JP2017180115A - Impeller and rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impeller and rotary machine having improved efficiency.SOLUTION: An impeller includes: a disc 11 with an axial line Ac as a center; a plurality of main blade 12 arranged with intervals in a circumferential direction of the axial line Ac on a main surface 11A facing one side of an axial line Ac direction of the disc 11, and extending in a radial direction of the axial line Ac; and an auxiliary blade 13 provided one side of a circumferential direction of each main blade 12 on the main surface 11A, extending from an outer peripheral side of the disc 11 toward a radial inside, and having a smaller dimension in the radial direction than the main blade 12.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an impeller and a rotary machine.

  As an example of a rotating machine, a centrifugal pump for pumping fluid is widely used (see Patent Document 1 below). In such a centrifugal pump, a fluid is pumped by rotating an impeller having a plurality of blades. The impeller has a disk-shaped disk and a plurality of blades arranged on the surface of the disk at intervals in the circumferential direction. In other words, the space (flow path) between a pair of adjacent blades gradually increases in area from the inner side to the outer side in the radial direction of the disk. Moreover, what is equipped with the same blade | wing as a diffuser of a pump is also known (refer the following patent document 2).

JP 2003-166491 A Japanese Patent Laid-Open No. 4-012200

  However, the impeller as described above has a large area expansion rate (area expansion rate from the radially inner side to the outer side) of the flow path formed between the blades, and therefore flows from the radially inner side to the outer side. There is a possibility that the fluid may not follow the surface of the blade and may cause flow separation on the surface. If such flow separation occurs, not only the desired lift can not be obtained, but also the efficiency of the centrifugal pump may be affected.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an impeller and a rotary machine with improved efficiency by reducing flow separation.

  According to the first aspect of the present invention, a plurality of impellers are arranged at intervals in the circumferential direction of the axis on the disk centered on the axis and on the principal surface facing one side in the axis direction of the disk. A main blade extending in the radial direction of the axis, and provided on one side of each of the main blades in the circumferential direction of the main surface, extending from the outer peripheral side of the disk toward the radial inner side, An auxiliary blade having a small radial dimension.

According to this configuration, the auxiliary blade having a smaller radial dimension than the main blade is provided on one circumferential side of the main blade. By providing such an auxiliary blade, the apparent area expansion rate of the flow path formed between a pair of adjacent main blades can be reduced.
In addition, the fluid existing on one side in the circumferential direction of the main blade can be circulated radially outward through the gap between the main blade and the auxiliary blade. Here, on the outer peripheral side of the disk, wake (turbulent flow) is likely to occur due to a difference in flow velocity with the surrounding fluid. According to the above configuration, the wake generated on the outer peripheral side of the disk can be blown off to the outer peripheral side by the fluid flowing through the gap between the main blade and the auxiliary blade.

  According to the second aspect of the present invention, the impeller may have a plurality of the auxiliary blades arranged at intervals in the circumferential direction.

  According to this structure, the some auxiliary | assistant blade arranged at intervals in the circumferential direction is provided in the circumferential direction one side of the main blade. Thereby, the apparent area expansion rate of the flow path formed between the main blades can be further reduced. In addition, the wake generated on the outer peripheral side of the disk as described above can be eliminated over a wider range by the fluid flowing between the auxiliary blades.

  According to the third aspect of the present invention, in the impeller described above, the plurality of auxiliary blades may have a smaller dimension in the radial direction as the auxiliary blades are provided on one side in the circumferential direction.

  According to this configuration, the dimension in the radial direction is smaller as the auxiliary blade is provided on one side in the circumferential direction among the plurality of auxiliary blades. Thereby, it is possible to reduce the possibility that the flow of the fluid flowing through one side in the circumferential direction of the main blade is hindered by these auxiliary blades.

  According to the fourth aspect of the present invention, in the impeller described above, the distance between the main blade and the auxiliary blade and the distance between the plurality of auxiliary blades are directed from the inner side to the outer side in the radial direction. It may be gradually enlarged according to.

