Impeller for centrifugal rotary machine, and centrifugal rotary machine

Abstract

An impeller for a centrifugal rotary machine has a plurality of blades (4) arranged at intervals in a circumferential direction on a face facing a direction of an axis of a disc (3) formed in a discoid shape about the axis, wherein the blades (4) each include a first section (10A) rising from the disc (3) and inclined toward an opposite direction of a rotary direction (R) as the distance from the disc and a second section (11A) continuing from the first section (10A) and inclined toward a forward direction of the rotary direction (R) as the distance from the disc (3) between the leading edges and the trailing edges in the blades (4).

Claims

1. An impeller for a centrifugal rotary machine, comprising: a disc formed in a discoid shape about an axis; a plurality of blades including a leading edge into which a fluid flows and a trailing edge out of which the fluid flows and arranged at intervals in a circumferential direction on a face facing a direction of the axis, and an impeller fluid flow path being defined by neighboring blades, wherein, between the leading edges and the trailing edges in the blades, each blade viewed in a cross-section perpendicular to the impeller fluid flow path includes: a first area rising from the disc and inclined toward an opposite direction of a rotary direction relative to the distance from the disc; a second area further rising from the first area and inclined toward a forward direction of the rotary direction as the distance from the disc; a seventh area disposed closer to the trailing edge than the first area, rising from the disc, and inclined toward the forward direction of the rotary direction relative to the distance from the disc; and an eighth area disposed closer to the trailing edge than the second area, further rising from the seventh area, and inclined toward the forward direction of the rotary direction relative to the distance from the disc.

2. The impeller for a centrifugal rotary machine according to claim 1, wherein each blade viewed in a cross-section perpendicular to the impeller flow path further includes: a third area disposed closer to the leading edge than the first area, rising from the disc, and inclined toward the forward direction of the rotary direction relative to the distance from the disc; and a fourth area disposed closer to the leading edge than the second area, further rising from the third area, and inclined toward the forward direction of the rotary direction relative to the distance from the disc.

3. The impeller for a centrifugal rotary machine according to claim 2, wherein each blade viewed in a cross-section perpendicular to the impeller flow path further includes: a fifth area disposed closer to the trailing edge than the first area and closer to the leading edge than the seventh area, rising from the disc, and inclined toward the opposite direction of the rotary direction relative to the distance from the disc; and a sixth area disposed closer to the trailing edge than the second area and closer to the leading edge than the eighth area, further rising from the fifth area, and inclined toward the opposite direction of the rotary direction relative to the distance from the disc.

4. A centrifugal rotary machine, comprising: a rotary shaft configured to rotate about an axis; the impeller for a centrifugal rotary machine according to claim 2 externally engaged with the rotary shaft and configured to rotate together with the rotary shaft; and a casing configured to rotatably support the rotary shaft and cover the impeller from an outer circumference side of the impeller.

5. The impeller for a centrifugal rotary machine according to claim 1, wherein each blade viewed in a cross-section perpendicular to the impeller flow path further includes: a fifth area disposed closer to the trailing edge than the first area and closer to the leading edge than the seventh area, rising from the disc, and inclined toward the opposite direction of the rotary direction relative to the distance from the disc; and a sixth area disposed closer to the trailing edge than the second area and closer to the leading edge than the eighth area, further rising from the fifth area, and inclined toward the opposite direction of the rotary direction relative to the distance from the disc.

6. A centrifugal rotary machine, comprising: a rotary shaft configured to rotate about an axis; the impeller for a centrifugal rotary machine according to claim 5 externally engaged with the rotary shaft and configured to rotate together with the rotary shaft; and a casing configured to rotatably support the rotary shaft and cover the impeller from an outer circumference side of the impeller.

7. A centrifugal rotary machine, comprising: a rotary shaft configured to rotate about an axis; the impeller for a centrifugal rotary machine according to claim 1 externally engaged with the rotary shaft and configured to rotate together with the rotary shaft; and a casing configured to rotatably support the rotary shaft and cover the impeller from an outer circumference side of the impeller.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is an overall schematic diagram showing a centrifugal compressor related to an embodiment of the present invention.

(2) FIG. 2 is a perspective view showing an impeller in the centrifugal compressor related to the embodiment of the present invention, a portion of which is cut out.

