the axis direction Da (hereinafter referred to as a radial direction Dr). The second space portions 22 are arranged at intervals in the axial direction Da of the first space portion 21. The first space portion 21 communicates with a plurality of second space portions 22. The first space 21 accommodates the rotary shaft 12, and the plurality of second space 22 accommodates the impellers 13.

The casing 11 is provided with an inflow passage 23 for introducing the working fluid G into the impeller 13 on one side (left side in fig. 1) in the axial direction Da. The casing 11 is provided with a discharge passage 24 for discharging the working fluid G from the impeller 13 on one side (upper side in fig. 1) in the radial direction Dr. The discharge passage 24 is bent in a U-shape on the downstream side toward the axis line O, and then is bent in an L-shape along the other side (right side in fig. 1) of the axis line direction Da. That is, although not shown, the discharge passage 24 is provided with a diffuser portion, a return bend portion, and a return passage on the downstream side. The discharge passage 24 communicates with the inflow passage 23 of the impeller 13 adjacent to the return passage in the axial direction Da.

The rotary shaft 12 is rotatably supported about an axis O with respect to the housing 11. Both ends of the rotation shaft 12 in the axial direction Da are rotatably supported by the housing 11 via bearings (not shown). The impeller 13 is fixed to the rotary shaft 12. The impeller 13 rotates integrally with the rotary shaft 12. The impeller 13 compresses the working fluid G by centrifugal force.

< basic Structure of impeller >

Fig. 2 is a front view showing the impeller.

As shown in fig. 1 and 2, the impeller 13 is a closed impeller including a hub 31, a shroud 32, and a plurality of blades 33. The impeller 13 is configured such that a plurality of blades 33 are arranged between the hub 31 and the shroud 32 at intervals (preferably, at equal intervals) in the circumferential direction Dc. One end of the plurality of blades 33 in the axial direction Da is fixed to the hub 31, and the other end is fixed to the shroud 32. The impeller 13 is provided with a plurality of impeller flow paths 34 surrounded by a hub 31, a shroud 32, and a plurality of blades 33. The impeller flow path 34 is bent approximately 90 degrees from the axis C side to the outer peripheral portion side, and is arranged in a spiral shape centering on the axis O.

The hub 31 has a disk shape centered on the axis O. The hub 31 gradually expands in diameter from one side to the other side in the axial direction Da to the outside in the radial direction Dr. The hub 31 has a circular through hole 41 penetrating in the axial direction Da at a position of the axis O which is a central portion. The boss 31 is integrally fixed to the rotary shaft 12 with the inner peripheral surface of the through hole 41 fitted into the outer peripheral surface of the rotary shaft 12.

The hub 31 has a main surface 42 formed on one side in the axial direction Da. The main surface 42 extends outward in the radial direction Dr from one side to the other side in the axial direction Da. The portion of the main surface 42 on one side in the axis direction Da faces outward in the radial direction Dr, and the portion on the other side in the axis direction Da faces one side in the axis direction Da. That is, the main surface 42 is curved so as to be directed to one side in the axial direction Da as going from one side to the other side in the axial direction Da, and is thus concavely curved.

The shroud 32 is disposed apart from the hub 31 by a predetermined distance in the other side in the axial direction Da. The shroud 32 gradually expands in diameter from one side to the other side in the axial direction Da to the outside in the radial direction Dr. The shroud 32 has an opposing surface 43 formed on the other side Dad in the axial direction Da. The facing surface 43 extends outward in the radial direction Dr from one side to the other side in the axial direction Da. The portion of the facing surface 43 on one side in the axis direction Da faces outward in the radial direction Dr, and the portion on the other side in the axis direction Da faces the other side in the axis direction Da. That is, the facing surface 43 is curved so as to be directed to the other side in the axial direction Da from one side to the other side in the axial direction Da, and is formed in a convex curved surface shape.

