JP2003343493A - Diffuser of pump and pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the degradation of a flow rate/head characteristic curve. <P>SOLUTION: In a diffuser 10 related to the embodiment 1, the straight line part 20s is provided in the diffuser flow path 20, and the diffuser bending part 20b is arranged on the latter half part 20t of the diffuser flow path 20. After the pressure of fluid is recovered by sufficiently reducing the speed of the fluid at the first half 201 of the diffuser flow path 20, the direction of flow can be changed into the rotating shaft 9 side of an impeller 3 at the diffuser bending part 20b. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a pump,
More specifically, the present invention relates to a diffuser of a pump and a pump having improved flow rate / lift characteristics and capable of stable operation.

[0002]

A pump is a machine that applies energy to a fluid and sends it from a low pressure section to a high pressure section. Among such pumps, mixed flow pumps and centrifugal pumps belonging to turbomachines are applied to a wide range of flow rates and pressures. FIG. 8 is an explanatory diagram showing an example of a flow rate / lift (hereinafter referred to as Q / H) characteristic showing a relationship between the discharge amount Q of the pump and the lift H.
Generally, in a mixed flow pump or a centrifugal pump, the head H becomes large when the discharge amount Q is small, and the head H becomes smaller as the discharge amount Q increases. Then, as shown by the curve A in FIG. 8, it is preferable that the pumping head H be decreased with the increase of the discharge amount Q in order to operate the pump stably.

[0003]

By the way, if a Q / H characteristic is dented as shown by a curve B in FIG. 8 due to design restrictions or the like, the ejection amount in the dent region C is reduced. When the pump is operated with Qc, surging may occur and the operation of the pump may become unstable. Therefore,
The present invention has been made in view of the above, and Q /
It is an object of the present invention to provide a pump diffuser and a pump that can be stably operated by reducing the depression of the H characteristic.

[0004]

In order to achieve the above object, a diffuser of a pump according to a first aspect of the invention slows down the fluid sent from an impeller and changes the direction of flow in the direction of the axis of rotation of the impeller. An annular diffuser flow path is provided around the rotary shaft and has a curved portion for causing the curved portion to be arranged in the latter half of the diffuser flow channel.

The inventors of the present invention have conducted extensive studies to improve the Q / H characteristics of the pump. As a result, when a fluid having a high velocity passes through the bend portion of the diffuser, the fluid flow cannot follow the bend, It was found that peeling occurred. In the conventional diffuser, this separation occurs on the upstream side in the diffuser flow path, that is, in the region where the flow velocity of the fluid is high and the pressure is not sufficiently recovered, so that the energy loss of the fluid is large and the Q / H It was found that a dent was generated in the characteristics.

In the diffuser of this pump, a bent portion that changes the flow of fluid in the direction of the rotation axis of the impeller is provided in the latter half of the diffuser flow path. With such a structure, the pressure of the fluid is recovered by sufficiently decelerating the fluid in the front half of the diffuser flow path, and thus the pressure recovery area of the fluid can be made larger than in the conventional case. As a result, the energy loss of the fluid in the diffuser is reduced more than before,
Since the dent of the Q / H characteristic can be reduced, the pump can be operated stably.

Further, as in the diffuser of the pump according to the second aspect, it is preferable that the bent portion is arranged at a position downstream from the inlet of the diffuser flow passage by more than 50% of the length of the diffuser flow passage. This is because, in a normal diffuser, when the fluid flows to this area, the pressure of the fluid is sufficiently recovered, so even if peeling occurs in this area or later, it has almost no effect on the energy loss of the fluid. is there.

A diffuser for a pump according to a third aspect of the present invention is the diffuser for a pump according to the first aspect or the second aspect, further, in the diffuser passage, from the inlet to the outlet of the diffuser passage. A diffuser vane is provided, and at least in a bent portion of the diffuser flow path, a base portion of the diffuser vane on a rotation shaft side of the impeller is inclined toward a pressure surface side.

