JP2015190383A - Centrifugal compressor and multistage compressor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand a working region of a first centrifugal compressor 27 into its small flow rate side while sufficiently increasing a compressing efficiency of the first centrifugal compressor 27.SOLUTION: An annular first diffuser 45 for reducing a speed of compressed air and increasing its pressure is formed at an outlet port of a first impeller 37 within a first housing 29, a plurality of first guide blades for rectifying compressed air are spaced apart in a circumferential direction and arranged within a first diffuser 45, a shroud end part 47s at a rear edge 47b of each of the first guide blades 47 is formed with a recess 51, and each of the first guide blades 47 is divided by the recess 51 into a long chord segment BL of 100% chord and a short chord segment BS with a chord length shorter than that of the long chord segment BL along a blade height direction.

Description

  The present invention relates to a centrifugal compressor or the like that compresses a fluid (including gas such as air) using centrifugal force.

  In recent years, various researches and developments have been made on centrifugal compressors used in industrial machines, gas turbines, etc. The general configuration of a centrifugal compressor will be briefly described as follows (Patent Document 1 and Patent Document). (See 2nd grade).

  The centrifugal compressor includes a housing, and the housing has a shroud inside. An impeller is provided in the housing so as to be rotatable about its axis (axis of the impeller). The impeller includes a disk, and a hub surface of the disk extends from one side in the axial direction (one side in the axial direction of the impeller) to the outside in the radial direction (outside in the radial direction of the impeller). Furthermore, a plurality of impeller blades are integrally provided on the hub surface of the disk at intervals in the circumferential direction (circumferential direction of the hub surface of the disk), and the leading edge of each impeller blade is connected to the shroud of the housing. It extends along.

  An annular diffuser that decelerates and pressurizes the compressed fluid (compressed fluid) is formed on the outlet side of the impeller in the housing. Also, in order to promote the diversion of the fluid outward in the radial direction and increase the compressor efficiency of the centrifugal compressor, normally, a plurality of guide vanes (diffuser vanes) for rectifying the compressed fluid are circumferentially provided in the diffuser. It is arranged at intervals in the direction (predetermined circumferential direction).

JP 2013-119828 A JP 2012-57489 A

  By the way, the guide vane often determines the operating range of the centrifugal compressor, the fluid flow angle (flow angle with respect to the radial direction of the impeller) is large in the operating region on the small flow rate side, and the fluid flow does not match the guide vane. The degree of the discrepancy of the blade angle of the guide blade with respect to the fluid flow increases. In such a case, as shown in FIG. 5, a separation region that leads to a surge of the centrifugal compressor develops on the trailing edge side of the guide vane, and it is difficult to expand the operation region of the centrifugal compressor to the small flow rate side. become. In addition, by shortening the cord length of the guide vane, the surge of the centrifugal compressor can be suppressed and the operating range of the centrifugal compressor can be expanded to the small flow rate side. This results in a decrease in the compressor efficiency of the centrifugal compressor.

  That is, there is a problem that it is not easy to expand the operating range of the centrifugal compressor to the small flow rate side while sufficiently increasing the compressor efficiency of the centrifugal compressor.

  Then, an object of this invention is to provide the centrifugal compressor which consists of a novel structure which can solve the above-mentioned problem.

  According to a first aspect of the present invention, there is provided a centrifugal compressor that compresses a fluid by utilizing centrifugal force, a housing having a shroud on the inside thereof, a rotatably provided inside the housing, and a hub surface on one side in the axial direction. A disk extending radially outward from the disk, and a hub surface of the disk integrally provided with a space in a circumferential direction thereof (a circumferential direction of the hub surface of the disk), and a leading edge of the shroud of the housing And an impeller having a plurality of impeller blades extending along the impeller, and an annular diffuser (diffuser flow path) that decelerates and pressurizes the compressed fluid is formed on the outlet side of the impeller in the housing A plurality of guide vanes (diffuser vanes) that rectify (guide radially outward) the fluid compressed in the diffuser in the circumferential direction ( A predetermined circumferential direction), and a notch (slit) is formed in at least one of the shroud end or the hub end on the rear edge side of each guide vane, and each guide vane has the notch Depending on the blade height direction (direction parallel to the axial direction) into a long cord portion (long wing portion) of the 100% cord and a short cord portion (short wing portion) whose cord length is shorter than the long cord portion It is a summary.

