Diffuser for centrifugal compressors

Abstract

This application discloses a diffuser for a centrifugal compressor, comprising at least one diffusion channel. The at least one diffusion channel outputs fluid radially along the centrifugal compressor and is configured to diffuse fluid entering the diffuser. Each of the at least one diffusion channel is defined by an upstream wall and a downstream wall disposed opposite each other perpendicular to the axis of the centrifugal compressor. The upstream wall has at least two concentric first recesses, each concentric first recess formed by recessing from the surface of the upstream wall and disposed around the axis of the centrifugal compressor. The downstream wall has at least two concentric second recesses, each concentric second recess formed by recessing from the surface of the downstream wall and disposed around the axis of the centrifugal compressor. The diffuser of this application has the advantage of suppressing surge when the flow rate of the centrifugal compressor is low.

Description

Technical Field

[0001] This application relates to the field of centrifugal compressors, and more particularly to diffusers used in centrifugal compressors. Background Technology

[0002] In existing technologies, when the flow rate of a centrifugal compressor decreases, the compressor is prone to surge. Summary of the Invention

[0003] This application provides a diffuser for a centrifugal compressor, comprising at least one diffusion channel. The at least one diffusion channel outputs fluid radially along the centrifugal compressor and is configured to diffuse fluid entering the diffuser. Each of the at least one diffusion channel is defined by an upstream wall and a downstream wall disposed opposite to each other perpendicular to the axis of the centrifugal compressor. The upstream wall has at least two concentric rings of first recesses, each ring of the first recess being recessed from the surface of the upstream wall and disposed around the axis of the centrifugal compressor. The downstream wall has at least two concentric rings of second recesses, each ring of the second recess being recessed from the surface of the downstream wall and disposed around the axis of the centrifugal compressor.

[0004] According to the diffuser for the centrifugal compressor described above, the first recess and the second recess are arranged offset from each other in the radial direction of the centrifugal compressor.

[0005] According to the diffuser for the centrifugal compressor described above, the at least two first recesses and the at least two second recesses are staggered in the radial direction of the centrifugal compressor.

[0006] According to the diffuser for the centrifugal compressor described above, each of the at least two first concave sections includes a curved section and a straight section, the curved section and the straight section being connected, the curved section being closer to the axis of the centrifugal compressor than the straight section. In the radial cross-section of the centrifugal compressor, the curved section is arc-shaped, and the straight section is a straight line.

[0007] According to the diffuser for the centrifugal compressor described above, each of the at least two turns of the first recess and each of the at least two turns of the first recess further includes an additional straight section, the curved section being disposed between the straight section and the additional straight section and connected to the straight section and the additional straight section. In the radial cross-section of the centrifugal compressor, the additional straight section is a straight line.

[0008] According to the diffuser for the centrifugal compressor described above, the inlet of each diffuser channel is located at the center of the upstream wall, and the outlet of each diffuser channel is located at the point where the diameter of the upstream and downstream walls is at its maximum.

[0009] According to the diffuser for a centrifugal compressor described above, the at least one diffuser channel is a single diffuser channel. The diffuser further includes a first diffuser plate and a second diffuser plate disposed opposite to each other, the first diffuser plate forming the upstream wall surface and the second diffuser plate forming the downstream wall surface.

[0010] According to the diffuser for a centrifugal compressor described above, the at least one diffusion channel is at least two diffusion channels. The diffuser further includes a first diffuser plate, a second diffuser plate, and at least one partition plate. The first diffuser plate and the second diffuser plate are disposed opposite to each other, with the first diffuser plate forming the upstream wall and the second diffuser plate forming the downstream wall. The at least one partition plate is disposed between the first diffuser plate and the second diffuser plate, thereby forming the at least two diffusion channels.

