Centrifugal compressor
The centrifugal compressor optimizes diffuser blade angles and thicknesses to reduce the throat area, addressing manufacturing challenges and maintaining efficiency at low flow rates.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- IHI CORP
- Filing Date
- 2024-02-15
- Publication Date
- 2026-06-02
AI Technical Summary
Centrifugal compressors face challenges in reducing the throat area, which is the cross-sectional area of the flow path between adjacent diffuser vanes, especially under conditions of low fluid flow rates.
The centrifugal compressor design includes diffuser blades with maximum blade angles and thicknesses at specific positions to minimize the throat area, optimizing the flow path geometry.
This design effectively reduces the throat area without complicating manufacturing or increasing pressure loss, ensuring efficient fluid pressurization even at low flow rates.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a centrifugal compressor. This application claims the benefit of priority based on Japanese Patent Application No. 2023-023315 filed on February 17, 2023, the content of which is incorporated herein by reference.
Background Art
[0002] There is a centrifugal compressor including a diffuser for converting the kinetic energy of a fluid compressed by a compressor impeller into pressure energy. In such a centrifugal compressor, for example, as disclosed in Patent Document 1, a plurality of diffuser vanes are arranged radially outside the compressor impeller and circumferentially spaced apart from the compressor impeller. As the fluid passes between adjacent diffuser vanes, the flow velocity of the fluid decreases and the pressure increases.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] When using a centrifugal compressor under conditions where the fluid flow rate is small, it is necessary to reduce the throat area, which is the cross-sectional area of the throat portion. The throat portion is the portion where the cross-sectional area of the flow path between adjacent diffuser vanes is minimized. Therefore, it is desired to appropriately reduce the throat area.
[0005] An object of the present disclosure is to provide a centrifugal compressor capable of appropriately reducing the throat area.
Means for Solving the Problems
[0006] To solve the above problems, the centrifugal compressor of this disclosure comprises a compressor impeller and a plurality of diffuser blades arranged radially outward from the compressor impeller and spaced apart in the circumferential direction of the compressor impeller, wherein the blade angle, which is the angle between the center line of the diffuser blade and the radial direction, has a maximum value, and the thickness of the diffuser blade is maximum downstream of the position where the blade angle has a maximum value.
[0007] The multiple diffuser blades include a first diffuser blade and a second diffuser blade adjacent to the first diffuser blade in the direction of rotation of the compressor propeller. The blade angle of the second diffuser blade may be maximized at a position corresponding to a position perpendicular to the center line of the first diffuser blade and facing the downstream end of the first diffuser blade.
[0008] The multiple diffuser blades include a first diffuser blade and a second diffuser blade adjacent to the first diffuser blade in the direction of rotation of the compressor propeller, wherein the thickness of the first diffuser blade may be maximized at a position corresponding to a position perpendicular to the center line of the second diffuser blade and facing the upstream end of the second diffuser blade. [Effects of the Invention]
[0009] According to this disclosure, the throat area can be appropriately reduced. [Brief explanation of the drawing]
[0010] [Figure 1] Figure 1 is a schematic cross-sectional view of a centrifugal compressor according to an embodiment of the present disclosure. [Figure 2] Figure 2 is an extracted view of the dashed-dotted line portion of Figure 1. [Figure 3] Figure 3 is a cross-sectional view taken along line III-III in Figure 2. [Figure 4] Figure 4 is a graph showing an example of the distribution of diffuser vane angle and thickness. [Modes for carrying out the invention]
[0011] Embodiments of this disclosure will be described below with reference to the attached drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for the purpose of facilitating understanding and do not limit this disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same function or configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to this disclosure are omitted from the illustrations.
[0012] Figure 1 is a schematic cross-sectional view of the centrifugal compressor C according to this embodiment. As shown in Figure 1, the centrifugal compressor C comprises a housing 1 including a first housing 2 and a second housing 3, and a compressor impeller 4.
[0013] In the following, the rotational axis direction, radial direction, and circumferential direction of the compressor impeller 4 will also be referred to simply as the rotational axis direction, radial direction, and circumferential direction, respectively.
