WO2019176426A1

WO2019176426A1 - Centrifugal pump

Info

Publication number: WO2019176426A1
Application number: PCT/JP2019/005098
Authority: WO
Inventors: 和寛塚本; ロマンプリュニエール; 崇沖原; 孝英長原
Original assignee: 株式会社日立製作所
Priority date: 2018-03-15
Filing date: 2019-02-13
Publication date: 2019-09-19
Also published as: JP2019157807A

Abstract

A centrifugal pump (P) of the present invention comprises: first crossover blades (25) in which a static flow path (21) is formed over a diffuser flow path (22), a curved flow path (23), and a return flow path (24); and the same number of second crossover blades (26) arranged in the return flow path (24) downstream of the first crossover blades (25). Between the first crossover blades (25) and the second crossover blades (26), slits (27) that have a uniform distance in a radial direction with respect to all the blades (25 and 26) arranged in a circumferential direction and connect pressure surfaces (25a) of the blades (25) and negative pressure surfaces (26f) to each other are provided. The centrifugal pump (P) is characterized in that, among the blades (25 and 26) separated by the slits (27), leading edges (26A) of the second crossover blades (26) are displaced on an upstream side in a rotational direction of a centrifugal impeller (13) with respect to trailing edges (25B) of the first crossover blades (25).

Description

Centrifugal pump

The present invention relates to a centrifugal pump.

Conventionally, a centrifugal fluid machine having a rotating centrifugal impeller has been used in various plants, air conditioners, liquid pumps, turbochargers and the like. In response to the recent increase in demand for reducing the environmental load, these fluid machines are required to have higher efficiency and higher operating range than ever before.

A centrifugal pump, which is a type of centrifugal fluid machine, includes an impeller attached to a rotating shaft, a diffuser flow path provided on the outer peripheral side of the impeller, and a return flow path provided on the downstream side of the diffuser flow path. In addition, a configuration including a curved flow path connecting the two flow paths is known.

For example, in a multistage centrifugal pump, a plurality of impellers are attached in multiple stages with respect to the rotating shaft. A diffuser flow path, a curved flow path, and a return flow path are provided on a flow path that guides the fluid that has passed through the impeller and discharged radially outward to the next-stage impeller. The diffuser channel and the return channel are often provided with stationary blade rows arranged in the circumferential direction.

In these flow paths, the effect of recovering the pressure mainly by decelerating the flow velocity of the fluid discharged from the impeller and the effect of adjusting the swirl angle of the flow flowing into the next stage impeller are obtained. . In order to obtain these effects more efficiently, various inventions such as the following Patent Documents 1 and 2 have been proposed.

Japanese Unexamined Patent Publication No. 2016-169672 (FIGS. 3A to 4B, etc.) Japanese Patent No. 3869816 (paragraph 0020, FIG. 9 (A) to (E), etc.)

The centrifugal pump described in Patent Document 1 is characterized in that at least one of the blade rows provided in the diffuser flow path or the return flow path is extended to the curved flow path (see FIGS. 3A to 4B). Further, the positional relationship between the extended blade and the blade provided in the return flow path is shifted to the suction surface side (downstream in the rotational direction of the impeller 6) of the extended blade. The configuration is adopted. With this structure, loss is prevented from occurring in a bent flow path that is not provided with a conventional blade, and high efficiency is achieved.

The multistage fluid machine described in Patent Document 2 has blades communicating from the diffuser flow path to the curved flow path and the return flow path. Then, as shown in FIGS. 9A to 9E, a structure is proposed in which one side of the wall surface of the flow path constituted by the blades is configured in a straight line (paragraph 0020). This structure is based on the premise that the hub side wall surface of the blade is straight, and the cross-sectional area of the blade is reduced by gradually changing the cross-sectional flow area between the blades on the hub side where the curved flow path is sharply bent. According to the report, it is possible to suppress an increase in loss due to a sudden change.

In either structure of Patent Documents 1 and 2, blades are provided in all of the diffuser flow path, the curved flow path, and the return flow path, and in particular, the loss reduction effect can be obtained by applying the blades to the curved flow path. It can be said that.
However, in the structures of Patent Documents 1 and 2, it is expected that the efficiency decrease due to the reduction of the outer diameter of the pump, which is one of the main development problems of the centrifugal pump, will become larger.