(3) FIG. 3 is a meridional view showing a major part of the impeller in the centrifugal compressor related to the embodiment of the present invention.

(4) FIG. 4A is a cross-sectional view of the blade of the impeller in the centrifugal compressor related to the embodiment of the present invention, showing a cross section X1-X1 of FIG. 3.

(5) FIG. 4B is a cross-sectional view of the blade of the impeller in the centrifugal compressor related to the embodiment of the present invention, showing a cross section X2-X2 of FIG. 3.

(6) FIG. 4C is a cross-sectional view of the blade of the impeller in the centrifugal compressor related to the embodiment of the present invention, showing a cross section X3-X3 of FIG. 3.

(7) FIG. 4D is a cross-sectional view of the blade of the impeller in the centrifugal compressor related to the embodiment of the present invention, showing a cross section X4-X4 of FIG. 3.

(8) FIG. 4E is a cross-sectional view of the blade of the impeller in the centrifugal compressor related to the embodiment of the present invention, showing a cross section X5-X5 of FIG. 3.

(9) FIG. 4F is a cross-sectional view of the blade of the impeller the centrifugal compressor related to the embodiment of the present invention, showing a cross section X6-X6 of FIG. 3.

(10) FIG. 5 is a cross-sectional view of the blade of the impeller in the centrifugal compressor related to the embodiment of the present invention, showing a direction of a secondary flow of FIG. 4C.

DESCRIPTION OF EMBODIMENTS

First Embodiment

(11) Hereinafter, a centrifugal compressor (centrifugal rotary machine) 100 related to an embodiment of the present invention will be described.

(12) As shown in FIG. 1, the centrifugal compressor 100 includes a casing 102, a rotary shaft 101 which is axially supported via a journal hearing 103 and a thrust bearing 104 inside the casing 102 and configured to be rotatable about an axis O, and an impeller 1 externally engaged with the rotary shaft 101 in parallel with an axis O direction.

(13) The centrifugal compressor 100 uses a centrifugal force of the impeller 1 rotated with the rotary shaft 101 to cause a fluid F0 supplied from a suction port 105c formed in the casing 102 to flow from a flow path 105a of an upstream side to a flow path 105b of a downstream side in stages. Also, while the fluid F0 flows, the centrifugal compressor 100 rises pressure of the fluid F0 and discharges the fluid F0 from a discharge port 105d.

(14) Next, the impeller 1 will be described.

(15) The impeller 1 is externally engaged with the rotary shaft 101 and rotates about the axis O with the rotary shaft 101 in a rotary direction R. Note that, in the embodiment, the plurality of (six) impellers 1 are provided and configures a multi-stage centrifugal compressor.

(16) As shown in FIG. 2, each impeller 1 includes a disc 3 formed in a substantially discoid shape when viewed in the axis O direction, a plurality of blades 4 provided on the disc 3, and a cover 5 configured to cover the blades 4 in the axis O direction.

(17) The disc 3 has an end face facing a first direction of the axis O direction and configured to have a small diameter and an end face facing a second direction of the axis O direction and configured to have a large diameter. Further, as the two end faces are connected by a curved surface 3a gradually enlarged in diameter from the first direction to the second direction of the axis O direction, the disc 3 has a substantially discoid shape when viewed in the axis O direction and is a member having substantially an umbrella shape as a whole.

(18) In addition, a through-hole 3b configured to penetrate through the disc 3 in the axis O direction is formed inside in a radial direction of the disc 3. As the rotary shaft 101 is inserted and fitted into the through-hole 3b, the impeller 1 can be fixed to the rotary shaft 101 and rotated integrally with the rotary shaft 101.

(19) The blades 4 are a plurality of members disposed at certain intervals in the circumferential direction of the axis O, i.e., the rotary direction R, so as to rise from the curved surface 3a in the disc 3 to the first direction in the axis O direction.

(20) In addition, the plurality of blades 4 are each formed to be curved toward the opposite direction of the rotary direction R as they go from the inside toward the outside in the radial direction of the disc 3. Also, a face facing the forward direction of the rotary direction R is a pressure side of the blade and a face facing the opposite direction of the rotary direction R is a suction side of the blade.

(21) The cover 5 is a member formed integrally with the plurality of blades 4 so as to cover the blades 4 from the first direction of the axis O direction, and has substantially an umbrella shape that gradually enlarges in diameter toward the second direction of the axis O direction. In other words, in the embodiment, the impeller 1 is a closed impeller having a cover 5.