  According to this configuration, the distance between the main blade and the auxiliary blade and the distance between the plurality of auxiliary blades gradually increase from the inner side toward the outer side in the radial direction. As a result, the flow velocity of the fluid flowing toward the outside in the radial direction in the region between the blades decreases as it goes outward in the radial direction. That is, since the flow velocity difference with the fluid staying on the outer peripheral side of the disk can be reduced, the possibility of wakes occurring on the outer peripheral side of the disk can be further reduced.

  According to the fifth aspect of the present invention, in the impeller described above, the main blade and the auxiliary blade are curved from the other side in the circumferential direction toward the one side from the inner side toward the outer side in the radial direction. Also good.

  According to this configuration, the main blade and the auxiliary blade are curved from the other side in the circumferential direction toward the one side, that is, from the front side to the rear side in the rotational direction of the impeller, from the inner side toward the outer side in the radial direction. doing. As a result, the possibility of fluid peeling off on the surfaces of the main blade and the auxiliary blade can be further reduced.

  According to the sixth aspect of the present invention, the rotating machine includes a rotor extending along an axis, the impeller according to any one of the first to fifth aspects attached to the rotor, and the impeller. A casing covering from the outer peripheral side.

  According to this configuration, it is possible to provide an impeller with improved efficiency and a rotary machine including the impeller.

  According to the present invention, it is possible to provide an impeller and a rotary machine with improved efficiency.

It is a schematic diagram which shows the structure of the rotary machine (pump) which concerns on 1st embodiment of this invention. It is sectional drawing which looked at the impeller which concerns on 1st embodiment of this invention from the axial direction. It is a principal part enlarged view of the impeller which concerns on 1st embodiment of this invention. It is a principal part enlarged view of the impeller which concerns on 2nd embodiment of this invention. It is a principal part enlarged view which shows the modification of the impeller which concerns on embodiment of this invention.

[First embodiment]
A first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a diagram illustrating a configuration of a centrifugal pump 1 (rotary machine) according to the present embodiment. As shown in the figure, the centrifugal pump 1 includes a rotor 2 extending along an axis Ac, an impeller 3 attached to the outer peripheral surface of the rotor 2, and a casing 4 that covers the rotor 2 and the impeller 3 from the outer peripheral side. It is equipped with.

  The rotor 2 has a cylindrical shape with the axis Ac as the center. Bearing devices 5 (journal bearing 6 and thrust bearing 7) are provided at both ends of the rotor 2 in the direction of the axis Ac. The rotor 2 is supported by these bearing devices 5 so as to be rotatable about the axis Ac. The journal bearing 6 is a bearing for supporting the load of the rotor 2 from the radial direction. The thrust bearing 7 is a bearing for supporting the load in the thrust direction (axial direction Ac) applied to the rotor 2.

  The impeller 3 is fixed to the outer peripheral surface of the rotor 2 by applying an interference fit or the like, for example. That is, the impeller 3 rotates about the axis Ac together with the rotor 2. As will be described in detail later, the impeller 3 includes a disk-shaped disk 11 and a plurality of blades provided on one surface of the disk 11 in the axis line Ac direction. A plurality (six) of impellers 3 are arranged on the rotor 2 in the direction of the axis Ac.

  The casing 4 houses the rotor 2 and the impeller 3 described above, and forms a fluid flow path 8 for circulating a fluid. More specifically, the fluid flow path 8 is formed on the inner peripheral surface of the casing 4 by repeatedly increasing and decreasing the diameter from one side to the other side in the axis Ac direction. An inlet 9 for introducing a fluid from the outside is formed on one side of the casing 4 in the axis Ac direction. On the other hand, on the other side in the axis Ac direction of the casing 4, a discharge port 10 for discharging the fluid pumped through the fluid flow path 8 is formed. In the following description, the side on which the introduction port 9 is located is called the upstream side, and the side on which the discharge port 10 is located is called the downstream side.

  Next, with reference to FIG. 2 and FIG. 3, the detailed structure of the impeller 3 is demonstrated. As shown in FIG. 2, the impeller 3 in this embodiment includes a disk-shaped disk 11 centered on the axis line Ac and a plurality of surfaces provided on one surface (main surface 11 </ b> A) of the disk 11 in the axis line Ac direction. Main blade 12 and auxiliary blade 13.