[0014] The first housing 2 and the second housing 3 are arranged side by side in the direction of the rotation axis. The first housing 2 and the second housing 3 are connected to each other by a fastening mechanism such as a G coupling. The compressor impeller 4 is rotatably housed in the housing 1.
[0015] An air intake port 5 is provided at the end of the first housing 2 opposite to the second housing 3. A diffuser passage 6 is formed between the first housing 2 and the second housing 3. The diffuser passage 6 is formed in an annular shape. The diffuser passage 6 is located radially outward from the compressor impeller 4. The diffuser passage 6 communicates with the air intake port 5 via the compressor impeller 4. Multiple diffuser blades 7 are provided in the diffuser passage 6. Details of the diffuser blades 7 will be described later.
[0016] A compressor scroll channel 8 is formed in the first housing 2. The compressor scroll channel 8 is formed in an annular shape. The compressor scroll channel 8 is located radially outward from the diffuser channel 6. The compressor scroll channel 8 communicates with the diffuser channel 6. The compressor scroll channel 8 also communicates with a discharge port (not shown).
[0017] In centrifugal compressor C, as the compressor impeller 4 rotates, a fluid such as air is drawn into the first housing 2 through the intake port 5. The drawn-in fluid is accelerated by centrifugal force as it passes through the space between the blades of the compressor impeller 4. The accelerated fluid is pressurized in the diffuser passage 6 and the compressor scroll passage 8. The pressurized fluid flows out from a discharge port (not shown).
[0018] The details of the diffuser vane 7 will be explained below with reference to Figures 2 to 4. Figure 2 is an extracted view of the dashed-dotted line portion of Figure 1. Figure 3 is a cross-sectional view taken along line III-III of Figure 2. Figure 3 shows only some of the diffuser vanes 7, namely diffuser vanes 7-1, 7-2, and 7-3, out of the multiple diffuser vanes 7.
[0019] As shown in Figure 2, the diffuser channel 6 is formed between the surface 2a of the first housing 2 and the surface 3a of the second housing 3. Surfaces 2a and 3a face each other in the direction of the rotation axis. For example, each of surfaces 2a and 3a extends perpendicular to the direction of the rotation axis. For example, surfaces 2a and 3a are parallel to each other.
[0020] As shown in FIGS. 2 and 3, a plurality of diffuser blades 7 are arranged radially outside the compressor impeller 4 and spaced apart in the circumferential direction of the compressor impeller 4. In the present embodiment, each diffuser blade 7 has a substantially identical shape to each other. That is, in the present embodiment, the first diffuser blade described later and the second diffuser blade described later (that is, the diffuser blade 7 adjacent to the first diffuser blade in the rotational direction of the compressor impeller 4) have a substantially identical shape to each other. The diffuser blade 7 is provided across between the surface 2a of the first housing 2 and the surface 3a of the second housing 3. The diffuser blade 7 is fixed to the surface 2a and the surface 3a, respectively.
[0021] However, the diffuser blade 7 may not be fixed to the surface 2a and may be, for example, separated from the surface 2a. The diffuser blade 7 may not be fixed to the surface 3a and may be, for example, separated from the surface 3a. The diffuser blade 7 may be integrally formed with the first housing 2 or may be a separate member from the first housing 2. The diffuser blade 7 may be integrally formed with the second housing 3 or may be a separate member from the second housing 3.
[0022] As shown in FIG. 3, the diffuser blade 7 extends intersecting the radial direction of the compressor impeller 4. Specifically, the center line 7a of the diffuser blade 7 extends intersecting the radial direction of the compressor impeller 4. The plurality of diffuser blades 7 are arranged at equal intervals in the circumferential direction. Specifically, the plurality of diffuser blades 7 are arranged rotationally symmetrically about the rotation axis of the compressor impeller 4. However, the intervals between some adjacent diffuser blades 7 may be different from the intervals between other adjacent diffuser blades 7.