(22) Also, a space surrounded by the two neighboring blades 4, the disc 3, and the cover 5 is defined as an impeller flow path FC in which the fluid F0 can flow from the inside toward the outside in the radial direction. The fluid F0 is introduced from the first direction of the axis O direction of the impeller 1, i.e., the leading edge 4a side of the blade 4, into the impeller flow path FC, and is discharged horn the trailing edge 4b side of the blade 4 serving as the outside in the radial direction.

(23) Next, the blades 4 will be described in greater detail.

(24) As shown in FIGS. 3 and 4A to 4F, the blades 4 each include a portion B, a portion A, a portion C, and a portion D in order from the leading edge 4a toward the trailing edge 4b.

(25) The portion A includes a first section 10A formed at a position near the disc 3 so as to continue from the disc 3 on a side closest to the leading edge 4a in the blade 4, and a second section 11A extending away from the disc so as to continue from the first section 10A. In other words, the first section 10A and the second section 11A are consecutively formed using an imaginary line L defined at a halfway position of a direction in which the blade 4 rises (in the embodiment, a central position of a direction in which the blade 4 rises) as a boundary.

(26) Here, in connection with the blade 4, an inclined angle formed between the blade 4 and an imaginary line L1 rising at a right angle from the curved surface 3a of the disc 3 (the imaginary line L1 rising at a right angle from a tangential line L2 in a contact point P between the blade 4 and the curved surface 3a) is assumed to be a lean angle .

(27) In the blade 4, the first section 10A rises from the disc 3 having the lean angle inclined toward the opposite direction of the rotary direction R and is formed to be smoothly curved as the distance from the disc 3.

(28) The second section 11A continues from the first section 10A toward the cover 5 and extends to be smoothly curved and inclined toward the forward direction of the rotary direction R the distance from the disc 3.

(29) Here, examples of positions in which the first section 10A and the second section 11A are formed are illustrated in FIGS. 4B, 4C, and 4D. In other words, in the embodiment, the first section 10A and the second section 11A are, for example, formed at a position corresponding to 1.5% to 65% along a meridional plane of the impeller 1 from the leading edge 4a.

(30) In the embodiment, in the first section 10A, the lean angle is maximized at a position of 40% while the lean angle gradually increases from the leading edge 4a side of the blade 4 and then gradually decreases toward the trailing edge 4b side of the blade 4. In other words, at a position corresponding to 40% along the meridional plane, the first section 10A of the blade 4 is most inclined toward the opposite direction of the rotary direction R. A position which is most inclined toward the opposite direction of the rotary direction R is not limited to the position corresponding to 40% along the meridional plane, and the numerical value of 40% is an example.

(31) In addition in the second section 11A, a degree of curvature is maximized at a position of 40% while the degree of curvature gradually increases from the leading edge 4a side of the blade 4, and then gradually decreases toward the trailing edge 4b side of the blade 4. In other words, at a position corresponding to 40% along the meridional plane, the second section 11A of the blade 4 is most inclined toward the forward direction of the rotary direction R. A position which is most inclined toward the forward direction of the rotary direction R is not limited to the position corresponding to 40% along the meridional plane, and the numerical value of 40% is an example.

(32) The portion B is a portion located closer to the leading edge 4a side of the blade 4 than the portion A, and includes a third section 10B formed at a position near the disc 3 so as to continue from the disc 3 and a fourth section 11B extending away from the disc so as to continue from the third section 10B using the imaginary line L as a boundary.

(33) As shown in FIG. 4A, the third section 10B is provided to have the lean angle inclined toward the forward direction of the rotary direction R, rise from the disc 3 at a side closer to the leading edge 4a of the blade 4 than the first section 10A, and extend in a linear shape as the distance from the disc 3.

(34) In addition, the fourth section 11B extends to straightly extend the third section 10B in a linear shape without being inclined from a connection section of the third section 10B and the fourth section 11B at a side closer to the leading edge 4a of the blade 4 than the second section 11A. In other words, the fourth section 11B is inclined toward the forward direction of the rotary direction R.