In the diffuser of this pump, the root of the diffuser vane on the rotary shaft side of the impeller is inclined to the pressure surface side at least at the diffuser bend portion. With such a configuration, it is possible to suppress the development of the velocity boundary layer and the accumulation of the low energy fluid near the root of the diffuser vane on the rotating shaft side of the impeller. As a result, the energy loss of the fluid can be further suppressed and the pressure of the fluid can be sufficiently restored, so that the depression of the Q / H characteristic can be further reduced. The diffuser vane may be tilted toward the pressure surface over the entire height direction, or only the root of the diffuser vane on the rotating shaft side of the impeller may be tilted toward the pressure surface. Here, the pressure surface is the surface on the ventral side (inside the curved portion) of the diffuser vane that is curved with respect to the meridional surface, and the suction surface is the back side (outside the curved portion), that is, the opposite of the pressure surface. The surface on the side (the same applies hereinafter). Figure 4 (b)
The surface indicated by reference numeral 31p is a pressure surface, and the surface indicated by reference numeral 31d is a negative pressure surface. In terms of pressure,
The pressure is higher than that on the suction surface (the same applies below).

A diffuser for a pump according to a fourth aspect is the diffuser for a pump according to the first or second aspect, and further, in the diffuser flow passage, a diffuser vane from an inlet to an outlet of the diffuser flow passage. Is provided, and at least in the bent portion of the diffuser flow path, a cross-sectional shape perpendicular to the flow direction of the diffuser vane is formed into a bow blade shape, and the root portion of the diffuser vane on the rotary shaft side of the impeller is pressed The feature is that it is inclined to the surface side.

In the diffuser of this pump, a cross section perpendicular to the flow direction of the diffuser vane has a bow blade shape at least in the curved portion of the diffuser, and the diffuser vane is inclined toward the pressure surface side. With such a configuration, it is possible to suppress the accumulation of the low-energy fluid that occurs near the root of the diffuser vane on the rotating shaft side of the impeller. As a result, the energy loss of the fluid can be further suppressed and the pressure of the fluid can be sufficiently restored, so that the dent of the Q / H characteristic can be further reduced,
More stable pump operation becomes possible. Here, the bow wing shape refers to a wing shape in which the cross-sectional shape perpendicular to the flow direction of the diffuser is an arc shape (the same applies hereinafter).

A diffuser for a pump according to a fifth aspect is the diffuser for a pump according to the first or second aspect, further comprising a diffuser vane in the diffuser passage from an inlet to an outlet of the diffuser passage. It is characterized in that at least the curved portion of the diffuser flow path has a structure for filling a dead water region generated at the base portion of the diffuser vane on the suction surface side on the rotary shaft side of the impeller.

In the diffuser of this pump, the root portion of the diffuser vane on the negative pressure surface side on the rotary shaft side of the impeller is preliminarily thickened at the time of manufacturing or a spacer is joined to fill the dead water region generated in this portion. Is done. As a result, it is possible to suppress the occurrence of dead water regions and suppress the accumulation of low energy fluid and the like. Further, since it is possible to suppress the backflow of the fluid passing through the diffuser by suppressing the development of the velocity boundary layer and the like, it is possible to suppress the separation of the fluid at the curved portion of the diffuser. By these interactions, the energy loss of the fluid can be further suppressed, the depression of the Q / H characteristic can be reduced, and the pump can be operated stably.

The diffuser of the pump according to claim 6 is provided in the diffuser flow passage having a curved portion for decelerating the fluid sent from the impeller and changing the direction of the flow, and the diffuser passage. A diffuser vane from the inlet to the outlet of the diffuser flow passage, and at least in the curved portion of the diffuser flow passage, the root of the diffuser vane on the rotary shaft side of the impeller is inclined toward the pressure surface side. Is characterized by.

In the diffuser of this pump, the root of the diffuser vane on the rotary shaft side of the impeller is inclined to the pressure surface side at least at the diffuser bend portion. With such a configuration, it is possible to suppress the development of the velocity boundary layer and the accumulation of the low energy fluid near the root of the diffuser vane on the rotating shaft side of the impeller. As a result, the energy loss of the fluid can be suppressed and the pressure of the fluid can be sufficiently restored, so that the depression of the Q / H characteristic can be reduced. The diffuser of this pump can be applied not only to the mixed flow pump but also to the diffuser of the centrifugal pump.