The reduction in the outer diameter of the pump leads to a reduction in pump volume, which directly leads to a reduction in cost. It is therefore necessary to develop smaller pumps while maintaining high efficiency.
The causes of the decrease in efficiency are as follows.

The reduction of the outer diameter reduces the speed reduction effect in the diffuser flow path, so the flow velocity flowing into the curved flow path increases. In particular, since the diffuser flow path is shortened, the effect of diverting the flow of the blade row in the flow path is reduced, so that the flow velocity component in the direction of turning in the circumferential direction is increased. The flow that has flowed into the curved flow path portion while the flow velocity component in the swirl direction is large is easily separated from the blade surface in the curved flow channel or the blade surface in the return flow channel, and is easily separated. This is because the fact that the flow velocity component in the swirling direction is dominant means that the component in the direction in which the flow is peeled off from the blade is dominant, so that the flow is separated from the wall surface with the conventional structure. When the flow peels from the wall surface, pressure loss occurs and fluid loss increases, leading to a decrease in efficiency. In addition, since the fluid does not flow along the blade surface, the fluid reaches the return flow passage outlet while the circumferential flow velocity component remains dominant, so the inflow angle to the impeller installed in the next stage is As a result, the fluid is impeded from flowing into the impeller, leading to a decrease in fluid performance at the next stage.

In order to increase the diversion of the flow in the diffuser flow path, it is possible to obtain the same speed reduction effect as before the outer diameter reduction by standing the blade rows installed in the flow path in the circumferential direction. However, if the blade row is set up in the circumferential direction, separation at the blade row portion is likely to occur during low flow rate operation, and stable operation may not be possible.
Therefore, a flow path structure that can suppress a decrease in efficiency due to a reduction in outer diameter is required. The reduction in efficiency here refers not only to the loss reduction in the static flow path but also to the effect of suppressing the reduction in efficiency of the next stage by making the angle of the flow flowing into the next stage impeller appropriate.

The present invention has been made in view of the above circumstances, and aims to provide a centrifugal pump with improved efficiency and high performance.

In order to solve the above problems, a centrifugal pump according to the present invention includes a plurality of centrifugal impellers attached to a rotating shaft, an annular partition provided around the rotating shaft of the centrifugal impeller, and a periphery of the annular partition. A first radial flow path formed to guide the fluid that has passed through the centrifugal impeller to the outside in the radial direction of the centrifugal impeller, and the first radial flow path across the annular partition wall A second radial flow path formed on the opposite side of the centrifugal impeller and configured to guide the fluid to a radially inner side of the centrifugal impeller, and the first radial flow path on an outer peripheral side of the annular partition wall A curved flow path configured to communicate the first radial flow path from the first radial flow path to the second radial flow path, and the first radial flow path. A channel formed in communication with the channel, the second radial channel, and the curved channel. The crossover blade has a slit in the second radial flow path, and is positioned downstream of the crossover blade divided by the slit with respect to the fluid flow direction. The leading edge of the downstream crossover blade is divided by the slit, and the centrifugal crossover blade is separated from the trailing edge of the upstream crossover blade positioned upstream with respect to the fluid flow direction. It is shifted upstream in the direction of rotation of the impeller.

According to the present invention, a centrifugal pump with improved efficiency and high performance can be provided.

1 is a longitudinal sectional view of a multistage pump according to Embodiment 1 of the present invention. FIG. 2 is an enlarged cross-sectional view of a meridional surface in the vicinity of a stationary flow channel according to the first embodiment. The side view of the static flow path of the state which removed the casing. FIG. 3B is an I direction arrow view of FIG. 3A. FIG. 3B is a view in the direction of arrow II in FIG. 3A. FIG. 3 is an enlarged perspective view of the vicinity of a slit constituted by a crossover blade and a downstream blade in the return flow path according to the first embodiment. The figure which shows the comparison with the exit blade | wing angle of the hub side wall surface of the crossover blade | wing in a return flow path, and the exit blade | wing angle of a shroud side wall surface. FIG. 5 is an external view of a stationary flow path section according to Embodiment 2 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
The present invention relates to a pump having a centrifugal impeller, and in particular, is an invention for reducing the outermost diameter of the pump and improving the efficiency.

<< Embodiment 1 >>
FIG. 1 shows a longitudinal section of a multistage pump P according to Embodiment 1 of the present invention.
In the multistage pump P of the first embodiment, the casing 11 forms an outer shell. In the multistage pump P, a rotating shaft 12 that penetrates the casing 11 and extends in the horizontal direction is disposed at the center.