[0011] This application also provides a diffuser for a centrifugal compressor, comprising a first diffuser plate, a second diffuser plate, and at least three blades. The second diffuser plate is disposed on one side of the first diffuser plate, spaced apart from the first diffuser plate by a certain distance. The at least three blades are disposed between the first diffuser plate and the second diffuser plate, and abut against the first diffuser plate and the second diffuser plate. Adjacent blades, the first diffuser plate, and the second diffuser plate define diffusion channels, each diffusion channel having an inlet near the axis of the centrifugal compressor and an outlet away from the axis of the centrifugal compressor. At least two first recesses and at least two second recesses are respectively provided on two opposite walls of the diffusion channels, the at least two first recesses being arranged along the inlet-to-outlet direction, and the at least two second recesses being arranged along the inlet-to-outlet direction.

[0012] According to the diffuser for the centrifugal compressor described above, the at least three blades are uniformly arranged circumferentially along the centrifugal compressor, and the arrangement direction of each of the at least three blades is inclined to the radial direction of the centrifugal compressor.

[0013] According to the diffuser for a centrifugal compressor described above, at least two first recesses and at least two second recesses are respectively disposed on the first diffuser plate and the second diffuser plate forming the diffuser channel, and the at least two first recesses and at least two second recesses extend circumferentially along the centrifugal compressor. Each of the first recesses and the second recesses includes a curved portion and a straight portion, the curved portion and the straight portion being connected, the curved portion being closer to the axis of the diffuser than the straight portion. In the radial cross-section of the diffuser, the curved portion is arc-shaped, and the straight portion is a straight line.

[0014] According to the diffuser for a centrifugal compressor described above, each of the first recess and the second recess further includes an additional straight section, the curved section being disposed between and connected to the straight section and the additional straight section. In the radial cross-section of the diffuser, the additional straight section is a straight line.

[0015] According to the diffuser for a centrifugal compressor described above, the at least two first recesses and at least two second recesses are respectively disposed on two opposite wall surfaces of two adjacent blades. Each of the first and second recesses includes a curved portion and a straight portion, the curved portion and the straight portion being connected, the curved portion being closer to the axis of the centrifugal compressor than the straight portion. In the axial cross-section of the centrifugal compressor, the curved portion is arc-shaped, and the straight portion is a straight line.

[0016] According to the diffuser for the centrifugal compressor described above, each of the first recess and the second recess further includes an additional straight section, the curved section being disposed between the straight section and the additional straight section, and connected to both the straight section and the additional straight section. In the axial cross-section of the centrifugal compressor, the additional straight section is a straight line.

[0017] The diffuser in this application can suppress surge when the flow rate of the centrifugal compressor is low. Attached Figure Description

[0018] The features and advantages of this application can be better understood by reading the following detailed description with reference to the accompanying drawings, in which the same reference numerals denote the same parts, wherein:

[0019] Figure 1A This is a perspective view of the centrifugal compressor of this application;

[0020] Figure 1B yes Figure 1A A partial cross-sectional view of the centrifugal compressor shown, illustrating a first embodiment of the diffuser;

[0021] Figure 1C This is a cross-sectional schematic diagram of diffuser 126;

[0022] Figure 2 yes Figure 1B The enlarged view at the center circle is a cross-sectional schematic of the diffuser;

[0023] Figure 3A This is a schematic diagram of the first embodiment of the recess;

[0024] Figure 3B This is a schematic diagram of fluid flow when the flow rate of the centrifugal compressor is relatively low;

[0025] Figure 3CThis is a schematic diagram of the second embodiment of the recess;

[0026] Figure 4A This is a perspective view of some components of the second embodiment of the diffuser;

[0027] Figure 4B This is a partial cross-sectional view of some components of the second embodiment of the diffuser;

[0028] Figure 5A This is a perspective view of some components of the third embodiment of the diffuser;

[0029] Figure 5B This is a partial front view of some components of the third embodiment of the diffuser;

[0030] Figure 6A This is the third embodiment of the recess in this application;

[0031] Figure 6B This is the fourth embodiment of the recess in this application;

[0032] Figure 7A This is a perspective view of some components of the fourth embodiment of the diffuser of this application;

[0033] Figure 7B This is a partial cross-sectional view of some components of the fourth embodiment of the diffuser. Detailed Implementation

[0034] Various specific embodiments of the invention will now be described with reference to the accompanying drawings, which form part of this specification. It should be understood that although terms indicating direction, such as "front," "rear," "up," "down," "left," "right," etc., are used in this invention to describe various exemplary structural parts and elements of the invention in a directional or orientational manner, these terms are used only for ease of description and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this invention can be arranged in different orientations, these terms indicating direction are illustrative only and should not be considered limiting. In the following drawings, the same reference numerals are used for the same parts.