Blades 33 connect hub 31 with shroud 32. One end of the vane 33 in the axial direction Da is fixed to the main surface 42 of the hub 31, and the other end in the axial direction Da is fixed to the facing surface 43 of the shroud 32. The vane 33 extends to curve from one side in the axial direction Da to the outside in the radial direction Dr. The plurality of blades 33 are arranged at intervals in the circumferential direction Dc around the axis O. The plurality of blades 33 are radially arranged outward in the radial direction Dr around the axis O. The blades 33 are curved so as to be directed rearward in the rotation direction of the impeller 40 from the inner side in the radial direction Dr toward the outer side in the radial direction Dr.

The impeller flow path 34 is divided in the circumferential direction Dc by a plurality of blades 33 between the hub 31 and the shroud 32. The impeller flow path 34 is curved and extends from the inside to the outside in the radial direction Dr as going from one side to the other side in the axial direction Da. The impeller flow path 34 has an inflow port 44 that opens on the inner side in the radial direction Dr and on one side in the axial direction Da. The impeller flow path 34 has an outflow port 45 that opens on the outer side in the radial direction Dr and on the other side in the axial direction Da. The inflow port 44 communicates with the inflow passage 23, and the outflow port 45 communicates with the discharge passage 24.

< shape of meridian plane of impeller >

Fig. 3 is a cross-sectional view at a position seen in view III of fig. 2 showing the meridian plane shape of the upper half of the impeller of the present embodiment, fig. 4 is a cross-sectional view at a position seen in view IV of fig. 2 showing the meridian plane shape of the upper half of the impeller of the present embodiment, fig. 5 is a cross-sectional view at a position seen in view V of fig. 2 showing the meridian plane shape of the upper half of the impeller of the present embodiment, and fig. 6 is a cross-sectional view at a position seen in view VI of fig. 2 showing the meridian plane shape of the upper half of the impeller of the present embodiment.

The impeller 13 is a closed impeller including a hub 31, a shroud 32, and a plurality of blades 33, and a plurality of impeller passages 34 are formed by the hub 31, the shroud 32, and the plurality of blades 33. Further, the meridian plane shape of the impeller 13 is different in the circumferential direction Dc.

That is, in the impeller 13, the positions of the outflow openings 45 on the outer peripheral side of the plurality of impeller flow paths 34 divided by the hub 31, the shroud 32, and the plurality of blades 33 are offset in the axial direction Da at different positions in the circumferential direction Dc.

Fig. 3 to 6 are sectional views showing the meridian plane shape of the upper half of the impeller 13 at different positions in the circumferential direction Dc. As shown in fig. 3, in the meridian plane shape of the impeller 13 at the first position, the outflow port 45 side of the impeller flow path 34-1 is located closest to the hub 31 side in the axial direction Da with respect to the reference impeller flow path 34-0. At this time, the height H1 of the outflow port 45 in the axial direction Da is shorter than the height H of the reference impeller flow path 34-0. As shown in fig. 4, in the meridian plane shape of the impeller 13 at the second position, the outflow port 45 side of the impeller flow path 34-2 is located slightly toward the hub 31 side with respect to the intermediate position between the hub 31 and the shroud 32 in the axial direction Da with respect to the reference impeller flow path 34-0. At this time, the height H2 of the outflow port 45 in the axial direction Da is shorter than the height H of the reference impeller flow path 34-0.

As shown in fig. 5, in the meridian plane shape of the impeller 13 at the third position, the outflow port 45 side of the impeller flow path 34-3 is located slightly toward the shroud 32 side with respect to the intermediate position between the hub 31 and the shroud 32 in the axial direction Da with respect to the reference impeller flow path 34-0. At this time, the height H3 of the outflow port 45 in the axial direction Da is shorter than the height H of the reference impeller flow path 34-0. As shown in fig. 6, in the meridian shape of the impeller 13 at the fourth position, the outflow port 45 side of the impeller flow path 34-4 is located closest to the shroud 32 side in the axial direction Da with respect to the reference impeller flow path 34-0. At this time, the height H4 of the outflow port 45 in the axial direction Da is shorter than the height H of the reference impeller flow path 34-0.

In the meridian shape of the impeller 13 at each position, the heights H1, H2, H3, and H4 of the impeller flow path 34 (the outflow port 45) in the axial direction Da may be the same height or may be different heights.