[0023] The fluid sent radially outward from the compressor impeller 4 passes through the flow path 9 between adjacent diffuser blades 7, causing the fluid velocity to decrease and the pressure to increase. As a result, the fluid in the diffuser flow path 6 is pressurized. Thus, in the diffuser flow path 6, the fluid flows from the radially inward to the radially outward. Therefore, the radially inward end of the diffuser blade 7 is the upstream end E1, and the radially outward end of the diffuser blade 7 is the downstream end E2.
[0024] A flow path 9 is formed between the downstream portion of a diffuser blade 7 (for example, diffuser blade 7-1), including its downstream end E2, and the upstream portion of an adjacent diffuser blade 7 (for example, diffuser blade 7-2), including its upstream end E1. The portion of the flow path 9 with the smallest cross-sectional area is the throat portion 9a. The throat portion 9a is formed at the upstream end of the flow path 9. In this embodiment, by modifying the shape of the diffuser blade 7, it is possible to appropriately reduce the throat area, which is the cross-sectional area of the flow path in the throat portion 9a.
[0025] In the example in Figure 3, the diffuser blades 7-1, 7-2, and 7-3 are arranged in this order circumferentially. That is, diffuser blade 7-1 and diffuser blade 7-2 are adjacent to each other. Diffuser blade 7-2 and diffuser blade 7-3 are adjacent to each other. In Figure 3, the rotation direction of the compressor propeller 4 is clockwise. That is, diffuser blade 7-2 is adjacent to diffuser blade 7-1 in the direction of rotation of the compressor propeller 4. Diffuser blade 7-3 is adjacent to diffuser blade 7-2 in the direction of rotation of the compressor propeller 4.
[0026] In Figures 3 and 4, the position on the diffuser vane 7 is indicated by a dimensionless position P along the centerline 7a of the diffuser vane 7. The dimensionless position P is 0 at the upstream end E1 and 1 at the downstream end E2.
[0027] Figure 4 is a graph showing an example of the distribution of the blade angle θ and thickness T of the diffuser blade 7. The blade angle θ is the angle between the center line 7a of the diffuser blade 7 and the radial direction of the compressor propeller 4 (see Figure 3). The thickness T is the length of the diffuser blade 7 in the direction perpendicular to the center line 7a when the diffuser blade 7 is viewed in the direction of the rotation axis (see Figure 3).
[0028] As shown in Figure 4, the diffuser vane 7 has a maximum value for the vane angle θ. In the example in Figure 4, the vane angle θ increases as you move from the upstream end E1 towards position P1. Position P1 is located between the upstream end E1 and the downstream end E2. Then, as you move from position P1 towards the downstream end E2, the vane angle θ decreases. In other words, at position P1, the vane angle θ reaches a maximum value (the maximum value in this embodiment). It should be noted that although the vane angle θ is said to be at a maximum value, this maximum value is not limited to a single point, but may have a range of degree (a region where the vane angle θ is constant). This range may be less than or equal to the maximum value of the thickness T of the diffuser vane 7, which will be described later.
[0029] As shown in Figure 4, the thickness T of the diffuser vane 7 is maximized downstream of position P1, where the vane angle θ is maximized. In the example in Figure 4, the thickness T increases as you move from the upstream end E1 towards position P2. Position P2 is located between the upstream end E1 and the downstream end E2, and is downstream of position P1. Then, the thickness T decreases as you move from position P2 towards the downstream end E2. In other words, the thickness T is maximized (maximum in this embodiment) at position P2. It should be noted that although the thickness T is maximized, the maximum is not limited to a single point, but may have a range of degree (a region where the thickness T is constant). This range may be less than or equal to the maximum value of the thickness T of the diffuser vane 7.
[0030] In the example shown in Figure 4, downstream of position P1 and upstream of position P2, the blade angle θ decreases monotonically as it approaches the downstream end E2, and the thickness T increases monotonically as it approaches the downstream end E2. In this embodiment, the blade angle θ and thickness T constantly decrease and increase as they approach the downstream end E2, but in this disclosure, monotonically decreasing and monotonically increasing may include portions where the blade angle θ and thickness T do not change. In other words, it also includes monotonically decreasing and monotonically increasing in a broad sense.