(35) Here, an example of positions in which the third section 10B and the fourth section 11B are formed is illustrated in FIG. 4A, in other words, in the embodiment, the third section 10B and the fourth section 11B are, for example, thrilled from a position corresponding to 0% on the meridional plane of the impeller 1 to a position of the leading edge 4a side of the portion A, i.e., near the leading edge 4a.

(36) The portion C is a portion located closer to the trailing edge 4b side of the blade 4 than the portion B, and includes a fifth section 10C formed at a position near the disc 3 so as to continue from the disc 3 and a sixth section 11C extending away from the disc 3 so as to continue from the fifth section 10C using the imaginary line L as a boundary.

(37) As shown in FIG. 4E, the fifth section 10C is provided to have the lean angle inclined toward the opposite direction of the rotary direction R, rise from the disc 3 at a side closer to the trailing edge 4b of the blade 4 than the first section 10A, and extend in a linear shape as the distance from the disc 3.

(38) In addition, the sixth section 11C extends to straightly extend the fifth section 10C in a linear shape without being inclined from a connection section of the fifth section 10C and the sixth section 11C at a side closer to the trailing edge 4b of the blade 4 than the second section 11A. In other words, the sixth section 11C is inclined toward the opposite direction of the rotary direction R.

(39) Here, an example of positions in which the fifth section 10C and the sixth section 11C are formed is illustrated in FIG. 4E. In other words, in the embodiment, the fifth section 10C and the sixth section 11C are, for example, formed from the trailing edge 4b side of the portion A to a position corresponding to 85% along the meridional plane of the impeller 1.

(40) The portion D is a portion located closer to the trailing edge 4b of the blade 4 than the portion C, and includes a seventh section 10D formed at a position near the disc 3 so as to continue from the disc 3 and an eighth section 11D extending away from the disc so as to continue from the seventh section 10D using the imaginary line L as a boundary.

(41) As shown in FIG. 4E, the seventh section 10D is provided to have the lean angle inclined toward the forward direction of the rotary direction R and extend in a linear shape away from the disc 3 at a side closer to the trailing edge 4b of the blade 4 than the fifth section 10C, as with the leading edge 4a of the blade 4.

(42) In addition, the eighth section 11D extends to straightly extend the seventh section 10D in a linear shape without being inclined from a connection section of the seventh section 10D and the eighth section 11D at a side closer to the trailing edge 4b of the blade 4 than the sixth section 11D. In other words, the eighth section 11D is inclined toward the forward direction of the rotary direction R as with the leading edge 4a.

(43) Here, an example of positions in which the seventh section 10D and the eighth section 11D are formed is illustrated in FIG. 4F. In other words, in the embodiment, the seventh section 10D and the eighth section 11D are, for example, formed from the trailing edge 4b side of the portion C to a position corresponding to 100% along the meridional plane of the impeller 1, i.e., near the trailing edge 4b.

(44) As described above, at at least one place between the leading edge 4a and the trailing edge 4b of the blade 4, there is a place inclined toward the opposite direction of the rotary direction R on a side closer to the disc 3 than the imaginary line L.

(45) Such a centrifugal compressor includes the first section 10A in which the blade 4 is inclined toward the opposite direction of the rotary direction R. The first section 10A is disposed to swell toward the opposite direction of the rotary direction R. Thus, when the secondary flow F flowing along the suction side of the blade 4 away from the disc 3 as shown in FIG. 5 occurs in the opposite direction of the rotary direction R of the blade 4 along with the rotation of the impeller 1, the secondary flow F may contact and push the first section 10A.

(46) In other words, the secondary flow F is divided into a tangential direction component F.sub.1 at a point A on the suction side of the blade 4 in contact with the first section 10A and a normal direction component F.sub.2 perpendicular to the tangential direction component F.sub.1. Also, the normal direction component F.sub.2 is a component pushing the secondary flow F toward the first section 10.

(47) Here, if the first section 10A is not inclined toward the opposite direction of the rotary direction R, the secondary flow is not in contact with the first section 10A and the normal direction component F.sub.2 becomes 0 (zero). As such, the entire secondary flow F flows away from the disc 3. On the other hand, in the embodiment, since a portion of the secondary flow F flows in a normal direction F.sub.2 and the remainder flows in a tangential direction F.sub.1, the entire secondary flow F does not flow toward a position away from the disc 3.

