JP2012052432A - Diffuser for centrifugal compressor and centrifugal compressor with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diffuser for a centrifugal compressor and the centrifugal compressor with the same, which can improve performance by combining blades different in an inlet angle in the blade height direction.SOLUTION: The diffuser includes a shroud sidewall surface 58 arranged on the downstream side of a centrifugal impeller, a hub sidewall surface oppositely arranged to the shroud sidewall surface 58, a plurality of shroud side blades 3 for fixing a base end part to the shroud sidewall surface 58, and a hub side blade 4 for fixing a base end part to the hub sidewall surface, The shroud side blade 3 and the hub side blade 4 are combined in a state of mutually butting at least a part of a tip part in the blade height direction so that the inlet angle becomes different. A connecting member 5 is provided in a clearance in which the tip part of the combined shroud side blade 3 and the tip part of the hub side blade 4 are not butted against each other, and the connecting member 5 connects the mutual tip parts to fill up at least a part of the clearance.

Description

  The present invention relates to a diffuser and a centrifugal compressor including the diffuser, and more particularly, to a diffuser in which blades having different inlet angles are combined in the blade height direction.

  As a conventionally known centrifugal compressor, FIG. 14 shows a main part of the centrifugal compressor shown in Patent Document 1, (A) is a longitudinal sectional view, (B) is a side view, (C) is the perspective view which expanded the shroud side wing | blade and the hub side wing | blade, (D) is a top view of (C).

  The illustrated centrifugal compressor 50 compresses a fluid such as gas or air introduced from the outside of the housing 51 by rotating an impeller 53 including a plurality of blades 52 in the housing 51. The fluid flow (airflow) formed in this way is sent to the outside through an impeller outlet (hereinafter also referred to as “diffuser inlet”) 54, a diffuser 55, and a volute 56, which is an outer peripheral end of the impeller 53. In addition, the code | symbol 57 in a figure is an axial centerline with which the impeller 53 rotates.

  The diffuser 55 described above is an airflow passage provided between the impeller outlet 54 and the volute 56, and has a function of restoring dynamic pressure to static pressure by decelerating the airflow discharged from the impeller outlet 54. ing. The diffuser 55 is usually formed of a pair of opposed wall surfaces. In the following description, one of the pair of opposed wall surfaces is referred to as a shroud side wall surface 58 and the other is referred to as a hub side wall surface 2.

  In the diffuser 51, a plurality of diffuser blades 60 are provided between the shroud side wall surface 58 and the hub side wall surface 2. The diffuser blade 60 includes a plurality of shroud side blades 3 provided on the shroud side wall surface 58 and a plurality of hub side blades 4 provided on the hub side wall surface 2. The shroud side wing 3 and the hub side wing 4 are obtained by combining two-dimensional wings having different blade inlet angles in the blade height direction.

  As described above, the shroud side blade 3 and the hub side blade 4 having different blade inlet angles are combined, and the flow angle of the airflow at the blade 52 exit (the angle formed by the streamline of the airflow and the cascade line) becomes the inlet angle of the diffuser blade 60. By approaching and preventing the separation of the flow at the leading edge of the diffuser blade 60, the advantage that the efficiency of the diffuser 55 can be increased and the operating range can be expanded is obtained.

Japanese Patent No. 3746740

  However, in the invention described in Patent Document 1, when the shroud side blade 3 and the hub side blade 4 having different blade inlet angles are combined, the shroud side blade 3 and the hub side blade 4 combined on the downstream side of the blade leading edge of the diffuser blade 60. The gap 63 may occur without overlapping. As described above, when the gap 63 is generated between the shroud side wing 3 and the hub side wing 4, the separation of the air flow and the generation of vortices (FIG. 14C and ( D) has a problem that the performance of the diffuser 55 is deteriorated.

  The present invention has been made in view of such circumstances, and a centrifugal compressor diffuser capable of improving performance by combining blades having different inlet angles in the blade height direction, and a centrifugal equipped with the same An object is to provide a compressor.

In order to achieve the above object, the present invention provides the following means.
According to the diffuser of the centrifugal compressor according to the present invention, the shroud side wall surface provided on the downstream side of the centrifugal impeller, the hub side wall surface provided opposite to the shroud side wall surface, and the base end portion on the shroud side wall surface A plurality of shroud-side wings, and a hub-side wing whose base end is fixed to the hub side wall surface. The shroud-side wing and the hub-side wing have different inlet angles and have a blade height. A gap in which at least a part of the tip end portions in the vertical direction are abutted against each other, and the tip end portion of the combined shroud side wing and the tip end portion of the hub side wing are not abutted with each other. A connecting member for connecting the tip portions to each other so as to fill at least a portion of the connecting portion.