[0035] Figure 1A This is a perspective view of the centrifugal compressor of this application. Figure 1B yes Figure 1A The partial cross-sectional view of the centrifugal compressor shown illustrates a first embodiment of the diffuser 126. (As shown) Figure 1A-1BAs shown, the centrifugal compressor includes a housing 112, a flow guide 114, an impeller 115, and a diffuser 126. The housing 112 defines an internal housing cavity and an annular cavity. The housing 112 has an inlet 102 communicating with the housing cavity and an outlet 104 communicating with the annular cavity. The flow guide 114 and the impeller 115 are disposed within the housing cavity. The flow guide 114 guides the fluid entering from the inlet 102. The impeller 115 has an impeller axis X (i.e., the axis X of the centrifugal compressor). The inlet 102 is generally circular, with its center located on the axis X of the centrifugal compressor. The impeller 115 is rotatable about the impeller axis X, thereby accelerating the fluid passing through the inlet 102 and the flow guide 114. The diffuser 126 is disposed within the housing cavity and downstream of the impeller 115. The diffuser 126 diffuses the fluid entering the diffuser 126 (i.e., the fluid exiting the impeller 115). The annular cavity is disposed approximately around the axis X of the centrifugal compressor. The outlet of the diffuser 126 communicates with the annular cavity, thereby allowing the diffused fluid to enter the annular cavity and exit from the outlet 104.

[0036] Figure 1C This is a cross-sectional schematic diagram of diffuser 126. (See attached diagram.) Figure 1C As shown, diffuser 126 includes a diffusion channel 132. The diffusion channel 132 is defined by a first diffuser plate 116 and a second diffuser plate 118. The first diffuser plate 116 and the second diffuser plate 118 are arranged opposite each other perpendicular to the axis X of the centrifugal compressor. The first diffuser plate 116 is generally annular. The inlet 122 of the diffusion channel 132 is located at the center of the first diffuser plate 116, and the center of the inlet 102 is located on the axis X of the centrifugal compressor. The second diffuser plate 118 is generally disk-shaped. The outlet 124 of the diffusion channel 132 is located at the point of maximum diameter of the first diffuser plate 116 and the second diffuser plate 118. The diffusion channel 132 discharges fluid radially along the centrifugal compressor.

[0037] Figure 2 yes Figure 1B The enlarged view at the center circle is a cross-sectional schematic of diffuser 126. Figure 2 In this configuration, the inlet 122 of the diffuser channel 132 is located at the bottom, and the outlet 124 of the diffuser channel 132 is located at the top. For example... Figure 2 As shown, the first diffuser plate 116 forms the upstream wall 201. The second diffuser plate 118 forms the downstream wall 203. The specific structures on the upstream wall 201 and the downstream wall 203 will be described below:

[0038] The upstream wall 201 has four concentric rings of first recesses 212. Each ring of first recesses 212 is formed by recessing from the surface of the upstream wall 201 and is arranged around the axis X of the centrifugal compressor. In other words, the center of each ring of first recesses 212 is located on the axis X of the centrifugal compressor. The downstream wall 203 has five rings of second recesses 214. Each ring of second recesses 214 is formed by recessing from the surface of the downstream wall 203 and is arranged around the axis X of the centrifugal compressor. In other words, the center of each ring of second recesses 214 is located on the axis X of the centrifugal compressor. The four rings of first recesses 212 and the five rings of second recesses 214 are staggered in the radial direction of the centrifugal compressor. In other words, the four rings of first recesses 212 and the five rings of second recesses 214 are arranged at intervals in the radial direction of the centrifugal compressor. Each ring of second recesses 214 is staggered relative to each other in the radial direction of the centrifugal compressor. In other words, the projections of the second recess 214 and the second recess 214 along the axis X of the centrifugal compressor do not coincide.