  In an area including the center of the disk 11, an introduction hole 14 for guiding the fluid flowing through the fluid flow path 8 is formed. In the present embodiment, three main blades 12 extend from the outer peripheral edge of the introduction hole 14 to the radially outer side (the outer peripheral edge of the disk 11). More specifically, these three main blades 12 are arranged on the main surface 11A at equal intervals in the circumferential direction of the axis line Ac.

  Furthermore, each main blade 12 is gradually curved from the other side in the circumferential direction toward the one side as it goes from the radially inner side to the outer side of the axis Ac. That is, the surface of the main blade 12 on one side in the circumferential direction is recessed so as to curve toward the other side in the circumferential direction. On the other hand, the surface on the other circumferential side of the main blade 12 protrudes so as to curve toward the other circumferential side.

  Of the two circumferential surfaces of the main blade 12, the other circumferential surface (projecting surface) is a positive pressure surface 12P. Of the two circumferential surfaces of the main blade 12, one circumferential surface (surface recessed) is a negative pressure surface 12N. In addition, the dimension in the circumferential direction of each main blade 12 (that is, the thickness of the main blade 12 when viewed from the axis Ac direction) is the same over the entire radial direction.

  A plurality (two) of auxiliary blades 13 adjacent to each other are provided in a region on one side in the circumferential direction of each main blade 12 on the main surface 11A (a region between the main blades 12). Each of these two auxiliary blades 13 is set to have a smaller dimension in the radial direction than the main blade 12. Further, of the two auxiliary blades 13, the auxiliary blade 13 on one side in the circumferential direction is set to have a smaller radial dimension than the auxiliary blade 13 on the other side in the circumferential direction. That is, the radial dimension becomes smaller as the auxiliary blade 13 is on one side in the circumferential direction.

  In the following description, of the two auxiliary blades 13, the auxiliary blade 13 on the other circumferential side (side adjacent to the main blade 12) is referred to as the first auxiliary blade 131, and the auxiliary blade 13 is adjacent to the first auxiliary blade 131. The blade 13 is referred to as a second auxiliary blade 132. That is, the second auxiliary blade 132 is set to have a smaller dimension in the radial direction than the first auxiliary blade 131.

  Furthermore, the first auxiliary blade 131 and the second auxiliary blade 132 are also curved from the other side in the circumferential direction toward the one side, as the main blade 12 moves from the inner side in the radial direction to the outer side. More specifically, in the present embodiment, each of the first auxiliary blade 131 and the second auxiliary blade 132 has a concentric arc shape having the same center point.

  In addition, the radially inner ends of the first auxiliary blade 131 and the second auxiliary blade 132 are arcuate from one circumferential side to the other. In other words, the radially inner ends of the first auxiliary blade 131 and the second auxiliary blade 132 are blunt.

  A gap extending in the radial direction is formed between the main blade 12 and the first auxiliary blade 131. This gap is the first auxiliary flow path F1. Further, a gap formed between the first auxiliary blade 131 and the second auxiliary blade 132 is a second auxiliary flow path F2. That is, the second auxiliary flow path F2 is set to have a smaller dimension in the radial direction than the first auxiliary flow path F1.

  Furthermore, as shown by the chain line in FIG. 2, the line (envelope L) connecting the radially inner ends of the main blade 12, the first auxiliary blade 131, and the second auxiliary blade 132 is from the radially inner side to the outer side. As it goes, it has a curved shape that is continuously curved from the other side in the circumferential direction toward one side. A space surrounded by the envelope L and the pressure surface 12P of the other main blade 12 positioned on one side in the circumferential direction of the envelope L is a fluid guided from the fluid flow path 8 through the introduction opening 14. Is the main flow path Fm through which the gas flows.

  That is, the dimension in the circumferential direction of the main flow path Fm gradually increases as it goes from the radially inner side to the outer side. Further, the main flow path Fm is curved from the other side in the circumferential direction toward one side as it goes from the inner side in the radial direction to the outer side.