  A diffuser of a centrifugal compressor having a shroud side blade and a hub side blade combined with each other having different inlet angles and at least a portion of the tip in the blade height direction being in contact with each other includes a tip of the combined shroud blade There may be a gap in which the front end of the hub side wing is not abutted. As described above, when a gap is formed in which the tip portions of the shroud side blade and the hub side blade are not abutted with each other, the performance of the diffuser deteriorates due to separation of a flow passing through the gap portion and generation of vortices.

In view of this, a connecting member for connecting the tip portions of the shroud side wing and the hub side wing is provided so as to fill at least a part of the gap formed without the butts of the tip ends of the combined shroud side wing and hub side wing. Thereby, the clearance gap produced between the front-end | tip part of a shroud side wing | blade and the front-end | tip part of a hub side wall wing | blade is covered with a connection member. Therefore, the gap flow can be eliminated, and flow separation and vortex generation due to the gap flow can be suppressed. Therefore, the performance of the diffuser can be improved.
Further, since the gaps formed between the tip portions of the shroud side wing and the hub side wing are connected by the connecting member, the rigidity of the wing can be increased. Therefore, the vibration strength of the blade can be improved.

  According to the diffuser of the centrifugal compressor according to the present invention, the connection member has an annular shape that continuously connects all the tip portions of the plurality of shroud side blades and the plurality of hub side blades in the circumferential direction. It is characterized by.

The connecting member was configured to continuously connect the entire tip of the shroud side blade and the hub side wall blade in an annular shape. Therefore, the gap between the tip of the shroud wing and the tip of the hub wing when combined can be covered by the connecting member, and the gap flow can be eliminated. Thereby, generation | occurrence | production of the peeling of the flow and eddy by a clearance gap flow can be suppressed. Therefore, the performance of the diffuser can be improved.
Further, since the shape of the connecting member is simple as an annular shape, the performance of the diffuser can be improved at a low cost.

  According to the diffuser of the centrifugal compressor according to the present invention, the connecting member has an inner diameter smaller than inner diameters of the shroud side wall surface and the hub side wall surface.

  According to a study by the inventors, even when the inner diameter of the annular connection member is smaller than the inner diameters of the shroud side wall surface and the hub side wall surface, the inner diameter of the annular connection member is reduced to the shroud side wall surface and the hub. Similarly to the case where the inner diameter of the side wall surface is the same, the flow through the gap generated between the tip of the shroud wing and the tip of the hub wing when combined is eliminated to improve the performance of the diffuser. It turns out that is possible.

  According to the diffuser of the centrifugal compressor according to the present invention, the connecting member extends from the leading edge of at least one of the tip portion of the shroud side blade or the tip portion of the hub side blade to the downstream of 60% of the blade length. It is characterized by connecting to fill.

  According to a study by the inventors, due to a gap formed from the leading edge of the tip of at least one shroud side wing or hub side wing to 60% downstream of the wing length, flow separation or vortex generation is caused by the gap flow. It was found that the performance degradation was significant.

  Therefore, the connecting member is connected in the circumferential direction so as to fill a gap between the front end portion of the tip portion of at least one shroud side wing or the hub side wing and 60% downstream of the blade length. Therefore, similarly to the case where the connecting member is connected in the circumferential direction so as to fill the gap from the leading edge to the entire blade length from the trailing edge, it is possible to suppress the separation of the flow and the generation of vortices due to the gap flow. Therefore, the performance of the diffuser can be improved.

  According to the diffuser of the centrifugal compressor according to the present invention, the shroud side wing and the hub side wing to be combined are arranged with their leading edges shifted in the circumferential direction.

  The front edges of the shroud side wing and the hub side wing combined with the shroud side wing are shifted in the circumferential direction. Therefore, when the shroud side wing and the hub side wing are combined, no gap is generated between the front end portions of the shroud side wing and the hub side wing. Therefore, it is possible to prevent flow separation and vortex generation due to the gap flow, and to improve the performance of the diffuser.

  According to the diffuser of the centrifugal compressor according to the present invention, the shroud side blade and the hub side blade combined together are arranged with their positions shifted in the circumferential direction so that 60% of the total length from the leading edge does not overlap. It is characterized by that.

  The shroud side wing and the hub side wing combined with the shroud side wing are provided so as to be shifted in the circumferential direction so as not to overlap each other up to 60% of the total length from the front edge. Therefore, there is no gap between the front edge of the shroud side wing and the hub side wing and 60% of the total length. Accordingly, it is possible to improve the performance of the diffuser by suppressing separation and vortex generation due to the gap flow.

  According to the diffuser of the centrifugal compressor according to the present invention, the shroud side wall surface provided on the downstream side of the centrifugal impeller, the hub side wall surface provided to face the shroud side wall surface, and the base end portion on the shroud side wall surface A plurality of shroud-side wings, and a hub-side wing whose base end is fixed to the hub side wall surface. The shroud-side wing and the hub-side wing have different inlet angles and have a blade height. The tip portions in the vertical direction are combined in a state where they are butted so that part of the blade thickness overlaps each other over the blade length.