The diffuser of the pump according to claim 7 is provided in the diffuser flow passage having a bent portion for decelerating the fluid sent from the impeller and changing the direction of the flow, and the diffuser passage. A diffuser vane directed from an inlet to an outlet of the diffuser flow passage, and at least at a curved portion of the diffuser flow passage, a cross-sectional shape perpendicular to a flow direction of the diffuser vane is formed into a bow blade shape, and rotation of the impeller is performed. The base portion of the diffuser vane on the shaft side is inclined to the pressure surface side.

In the diffuser of this pump, a cross section perpendicular to the flow direction of the diffuser vane has a bow blade shape at least in the curved portion of the diffuser, and the diffuser vane is inclined toward the pressure surface side. With such a configuration, it is possible to suppress the accumulation of the low-energy fluid that occurs near the root of the diffuser vane on the rotating shaft side of the impeller. As a result, the energy loss of the fluid can be suppressed and the pressure of the fluid can be sufficiently restored, so that the depression of the Q / H characteristic can be reduced. The diffuser of this pump can be applied not only to the mixed flow pump but also to the diffuser of the centrifugal pump.

The diffuser of the pump according to claim 8 is provided in the diffuser passage having a bent portion for decelerating the fluid sent from the impeller and changing the direction of the flow, and in the diffuser passage. A diffuser vane is provided, and at least the curved portion of the diffuser flow path is configured to fill a dead water region generated at the suction surface side root portion of the diffuser vane on the rotating shaft side of the impeller.

In the diffuser of this pump, the root portion of the diffuser vane on the negative pressure surface side on the rotary shaft side of the impeller is preliminarily thickened at the time of manufacturing, or a spacer is joined to fill the dead water region generated in this portion. There is. As a result, it is possible to suppress the occurrence of dead water regions and suppress the accumulation of low-energy fluids, etc. Therefore, it is possible to suppress the energy loss of the fluids, reduce the dents in the Q / H characteristics, and stably operate the pump. The diffuser of this pump can be applied not only to the mixed flow pump but also to the diffuser of the centrifugal pump.

A pump according to a ninth aspect is the impeller for imparting velocity energy to the fluid, and the velocity energy of the fluid sent from the impeller is converted into pressure energy. And a diffuser as described above. Since this pump is provided with the diffuser of the above-mentioned pump, it is possible to secure a large fluid pressure recovery region. Also, because it is possible to suppress peeling at the bend and accumulation of low-energy fluid, etc.
Due to these effects, stable operation is possible even in a wide flow rate range.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. Further, the present invention is particularly suitable for a mixed flow pump and a centrifugal pump. Further, the pump to which the present invention is applied is suitable for sending water, a slurry, or a fluid such as a low temperature fuel used in a chemical plant.

(Embodiment 1) FIG. 1 is a sectional view showing a pump according to Embodiment 1 of the present invention. Also, FIG.
FIG. 3 is an explanatory diagram showing a diffuser of the pump according to Embodiment 1 of the present invention. The pump 100 includes a curved portion 2 of a diffuser flow passage 20 that constitutes the diffuser 10.
0b is arranged in the rear half 20t of the diffuser 10.

This pump 100 is a mixed flow pump, and the fluid taken in from the pump inlet 1 is sent by the impeller 3 to the diffuser flow passage 20 which constitutes the diffuser 10 (the portion surrounded by the dotted line in FIG. 1). Although not apparent from FIG. 1, the diffuser flow passage 20 is provided around the rotary shaft 9 of the impeller 3, and the sectional shape perpendicular to the rotary shaft 9 is annular. The fluid sent to the diffuser flow path 20 is rectified here and then discharged from the pump outlet 5. The diffuser 10 plays a role of converting velocity energy given to the fluid by the impeller 3 into pressure energy.

FIG. 3 is an explanatory view showing a conventional diffuser. In the conventional diffuser 910, the impeller 90
The fluid flowing out of No. 1 was changed in its flow direction to the rotating shaft 909 side of the impeller 901 by the diffuser bending portion 920b provided in the front half of the diffuser flow passage 920. As a result of earnest studies by the present inventors, when a fluid having a high velocity passes through the diffuser bending portion 920b, the flow of the fluid cannot follow this bending, and as shown in FIG. It was found that peeling 940 occurred. And the conventional diffuser 9
In FIG. 10, this peeling 940 is the diffuser flow path 9
It has been found that the energy loss of the fluid is large and the Q / H characteristic is dented because it occurs in the upstream side of 20, that is, in the region where the flow velocity of the fluid is high and the pressure is not sufficiently recovered.