  In the specification and claims of the present application, “provided” means that it is indirectly provided via another member in addition to being directly provided, The phrase “provided integrally” includes including being integrally formed. The term “arranged” is intended to include being disposed indirectly through another member in addition to being disposed directly. Further, “one side in the axial direction” means one side in the axial direction, and “axial direction” means the axial direction of the impeller. The “radially outer side” means the outer side in the radial direction, and the “radial direction” means the radial direction of the impeller. Furthermore, the “shroud end” refers to the end of the diffuser that faces the shroud side wall surface, and the “shroud side wall surface” is located on the side of the housing that extends radially outward from the shroud. Refers to the wall surface. “Hub end” refers to the end of the diffuser that faces the hub side wall surface. “Hub side wall surface” refers to the wall surface located on the surface side of the disk hub surface extending radially outward. I mean.

  According to the first feature, by rotating the impeller around its axis, fluid can be taken into the housing and compressed using centrifugal force. On the other hand, the compressed fluid (compressed fluid) is pressurized by the diffuser while being rectified by the plurality of guide vanes, and is discharged to the outside of the housing.

  Here, the flow angle of the fluid in the diffuser (the flow angle with respect to the radial direction of the impeller) has a distribution in the blade height direction of the guide blade. Generally, the fluid flow angle at the shroud end and the hub end of the guide vane is large, and the fluid flow angle at the midspan of the guide vane is small. Accordingly, in the operating region on the small flow rate side of the centrifugal compressor, the degree of mismatch between the fluid flow and the guide vanes at the shroud end and the hub end of the guide vanes tends to become significant.

  In the centrifugal compressor, in consideration of the state of the flow field of the diffuser, the notch is formed in at least one of the shroud end or the hub end on the rear edge side of each guide blade, Each guide blade is divided into the long code portion and the short code portion along the blade height direction by the notch. Thereby, while sufficiently ensuring the rectifying property of the guide vanes including the introduction property of the fluid on the front edge side of the guide vanes, the tendency is reduced in the operating region on the small flow rate side of the centrifugal compressor, The degree of the mismatch can be reduced over the blade height direction of the guide blade.

  A second feature of the present invention is a multistage compressor that compresses a fluid (including gas such as air) stepwise using a centrifugal force, and the centrifugal compressor having the first feature is included in the upstream centrifugal compressor. The gist is that a compressor is used.

  According to the 2nd characteristic, there exists an effect | action similar to the effect | action by a 1st characteristic.

  According to the present invention, it is possible to reduce the degree of mismatch over the height direction of the guide vanes in the operating region on the small flow rate side of the centrifugal compressor while sufficiently ensuring the rectification of the guide vanes. Therefore, the operating range of the centrifugal compressor can be expanded to the small flow rate side while sufficiently increasing the compressor efficiency of the centrifugal compressor.

FIG. 1 is a plan sectional view of a first centrifugal compressor according to an embodiment of the present invention. 2A is an enlarged view of the arrow II in FIG. 1 and shows a state in which the notch is formed at the shroud end on the front edge side of the guide vane. FIG. 2B is a notch. Shows the state formed at the hub end on the front edge side of the guide vane FIG. 3 is a view taken along line III-III in FIG. 2, and FIG. 3 (a) shows a state in which the rear edge of the short cord portion of the first guide vane has a predetermined curved surface, FIG. 3B shows a state in which the rear edge side of the short cord portion of the first guide vane has a tapered shape. FIG. 4 is a plan sectional view of the multistage compression device according to the embodiment of the present invention. FIG. 5 is a view for explaining the problem of the present invention, and is a schematic view of the diffuser as seen from the axial direction.

  An embodiment of the present invention will be described with reference to FIGS. As shown in the drawing, “FF” is the forward direction, “FR” is the backward direction, “R” is the right direction, “L” is the left direction, “D1” is the axial direction, and “D2”. Is the radial direction, “D3” is the circumferential direction, and “D4” is the blade height direction.

  As shown in FIG. 4, the multistage compression apparatus 1 which concerns on embodiment of this invention compresses air in steps using a centrifugal force. And the specific structure of the multistage compressor 1 is as follows.