The shroud-side wing and the hub-side wing have different inlet angles, and the tip portions in the blade height direction are abutted so that part of the blade thickness overlaps the blade length. Therefore, when the shroud side wing and the hub side wing are combined, no gap is generated between the tip portion of the shroud side wing and the tip portion of the hub side wing. Therefore, it is possible to prevent flow separation and vortex generation due to the gap flow, and to improve the performance of the diffuser.
Further, since the tip portions in the blade height direction of the shroud side wing and the hub side wing are brought together so that part of the blade thickness overlaps each other over the blade length, the rigidity of the blade can be increased. Therefore, the vibration strength of the blade can be improved.

  According to the diffuser of the centrifugal compressor according to the present invention, the blade thickness of each trailing edge of the shroud side blade and the hub side blade is thinner than the blade thickness at the center of the blade length.

  For the shroud side wing and the hub side wing, the blade thickness at each trailing edge was made thinner than the blade thickness at the center of the blade length. Therefore, the wake of the shroud side wing and the hub side wing can be reduced. Therefore, the performance of the diffuser can be improved.

  The diffuser of the centrifugal compressor according to the present invention is characterized in that one of the shroud side wing and the hub side wing is a thick wing and the other is a thin wing.

One of the shroud side wing and the hub side wing is a thick wing (for example, a cross-sectional shape perpendicular to the blade height direction is a wedge type or a channel type), and the other is a thin wing. As a result, when the shroud side wing and the hub side wing are brought into contact with each other, the tip portion on the thin blade side overlaps with a part of the tip portion on the thick blade side. Therefore, there is no gap between the tip of the shroud wing and the tip of the hub wing. Therefore, it is possible to prevent flow separation and vortex generation due to the gap flow, and to improve the performance of the diffuser.
In addition, as a thick wing | blade, the width of the cross-sectional shape orthogonal to a wing | blade height with respect to a thin wing | blade is preferable about 2 times or more.

  According to the centrifugal compressor which concerns on this invention, it is equipped with the diffuser of the centrifugal compressor in any one of the above.

  It was decided to use a diffuser capable of improving the performance by suppressing the separation of the flow and the generation of vortices in the gaps where the tip ends of the combined shroud side wing and hub side wing are not abutted. Therefore, the velocity energy of the flow passing through the diffuser can be effectively converted into pressure. Therefore, it is possible to increase the efficiency and the operability of the centrifugal compressor.

According to the diffuser of the centrifugal compressor according to the present invention, the connecting member that connects the tip portions of the shroud side blades and the hub side blades connected to each other so as to fill at least a part of the gap formed without being abutted. It was decided to provide. Thereby, the clearance gap produced between the front-end | tip part of a shroud side wing | blade and the front-end | tip part of a hub side wall wing | blade is covered with a connection member. Therefore, the gap flow can be eliminated, and flow separation and vortex generation due to the gap flow can be suppressed. Therefore, the performance of the diffuser can be improved.
Further, since the tip portions of the shroud side wing and the hub side wing are connected by the connecting member, the rigidity of the wing can be increased. Therefore, the vibration strength of the blade can be improved.

It is the shroud side blade | wing and hub side blade | wing provided in the diffuser of the centrifugal compressor which concerns on 1st Embodiment of this invention, (A) is the perspective view, (B) is a top view of (A). is there. It is the modification 2 of the wing | blade shown in FIG. 1, (A) is the perspective view, (B) is a top view of (A). It is the shroud side blade | wing and hub side blade | wing provided in the diffuser of the centrifugal compressor which concerns on 2nd Embodiment of this invention, (A) is the perspective view, (B) is the top view of (A). is there. It is a top view of the modification 1 of the wing | blade shown in FIG. It is a top view of the modification 2 of the wing | blade shown in FIG. It is the shroud side wing | blade and hub side wing | blade provided in the diffuser of the centrifugal compressor which concerns on 4th Embodiment of this invention, (A) is the perspective view, (B) is a top view of (A). (C) is a cross-sectional view taken along the line AA of (A) and (B). It is the shroud side blade | wing and hub side blade | wing provided in the diffuser of the centrifugal compressor which concerns on 5th Embodiment of this invention, (A) is the perspective view, (B) is the top view of (A). is there. It is the shroud side blade | wing and hub side blade | wing provided in the diffuser of the centrifugal compressor which concerns on 6th Embodiment of this invention, (A) is the perspective view, (B) is the top view of (A). is there. FIG. 8 is a modification of the wing shown in FIG. 8, (A) is a perspective view thereof, and (B) is a top view of (A). It is the shroud side blade | wing and hub side blade | wing provided in the diffuser of the centrifugal compressor which concerns on 7th Embodiment of this invention, (A) is the perspective view, (B) is the top view of (A). is there. FIGS. 10A and 10B are modifications of the wing shown in FIG. It is the shroud side blade | wing and hub side blade | wing provided in the diffuser of the centrifugal compressor which concerns on 8th Embodiment of this invention, (A) is the perspective view, (B) is the top view of (A). is there. FIG. 12 is a modification of the wing shown in FIG. 12, (A) is a perspective view thereof, and (B) is a top view of (A). The principal part of the conventional centrifugal compressor is shown, (A) is a longitudinal sectional view, (B) is a side view, and (C) is an enlarged perspective view of a shroud side blade and a hub side blade. (D) is a top view of (C).