[0039] On the upstream wall 201, the distance between the inner edge of the innermost first recess 212 (i.e., the one closest to the centrifugal compressor axis X) and the outer edge of the outermost first recess 212 (i.e., the one furthest from the centrifugal compressor axis X) is a first distance D1. On the downstream wall 203, the distance between the inner edge of the innermost second recess 214 (i.e., the one closest to the centrifugal compressor axis X) and the outer edge of the outermost second recess 214 (i.e., the one furthest from the centrifugal compressor axis X) is a second distance D2. (Reference) Figure 1C The distance between inlet 122 and outlet 124 is the radial length L. As an example, the first distance D1 and the radial length L satisfy: D1 / L ≥ 0.5. The second distance D2 and the radial length L satisfy: D2 / L ≥ 0.5.

[0040] Figure 3A This is a first embodiment of the recesses (i.e., the first recess 212 and the second recess 214) of this application. Figure 3A As shown, each of the four first recesses 212 and each of the five second recesses 214 includes a curved section 302 and a straight section 304. The curved section 302 and the straight section 304 are connected, and the curved section 302 is closer to the axis X of the centrifugal compressor than the straight section 304. In the radial section of the centrifugal compressor, the curved section 302 is arc-shaped, and the straight section 304 is a straight line.

[0041] After the fluid enters the diffuser passage 132 from the diffuser inlet 122, the fluid moves approximately radially along the centrifugal compressor along the diffuser passage 132. A portion of the fluid located at the center (i.e., the main flow) continues to flow approximately radially outwards along the centrifugal compressor, while a portion of the fluid near the upstream wall 201 and downstream wall 203 flows from the end of the curved section 302 near the axis X of the centrifugal compressor (i.e., as shown in the image). Figure 3A Point B (as shown), then flows through the curved section 302 and the straight section 304, finally reaching the end of the straight section 304 away from the axis X of the centrifugal compressor (i.e., as shown in point B). Figure 3A After point A (as shown), it flows into the mainstream.

[0042] Figure 3B This is a schematic diagram of fluid flow when the flow rate of a centrifugal compressor is relatively small. For example... Figure 3B As shown, when the flow rate of the centrifugal compressor is low, a stall cluster will form within the diffuser channel 132. This stall cluster may be a fluid cluster with a lower flow velocity than the overall fluid, or it may be a rotating vortex. When a stall cluster forms in the diffuser channel 132, it affects the flow near the upstream wall 201 and the downstream wall 203, causing the fluid near the upstream wall 201 and the downstream wall 203 to first pass through the end of the straight section 304 away from the axis X of the centrifugal compressor when entering the adjacent first recess 212 and / or second recess 214 (i.e., as shown). Figure 3A Point A (as shown) flows through the straight section 304 and the curved section 302, reaching one end of the curved section 302 near the axis X of the centrifugal compressor (i.e., as shown). Figure 3A (Point B shown). The counter-flowing fluid impacts the stall cluster in the main flow, thereby dispersing the stall cluster and suppressing surge.

[0043] Figure 3C This is a second embodiment of the recesses (i.e., the first recess 212 and the second recess 214) of this application. Figure 3A Compared to the first embodiment, Figure 3C The second embodiment of the recesses shown (i.e., the first recess 212 and the second recess 214) further includes an additional straight section 306. A curved section 302 is disposed between and connected to the straight section 304 and the additional straight section 306. In the radial section of the centrifugal compressor, the additional straight section 306 is a straight line.