  Next, operations of the centrifugal pump 1 and the impeller 3 according to the present embodiment will be described. In operating the centrifugal pump 1, first, the rotor 2 is rotationally driven around the axis Ac by a drive source (not shown). As the rotor 2 rotates, the impeller 3 provided integrally on the rotor 2 also rotates. By the rotation of the impeller 3, an external fluid is guided into the fluid flow path 8 through the introduction port 9. At this time, the pressure of the fluid rises while passing through the main flow path Fm formed in the impeller 3. Here, in the present embodiment, the centrifugal pump 1 is provided with six impellers 3. That is, the fluid is pumped from the upstream side to the downstream side while the pressure is sequentially increased by these six impellers 3. Thereafter, the high pressure fluid is discharged from the discharge port 10 provided on the downstream side of the casing 4 to the outside. During the operation of the centrifugal pump 1, the above cycle is continuously repeated.

  Subsequently, the behavior of the fluid in the main flow path Fm will be described with reference to FIG. 3 again. As shown in the figure, during the operation of the centrifugal pump 1, the impeller 3 rotates from the other side in the circumferential direction toward one side (arrow in FIG. 3). As the impeller 3 rotates, the fluid that flows into the main flow path Fm from the introduction hole 14 of the disk 11 flows from the radially inner side to the outer side along the main flow path Fm.

  Here, when the auxiliary blade 13 is not provided in the impeller 3, that is, when only the main blade 12 is provided on the main surface 11A, the gap between the three main blades 12 is an auxiliary. It becomes larger than the case where the blade 13 is provided. That is, the area enlargement ratio in the region between the main blades 12 increases. When the area expansion rate is large as described above, the fluid flowing from the radially inner side to the outer side may not follow the surface of the main blade 12 and may cause flow separation on the surface. When such flow separation occurs, not only the desired lift is not obtained, but also the efficiency of the centrifugal pump 1 may be affected.

  Furthermore, in the region on the outer peripheral side of the disk 11, the wake W is likely to occur because the fluid flow is poor compared to other regions. The wake W refers to a turbulent flow field generated when fluids having different flow velocities collide with each other. When such a wake W develops, the efficiency of the centrifugal pump 1 may be affected.

  However, in the impeller 3 according to the present embodiment, the auxiliary blade 13 having a smaller radial dimension than the main blade 12 is provided on one circumferential side of the main blade 12. By providing such an auxiliary blade 13, it is possible to reduce an apparent area expansion rate of a flow path formed between a pair of adjacent main blades 12.

  In addition, the fluid existing on one side in the circumferential direction of the main blade 12 can be circulated radially outward through the gap between the main blade 12 and the auxiliary blade 13. That is, the wake W generated on the outer peripheral side of the disk 11 can be blown off to the outer peripheral side by the fluid flowing through the gap between the main blade 12 and the auxiliary blade 13 and between the auxiliary blades 13.

  More specifically, a centrifugal force from the radially inner side to the outer side acts on the fluid flowing through the main flow path Fm as the impeller 3 rotates. Due to this centrifugal force, the fluid in the main channel Fm flows into the first auxiliary channel F1 and the second auxiliary channel F2. The fluid that has flowed into the first auxiliary flow path F1 and the second auxiliary flow path F2 further flows outward in the radial direction, and then flows out to the outer peripheral side of the disk 11. Thereby, the wake W generated on the outer peripheral side of the disk 11 can be blown off to the outer peripheral side. Therefore, the efficiency of the centrifugal pump 1 can be improved.

  In addition, according to the configuration as described above, the main blade 12 and the auxiliary blade 13 are directed from the other side in the circumferential direction toward the one side, that is, in the rotational direction of the impeller 3, from the inner side toward the outer side in the radial direction. It is curved from the front side toward the rear side. Thereby, it is possible to further reduce the possibility of fluid peeling on the surfaces of the main blade 12 and the auxiliary blade 13.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to said 1st embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. As shown in the figure, in this embodiment, the distance (distance) between the two auxiliary blades 13 (the first auxiliary blade 131 and the second auxiliary blade 132) gradually increases from the radially inner side toward the outer side. doing.