[First Embodiment]
The shroud side wing and the hub side wing provided in the diffuser of the centrifugal compressor according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 14.
The diffuser 1 shown in FIG. 1 decelerates the airflow (flow) discharged from the outer peripheral end of the impeller 53 (see FIG. 14) rotating in the housing 51 (see FIG. 14) of the centrifugal compressor 50 (see FIG. 14). Thus, the dynamic pressure of the airflow is restored to static pressure. The diffuser 1 includes a shroud side wall surface 58 provided on the downstream side of the impeller (centrifugal impeller) 53, a hub side wall surface 2 provided to face the shroud side wall surface 58, and a base end portion on the shroud side wall surface 58. A plurality of shroud side blades 3 (only one blade is shown in FIG. 1) and a plurality of blades whose base end is fixed to the hub side wall surface 2 (only one blade is shown in FIG. 1). .) Hub side wing 4.

  In this embodiment, the shroud side wing 3 and the hub side wing 4 are two-dimensional wings, and are thin wings having the same blade length. The shroud side wing 3 and the hub side wing 4 are combined such that the entrance angles are different and the leading edges (at least a part) of the tip in the blade height direction are abutted with each other. In addition, their trailing edges are separated in the circumferential direction.

  As described above, the gaps 63 (see FIG. 14) in which the tip of the shroud-side blade 3 and the tip of the hub-side blade 4 are not connected to each other are connected to each other so as to fill the gap 63. A connecting wall (connecting member) 5 is provided. The connection wall 5 is provided along the entire length from the front edge to the rear edge of the shroud side wing 3 and the hub side wing 4.

  As described above, the connection wall 5 is provided in the gap 63 between the shroud-side wing 3 and the hub-side wing 4, so that the airflow guided from the front edge of the shroud-side wing 3 is the upper surface of the connection wall 5 (above FIG. 1A). ) Flow along. Therefore, it is possible to suppress the separation of airflow and the generation of vortices due to the gap flow.

As described above, according to the diffuser 1 of the centrifugal compressor and the centrifugal compressor including the centrifugal compressor according to the present embodiment, the following effects can be obtained.
The tip portions of the shroud side blade 3 and the hub side blade 4 are connected to each other so as to fill a gap 63 (see FIG. 14) generated without the tip portions of the shroud side blade 3 and the hub side blade 4 being combined with each other. A connecting wall (connecting member) 5 is provided. As a result, a gap 63 formed between the tip of the shroud side blade 3 and the tip of the hub side wall blade 4 is covered by the connection wall 5. Therefore, the gap flow can be eliminated, and flow separation and vortex generation due to the gap flow can be suppressed. Therefore, the performance of the diffuser 1 can be improved.
Further, since the tips of the shroud side wing 3 and the hub side wing 4 are connected by the connection wall 5, the rigidity of the shroud side wing 3 and the hub side wing 4 can be increased. Therefore, the vibration strength of the shroud side wing 3 and the hub side wing 4 can be improved.

  In the present embodiment, the connection wall 5 has been described as being provided over the entire blade length from the front edge to the rear edge of the shroud side blade 3 and the hub side blade 4, but the present invention is not limited to this. As a first modification of the embodiment, the gap 63 from the leading edge of the shroud side wing 3 and the hub side wing 4 to the middle part of the wing length (for example, up to 60% of the wing length) may be covered.

  According to a study by the inventors, the performance due to the separation of the flow due to the gap flow and the generation of the vortex by the gap 63 formed from the leading edge of at least one shroud side blade 3 or the hub side blade 4 to 60% of the blade length. The decrease was found to be significant. Therefore, even when the gap 63 between the leading edges of the shroud side blade 3 and the hub side blade 4 from the leading edge to 60% of the blade length is connected by the connecting wall 5, the connecting wall 5 is connected to the entire blade from the leading edge to the trailing edge. As in the case where the gap 63 is connected so as to fill the length, it is possible to suppress the separation of the flow and the generation of the vortex due to the gap flow. Therefore, the performance of the diffuser 1 can be improved.