  The multistage compressor 1 includes a box-shaped base frame 3 extending in the front-rear direction, and a front rotary shaft 5 extending in the left-right direction is provided at a front portion of the base frame 3 via a plurality of bearings 7. It is provided so as to be rotatable. A rear rotating shaft 9 extending in the left-right direction is provided at the rear portion of the base frame 3 so as to be rotatable via a plurality of bearings 11. The rear rotating shaft 9 is parallel to the front rotating shaft 5. It is.

  A drive shaft 13 extending in the left-right direction is provided between the front rotary shaft 5 and the rear rotary shaft 9 in the base frame 3 so as to be rotatable through a bearing 15. 5 and the rear rotating shaft 9 are parallel to each other. The drive shaft 13 is linked to the front rotary shaft 5 and the rear rotary shaft 9 via a speed increasing gear mechanism 17. The speed increasing gear mechanism 17 includes a main drive gear 19 provided integrally with the drive shaft 13, a front driven gear 21 provided integrally with the front rotary shaft 5 and meshed with the main drive gear 19, and a rear rotary shaft. 9 and a rear driven gear 23 that is integrally provided with the main drive gear 19 and meshes with the main drive gear 19. Furthermore, a rotation motor 25 that rotates the drive shaft 13 is provided at an appropriate position outside the base frame 3, and an output shaft (not shown) of the rotation motor 25 is connected via a coupling (not shown). The drive shaft 13 is linked and connected.

  A first centrifugal compressor 27 that compresses air using centrifugal force is disposed on the left front portion of the base frame 3, and the configuration of the first centrifugal compressor 27 is as follows. .

  As shown in FIGS. 1 and 4, the first centrifugal compressor 27 is a centrifugal compressor on the upstream stage side of the multistage compressor 1, and includes a first housing 29. The first housing 29 includes a first housing body 31 having a shroud 31 s inside, and an annular first seal plate that is provided on the right side of the first housing body 31 and is fixed to the lower left portion of the base frame 3. 33. The first seal plate 33 is provided with a first packing 35 that prevents air leakage from the first housing 29.

  A first impeller 37 is provided in the first housing 29 so as to be rotatable about its axis (the axis of the first impeller 37). The first impeller 37 is provided at the left end of the front rotary shaft 5. They are connected together. The first impeller 37 includes a first disk 39, and a hub surface 39h of the first disk 39 is radially outward (first impeller 37) from the left direction (one axial direction of the first impeller 37). Extending radially outward). A plurality of first impeller blades 41 are integrally formed on the hub surface 39h of the first disk 39 at intervals in the circumferential direction (the circumferential direction of the hub surface 39h of the first disk 39). The tip edge 41 t of the impeller blade 41 extends along the shroud 31 s of the first housing body 31.

  A first intake port 43 for taking air into the first impeller 37 side is formed on the inlet side of the first impeller 37 in the first housing 29 (upstream side when viewed from the main flow direction). An annular first diffuser (first diffuser flow path) that decelerates and pressurizes compressed air on the outlet side of the first impeller 37 in the first housing 29 (downstream side when viewed from the main flow direction). 45 is formed. Here, the shroud side wall surface 45s of the first diffuser 45 is positioned on the surface side of the shroud 31s of the first housing body 31 that extends radially outward, and the hub side wall surface 45h of the first diffuser 45 is the first The hub surface 39h of the disk 39 is located on the wall surface located on the surface side extending outward in the radial direction. In the first diffuser 45, a plurality of first guide vanes (first diffuser vanes) 47 that rectify (guide radially outward) compressed air are spaced in the circumferential direction (predetermined circumferential direction). Is arranged.

  A spiral first scroll (first scroll channel) 49 is formed on the outlet side of the first diffuser 45 in the first housing 29, and the first scroll 49 communicates with the first diffuser 45. is there. The cross-sectional area of the first scroll 49 is configured to gradually increase along the mainstream flow direction (from the winding start side to the winding end side). Furthermore, a first discharge port (not shown) for discharging the compressed air to the outside of the first housing 29 is formed at an appropriate position of the first housing 29.

  Then, the characteristic part of the 1st centrifugal compressor 27 concerning the embodiment of the present invention is explained.