[0044] Figure 4A This is a perspective view of some components of the second embodiment of the diffuser 126 of this application. Figure 4B This is a partial cross-sectional view of a second embodiment of the diffuser 126 of this application. (See attached image.) Figures 4A-4BAs shown, the main difference between the second embodiment of diffuser 126 and the first embodiment is that the second embodiment of diffuser 126 has two diffusion channels 132. Specifically, the second embodiment of diffuser 126 further includes a partition 402 and a fixing member 404. The partition 402 is generally annular. The partition 402 is connected to the second diffuser plate 118 via the fixing member 404, thereby positioning the partition 402 between the first diffuser plate 116 and the second diffuser plate 118 to form two diffusion channels 132. For the diffusion channel 132 located on the left, the first diffuser plate 116 forms the upstream wall 201, and the left surface of the partition 402 forms the downstream wall 203. For the diffusion channel 132 located on the right, the right surface of the partition 402 forms the upstream wall 201, and the second diffuser plate 118 forms the downstream wall 203. Nine rings of first recesses 212 are provided on the upstream wall 201 of the diffuser channel 132 on the left side, and nine rings of second recesses 214 are provided on the downstream wall 203 of the diffuser channel 132 on the left side. The nine rings of first recesses 212 and nine rings of second recesses 214 are staggered in the radial direction of the centrifugal compressor. In other words, the nine rings of first recesses 212 and nine rings of second recesses 214 are arranged at intervals in the radial direction of the centrifugal compressor. Each ring of second recesses 214 is staggered relative to each other in the radial direction of the centrifugal compressor. In other words, the projections of the second recesses 214 along the axis X of the centrifugal compressor do not coincide.

[0045] Eight rings of first recesses 212 are provided on the upstream wall 201 of the right-side diffuser channel 132, and nine rings of second recesses 214 are provided on the downstream wall 203 of the right-side diffuser channel 132. The eight rings of first recesses 212 and the nine rings of second recesses 214 are staggered in the radial direction of the centrifugal compressor. In other words, the eight rings of first recesses 212 and the nine rings of second recesses 214 are arranged at intervals in the radial direction of the centrifugal compressor. Each ring of second recesses 214 is staggered relative to each other in the radial direction of the centrifugal compressor. In other words, the projections of the second recesses 214 along the axis X of the centrifugal compressor do not coincide.

[0046] For the first recess 212 and the second recess 214 on both sides of each diffuser channel 132, the first distance D1 and the radial length L satisfy: D1 / L≥0.5. The second distance D2 and the radial length L satisfy: D2 / L≥0.5.

[0047] The structure of at least two first recesses 212 and at least two second recesses 214 in the second embodiment of the diffuser 126 is the same as that of at least two first recesses 212 and at least two second recesses 214 in the first embodiment of the diffuser 126, and will not be described again here.

[0048] It should be noted that although the first recess 212 and the second recess 214 with a specific number of turns are shown in the first and second embodiments of the diffuser 126, at least two turns of the first recess 212 and at least two turns of the second recess 214 are both within the scope of protection of this application.

[0049] Figure 5A This is a perspective view of some components of the third embodiment of the diffuser 126 of this application. Figure 5B yes Figure 5A A partial front view of some components of the third embodiment of the diffuser 126 shown. The main difference between the third embodiment of the diffuser 126 and the first embodiment is that the third embodiment of the diffuser 126 has ten diffusion channels 132 arranged therein. Specifically, as Figures 5A-5B As shown, diffuser 126 includes a first diffuser plate 116, a second diffuser plate 118, and ten blades 502. The second diffuser plate 118 is disposed to the right of the first diffuser plate 116 and spaced apart from it by a distance. The ten blades 502 are disposed between the first diffuser plate 116 and the second diffuser plate 118 and abut against them, thereby allowing adjacent blades 502, the first diffuser plate 116, and the second diffuser plate 118 to define a diffusion channel 132. In other words, ten diffusion channels 132 can be formed between the ten blades 502. The diffusion channel 132 has an inlet 122 and an outlet 124. The inlet 122 is close to the axis X of the centrifugal compressor, and the outlet 124 is away from the axis X of the centrifugal compressor. Ten blades 502 are evenly arranged along the circumference of the centrifugal compressor, and each blade 502 is inclined to the radial direction of the centrifugal compressor, so that the width of the inlet 122 of each diffuser channel 132 is smaller than the width of the outlet 124 in the circumference of the centrifugal compressor.