  In the present embodiment, the shroud side wing 3 and the hub side wing 4 have been described as having the same wing length. However, the present invention is not limited to this, and as shown in FIG. As a modified example 2 of the above, the blade length of the hub side blade 6 may be shorter than that of the shroud side blade 3.

As a second modification of the present embodiment, FIG. 2A shows a perspective view, and FIG. 2B shows a top view of FIG.
The hub side wing 6 has a wing length shorter than that of the shroud side wing 3. The leading edge of the hub side wing 6 is located at a midway position on the downstream side of the blade length of the shroud side wing 3.

  A connecting wall (connecting member) 7 is provided in the gap where the tip of the combined shroud side wing 3 and the tip of the hub side wing 4 are not in contact with each other substantially parallel to the shroud side wall surface 58 and the hub side wall surface. Yes. Since the front edge of the hub side wing 6 is located at a midway position on the downstream side of the shroud side wing 3, the connection wall 7 extends over the entire length of the hub side wing 6 from the front edge of the hub side wing 6 to the rear edge of the hub side wing 6. Will be provided.

  Furthermore, the connection wall 7 of Modification 2 may cover a gap from the leading edge of the hub side blade 6 to the middle part of the blade length of the hub side blade 6 (for example, 60% of the blade length).

[Second Embodiment]
The diffuser of the present embodiment is different from the first embodiment in that a disk for connecting all the tip portions of the shroud side wing and the hub side wing is provided, and the others are the same. Therefore, about the same structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
The disk (connecting member) 8 continuously connects the tip portions of a plurality (only one blade is shown in FIG. 3) of the shroud side blade 3 and the hub side blade 4 in the circumferential direction. The disk 8 has an annular shape and is provided substantially parallel to the shroud side wall surface 58 and the hub side wall surface (not shown).

  The disk 8 has an annular shape like the shroud side wall surface 58 and the hub side wall surface. The annular disk 8 is provided from the front edge to the rear edge of the shroud side wing 3 and the hub side wing 4.

  In this manner, by providing the disk 8 so as to be sandwiched between all the tip portions of the plurality of shroud side blades 3 and the hub side blade 4, the airflow (black arrow) guided from the front edge of the shroud side blade 3 to the shroud side blade 3 And the air flow (indicated by a white arrow) guided from the front edge of the hub side wing 4 to the hub side wing 4 can be separated. Therefore, the airflow does not pass through the gap where the tip portion of the combined shroud side blade 3 and the tip portion of the hub side blade 4 are not abutted, and it is possible to suppress the separation of the airflow and the generation of vortices due to the gap flow. it can.

As described above, according to the diffuser 1 of the centrifugal compressor and the centrifugal compressor including the centrifugal compressor according to the present embodiment, the following effects can be obtained.
The disk (connection member) 8 continuously connects the entire tip portions of the shroud side wing 3 and the hub side wing 4 in an annular shape. Therefore, the gap generated between the shroud side wing 3 and the hub side wing 4 can be covered with the disk 8 to eliminate the gap flow. Thereby, generation | occurrence | production of the peeling of the flow and eddy by a clearance gap flow can be suppressed. Therefore, the performance of the diffuser 1 can be improved.
Further, since the shape of the disk 8 is simple and annular, the performance of the diffuser 1 can be improved at low cost.

  In the present embodiment, the shroud side wing 3 and the hub side wing 4 have been described as having the same wing length. However, the present invention is not limited to this, and as shown in FIG. As a modified example 1 of the above, the blade length of the hub side blade 6 may be shorter than that of the shroud side blade 3.

  Further, as shown in FIG. 5, as a second modification of the present embodiment, the blade length of the hub side blade 6 is shorter than that of the shroud side blade 3, and the circumferential phase of the hub side blade 3 and the shroud side blade 6 is changed. It is good as a thing.

  That is, the hub side wing 6 and the shroud side wing 3 having a blade length shorter than that of the shroud side wing 3 are provided at positions where the front edge and the rear edge are different in the circumferential direction and do not overlap each other.

[Third Embodiment]
The diffuser of the present embodiment is different from the second embodiment in that the inner diameter of the disk connecting between the blade ends of the shroud side wing and the hub side wing is different, and the others are the same. Therefore, the description of the same configuration is omitted.

  An annular disk (connecting member) continuously connected in the circumferential direction between the tip ends of a plurality of shroud side blades and a plurality of hub side blades has an inner radius of each of the leading edges of the shroud side blades and the hub side blades. It is supposed to be smaller than the radius.

  That is, the inner peripheral edge of the annular disk protrudes in the inner diameter direction from the front edges of the shroud side wing and the hub side wing, and the front edges of the shroud side wing and the hub side wing are provided in the middle of the disk in the radial direction. It will be.