As shown in fig. 7, with the impeller 13, the position of the outflow port 45 in the impeller flow path 34 is offset in the axial direction Da at different positions in the circumferential direction Dc. Therefore, the shape of the outflow port 45 when the impeller 13 is viewed in the radial direction Dr from the outer peripheral portion side is arranged along the inclined line L2, and the inclined line L2 has a predetermined inclination angle θ with respect to the reference line L1 along the circumferential direction Dc. At this time, the passage shape of the outflow port 45 has a quadrangular shape (parallelogram shape).

The vane 33 has a main body portion 33a and two extension portions 33b, 33c. One end of the main body 33a in the axial direction Da is fixed to the hub 31, and the other end is fixed to the shroud 32. The extension portion 33b extends from the main body portion 33a to one of the circumferential directions Dc so as to taper along the tip end of the shroud 32, and is fixed to the shroud 32. The extension portion 33c extends from the main body portion 33a to the other side in the circumferential direction Dc so as to taper along the front end of the hub 31, and is fixed to the hub 31. The impeller flow path 34 (the outflow port 45) is formed by dividing a surface 34a of the main body portion 33a of the vane 33, a surface 34b of the extension portion 33b, a surface 34c of the main body portion 33a of the adjacent vane 33, and a surface 34d of the extension portion 33c, and has a quadrangular shape (a parallelogram shape). Since the impeller 13 rotates to the other side (left side in fig. 7) in the circumferential direction Dc, the surface 34d of the vane 33 becomes a pressure surface, and the surface 34b becomes a negative pressure surface.

In this case, the shape of the impeller flow path 34 (the outflow port 45) at each position in fig. 3 to 6 is continuously changed in the longitudinal direction of the impeller flow path 34 with respect to the impeller flow path 34-1, 34-2, 34-3, 34-4, whereby the surfaces 34b, 34d are formed, and the outflow port 45 is formed in a quadrangular shape (a parallelogram shape). The shape of the impeller flow path 34 (the outflow port 45) at each position in fig. 3 to 6 may be changed stepwise in the longitudinal direction of the impeller flow path 34 by the impeller flow paths 34-1, 34-2, 34-3, 34-4.

Fig. 8 is a schematic view showing a blade shape on a hub side in the impeller, fig. 9 is a schematic view showing a blade shape on an intermediate portion between a hub and a shroud in the impeller, and fig. 10 is a schematic view showing a blade shape on a shroud side in the impeller.

As described above, since the shape of the outflow port 45 of the impeller 13 is hexagonal along the inclined line L2, the thickness of the vane 33 varies at different positions in the axial direction Da. Fig. 8 shows the blade shape on the hub 31 side, fig. 9 shows the blade shape on the intermediate portion between the hub 31 and the shroud 32, and fig. 10 shows the blade shape on the shroud 32 side. As shown in fig. 8 to 10, with respect to the blades 33, the thickness of the outer peripheral portion side (outflow port 45) at the intermediate portion of the hub 31 and the shroud 32 is thinner than the thickness of the outer peripheral portion side (outflow port 45) at the hub 31 side and the thickness of the outer peripheral portion side (outflow port 45) at the shroud 32 side.

That is, as shown in fig. 7, with respect to the vane 33, the thickness C1 of the outer peripheral portion side (the outflow port 45 side) at the hub 31 side is the same as the thickness C3 of the outer peripheral portion side (the outflow port 45 side) at the shroud 32 side. The thickness C2 of the blades 33 on the outer peripheral side (the outflow port 45 side) of the hub 31 and the shroud 32 at the intermediate portion is set to be smaller than the thickness C1 of the hub 31 side and the thicknesses C1 and C3 of the shroud 32 side.

As shown in fig. 8 to 10, the thickness of the blades 33 at the hub 31 side and the thickness at the shroud 32 side gradually become thicker from the axis O side toward the outer peripheral portion side of the impeller 13. Therefore, the width of the impeller flow path 34 on the hub 31 side is substantially the same as the width of the shroud 32 side, and the abrupt expansion of the passage area of the impeller flow path 34 from the inflow port 44 toward the outflow port 45 is suppressed. Therefore, the impeller 13 suppresses abrupt expansion of the passage area in the impeller passage 34, thereby suppressing the working fluid from peeling from the inner surface of the impeller passage 34 and reducing the loss.