Therefore, in the diffuser 10 according to the first embodiment of the present invention, as shown in FIG. 2, the diffuser flow passage 20 is provided with the straight portion 20s, and the diffuser flow passage 20 is provided.
The diffuser bent portion 20b is arranged in the latter half portion 20t of the. Also, the diffuser vane 30
Also, with the diffuser channel 20 having such a shape, the diffuser channel 20 has a shape similar to the cross-sectional shape of the diffuser channel 20. The straight line portion 20s is not a literal straight line, but a gentle curved line portion 20 as shown by a dotted line in FIG.
The diffuser bent portion 20b may be provided in the rear half portion 20t of the diffuser flow path 20 by providing the c.

With such a structure, in the diffuser 10, the pressure of the fluid is recovered by sufficiently decelerating the fluid in the front half portion 20l of the diffuser flow passage 20, and then the flow direction of the impeller 3 is changed by the diffuser bending portion 20b. It can be changed to the rotating shaft 9 side. As a result, the pressure recovery region of the fluid can be made larger than in the conventional case, so that the energy loss of the fluid in the diffuser 10 can be made smaller than in the conventional case. As a result, the dent of the Q / H characteristic can be reduced, and the pump 100 can be operated stably.

The speed of the fluid is reduced in the diffuser 10 and the pressure of the fluid gradually recovers from the diffuser inlet 20i to the diffuser outlet 20e. In the present invention, however, the fluid is sufficiently decelerated and the pressure is sufficiently reduced. The diffuser bent portion 20b is provided after the recovery. From this point of view, the position where the diffuser bent portion 20b is provided is preferably a region of 0.5 or more (50% or more in% display) when expressed by the flow channel length x / L (dimensionless display) of the diffuser flow channel 20. This is because, in a normal diffuser, when the fluid flows to this area, the pressure of the fluid is sufficiently recovered, so even if peeling occurs in this area or later, it has almost no effect on the energy loss of the fluid. is there. If it is desired to further reduce the energy loss of the fluid, the diffuser bent portion 20b may be provided in the region where x / L is 0.6 or more. Here, it is preferable to arrange the diffuser bent portion 20b in the latter half of the diffuser flow path 20 as much as possible, but if it is arranged too much in the latter half, the outer dimension of the pump 100 itself becomes large and the weight also increases, so x / L The value of is realistic up to about 0.7. Here, L is the total flow path length of the diffuser flow path 20, and along the center position in the height direction of the diffuser flow path 20 (the one-dot chain line C _{1 in} FIG. 2), from the diffuser inlet 20i to the diffuser exit 20e. It is the length when measured up to. Further, x is the diffuser inlet 20i
Is the distance from.

(Second Embodiment) FIG. 4 is a front view showing a diffuser of a pump according to a second embodiment of the present invention. This diffuser 11 includes a diffuser bending portion 2
In 1b, the vane mounting angle θ in the root portion 31x of the diffuser vane 31 on the hub 7 (rotating shaft 9) side on the suction surface 31d side is larger than 90 degrees. That is, the diffuser bent portion 21b is characterized in that the root portion 31x of the diffuser vane 31 on the rotary shaft 9 side of the impeller 3 is inclined toward the pressure surface 31p side. At least the bent portion 21b
It is necessary to incline the diffuser vane 31 in, but the diffuser vane 31 may be inclined in other regions or the entire region of the diffuser flow passage 21.

As shown in FIG. 4D, in the diffuser bending portion 920b of the conventional diffuser 910,
In the vicinity of the root portion 930x on the negative pressure surface 930d side of the diffuser vane 930, the velocity boundary layer was developed and the low energy fluid was accumulated to form the dead water region 942. As a result, the energy loss of the fluid flowing through the diffuser 910 was large. Therefore, the dead water area 942 does not occur in this portion, or the dead water area 9
Even if 42 occurs, if it is in a region as small as possible, energy loss of the fluid can be reduced.