As described above, according to the diffuser of the centrifugal compressor and the centrifugal compressor including the same according to the present embodiment, the following effects can be obtained.
According to a study by the inventors, even when the inner diameter of the annular disk (connecting member) is smaller than the leading edge radius of the shroud side wing and the hub side wing, the inner diameter of the annular disk is reduced to the shroud side wing and As in the case where the radius of the front edge of the hub side wing is the same, it has been found that the performance of the diffuser can be improved by eliminating the flow passing through the gap generated between the shroud side wing and the hub side wing.

[Fourth Embodiment]
The diffuser of the present embodiment is different from the first embodiment in that the front edges of the shroud side wing and the hub side wing are shifted in the circumferential direction, and the others are the same. Therefore, about the same structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 6, the shroud side wing 3 and the hub side wing 4 that are combined with each other are arranged such that the leading edges are shifted in the circumferential direction, and the trailing edges are also shifted from each other in the circumferential direction. The shroud side wing 3 and the hub side wing 4 are shifted in the circumferential direction so that they do not overlap at least 60% or less of the blade length from the blade leading edge.

  That is, in the case of FIG. 6C, which is a cross-sectional view taken along a line AA in FIG. 6B, the shroud side wing 3 extends over the entire blade length direction from the front edge to the rear edge of the shroud side wing 3 and the hub side wing 4. The hub side wing 4 is separated. In addition, it may overlap after 60% of the blade length from the leading edge.

  Thus, since the shroud side wing 3 and the hub side wing 4 are separated from the front edge to the rear edge of the shroud side wing 3 and the hub side wing 4, the shroud side wing combined as in the first embodiment. Thus, there is no gap in which the front end portion of 3 and the front end portion of the hub side blade 4 are not abutted. Therefore, the airflow guided from the leading edge of the shroud side wing 3 and the airflow guided from the leading edge of the hub side wing 4 flow along the shroud side wing 3 and the hub side wing 4 and the separation of the flow caused by the gap flow. And the generation of vortices can be suppressed.

  On the other hand, according to the above, the inventors have considered that “a gap may be formed after 60% of the blade length from the leading edge.” It has been found that the gap 63 formed from the leading edge of one shroud side blade 3 or hub side blade 4 to 60% of the blade length significantly reduces the performance of the diffuser 1 due to the separation of the flow due to the gap flow and the generation of vortices. It is because of that.

As described above, according to the diffuser 1 of the centrifugal compressor and the centrifugal compressor including the centrifugal compressor according to the present embodiment, the following effects can be obtained.
Each front edge and each rear edge of the shroud side wing 3 and the hub side wing 4 combined with the shroud side wing 3 are provided to be shifted in the circumferential direction. Therefore, when the shroud side wing 3 and the hub side wing 4 are combined, there is no gap between the front end portions of the shroud side wing 3 and the hub side wing 4. Therefore, flow separation and vortex generation due to the gap flow can be prevented, and the performance of the diffuser 1 can be improved.

[Fifth Embodiment]
The diffuser of the present embodiment is different from the fourth embodiment in that a disk for connecting the tip portions of the shroud side wing and the hub side wing is provided, and the others are the same. Therefore, about the same structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG.
The disk (connecting member) 8 has an annular shape like the shroud side wall surface 58 and the hub side wall surface (not shown), and is provided substantially parallel to the shroud side wall surface 58 and the hub side wall surface. The annular disk 8 is provided from the front edge to the rear edge of the shroud side wing 3 and the hub side wing 4.

  In this manner, by providing the disk 8 so as to be sandwiched between all the tip portions of the plurality of shroud side blades 3 and the hub side blade 4, the flow path of the air flow guided from the front edge of the shroud side blade 3 to the shroud side blade 3 The flow path of the airflow guided from the front edge of the hub side wing 4 to the hub side wing 4 can be separated. Therefore, it is possible to suppress the separation of airflow and the generation of vortices due to the gap flow.

As described above, according to the diffuser 1 of the centrifugal compressor and the centrifugal compressor including the centrifugal compressor according to the present embodiment, the following effects can be obtained.
The disk (connection member) 8 continuously connects the entire tip portions of the shroud side wing 3 and the hub side wing 4 in an annular shape. Therefore, the gap generated between the tip portions of the shroud side wing 3 and the hub side wing 4 can be covered by the disk 8 to eliminate the gap flow. Thereby, generation | occurrence | production of the peeling of the flow and eddy by a clearance gap flow can be suppressed. Therefore, the performance of the diffuser 1 can be improved.
Further, since the shape of the disk 8 is simple and annular, the performance of the diffuser 1 can be improved at low cost.

[Sixth Embodiment]
The diffuser of the present embodiment is different from the first embodiment in that the tip of the shroud side wing and the hub side wing are abutted so that part of the blade thickness overlaps each other over the blade length, and the others are the same. is there. Therefore, about the same structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
Hereinafter, a sixth embodiment of the present invention will be described with reference to FIG.