On the other hand, the thickness of the hub 31 of the vane 33 and the intermediate portion of the shroud 32 is substantially constant from the axis O side toward the outer peripheral portion side of the impeller 13. In the impeller 13, the working fluid is compressed more efficiently in the region between the hub 31 and the shroud 32 than in the region on the hub 31 side and the region on the shroud 32 side in the impeller flow path 34. Therefore, by sufficiently securing the volume of the region, the head (pressure) can be secured efficiently, and the efficiency can be improved.

Further, with respect to the blades 33, the thickness of the hub 31 at the outflow port 45 side at the intermediate portion of the shroud 32 is thinner than the thicknesses of the hub 31 side and the outflow port 45 side at the shroud 32 side. In this way, the plurality of outflow openings 45 provided in the outer peripheral portion of the impeller 13 are substantially continuous in the circumferential direction Dc. That is, the plurality of outflow openings 45 are interrupted only by an amount corresponding to the thickness of the main body portion 33a in the vane 33. Therefore, the discharge of the working fluid from each outflow port 45 is not easily interrupted, and the pressure fluctuation is reduced, so that the occurrence of pressure pulsation can be suppressed.

The impeller 13 of the present embodiment is manufactured by cutting, but the manufacturing method is not limited. For example, the sheet may be manufactured by a three-dimensional lamination molding method such as AM (Additive Manufacturing).

Modification example

Fig. 11 is a main part side view of an impeller showing an outflow port of an impeller of a first modification, fig. 12 is a main part side view of an impeller showing an outflow port of an impeller of a second modification, and fig. 13 is a main part side view of an impeller showing an outflow port of an impeller of a third modification.

In the first modification, as shown in fig. 11, the impeller 13A is a closed impeller including a hub 31, a shroud 32, and a plurality of blades 33A, and a plurality of impeller passages 34A are formed by the hub 31, the shroud 32, and the plurality of blades 33A. Further, the meridian shape of the impeller 13A is different in the circumferential direction Dc. That is, in the impeller 13A, the positions of the outflow openings 45 on the outer peripheral side of the plurality of impeller flow paths 34A divided by the hub 31, the shroud 32, and the plurality of blades 33A are offset in the axial direction Da at different positions in the circumferential direction Dc.

As shown in fig. 3 to 6, the meridian plane shape at different positions in the circumferential direction Dc of the impeller 13A is different. That is, the meridian plane shape of the impeller 13A changes in the order of fig. 3, 4, 5, and 6 from the upstream side in the rotation direction. The change in the meridian plane shape of the impeller 13A is the same as that of the above-described embodiment. The shape of the outflow port 45 when the impeller 13A is viewed in the radial direction Dr from the outer peripheral portion side is arranged along an inclined line L3, and the inclined line L3 has a predetermined inclination angle θ with respect to a reference line L1 along the circumferential direction Dc. At this time, the passage shape of the outflow port 45 is hexagonal.

The vane 33A has a main body portion 33A and two extension portions 33b, 33c. One end of the main body 33a in the axial direction Da is fixed to the hub 31, and the other end is fixed to the shroud 32. The extension portion 33b extends from the main body portion 33a to one of the circumferential directions Dc so as to taper along the tip end of the shroud 32, and is fixed to the shroud 32. The extension portion 33c extends from the main body portion 33a to the other side in the circumferential direction Dc so as to taper along the front end of the hub 31, and is fixed to the hub 31. The impeller flow path 34A (the outflow port 45) is formed by dividing a surface 34A of the main body portion 33A of the vane 33A, a surface 34b of the extension portion 33b, a surface 34c of the shroud 32, a surface 34d of the main body portion 33A of the adjacent vane 33A, a surface 34e of the extension portion 33c, and a surface 34f of the hub 31, and has a hexagonal shape.

In the second modification, as shown in fig. 12, the impeller 13B is a closed impeller including a hub 31, a shroud 32, and a plurality of blades 33B, and a plurality of impeller passages 34B are formed by the hub 31, the shroud 32, and the plurality of blades 33B. Further, the meridian shape of the impeller 13B is different in the circumferential direction Dc. That is, in the impeller 13B, the positions of the outflow openings 45 on the outer peripheral side of the plurality of impeller flow paths 34B divided by the hub 31, the shroud 32, and the plurality of blades 33B are offset in the axial direction Da at different positions in the circumferential direction Dc.