[0031] As explained above, the centrifugal compressor C is equipped with a plurality of diffuser blades 7, each having a maximum blade angle θ and a maximum thickness T downstream of the position P1 where the blade angle θ is maximum. By having a maximum blade angle θ upstream of the position P2 where the thickness T is maximum, the position P1 where the blade angle θ is maximum can be formed on the upstream portion of the diffuser blade 7. Therefore, the upstream portion of a diffuser blade 7 (for example, diffuser blade 7-2) can be brought closer to the downstream portion of an adjacent diffuser blade 7 (for example, diffuser blade 7-1). Furthermore, by having a maximum thickness T downstream of the position P1 where the blade angle θ is maximum, the position P2 where the thickness T is maximum can be formed on the downstream portion of the diffuser blade 7. Therefore, the downstream portion of one diffuser blade 7 (for example, diffuser blade 7-1) can be brought closer to the upstream portion of the adjacent diffuser blade 7 (for example, diffuser blade 7-2). Thus, the throat area of the flow path 9 formed between adjacent diffuser blades 7 can be reduced.
[0032] Other methods can be considered to reduce the throat area of the flow path 9. For example, increasing the number of diffuser blades 7 can reduce the throat area of the flow path 9. However, this method makes it difficult to process and assemble the parts of the centrifugal compressor C. For example, reducing the height of the diffuser flow path 6 in the axial direction can reduce the throat area of the flow path 9. However, this method also makes it difficult to process and assemble the parts of the centrifugal compressor C. For example, increasing the overall blade angle θ of the diffuser blades 7 can reduce the throat area of the flow path 9. However, this method results in increased pressure loss due to the blade angle θ at the downstream end E2 becoming excessively large compared to the appropriate value.
[0033] On the other hand, in this embodiment, the throat area can be reduced while resolving problems such as the difficulty in manufacturing the centrifugal compressor C and the increase in pressure loss. Thus, according to this embodiment, the throat area can be appropriately reduced. Therefore, even when using the centrifugal compressor C under conditions of low fluid flow rate, the fluid can be appropriately pressurized in the diffuser flow path 6.
[0034] In particular, in the centrifugal compressor C, the multiple diffuser blades 7 include a first diffuser blade and a second diffuser blade adjacent to the first diffuser blade in the rotational direction of the compressor impeller 4. The blade angle θ of the second diffuser blade is maximized at a position corresponding to a position perpendicular to the center line 7a of the first diffuser blade and facing the downstream end E2 of the first diffuser blade.
[0035] For example, in the example shown in Figure 3, if diffuser blade 7-1 is the first diffuser blade described above, then diffuser blade 7-2 becomes the second diffuser blade described above. Of the diffuser blade 7-2, the position that is perpendicular to the center line 7a of diffuser blade 7-1 and faces the downstream end E2 of diffuser blade 7-1 is, for example, the position of the center line 7a of diffuser blade 7-2 that intersects with the normal to the downstream end E2 of the center line 7a of diffuser blade 7-1. Position P1 of diffuser blade 7-2 is set at such a position. This appropriately brings the upstream part of diffuser blade 7-2 closer to the downstream part of diffuser blade 7-1.
[0036] However, among the second diffuser vanes (e.g., diffuser vane 7-2), a position that is offset to some extent from the position of the first diffuser vane (e.g., diffuser vane 7-1) that is perpendicular to the center line 7a of the first diffuser vane and facing the downstream end E2 of the first diffuser vane is also included in the position of the second diffuser vane that is perpendicular to the center line 7a of the first diffuser vane and facing the downstream end E2 of the first diffuser vane. For example, the position P1 of the diffuser vane 7-2 may be set within a predetermined range (for example, a range with a width of ±0.1 in dimensionless position P) centered on the position of the diffuser vane 7-2 that is perpendicular to the center line 7a of the diffuser vane 7-1 and facing the downstream end E2 of the diffuser vane 7-1.
[0037] In particular, in the centrifugal compressor C, the multiple diffuser blades 7 include a first diffuser blade and a second diffuser blade adjacent to the first diffuser blade in the rotational direction of the compressor impeller 4. The thickness T of the first diffuser blade is maximized at a position corresponding to a position perpendicular to the center line 7a of the second diffuser blade and facing the upstream end E1 of the second diffuser blade.