  The shroud side wing 11 and the hub side wing 12 are thick wings whose cross-sectional shape perpendicular to the blade height direction has a wedge shape. The shroud-side wing 11 and the hub-side wing 12 which are wedge-shaped thick wings have a substantially triangular cross-sectional shape perpendicular to the blade height direction, and gradually expand from the leading edge toward the trailing edge. ing.

  The wedge-shaped shroud side wing 11 and the hub side wing 12 are in contact with each other such that the inlet angles are different and the tip portions in the blade height direction overlap with each other over the blade length. Are combined. Therefore, each tip end portion has an overlapping portion 13 (see FIG. 8B) in which part of the blade thickness overlaps with each other over the blade length.

  In this way, when the wedge-shaped shroud side blade 11 and the thick blade hub side blade 12 are abutted so as to overlap each other and have an overlapping portion 13, there is a gap between the combined shroud side blade 11 and the tip end portion of the hub side blade 12. The airflow guided from the leading edge of the shroud-side wing 11 and the airflow guided from the leading edge of the hub-side wing 12 flow along the shroud-side wing 11 and the hub-side wing 12. Therefore, it is possible to suppress the separation of airflow and the generation of vortices.

As described above, according to the diffuser 1 of the centrifugal compressor and the centrifugal compressor including the centrifugal compressor according to the present embodiment, the following effects can be obtained.
The shroud side wing 11 and the hub side wing 12 have different entrance angles, and the tip portions in the blade height direction are abutted so that part of the blade thickness overlaps with each other over the blade length. Therefore, when the shroud side wing 11 and the hub side wing 12 are combined, there is no gap between the tip portions of the shroud side wing 11 and the hub side wing 12. Therefore, flow separation and vortex generation due to the gap flow can be prevented, and the performance of the diffuser 1 can be improved.
Further, since the tip portions in the blade height direction of the shroud side wing 11 and the hub side wing 12 are attached so that part of the blade thickness overlaps each other over the blade length, the shroud side wing 11 and the hub side wing 12 Stiffness can be increased. Therefore, the vibration strength of the shroud side wing 11 and the hub side wing 12 can be improved.

  In the present embodiment, the shroud side wing 11 and the hub side wing 12 have been described as having the same wing length. However, the present invention is not limited to this, and as shown in FIG. As a modified example, the blade length of the hub side blade 14 may be shorter than that of the shroud side blade 11.

  The hub-side wing 14 has a shorter blade length than the shroud-side wing 11, so that a part of the blade thickness overlaps the shroud-side wing 11 and the hub-side wing 14 along the wing length and has a hub 13. The side wings 14 are combined so that the leading edge of the side wings 14 is located in the middle of the blade length of the shroud side wings 11.

[Seventh Embodiment]
The diffuser of this embodiment is different from the sixth embodiment in that the blade thickness of the trailing edge of the combined shroud side wing and hub side wing is thin, and the others are the same. Therefore, about the same structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
Hereinafter, a seventh embodiment of the present invention will be described with reference to FIG.

  The shroud side wing 15 and the hub side wing 16 are thick wings whose cross-sectional shape perpendicular to the blade height direction has a substantially wedge shape. The substantially wedge-shaped shroud-side wing 15 and the hub-side wing 16 have a shape that gradually spreads from the front edge toward the rear edge. The blade thicknesses of the shroud-side wing 15 and the hub-side wing 16 are the center of the blade length. It becomes thinner from the middle of the downstream toward the trailing edge.

  The shroud-side wing 15 and the hub-side wing 16, whose blade thickness decreases toward the trailing edge, have a different inlet angle, and the tip in the blade height direction has a part of the blade thickness over the blade length. They are combined in a state where they are abutted so as to overlap each other. That is, each tip end portion has an overlapping portion 17 (see FIG. 10B) in which part of the blade thickness overlaps with each other over the blade length. The blade length on the suction surface side of the hub side blade 16 is substantially the same as the blade length on the pressure surface side of the shroud side blade 15 to form the overlapping portion 17.

As described above, according to the diffuser 1 of the centrifugal compressor and the centrifugal compressor including the centrifugal compressor according to the present embodiment, the following effects can be obtained.
In the shroud side blade 15 and the hub side blade 16, the blade thickness of each trailing edge is made thinner than the thickness of each blade at the center of the blade length. Therefore, the wake of the shroud side wing 15 and the hub side wing 16 can be reduced. Therefore, the performance of the diffuser 1 can be improved.

  In the present embodiment, the shroud side blade 15 and the hub side blade 16 have been described as having the same blade length. However, the present invention is not limited to this, and as shown in FIG. As a modified example, the blade length of the hub side blade 18 may be shorter than that of the shroud side blade 15.

[Eighth Embodiment]
The diffuser of the present embodiment is different from the sixth embodiment in that a thick blade shroud side blade and a thin blade hub side blade are combined, and the others are the same. Therefore, about the same structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
Hereinafter, an eighth embodiment of the present invention will be described with reference to FIG.