  As shown in FIGS. 1 and 2A, a rectangular notch (slit) 51 is formed at the shroud end 47 s on the rear edge 47 b side of each first guide blade 47. Further, instead of the shroud end portion 47s on the rear edge 47b side of each first guide blade 47, as shown in FIG. 2B, the hub end portion 47h on the rear edge 47b side of each first guide blade 47 has a rectangular shape. A notch 51 having a shape may be formed. Or although illustration is abbreviate | omitted, you may make it each form the rectangular notch 51 in the shroud edge part 47s and the hub edge part 47h in the rear edge 47b side of each 1st guide blade 47. As shown in FIG.

  As shown in FIGS. 2A and 2B, each first guide blade 47 has a long cord portion (long wing portion) BL of a 100% cord and a short cord length shorter than the long cord portion BL by a notch 51. The cord portion (short blade portion) BS is divided along the blade height direction. Further, as shown in FIG. 3A, the rear edge BSb of the short cord portion BS of each first guide vane 47 is on a circumference S centered on the axis of the first impeller 37 (see FIG. 1). It presents a predetermined curved surface. Instead of the trailing edge BSb of the short cord portion BS of each first guide vane 47 having a predetermined curved surface, the trailing edge of the short cord portion BS of each first guiding vane 47 is shown in FIG. The BSb side may have a tapered shape in which a step 47u is provided between the long cord portion BL and the short cord portion BS on the negative pressure surface 47n of each first guide vane 47. Further, in order to suppress a decrease in the rectifying property of the first guide vanes 47, the rear edge BSb of each short guide portion BS of each first guide vane 47 is located downstream of the throat position SP between the first guide vanes 47. doing.

  Here, the height (length in the blade height direction) k of each notch 51 of each first guide blade 47 is set to 3 to 12% of the blade height j of the first guide blade 47 (FIG. 2). (See (a) and (b)). When the height k of the notch 51 of each first guide vane 47 is less than 3% of the blade height j of the first guide vane 47, the air at the shroud end 47s or the hub end 47h of the first guide vane 47 This is because it becomes difficult to sufficiently reduce the degree of mismatch between the first flow and the first guide blade 47. This is because if the height k of the notch 51 of each first guide vane 47 exceeds 12% of the blade height j of the first guide vane 47, there is a concern that the rectification of the first guide vane 47 may be reduced. In addition, when the notch 51 is each formed in the shroud end part 47s and the hub end part 47h in the rear edge 47b side of each 1st guide blade 47, what is the height k of the notch 51 of each 1st guide blade 47? The total height of the two notches 51 is obtained.

  The cord length m of the short cord portion BS of each first guide vane 47 is set to 50 to 90% cord (see FIGS. 3A and 3B). This is because if the cord length m of the short cord portion BS of each first guide vane 47 is less than 50% cord, the rectification of the first guide vane 47 may be lowered. When the cord length m of the short cord portion BS of each first guide vane 47 exceeds 90% cord, the length of the notch 51 of each first guide vane 47 is shortened, and the shroud end portion 47s of the first guide vane 47 is shortened. Alternatively, it is difficult to sufficiently reduce the degree of mismatch between the air flow and the first guide vane 47 at the hub end 47h.

  As shown in FIG. 4, a second centrifugal compressor 53 that compresses air (first-stage compressed air) from the first centrifugal compressor 27 using a centrifugal force at the right front portion of the base frame 3. Is arranged. The second centrifugal compressor 53 is a middle-stage centrifugal compressor in the multistage compressor 1 and has a capacity smaller than that of the first centrifugal compressor 27. The second centrifugal compressor 53 is similar to the first centrifugal compressor 27 in that the second housing 55 (the second housing body 57 and the second seal plate 59), the second packing 61, and the second impeller 63 (the second impeller 63). The disc 65 and the plurality of second impeller blades 67), the second intake port 69, the second diffuser 71, the plurality of second guide vanes 73, the second scroll 75, and the second discharge port (not shown) are the constituent elements. . Here, the second impeller 63 is integrally connected to the right end portion of the front rotary shaft 5, and the second intake port 69 has a pipe (not shown) connected to the first discharge port of the first centrifugal compressor 27. Connected through. Further, the second guide vane 73 has the same configuration as the first guide vane 47.