Therefore, as shown in FIG. 4 (a), in the diffuser 11 of the pump according to the second embodiment of the present invention, the diffuser vane 31 in the diffuser bent portion 21b is inclined toward the pressure surface 31p side to form the negative pressure surface 31d. Mounting angle θ on the hub 7 (rotating shaft 9) side of
Is larger than 90 degrees. Specifically, for example, the hub-side vane shape 31 is formed into a shape as shown in FIG.
h, central vane shape 31m, tip side vane shape 31
and c. By doing so, the diffuser vane 31 can be inclined to the pressure surface 31p side, and the vane mounting angle θ on the negative pressure surface 31d side of the diffuser vane 31 can be made larger than 90 degrees. Here, FIG. 4 (b)
FIG. 6 is a view of the diffuser vane 31 as viewed from the chip 2 side thereof. Further, the fluid sent from the impeller (not shown) proceeds in the direction of arrow Y in FIG. 4 (b).

With such a structure, the base portion 31x
Since the development of the velocity boundary layer and the accumulation of the low energy fluid on the negative pressure surface 31d side can be suppressed, the energy loss of the fluid can be suppressed and the depression of the Q / H characteristic can be reduced. It should be noted that the diffuser vanes 31 'are not tilted over the entire height direction of the diffuser vanes 31', but are shown in FIG.
As shown in, only the vicinity of the base 31'x may be inclined. Even in this case, the same action and effect can be obtained.

Further, the invention according to the first embodiment may be further applied to the diffuser vane 31 and the like according to the second embodiment. By doing so, the effect of expanding the pressure recovery region of the fluid by arranging the bent portion produced by the diffuser 10 according to the first embodiment in the latter half of the diffuser flow path can also be used. As a result, the energy loss of the fluid can be further reduced and the Q / H characteristic can be improved, so that the pump 100 can be stably operated in a wider flow rate range.

(Third Embodiment) FIG. 5 is a front view showing a diffuser vane according to a third embodiment. The diffuser vane 32 has substantially the same configuration as the diffuser vane 31 according to the second embodiment, except that at least the bent portion 22b of the diffuser flow path 22 uses a bow blade for the diffuser vane 32. Since other configurations are similar to those of the second embodiment, the description thereof will be omitted and the same components will be denoted by the same reference numerals.
In addition, at least in the curved portion 22b, the shape of the diffuser vane 32 needs to be a bow blade shape.
The shape of the diffuser vane 32 may be a bow blade shape in another region or the entire region of the diffuser flow path 22.

As described above, by using the bow blades for the diffuser vane 32, the diffuser vane 32
The vane attachment angle θ of the root portion 32x on the negative pressure surface 32d side can be made larger than 90 degrees. As a result, it is possible to suppress the development of the velocity boundary layer and the accumulation of the low energy fluid that have occurred on the suction surface 32d side of the root portion 32x of the diffuser vane 32. Further, since the backflow of the fluid passing through the diffuser 12 can be suppressed by suppressing the development of the velocity boundary layer, the separation of the fluid at the diffuser curved portion 22b can also be suppressed. Due to these interactions, the energy loss of the fluid can be reduced and the depression of the Q / H characteristic can be reduced.

At least one of the inventions according to the first or second embodiment may be further applied to the diffuser vane 32 according to the third embodiment. By doing so, the effect of expanding the pressure recovery region of the fluid by arranging the bent portion produced by the diffuser 10 according to the first embodiment in the latter half of the diffuser flow path can also be used. Also,
The low energy fluid accumulated in the vicinity of the root portion 32x on the suction surface 32d side of the diffuser vane 32 can be removed more efficiently. As a result, the energy loss of the fluid can be further reduced and the Q / H characteristic can be improved, so that the pump 100 can be stably operated in a wider flow rate range.

(Fourth Embodiment) FIG. 6 is a front view showing a diffuser vane according to a fourth embodiment. The diffuser vane 33 is different in that at least the curved portion 23b of the diffuser flow path 23 is configured to fill a dead water region generated near the root portion 33x on the suction surface side of the diffuser vane 33. Since other configurations are similar to those of the second embodiment, the description thereof will be omitted and the same components will be denoted by the same reference numerals. In addition, at least in the bent portion 23b, the diffuser vane 33
The root portion 33x on the negative pressure surface side is required to have the above structure, but the other region or the entire region of the diffuser flow path 23 may be configured to be the above structure.