The casing 11 includes a suction port 15 for sucking fluid (arrow α11 in FIG. 1) and a discharge port 16 for discharging the fluid after increasing the pressure (arrow α12 in FIG. 1). Therefore, in the axial direction of the rotating shaft 12, the suction port 15 side is the upstream side, and the discharge port 16 side is the downstream side.

The casing 11 accommodates eight impellers 13 and seven stationary flow paths 21 corresponding to the seven impellers 13 excluding the final stage impeller 13. The eight impellers 13 are fixed to the rotating shaft 12. The number of impellers 13 is not limited to eight. That is, the number of impellers 13 is not limited as long as it is one or more.

FIG. 2 shows an enlarged cross-sectional view of the meridional surface in the vicinity of the stationary flow path 21 of the first embodiment.
The stationary flow path 21 forms an outlet-side flow path of the impeller 13 and an inlet-side flow path following the next-stage impeller 13, and is fixed to the casing 11. The stationary flow path 21 is formed by an outer casing 11 and an inner annular partition wall 11k.

The stationary flow path 21 includes a diffuser flow path 22, a curved flow path 23, and a return flow path 24.
The rotary shaft 12 is rotationally driven by a drive source (not shown).
The impeller 13 is fixed to the rotating shaft 12 and rotates together with the rotating shaft 12.

<Static flow path 21>
Next, the stationary flow path 21 will be described with reference to FIGS.
As shown in FIG. 2, the flow path between adjacent impellers 13 is constituted by a stationary flow path 21. The static flow path 21 has a role of changing the dynamic pressure of the fluid due to the rotation of the preceding impeller 13 to a static pressure and reducing the force of the swirling component of the fluid.
The fluid flows into the inside of the impeller 13 from the impeller inlet 13A located at the radial center of the impeller 13 (α21 in FIG. 2).

The fluid that has flowed into the impeller 13 receives a centrifugal force due to the rotation of the impeller 13, increases the pressure, and flows out from the outer impeller outlet 13 </ b> B toward the stationary flow path 21. The fluid flowing out from the impeller outlet 13B flows into the diffuser flow path 22 (α22 in FIG. 2).
The fluid that has passed through the diffuser flow path 22 flows through the curved flow path 23, so that the flow direction is turned from the outward direction to the inward direction. The flow turned inward is guided to the next stage impeller 13 through the return flow path 24. Thus, the fluid passes through the stationary flow path 21 (α23 in FIG. 2) and is guided to the next stage impeller 13 (the right impeller 13 in FIG. 2).

3A to 3C show the outer shape of the stationary flow path 21 with the casing 11 removed. FIG. 3A shows a side view of the stationary flow path 21 with the casing 11 removed, FIG. 3B shows a view in the direction I of FIG. 3A, and FIG. 3C shows a view in the direction II of FIG. 3A.

As shown in FIGS. 3A to 3C, the stationary flow path 21 has a first crossover blade 25 formed over the diffuser flow path 22, the curved flow path 23, and the return flow path 24.
A plurality of first crossover blades 25 are provided in the stationary flow path 21 uniformly in the circumferential direction. In the return flow path 24, the same number of second crossover blades 26 (see FIG. 3C) are arranged downstream of the first crossover blades 25.

A slit 27 is provided between the first crossover blade 25 and the second crossover blade 26. The slit 27 has a uniform distance in the radial direction of the impeller 13 with respect to all the blades (25, 26) arranged in the circumferential direction. The slit 27 connects the pressure surface 25a of the first crossover blade 25 and the negative pressure surface 26f of the second crossover blade 26 to the flow of fluid (arrow α30 in FIG. 3C).

The position of the slit 27 is disposed in the return channel 24 where the curved channel 23 (see FIG. 2) ends. This is because when the slit 27 is formed in the bent flow path 23, the flow swells due to the bending of the flow path, and loss occurs. Further, the flow flows into the slit 27 in the curved flow path 23, the flow swells and a loss occurs.
On the other hand, in the conventional Patent Document 1, the slit between the radial side end portions 25 and 35 seems to be located in the curved flow path (FIG. 4A of Patent Document 1, paragraph 0045, etc.). is there.