  A third centrifugal compressor 77 that compresses air (second stage compressed air) from the second centrifugal compressor 53 by using centrifugal force is disposed at the left rear portion of the base frame 3. The third centrifugal compressor 77 is a centrifugal compressor on the downstream stage side of the multistage compressor 1, and has a smaller capacity than the first centrifugal compressor 27 and the second centrifugal compressor 53. The third centrifugal compressor 77 includes the third housing 79 (the third housing body 81 and the third seal plate 83), the third packing 85, the same as the first centrifugal compressor 27 and the second centrifugal compressor 53. A third impeller 87 (a third disk 89 and a plurality of third impeller blades 91), a third intake port 93, a third diffuser 95, a plurality of third guide vanes 97, a third scroll 99, and a third discharge port (illustrated) (Omitted) is a component. Here, the third impeller 87 is integrally connected to the left end portion of the rear rotating shaft 9, and the third intake port 93 is connected to a pipe (not shown) at the second discharge port in the second centrifugal compressor 53. Connected through. Further, the third guide vane 97 has the same configuration as the first guide vane 47.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  By rotating the drive shaft 13 by driving the rotary motor 25, the front rotary shaft 5 and the rear rotary shaft 9 are rotated at an increased speed via the speed increasing gear mechanism 17. Accordingly, the first impeller 37 in the first centrifugal compressor 27 and the second impeller 63 in the second centrifugal compressor 53 are amplified and rotated integrally with the front rotary shaft 5, and the third impeller in the third centrifugal compressor 77 is rotated. 87 can be amplified and rotated integrally with the rear rotating shaft 9.

  As a result, air can be taken into the first impeller 37 side from the first intake port 43 in the first centrifugal compressor 27 and compressed using centrifugal force. On the other hand, the compressed air is pressurized by the first diffuser 45 while being rectified by the plurality of first guide vanes 47 in the first centrifugal compressor 27, and is first supplied from the first outlet through the first scroll 49. The compressed air is discharged to the outside of the housing 29 as the first stage compressed air, and sent to the second intake port 69 side of the second centrifugal compressor 53.

  Subsequently, the first stage of compressed air can be introduced from the second intake port 69 to the second impeller 63 side in the second centrifugal compressor 53 and compressed by centrifugal force. On the other hand, the compressed air that has been compressed is boosted by the second diffuser 71 while being rectified by the plurality of second guide vanes 73 in the second centrifugal compressor 53, and is supplied from the second outlet through the second scroll 75. 2 is discharged to the outside of the housing 55 as second-stage compressed air and sent to the third intake port 93 side of the third centrifugal compressor 77.

  Furthermore, the second stage of compressed air can be introduced from the third intake port 93 to the third impeller 87 side in the third centrifugal compressor 77 and compressed using centrifugal force. On the other hand, the compressed air (third-stage compressed air) is pressurized by the third diffuser 95 while being rectified by the plurality of third guide vanes 97 in the third centrifugal compressor 77, and passes through the third scroll 99. Then, the compressed air in the third stage is discharged from the third discharge port to the outside of the third housing 79 (normal operation of the embodiment of the present invention).

  Here, in the first centrifugal compressor 27, the flow angle of air in the first diffuser 45 (flow angle with respect to the radial direction of the first impeller 37) has a distribution in the blade height direction of the first guide blade 47. In general, the air flow angle at the shroud end 47s and the hub end 47h of the first guide vane 47 is large, and the air flow angle at the midspan of the first guide vane 47 is small. Accordingly, in the operating range on the small flow rate side of the first centrifugal compressor 27, the degree of mismatch between the air flow and the first guide vane 47 at the shroud end 47s and the hub end 47h of the first guide vane 47 is remarkable. Tend to be.

  In the first centrifugal compressor 27, in consideration of the state of the flow field of the first diffuser 45, the shroud end 47s or the hub end 47h on the rear edge 47b side of each first guide vane 47 A notch 51 is formed in at least one of the first guide blades 47, and the first guide blades 47 are divided by the notches 51 along the long cord portion BL, the short cord portion BS, and the blade height direction. Thereby, while ensuring sufficient rectification of the first guide vane 47 including air introduction property on the front edge 47a side of the first guide vane 47, the tendency is reduced and the vane height of the first guide vane 47 is reduced. In the longitudinal direction, the degree of mismatch in the operating region on the small flow rate side of the first centrifugal compressor 27 can be reduced.