As shown in FIG. 4D, in the diffuser bending portion 920b of the conventional diffuser 910,
Hub 90 of suction surface 930d of diffuser vane 930
At the base portion 930x on the 7 side, the velocity boundary layer develops and the low energy fluid accumulates, and the dead water area 94
Had formed 2. As a result, the energy loss of the fluid flowing through the diffuser 910 is increased, which is one of the causes of causing a dent in the Q / H characteristics.

Therefore, as shown in FIG. 6A, the root portion 3 of the suction surface 33d on the hub 7 (rotating shaft 9) side.
If the dead water area generated in 3x is filled in advance, the occurrence of the dead water area can be suppressed, and the accumulation of the low energy fluid can be suppressed. Further, since the development of the velocity boundary layer can be suppressed, the backflow of the fluid passing through the diffuser 13 can also be suppressed. As a result, it is possible to suppress the separation of the fluid in the diffuser bent portion 23b. By these interactions, the energy loss of the fluid can be suppressed and the depression of the Q / H characteristic can be reduced.

As means for filling the dead water area, for example, FIG.
As shown in (a), the tip 2 and the hub 7 are formed by casting.
When integrally manufacturing the diffuser vane 33 and the diffuser vane 33, there is a means to make the root portion 33x of the negative pressure surface 33d on the hub 7 (rotating shaft 9) side thick in advance so as to fill this portion. Further, as shown in FIG. 7B, the spacer 33s is attached to the hub 7 (rotating shaft 9) of the suction surface 33d by welding or the like.
You may join to the root part 33x in the side. Furthermore, after joining the diffuser vane 33 and the hub 7, the base portion 3 of the suction surface 33d on the hub 7 (rotating shaft 9) side.
After overlaying 3x, it may be finished by cutting or the like.

Here, as shown in FIG. 6 (c), the root portion 33x of the suction surface 33d on the hub 7 (rotating shaft 9) side is gradually filled from the diffuser inlet 23i to the diffuser bent portion 23b. Is preferred. Here, the fluid is sent from an impeller (not shown) in the direction of the arrow Y in FIG. 6 (c). If you do this,
The fluid smoothly flows along the root 33x on the hub 7 (rotating shaft 9) side of the negative pressure surface 33d. Further, the separation of the fluid is suppressed and the energy loss of the fluid is further reduced, which contributes to the improvement of the Q / H characteristic. Note that this example is a case where the spacer 33s is used, but fluid separation can be suppressed by using a similar configuration for casting and overlaying.

The invention according to at least one of the first to third embodiments may be further applied to the diffuser vane 33 according to the fourth embodiment. By doing so, the effect of expanding the pressure recovery region of the fluid by arranging the bent portion produced by the diffuser 10 according to the first embodiment in the latter half of the diffuser flow path can also be used. Further, the low energy fluid that could not be eliminated by the structure that fills the dead water region in the vicinity of the root portion 33x on the hub 7 (rotating shaft 9) side on the suction surface 33d side of the diffuser vane 33 can be efficiently eliminated. As a result, the energy loss of the fluid can be further reduced and the Q / H characteristic can be improved, so that the pump 100 can be stably operated in a wider flow rate range.

(Fifth Embodiment) FIG. 7 is an explanatory view showing a diffuser according to a fifth embodiment of the present invention. In the fifth embodiment, the diffusers 11 to 13 according to the second to fourth embodiments are applied to a centrifugal pump. FIG. 7A is a sectional view showing the centrifugal pump 101 parallel to the axial direction. The fluid is sucked into the impeller 4 from the arrow Y, given velocity energy, and then discharged from the diffuser inlet 24i into the diffuser passage 24. Then, while this fluid passes through the diffuser vane 34 provided in the diffuser flow path 24, velocity energy is converted into pressure energy and discharged from the diffuser outlet 24e.