[0038] For example, in the example shown in Figure 3, as described above, if diffuser blade 7-1 is the first diffuser blade, then diffuser blade 7-2 becomes the second diffuser blade. Of the diffuser blade 7-1, the position perpendicular to the center line 7a of diffuser blade 7-2 and facing the upstream end E1 of diffuser blade 7-2 is, for example, the position of the center line 7a of diffuser blade 7-1 that intersects with the normal to the upstream end E1 of the center line 7a of diffuser blade 7-2. Position P2 of diffuser blade 7-1 is set at such a position. This appropriately brings the downstream portion of diffuser blade 7-1 closer to the upstream portion of diffuser blade 7-2.
[0039] However, among the first diffuser blades (e.g., diffuser blade 7-1), a position that is offset to some extent from the position of the second diffuser blade (e.g., diffuser blade 7-2) that is perpendicular to the center line 7a of the second diffuser blade and facing the upstream end E1 of the second diffuser blade is also included in the position of the first diffuser blade that is perpendicular to the center line 7a of the second diffuser blade and facing the upstream end E1 of the second diffuser blade. For example, the position P2 of diffuser blade 7-1 may be set within a predetermined range (for example, a range with a width of ±0.1 in dimensionless position P) centered on the position of diffuser blade 7-1 that is perpendicular to the center line 7a of diffuser blade 7-2 and facing the upstream end E1 of diffuser blade 7-2.
[0040] In the example shown in Figure 3, as a result of setting positions P1 and P2 on each diffuser vane 7 as described above, positions P1, P2, P1, P2, P1, P2, P1, P2, P1, P1, P2, P1, P2, P1, P2, P1, P2, P2 on diffuser vane 7-1, P1, P2 on diffuser vane 7-3 are arranged in this order in the circumferential direction.
[0041] In the above, an example of the distribution of the blade angle θ and thickness T of the diffuser blade 7 was explained with reference to Figure 4. However, the distribution of the blade angle θ and thickness T of the diffuser blade 7 is not limited to the example in Figure 4. For example, there may be multiple positions in a single diffuser blade 7 where the blade angle θ is at its maximum value. For example, an additional region may be added upstream of position P1 where the blade angle θ decreases as it approaches the downstream end E2. For example, an additional region may be added downstream of position P1 where the blade angle θ increases as it approaches the downstream end E2. For example, there may be multiple positions where the thickness T is at its maximum value, even if they are within a range with a certain width.
[0042] While embodiments of this disclosure have been described above with reference to the attached drawings, it goes without saying that this disclosure is not limited to such embodiments. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure. [Explanation of symbols]
[0043] 4: Compressor propeller 7: Diffuser blades 7-1: Diffuser blades 7-2: Diffuser blades 7-3: Diffuser blades 7a: Centerline C: Centrifugal compressor E1: Upstream end E2: Downstream end P1: Position P2: Position T: Thickness θ: Blade angle
Claims
1. Compressor propeller, A plurality of diffuser blades arranged radially outward from the compressor propeller and spaced apart in the circumferential direction of the compressor propeller, wherein the blade angle, which is the angle between the center line of the diffuser blade and the radial direction, has a maximum value, and the thickness of the diffuser blade is maximum downstream of the position where the blade angle has a maximum value, Equipped with, Centrifugal compressor.
2. The plurality of diffuser blades include a first diffuser blade and a second diffuser blade adjacent to the first diffuser blade in the rotational direction of the compressor propeller. At a position on the second diffuser blade that is perpendicular to the center line of the first diffuser blade and facing the downstream end of the first diffuser blade, the blade angle of the second diffuser blade becomes the maximum value. The centrifugal compressor according to claim 1.
3. The plurality of diffuser blades include a first diffuser blade and a second diffuser blade adjacent to the first diffuser blade in the rotational direction of the compressor propeller. In the first diffuser vane, the thickness of the first diffuser vane is maximized at a position corresponding to a position perpendicular to the center line of the second diffuser vane and facing the upstream end of the second diffuser vane. A centrifugal compressor according to claim 1 or 2.