In addition, the slit 27 is preferably arranged at a position that is not too downstream in the return flow path 24.
By providing the slit 27, as shown in FIG. 3C, momentum is brought from the pressure surface 25a side of the first crossover blade 25 into the thick velocity boundary layer on the suction surface 26f side of the second crossover blade 26 (see FIG. 3C). 3C arrow α30) becomes possible. For this reason, the velocity boundary layer can be thinned, and peeling can be suppressed. If the separation can be suppressed, an increase in loss due to the separation can be suppressed and the efficiency can be improved. FIG. 4 shows the first crossover blade 25 and the second crossover blade in the return flow path 24 according to the first embodiment. An enlarged perspective view of the vicinity of the slit 27 constituted by 26 is shown.

As shown in FIG. 4, of the first crossover blade 25 and the second crossover blade 26 divided by the slit 27, the leading edge 26A of the second crossover blade 26 is the trailing edge of the first crossover blade 25. It is characterized in that it is shifted to the upstream side of the rotational direction of the impeller 13 (arrow α31 in FIGS. 4 and 5) with respect to 25B, that is, located on the upstream side. The leading edge 26A of the second crossover blade 26 is shifted by about 10 to 15% (= d1 / d) with respect to the interval d of the first crossover blade 25. On the other hand, in Patent Document 1, the return vane (31) is shifted to the downstream side with respect to the diffuser vane (21) (see FIG. 4A of Patent Document 1).

By providing the slit 27, which is a feature of the first embodiment, the pressure of the first crossover blade 25 is increased in the thick velocity boundary layer on the suction surface 26f (FIG. 3C, FIG. 5) side of the second crossover blade 26. It becomes possible to bring in the momentum of the fluid from the side of the surface 25a (FIGS. 3C and 5). As a result, the velocity boundary layer of the suction surface 26f of the second crossover blade 26 can be thinned, and separation of fluid from the suction surface 26f can be suppressed. If the peeling can be suppressed, it is possible to suppress an increase in pressure loss due to the peeling, and it is possible to improve the efficiency.

Further, by suppressing the separation of the fluid from the suction surface 26f of the second crossover blade 26, it becomes possible to appropriately turn the flow along the suction surface 26f. If the flow can be properly turned, components in the turning direction of the impeller 13 can be removed, so that the fluid can smoothly flow into the subsequent impeller 13. Therefore, the efficiency of the next stage impeller 13 can be improved.

FIG. 5 shows a comparison between the outlet blade angle θ1 of the hub side wall surface 28 (see FIG. 2) of the first crossover blade 25 in the return flow path 24 and the outlet blade angle θ2 of the shroud side wall surface 29 (see FIG. 2). Show.
In this configuration, the outlet blade angle of the trailing edge 25B of the first crossover blade 25 is such that the outlet blade angle θ1 of the hub side wall surface 28 (see FIG. 2) and the outlet of the shroud side wall surface 29 (see FIG. 2). It differs depending on the blade angle θ2. More specifically, the outlet blade angle θ1 on the hub side wall surface 28 side is circumferential with respect to the outlet blade angle θ2 on the shroud side wall surface 29 side (the rotational direction of the impeller 13 (arrow α31 in FIG. 5)). It is characterized by having a (small) blade angle.

The exit blade angle θ1 is an arc centered on the center line of the impeller 13 at the point 25p where the center line 25o1 of the first crossover blade 25 on the hub side wall surface 28 passes the trailing edge 25B and the center line 25o1. The angle between the tangent line 13s of 13e. Similarly, the exit blade angle θ2 is an arc centered on the center line of the impeller 13 at the point 25q where the center line 25o2 of the first crossover blade 25 on the shroud side wall surface 29 passes through the trailing edge 25B and the center line 25o2 The angle between the tangent line 13s of 13e.

The reason why the outlet blade angle θ1 of the hub side wall surface 28 of the trailing edge 25B of the first crossover blade 25 is different from the outlet blade angle θ2 of the shroud side wall surface 29 is as follows.
Due to the action of the centrifugal force on the fluid, the flow having a higher flow velocity in the curved flow path 23 is biased toward the shroud side wall surface 29 side located outside. Therefore, in the first crossover blade 25, the flow turning angle needs to be larger on the side of the shroud side wall surface 29 (see FIG. 2) than on the side of the hub side wall surface 28 (see FIG. 2).