  The shroud side wing 11 is a thick wing whose cross-sectional shape perpendicular to the blade height direction has a wedge shape. The wedge-shaped shroud side wing 11 has a substantially triangular shape, and has a shape that gradually spreads from each front edge toward the rear edge. The hub side wing 4 is a thin wing. The shroud side wing 11 has a width of a cross-sectional shape perpendicular to the blade height of the hub side wing 4, which is a thin wing, about twice or more.

  The thick wing shroud side wing 11 and the thin wing hub side wing 4 are combined so as to have different entrance angles. Further, the blades are combined in a state where the tip in the blade height direction of the thin-blade hub side blade 4 is abutted with the tip in the blade height direction of the thick blade shroud side blade 11. Therefore, as shown in FIG. 12 (B), when viewed from above, the entire tip of the hub side blade 4 of the thin blade overlaps with a part of the tip of the shroud blade 11 of the thick blade.

As described above, according to the diffuser 1 of the centrifugal compressor and the centrifugal compressor including the centrifugal compressor according to the present embodiment, the following effects can be obtained.
The thick blade shroud side blade 11 and the thin blade hub side blade 4 have different inlet angles, and the entire tip of the hub side blade 4 in the blade height direction spans the blade length and part of the blade thickness of the shroud side blade 11. It was decided to face each other so as to overlap. Therefore, when the shroud side wing 11 and the hub side wing 4 are combined, there is no gap between the shroud side wing 11 and the hub side wing 4. Therefore, flow separation and vortex generation due to the gap flow can be prevented, and the performance of the diffuser 1 can be improved.

  In the present embodiment, the shroud side wing 11 and the hub side wing 4 have been described as having the same wing length. However, the present invention is not limited to this, and as shown in FIG. As a modified example, the blade length of the hub side blade 6 may be shorter than that of the shroud side blade 11.

  In the present embodiment, the cross-sectional shape perpendicular to the blade height direction of the shroud-side blade 11 that is a thick blade is described as a wedge shape, but a channel shape may be used.

1 Diffuser 3 Shroud side wing 4 Hub side wing 5 Connection wall (connection member)
58 shroud side wall

Claims (10)

A shroud side wall provided on the downstream side of the centrifugal impeller;
A hub side wall provided to face the shroud side wall;
A plurality of shroud side wings whose base ends are fixed to the shroud side wall surface and a hub side wings whose base end portions are fixed to the hub side wall surface;
The shroud side wing and the hub side wing are combined with each other such that the entrance angle is different and at least a part of the tip in the blade height direction is abutted with each other.
In the gap where the tip portion of the combined shroud side wing and the tip portion of the hub side wing are not abutted, a connecting member is provided for connecting the tip portions of each other so as to fill at least a part of the gap. This is a centrifugal compressor diffuser.   2. The centrifugal compressor according to claim 1, wherein the connection member has an annular shape that continuously connects all the tip portions of the plurality of shroud side blades and the plurality of hub side blades in a circumferential direction. Diffuser.   The diffuser of a centrifugal compressor according to claim 2, wherein the connection member has an inner diameter smaller than a leading edge radius of the shroud side blade and the hub side blade.   The connection member is connected so as to fill up to 60% downstream of the blade length from at least one leading edge of the tip portion of the combined shroud side blade or the tip portion of the hub side blade. The diffuser of the centrifugal compressor in any one of Claims 1-3.   The diffuser of the centrifugal compressor according to any one of claims 1 to 4, wherein the shroud side wing and the hub side wing to be combined are arranged with their leading edges shifted in the circumferential direction. .   The said shroud side wing | blade and said hub side wing | blade combined are arrange | positioned by shifting the position in the circumferential direction, respectively so that 60% of the total length may not overlap from a front edge. The diffuser of the centrifugal compressor in any one. A shroud side wall provided on the downstream side of the centrifugal impeller;
A hub side wall provided to face the shroud side wall;
A plurality of shroud side wings whose base ends are fixed to the shroud side wall surface and a hub side wings whose base end portions are fixed to the hub side wall surface;
The shroud-side wing and the hub-side wing are combined in such a state that the inlet angle is different and the tip in the blade height direction is abutted so that part of the blade thickness overlaps the blade length. A diffuser of a centrifugal compressor characterized by   The diffuser of the centrifugal compressor according to claim 7, wherein the blade thickness of each trailing edge of the shroud side blade and the hub side blade is thinner than the blade thickness at the center portion of the blade length.   The diffuser of a centrifugal compressor according to claim 7 or 8, wherein one of the shroud side wing and the hub side wing is a thick wing and the other is a thin wing.   A centrifugal compressor comprising the diffuser of the centrifugal compressor according to any one of claims 1 to 9.

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