FIG. 7 (b) shows an example in which the diffuser according to the second embodiment is applied, FIG. 7 (c) shows an example in which the diffuser according to the third embodiment is applied, and FIG. 7 (d).
Shows an example in which the diffuser according to the fourth embodiment is applied. The diffuser according to each embodiment is thus applied to the centrifugal pump 101. In these diffusers 14 to 14 ″, it is possible to suppress separation and accumulation of low-energy fluid that occur near the root portion 34 x and the like on the negative pressure surface 34 d side of the diffuser vane 34 and the like. As a result, the energy loss of the fluid is reduced, the dent of the Q / H characteristic is improved, and the centrifugal pump 101 can be stably operated in a wide flow rate range.

[0044]

As described above, in the diffuser of the pump according to the present invention (claim 1), the bent portion for changing the flow of the fluid is provided in the latter half of the diffuser flow passage. With such a structure, the pressure recovery region of the fluid can be made larger than in the conventional case, so that the energy loss of the fluid in the diffuser can be reduced as compared with the conventional case. As a result, the dent of the Q / H characteristic can be reduced, and the pump can be operated stably.

Further, in the diffuser of the pump according to the present invention (claim 2), the bent portion is arranged at a position downstream from the inlet of the diffuser flow path by more than 50% of the length of the diffuser flow path. did. For this reason, since the fluid flows to the bent portion after the fluid pressure is sufficiently recovered, the energy loss of the fluid can be reduced and the dent of the Q / H characteristic can be improved.

Further, in the diffuser of the pump according to the present invention (claim 3), the root of the diffuser vane on the rotary shaft side of the impeller is inclined toward the pressure surface side at least in the diffuser bend portion. As a result, it is possible to suppress the development of the velocity boundary layer and the accumulation of the low energy fluid, and further suppress the energy loss of the fluid to sufficiently recover the pressure of the fluid, so that the dent of the Q / H characteristic can be further reduced. .

Further, in the diffuser of the pump according to the present invention (claim 4), the cross section perpendicular to the flow direction of the diffuser vane has a bow blade shape at least in the curved portion of the diffuser, and the diffuser vane is inclined toward the pressure surface side. did. Therefore, the accumulation of the low-energy fluid can be suppressed, so that the energy loss of the fluid can be further suppressed and the pressure of the fluid can be sufficiently restored. As a result, it is possible to further reduce the dent of the Q / H characteristic and operate the pump more stably.

Further, in the diffuser of the pump according to the present invention (claim 5), the dead water region generated at the root portion of the diffuser vane on the suction surface side on the rotary shaft side of the impeller is filled. As a result, it is possible to suppress the occurrence of dead water regions that occur in this portion, suppress the accumulation of low-energy fluid, etc., and also suppress the separation of fluid in the curved portion of the diffuser. By these interactions, the energy loss of the fluid can be further suppressed, the depression of the Q / H characteristic can be reduced, and the pump can be operated stably.

Further, in the diffuser of the pump according to the present invention (claim 6), the root of the diffuser vane on the rotary shaft side of the impeller is inclined toward the pressure surface side at least at the diffuser bend portion.
Therefore, the energy loss of the fluid can be suppressed and the pressure of the fluid can be sufficiently restored, so that the depression of the Q / H characteristic can be reduced and the mixed flow pump and the centrifugal pump can be stably operated.

Further, in the diffuser of the pump according to the present invention (claim 7), the cross section perpendicular to the flow direction of the diffuser vane has a bow blade shape at least in the curved portion of the diffuser, and the diffuser vane is inclined toward the pressure surface side. did. As a result, the energy loss of the fluid can be suppressed and the pressure of the fluid can be sufficiently restored. Then, the dent of the Q / H characteristic can be reduced, and the mixed flow pump and the centrifugal pump can be stably operated.

Further, in the diffuser of the pump according to the present invention (claim 8), the dead water region generated in the root portion of the diffuser vane on the suction surface side on the rotary shaft side of the impeller is filled. As a result, it is possible to suppress the accumulation of the low energy fluid and the like, so that it is possible to suppress the energy loss of the fluid and reduce the depression of the Q / H characteristic. Then, the mixed flow pump and the centrifugal pump can be stably operated in a wide flow rate range.

A pump according to the present invention (claim 9)
Then, since the diffuser of the pump is provided, stable operation is possible even in a wide flow rate range.

[Brief description of drawings]

FIG. 1 is a sectional view showing a pump according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a diffuser of the pump according to the first embodiment of the present invention.