Therefore, the blade angle of the trailing edge 25B of the first crossover blade 25 is varied in the height direction of the first crossover blade 25 (the direction from the hub side wall surface 28 to the shroud side wall surface 29). That is, the blade angle of the trailing edge 25B of the first crossover blade 25 is such that the outlet blade angle θ1 on the side of the hub side wall 28 (see FIG. 2) in the return channel 24 is the shroud side wall in the return channel 24. Smaller than the outlet blade angle θ2 on the 29 (see FIG. 2) side.

Accordingly, by receiving a larger load of fluid on the shroud side wall surface 29 (see FIG. 2) side (exit blade angle θ2 side) of the first crossover blade 25, pressure loss can be suppressed and efficiency can be improved.
On the other hand, in Patent Document 1, the exit vane angle of the diffuser vane (21) is constant (see FIG. 4A of Patent Document 1).

According to the above configuration, the vane row (25, 26) communicates from the diffuser flow path 22 to the curved flow path 23 and the return flow path 24, and the blade (25, By suppressing the separation from the surface of 26), it is possible to reduce the loss and control the inflow angle of the next stage.

Therefore, it can be expected to reduce the cost of the multistage pump P and improve the operation efficiency. Therefore, the highly efficient multistage pump P can be provided while reducing the outer diameter of the multistage pump P. In addition, the reduction of the outer diameter of the multistage pump P can also reduce the exclusive space.

From the above, it is possible to provide a centrifugal pump capable of stable operation in the entire flow rate range while maintaining high efficiency even when the pump outer diameter is reduced.

<< Embodiment 2 >>
FIG. 6 shows an external view of the stationary flow path 21 portion according to Embodiment 2 of the present invention.
The second embodiment is characterized by having a slit 27 between the first crossover blade 25 and the second crossover blade 26, as in the first embodiment, but in the second embodiment, the first crossover blade 25 has the first crossover blade 26. By controlling the thickness 25t of the over blade 25, further increase in efficiency is realized.

In the second embodiment, by changing the thickness 25t of the first crossover blade 25 in the curved flow path 23, the inter-blade flow path disconnection formed between adjacent first crossover blades 25 in the curved flow path 23 is performed. Controls the change in the cross-sectional area of the area.
In general, the flow in a pipe having a curvature is likely to be separated from the flow because the flow direction changes suddenly at the bent portion. In order to suppress the peeling at the bent portion, two points are important: a gentle curvature or a small change in flow path cross-sectional area at the bent portion.

The first crossover blade 25 has an effect of turning the flow from the swirling direction to the flow direction of the curved flow path 23 even in the curved flow path 23. Therefore, a fluid load acts on the blade surface of the first crossover blade 25. The fact that the load due to the fluid is acting means that the first crossover blade 25 is bent or twisted in the curved flow path 23, so that the adjacent first crossover blade 25 changes according to its shape change. The channel cross-sectional area between them also changes. When the flow path cross-sectional area between the first crossover blades 25 changes abruptly, loss due to fluid separation or acceleration occurs with changes in the flow path cross-sectional area.

In order to suppress the occurrence of this flow loss, by changing the thickness 25t of the first crossover blade 25 in the curved flow path 23, the first crossover blade 25 is appropriately bent and the cross-sectional area of the flow path is reduced. It is possible to control so that the change of the signal is moderated or not changed.

Generally, the fluid flowing out from the impeller outlet 13B (see FIG. 2) of the centrifugal pump such as the multistage pump P is a flow in which the swirl direction component due to the rotation of the impeller 13 is dominant. Although this swirl direction component is turned in the diffuser flow path 22 shown in FIG. 2, the swirl direction component is still dominant at the inlet 23i (see FIG. 2) of the bend flow path 23 in many cases. If the flow is guided to the return flow path 24 shown in FIG. 2 while maintaining this swirl direction component, the strong swirl component cannot be removed, so the suction surface 26f of the second crossover blade 26 (see FIG. 3C). ) Peeling easily occurs. Therefore, it can be said that the flow should be redirected as much as possible even in the curved flow path 23.

When a fluid load is applied to the first crossover blade 25 to remove the swirl direction component of the fluid in the curved flow path 23, the thickness of the first crossover blade 25 is constant. In this case, the cross-sectional area of the flow path between the adjacent first crossover blades 25 becomes larger due to the bending of the flow path toward the return flow path 24.