As shown in fig. 3 to 6, the meridian plane shape at different positions in the circumferential direction Dc of the impeller 13B is different. That is, the meridian plane shape of the impeller 13A changes in the order of fig. 6, 5, 4, and 3 from the upstream side in the rotation direction. The change in the meridian plane shape of the impeller 13B is opposite to the first modification described above. The shape of the outflow port 45 when the impeller 13B is viewed in the radial direction Dr from the outer peripheral side is arranged along an inclined line L4, and the inclined line L4 is inclined with respect to a reference line L1 along the circumferential direction Dc. At this time, the passage shape of the outflow port 45 is a parallelogram shape. That is, in the meridian plane shape of the impeller 13B at each position different in the circumferential direction Dc, the height of the outflow port 45 along the axis direction Da is the same height.

In the third modification, as shown in fig. 13, the impeller 13C is a closed impeller including a hub 31, a shroud 32, and a plurality of blades 33C and 33D, and a plurality of impeller passages 34A and 34B are formed by the hub 31, the shroud 32, and the plurality of blades 33C and 33D. Further, the meridian shape of the impeller 13C is different in the circumferential direction Dc. That is, in the impeller 13C, the positions of the outflow openings 45 on the outer peripheral side of the plurality of impeller flow paths 34A, 34B partitioned by the hub 31, the shroud 32, and the plurality of blades 33C, 33D are offset in the axial direction Da at different positions in the circumferential direction Dc.

That is, the impeller 13C is a combination of the first embodiment (fig. 7) and the second modification (fig. 12), and the differently shaped blades 33C and 33D are alternately arranged in the circumferential direction Dc, so that the differently shaped impeller flow paths 34A and 34B are alternately arranged in the circumferential direction Dc.

[ effects of the present embodiment ]

The impeller of the first aspect is provided with: a hub 31 having a disk shape centered on the axis O; a shroud 32 disposed so as to face the hub 31 in the axial direction Da; and a plurality of blades 33, 33A, 33B, 33C, 33D arranged at intervals in the circumferential direction Dc between the hub 31 and the shroud 32, the radial shape of the impeller being different in the circumferential direction Dc.

According to the impeller of the first aspect, since the meridional shapes of the impellers 13, 13A, 13B, and 13C are different in the circumferential direction Dc, for example, the plurality of outflow ports 45 are substantially continuous in the circumferential direction Dc by shifting the specific positions of the outflow ports 45 toward the hub 31 side and the shroud 32 side. That is, the plurality of outflow ports 45 are interrupted only by the amount corresponding to the thickness of the plurality of main body portions 33A of the vanes 33, 33A, 33B, 33C, 33D, and the discharge of the working fluid from each outflow port 45 is not easily interrupted, the pressure fluctuation becomes small, and the pressure fluctuation in the circumferential direction at the outflow port 45 is reduced, whereby the occurrence of pressure pulsation can be suppressed.

In the impeller of the second aspect, the positions of the outflow openings 45 on the outer peripheral side of the impeller flow paths 34, 34A, 34B divided by the hub 31, the shroud 32, and the pair of blades 33, 33A, 33B, 33C, 33D are offset in the axial direction Da at different positions in the circumferential direction Dc. This makes it possible to bring the plurality of outflow ports 45 as close to each other as possible in the circumferential direction Dc, and to reduce pressure fluctuation at the outflow ports 45, thereby suppressing occurrence of pressure pulsation.

In the impeller of the third aspect, the outflow port 45 is arranged along inclined lines L2, L3, L4, and the inclined lines L2, L3, L4 have a predetermined inclination angle θ with respect to a reference line L1 along the circumferential direction Dc. This makes it possible to bring the plurality of outflow openings 45 as close to each other as possible in the circumferential direction Dc.

In the impeller of the fourth aspect, the passage shape of the outflow port 45 is a quadrangular shape. This can reduce the area where the outflow port 45 is closed by the vane 33 in the circumferential direction Dc, effectively suppress pressure pulsation in the circumferential direction Dc, and improve performance.