FIG. 3 is an explanatory view showing a conventional diffuser.

FIG. 4 is a front view showing a diffuser of a pump according to a second embodiment of the present invention.

FIG. 5 is a front view showing a diffuser vane according to a third embodiment.

FIG. 6 is a front view showing a diffuser vane according to a fourth embodiment.

FIG. 7 is an explanatory diagram showing a diffuser according to a fifth embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of a flow rate / lift (hereinafter referred to as Q / H) characteristic showing a relationship between a pump discharge amount Q and a lift H.

[Explanation of symbols]

1 pump inlet 2 chips Three and four impellers 5 pump outlet 7 hub 9 rotation axis 10, 11, 12, 13, 14, diffuser 20, 21, 22, 23, 24 Diffuser flow path 20b, 21b, 22b, 23b Bent part 20e, 24e diffuser outlet 20i, 23i, 24i diffuser inlet 20l first half 20t latter half 30, 31, 32, 33, 34 Diffuser vanes 31p pressure side 31x, 31'x, 32x, 33x, 34x Root 31d, 32d, 34d Suction surface 100 pumps 101 Centrifugal pump

Claims (9)

[Claims] 1. A fluid sent from an impeller is decelerated,
And having a bent portion for changing the direction of flow in the direction of the rotation axis of the impeller, an annular diffuser flow path provided around the rotation shaft is provided, and the bend portion is provided in the latter half of the diffuser flow path. The diffuser of the pump characterized by having been arranged. 2. The diffuser for a pump according to claim 1, wherein the bent portion is arranged at a position downstream from an inlet of the diffuser flow path by more than 50% of the diffuser flow path length. . 3. Further, in the diffuser channel,
A diffuser vane is provided from the inlet to the outlet of the diffuser flow passage, and at least in the curved portion of the diffuser flow passage, the root of the diffuser vane on the rotary shaft side of the impeller is inclined toward the pressure surface side. The diffuser for a pump according to claim 1 or 2, characterized in that. 4. The diffuser flow path further includes:
A diffuser vane is provided from the inlet to the outlet of the diffuser flow passage, and at least in the curved portion of the diffuser flow passage, a cross-sectional shape perpendicular to the flow direction of the diffuser vane is formed into a bow blade shape, and the impeller of the impeller is formed. The diffuser of the pump according to claim 1 or 2, wherein a root portion of the diffuser vane on the rotating shaft side is inclined toward the pressure surface side. 5. A diffuser vane is provided in the diffuser flow passage from an inlet of the diffuser flow passage toward an outlet thereof, and at least in a curved portion of the diffuser flow passage, the diffuser vane is provided on a rotation shaft side of the impeller. The diffuser for a pump according to claim 1 or 2, wherein the diffuser vane has a structure that fills a dead water region generated at a root portion on the suction surface side. 6. The fluid sent from the impeller is decelerated,
And a diffuser flow path having a bent portion for changing the flow direction, and a diffuser vane provided in the diffuser flow path from the inlet to the outlet of the diffuser flow path, and at least the bent portion of the diffuser flow path In the pump diffuser, the base portion of the diffuser vane on the rotary shaft side of the impeller is inclined toward the pressure surface side. 7. The fluid sent from the impeller is decelerated,
And a diffuser flow path having a bent portion for changing the flow direction, and a diffuser vane provided in the diffuser flow path from the inlet to the outlet of the diffuser flow path, and at least the bent portion of the diffuser flow path In, the cross-sectional shape perpendicular to the flow direction of the diffuser vane is formed into a bow blade shape, and the root of the diffuser vane on the rotating shaft side of the impeller is inclined to the pressure surface side. Diffuser. 8. The fluid sent from the impeller is decelerated,
And a diffuser flow path having a curved portion that changes the direction of flow, and a diffuser vane provided in the diffuser flow channel. At least in the curved portion of the diffuser flow channel, the diffuser flow path on the rotary shaft side of the impeller is provided. A diffuser for a pump, characterized in that it has a structure that fills a dead water region that occurs at the root of the diffuser vane on the suction surface side. 9. An impeller for imparting velocity energy to the fluid, and a diffuser according to claim 1, which converts velocity energy of the fluid sent from the impeller into pressure energy. A pump characterized by that.