Generally, when the cross-sectional area is enlarged in a flow path having a curvature, the flow is easily separated from the wall surface, and the loss increases. Therefore, the loss can be suppressed by changing the thickness of the crossover blade 2 in the curved flow path 23. Therefore, in a channel having a bend, reducing the channel cross-sectional area change as much as possible leads to an improvement in efficiency.

Therefore, in the second embodiment, the blade thickness of the first crossover blade 25 in the curved flow path 23 is gradually increased from the outlet 22o of the diffuser flow path 22 (see FIG. 2) to the inlet 24i of the return flow path 24. It is thick. That is, as shown in FIG. 6, the thickness is gradually increased from the bent channel inlet blade thickness 25t1 to the bent channel outlet blade thickness 25t2.

With the structure of the second embodiment, the change in the cross-sectional area of the flow path between the first crossover blades 25 constituted by the first crossover blades 25 adjacent in the circumferential direction can be controlled so as to be gradual or not change. Become.
As a result, fluid loss in the bent flow path 23 can be suppressed, and efficiency can be improved. On the other hand, unlike the second embodiment, the conventional Patent Document 1 has a constant thickness of the diffuser vane (21) (see FIG. 4A of Patent Document 1).

<< Other Embodiments >>
1． Although various configurations have been described in the first and second embodiments, these configurations may be combined as appropriate.
2． In addition, this invention is not limited to embodiment mentioned above, A various change is possible in the range which does not deviate from the meaning of this invention.

11 Casing 11k Annular partition 12 Rotating shaft 13 Impeller (centrifugal impeller)
21 Static flow path 22 Diffuser flow path (first radial flow path)
23 Curved channel 24 Return channel (second radial channel)
25 First crossover wing (upstream crossover wing, crossover wing)
25B Trailing edge 25t thickness 25t1 Curved channel inlet blade thickness 25t2 Curved channel outlet blade thickness 26 Second crossover blade (downstream crossover blade, crossover blade)
26A Front edge 27 Slit 28 Hub side wall surface (first surface)
29 Shroud side wall (second surface)
P Multistage pump (centrifugal pump)
θ1 Outlet blade angle on the shroud side (blade angle on the first side of the trailing edge)
θ2 Blade angle at the hub side exit (blade angle on the second side of the trailing edge)

Claims

A plurality of centrifugal impellers attached to a rotating shaft;
An annular partition provided around the rotary shaft of the centrifugal impeller;
A first radial flow path formed around the annular partition and configured to guide the fluid that has passed through the centrifugal impeller to the radially outer side of the centrifugal impeller;
A second radial flow path formed on the opposite side of the first radial flow path across the annular partition and configured to guide the fluid inward in the radial direction of the centrifugal impeller;
The first radial flow path and the second radial flow path are communicated with each other on the outer peripheral side of the annular partition so as to guide the fluid from the first radial flow path to the second radial flow path. A curved flow path configured in
A crossover blade formed in communication with the first radial flow path, the second radial flow path and the curved flow path;
The crossover blade has a slit in the second radial flow path;
Of the crossover wings divided by the slit, the leading edge of the downstream crossover wing located on the downstream side with respect to the fluid flow direction,
Among the crossover blades divided by the slit, the upstream edge of the upstream crossover blade located upstream with respect to the fluid flow direction is shifted upstream in the direction in which the centrifugal impeller rotates. A centrifugal pump characterized by
The centrifugal pump according to claim 1,
The centrifugal pump, wherein a blade angle of a trailing edge of the upstream crossover blade is different in a height direction of the crossover blade.
The centrifugal pump according to claim 1,
The blade angle of the trailing edge of the upstream crossover blade is such that, in the second radial flow path, the first surface side of the annular partition wall is closer to the second surface facing the first surface. Centrifugal pump characterized by its small size.
The centrifugal pump according to claim 1,
The centrifugal pump characterized in that the thickness of the upstream crossover blade changes in the curved flow path.
The centrifugal pump according to claim 1,
The blade angle of the trailing edge of the upstream crossover blade is different in the height direction of the crossover blade,
The centrifugal pump characterized in that a thickness of the upstream crossover blade changes in the curved flow path.
The centrifugal pump according to claim 1,
The blade angle of the trailing edge of the upstream crossover blade is different in the height direction of the crossover blade,
The centrifugal pump according to claim 1, wherein a thickness of the upstream crossover blade in the curved flow path is thicker on the second radial flow path side than on the first radial flow path side.