  Similarly, the second centrifugal guide is provided over the height direction of the second guide vane 73 while sufficiently ensuring the rectifying property of the second guide vane 73 including the air introduction property of the front edge side of the second guide vane 73. In the operating region on the small flow rate side of the compressor 53, the degree of mismatch between the air flow and the second guide vanes 73 can be reduced. Further, the third centrifugal compression is performed over the height direction of the third guide vane 97 while sufficiently ensuring the rectification property of the third guide vane 97 including the air introduction property of the leading edge side of the third guide vane 97. The degree of mismatch between the air flow and the third guide vane 97 in the operating region on the small flow rate side of the machine 77 can be reduced.

  Therefore, according to the embodiment of the present invention, the first centrifugal compressor 27 and the like are arranged in the blade height direction of the first guide blade 47 and the like while sufficiently ensuring the rectification of the first guide blade 47 and the like. Since the degree of mismatch in the operating region on the small flow rate side can be reduced, the operating region of the first centrifugal compressor 27 and the like is expanded to the small flow rate side while sufficiently increasing the compressor efficiency of the first centrifugal compressor 27 and the like. be able to. In other words, the operating range of the multistage compressor 1 can be expanded to the small flow rate side while sufficiently increasing the compressor efficiency of the multistage compressor 1.

  The present invention is not limited to the description of the above-described embodiment. For example, a technical idea applied to the first centrifugal compressor 27 of the multistage compressor 1 is applied to a gas turbine or a turbocharger centrifugal compressor ( (Not shown) may be applied. In addition, the first centrifugal compressor 27 may include a slide member (not shown) that can move forward and backward (can enter and leave) in the notch 51 of each first guide vane 47. The scope of rights encompassed by the present invention is not limited to the above-described embodiment.

  1: multistage compressor, 27: first centrifugal compressor, 29: first housing, 31: first housing body, 31s: shroud, 37: first impeller, 39: first disk, 39h: hub surface, 41: First impeller blade, 41t: tip edge, 45: first diffuser, 45s: shroud side wall surface, 47: first guide vane, 47a: front edge, 47b: rear edge, 47h: hub end, 47n: suction surface, 47s: shroud end, 51: notch, BL: long cord portion, BS: short cord portion, BSb: trailing edge, SP: throat position, 53: second centrifugal compressor, 55: second housing, 63: second Impeller, 65: second disk, 67: second impeller blade, 71: second diffuser, 73: second guide vane, 77: third centrifugal compressor, 79: third housing, 87: third impeller , 89: third disk, 91: third impeller blade, 95: third diffuser, 97: third guide vane

Claims (5)

In a centrifugal compressor that compresses fluid using centrifugal force,
A housing having a shroud inside;
A disc rotatably provided in the housing, and a hub surface extending radially outward from one axial direction; and a tip provided integrally with the hub surface of the disc at intervals in the circumferential direction An impeller comprising a plurality of impeller blades whose edges extend along the shroud of the housing;
An annular diffuser that decelerates and pressurizes the compressed fluid is formed on the outlet side of the impeller in the housing, and a plurality of guide vanes that rectify the compressed fluid in the diffuser are spaced apart in the circumferential direction. Arranged,
A notch is formed in at least one of the shroud end or the hub end on the rear edge side of each guide vane, and each guide vane has a long cord portion of 100% cord and a cord length longer than the long cord portion by the notch. A centrifugal compressor characterized by being divided along a blade height direction into short short cord portions.   The centrifugal compressor according to claim 1, wherein a cord length of the short cord portion of each guide blade is set to 50 to 90% cord.   The centrifugal compressor according to claim 1 or 2, wherein a height of the notch of each guide blade is set to 3 to 12% of a height of the guide blade.   The trailing edge of the short cord portion of each guide vane is located downstream of the throat position between the guide vanes, according to any one of claims 1 to 3. Centrifugal compressor. In a multistage compression device that compresses fluid in stages using centrifugal force,
A multi-stage compression apparatus using the centrifugal compressor according to any one of claims 1 to 4 for at least one of the centrifugal compressors.

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