(48) In addition, as the blade 4 includes the second section 11A inclined toward the forward direction of the rotary direction R, it is possible for the blade 4 to receive the pressing force of the fluid F0 on the pressure side of the blade 4. For this reason, even when the first section 10A is inclined toward the opposite direction of the rotary direction R, compression efficiency is not reduced.

(49) In addition, the blade 4 includes the third section 10B and the fourth section 11B which are inclined toward the forward direction of the rotary direction R at the position corresponding to 0% along the meridional plane. As such, when the fluid F0 is introduced into the flow path FC, it is possible for the blade 4 to reliably receive the pressing force of the fluid F0 on the pressure side at the leading edge 4a side of the blade 4. Therefore, the fluid F0 can be compressed with higher efficiency.

(50) According to the centrifugal rotary machine of the embodiment, the first section 10A of the blade 4 is inclined toward the opposite direction of the rotary direction R and the second section 11A of the blade 4 is inclined toward the forward direction of the rotary direction R between the leading edge 4a and the trailing edge 4b. For this reason, the secondary flow F flowing away from the disc 3 in the opposite direction of the rotary direction R can be suppressed, and accumulation of the low energy fluid at a position in the opposite direction of the rotary direction R of the blade 4, which is a position away from the disc 3, i.e., close to the cover 5, can be suppressed.

(51) In addition, the pressure side of the blade 4 can receive the pressing force from the fluid F0 to effectively use the force, maintain compression efficiency while suppressing the secondary flow F, and improve performance.

(52) The embodiments of the present invention have been described above in detail, but some design changes can be made without departing from the spirit of the technical scope of the present invention.

(53) For example, the blade 4 may have the first section 10A inclined toward the opposite direction of the rotary direction R and the second section 11A inclined toward the forward direction of the rotary direction R so as to continue from the first section 10A provided on at least one place between the leading edge 4a and the trailing edge 4b of the blade 4. Therefore, an inclination direction and a shape with respect to the third section 10B, the fourth section 11B, the fifth section 10C, the sixth section 11C, the seventh section 10D, and the eighth section 11D are not limited to the above-described embodiments. Further, the third section 10B, the fourth section 11B, the fifth section 10C, the sixth section 11C, the seventh section 10D, and the eighth section 11D may be provided to be arranged on the imaginary line L1 without being inclined in the rotary direction R.

(54) In addition, the first section 10A and the second section 11A are provided to be curved in the above-described embodiments, but may be provided in a linear shape.

(55) In addition, the description has been made on the assumption that the impeller is the closed impeller in the above-described embodiments, but an open impeller having no cover 5 may be used.

(56) In addition, the centrifugal compressor 100 is not limited to the multi-stage compressor, and the above-described blade 4 of the impeller 1 can also be applied to a single-stage compressor.

(57) Also, the centrifugal compressor is not necessarily used as the centrifugal rotary machine in the present invention, and a blower and a centrifugal pump may be used.

INDUSTRIAL APPLICABILITY

(58) According to the impeller and the centrifugal rotary machine described above, as the blade includes the first section and the second section, it is possible to suppress the secondary flow flowing away from the disc in the opposite direction of the rotary direction, effectively use the pressing force from the fluid, and improve performance.

REFERENCE SIGNS LIST

(59) 1 Impeller

(60) 3 Disc

(61) 3a Curved surface

(62) 3b Through-hole

(63) 4 Blade

(64) 4a Leading edge

(65) 4b Trailing edge

(66) 5 Cover

(67) 10A First section

(68) 11A Second section

(69) 10B Third section

(70) 11B Fourth section

(71) 10C Fifth section

(72) 11C Sixth section

(73) 10D Seventh section

(74) 11D Eighth section

(75) O Axis

(76) F0 Fluid

(77) F Secondary flow

(78) P Contact point

(79) F.sub.1 Tangential direction component

(80) F.sub.2 Normal direction component

(81) FC Impeller flow path

(82) L, L1 Imaginary line

(83) L2 Tangential line

(84) R Rotary direction

(85) 100 Centrifugal compressor (centrifugal rotary machine)

(86) 101 Rotary shaft

(87) 102 Casing

(88) 103 Journal bearing

(89) 104 Thrust bearing

(90) 105a Flow path

(91) 105b Flow path

(92) 105c Suction port

(93) 105d Discharge port