  That is, the first auxiliary blade 131 extends in the same direction as the main blade 12, while the second auxiliary blade 132 extends in a direction different from the main blade 12 and the first auxiliary blade 131. More specifically, the radially outer end of the second auxiliary blade 132 is located further on the one circumferential side than the radially outer end of the second auxiliary blade 132 in the first embodiment.

  According to such a configuration, the distance between the main blade 12 and the auxiliary blade 13 and the distance between the plurality of auxiliary blades 13 gradually increase from the radially inner side toward the outer side. As a result, the flow velocity of the fluid flowing toward the outside in the radial direction in the region between the blades decreases as it goes outward in the radial direction. That is, since the difference in flow velocity with the fluid staying on the outer peripheral side of the disk 11 can be reduced, the possibility of wake W occurring on the outer peripheral side of the disk 11 can be further reduced. Even if the wake W occurs, the gap between the main blade 12 and the auxiliary blade 13 (first auxiliary flow path F1) and the auxiliary blades 13 are similar to each other as in the first embodiment. The wake W generated on the outer peripheral side of the disk 11 can be blown off to the outer peripheral side by the fluid flowing through the gap (second auxiliary flow path F2).

The embodiments of the present invention have been described above. Various modifications can be made to each of the above configurations without departing from the gist of the present invention.
For example, in addition to the above embodiment, the configuration shown in FIG. 5 can be adopted. In the configuration shown in the figure, the first auxiliary blade 131 and the second auxiliary blade 132 extend in directions opposite to each other in the circumferential direction. More specifically, the first auxiliary blade 131 extends from one circumferential side to the other side from the radially inner side to the outer side. On the other hand, the second auxiliary blade 132 extends from the other side in the circumferential direction toward one side as it goes from the radially inner side to the outer side. Thereby, as for the 1st auxiliary flow path F1, the dimension of the circumferential direction becomes small gradually as it goes to an outer side from radial inside. On the other hand, as for the 2nd auxiliary flow path F2, the dimension of the circumferential direction becomes large gradually as it goes to an outer side from radial inside. Even if it is such a structure, the effect similar to what was demonstrated by the said embodiment can be acquired.

DESCRIPTION OF SYMBOLS 1 ... Centrifugal pump 2 ... Rotor 3 ... Impeller 4 ... Casing 5 ... Bearing apparatus 6 ... Journal bearing 7 ... Thrust bearing 8 ... Fluid flow path 9 ... Inlet 10 ... Discharge port 11 ... Disc 11A ... Main surface 12 ... Main blade 12P ... Positive pressure surface 12N ... Negative pressure surface 13 ... Auxiliary blade 131 ... First auxiliary blade 132 ... Second auxiliary blade 14 ... Introduction hole Ac ... Axis Fm ... Main flow path F1 ... First auxiliary flow path F2 ... Second auxiliary flow path L ... Envelope W ... Wake

Claims (6)

A disc centered on the axis,
A plurality of main blades extending in the radial direction of the axis, arranged in the circumferential direction of the axis on the main surface facing one side in the axial direction of the disk;
An auxiliary blade provided on one side in the circumferential direction of each of the main blades of the main surface, extending from the outer peripheral side of the disk toward the radially inner side, and having a smaller radial dimension than the main blade;
Impeller equipped with.   The impeller according to claim 1, comprising a plurality of the auxiliary blades arranged at intervals in the circumferential direction.   3. The impeller according to claim 2, wherein the plurality of auxiliary blades gradually decrease in size in the radial direction as the auxiliary blade is provided on one side in the circumferential direction.   The impeller according to claim 2 or 3, wherein a distance between the main blade and the auxiliary blade and a distance between the plurality of auxiliary blades gradually increase from the inner side toward the outer side in the radial direction.   The impeller according to any one of claims 1 to 4, wherein the main blade and the auxiliary blade are curved from the other side in the circumferential direction toward the one side from the radially inner side toward the outer side. A rotor extending along an axis;
The impeller according to any one of claims 1 to 5, attached to the rotor,
A casing covering the impeller from the outer peripheral side;
Rotating machine with

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