In the impeller of the fifth aspect, the passage shape of the outflow port 45 is hexagonal. This can reduce the area where the outflow port 45 is closed by the vane 33 in the circumferential direction Dc, effectively suppress pressure pulsation in the circumferential direction Dc, and improve performance.

In the impeller of the sixth aspect, the thickness C2 on the outer peripheral portion side at the intermediate portion of the hub 31 and the shroud 32 is thinner than the thickness C1 on the outer peripheral portion side at the hub 31 side and the thickness C3 on the outer peripheral portion side at the shroud 32 side with respect to the blades 33, 33A, 33B, 33C, 33D. Thus, by gradually thickening the thicknesses of the blades 33, 33A, 33B, 33C, 33D on the hub 31 side and the shroud 32 side toward the outer peripheral portion side, abrupt expansion of the passage areas of the impeller flow paths 34, 34A, 34B can be suppressed. Therefore, the working fluid can be prevented from being peeled off from the inner surface of the impeller flow path 34, and loss can be reduced. On the other hand, since the thicknesses of the blades 33, 33A, 33B, 33C, 33D at the intermediate portion of the hub 31 and the shroud 32 are substantially constant toward the outer peripheral portion side, the volume of this region is sufficiently ensured, whereby the head (pressure) can be effectively ensured, and the efficiency can be improved.

The impeller of the seventh embodiment is a closed impeller in which one end of a plurality of blades 33, 33A, 33B, 33C, 33D is fixed to the hub 31 and the other end is fixed to the shroud 32. This reduces pressure fluctuations at the outflow port 45 of the impellers 13, 13A, 13B, 13C, and suppresses the occurrence of pressure pulsation.

The rotary machine of the eighth aspect has impellers 13, 13A, 13B, 13C. As a result, the pressure fluctuation at the outflow port 45 of the impellers 13, 13A, 13B, 13C is reduced, and the occurrence of pressure pulsation can be suppressed, and as a result, the efficiency of the rotary machine can be improved.

In the above-described embodiment, the radial shapes of the impellers 13, 13A, 13B, and 13C are changed in the circumferential direction Dc in the order of fig. 3 to 6 or in the opposite direction, and the shape of the outflow port 45 is a hexagonal shape or a quadrangular shape, but the shape is not limited thereto. Any shape may be used as long as the meridian shape of the impeller differs at different positions in the circumferential direction Dc.

In the above-described embodiment, the impellers 13, 13A, 13B, and 13C are closed impellers, but may be open impellers in which the hub and blades rotate relative to the shroud.

In the above embodiment, the rotary machine was described as a centrifugal compressor, but other rotary machines may be used.

Claims

1. An impeller, wherein,

the impeller is provided with:

a hub having a circular plate shape centered on the axis;

a shroud disposed opposite to the hub in a direction of the axis; and

a plurality of blades arranged at intervals in the circumferential direction between the hub and the shroud,

the meridian plane shape of the impeller is circumferentially different.

2. The impeller of claim 1, wherein,

the positions of the outflow openings on the outer peripheral side of the flow path divided by the hub, the shroud, and the pair of blades are offset in the axial direction at different positions in the circumferential direction.

3. The impeller of claim 2, wherein,

the outflow port is disposed along an inclined line having a predetermined inclination angle with respect to a reference line along the circumferential direction.

4. The impeller of claim 3, wherein,

the passage shape of the outflow port is quadrilateral.

5. The impeller of claim 3, wherein,

the passage shape of the outflow port is hexagonal.

6. The impeller according to any one of claims 1 to 5, wherein,

the thickness of the hub of the blade on the outer peripheral portion side at the intermediate portion of the shroud is thinner than the thickness of the hub on the outer peripheral portion side and the thickness of the shroud on the outer peripheral portion side.

7. The impeller according to any one of claims 1 to 6, wherein,

the impeller is a closed impeller with one end of a plurality of blades fixed on the hub and the other end fixed on the shield.

8. A rotary machine, wherein,

the rotary machine has the impeller of any one of claims 1 to 7.