[0050] The blades 502 on both sides of each diffuser channel 132 form a first wall and a second wall, respectively. Two first recesses 512 are provided on the first wall and two second recesses 514 are provided on the second wall, and are arranged along the direction from the inlet 122 to the outlet 124, respectively.

[0051] Figure 6A This is a third embodiment of the recesses (i.e., the first recess 512 and the second recess 514) of this application. Figure 6A As shown, each of the first recess 512 and the second recess 514 includes a curved portion 302 and a straight portion 304. The curved portion 302 and the straight portion 304 are connected, and the curved portion 302 is closer to the axis X of the centrifugal compressor than the straight portion 304. In the axial section of the centrifugal compressor, the curved portion 302 is arc-shaped, and the straight portion 304 is a straight line.

[0052] Figure 6B This is the fourth embodiment of the recesses (i.e., the first recess 512 and the second recess 514) of this application. Figure 6A Compared to the third embodiment, Figure 6B The fourth embodiment of the first recess 512 and the second recess 514 shown also includes an additional straight section 306. A curved section 302 is disposed between and connected to the straight section 304 and the additional straight section 306. In the axial section of the centrifugal compressor, the additional straight section 306 is a straight line.

[0053] In the third and fourth embodiments of the recesses (i.e., the first recess 512 and the second recess 514), the first recess 512 and the second recess 514 are respectively channel-shaped. The inlet and outlet of the channel are both located on the wall surface (i.e., the first wall surface and the second wall surface), and the channel extends towards the interior of the blade. The blade 502 is integrally formed with the second diffuser plate 118. The first recess 512 and the second recess 514 are machined.

[0054] Figure 7A This is a perspective view of some components of the fourth embodiment of the diffuser 126 of this application. Figure 7B yes Figure 7A A partial cross-sectional view of some components of the fourth embodiment of the diffuser 126 shown. Figures 7A-7B The fourth embodiment of the diffuser 126 shown is similar to Figures 5A-5B The main difference between the third embodiment of the diffuser 126 shown is that, in the third embodiment, the first recess 512 and the second recess 514 are disposed on the blades 502 on both sides of the diffuser channel 132, while in the fourth embodiment, the first recess 512 and the second recess 514 are disposed on the first diffuser plate 116 and the second diffuser plate 118 on both sides of the diffuser channel 132. Specifically, for each diffuser channel 132, the first recess 512 and the second recess 514 are respectively formed extending circumferentially along the centrifugal compressor and extending to the sidewalls of the blades 502 on both sides of the diffuser channel 132. The first recess 512 and the second recess 514 are radially offset from each other in the centrifugal compressor. The specific shapes of the first recess 512 and the second recess 514 can be as follows: Figures 3A-3B The aforementioned surface recess forming the wall can also be as follows: Figures 6A-6BThe channel-like shape is described above. Specifically, each of the first recess 512 and the second recess 514 includes a curved portion 302 and a straight portion 304. The curved portion 302 and the straight portion 304 are connected, and the curved portion 302 is closer to the axis X of the centrifugal compressor than the straight portion 304. In the radial section of the centrifugal compressor, the curved portion 302 is arc-shaped, and the straight portion 304 is a straight line. In another embodiment, the first recess 512 and the second recess 514 also include an additional straight portion 306. The curved portion 302 is disposed between and connected to the straight portion 304 and the additional straight portion 306. In the radial section of the centrifugal compressor, the additional straight portion 306 is a straight line.

[0055] It should be noted that although a specific number of blades are shown in the third and fourth embodiments of the diffuser 126, at least three blades are within the scope of protection of this application.

[0056] Although this disclosure has been described in conjunction with examples of the embodiments outlined above, various alternatives, modifications, variations, improvements, and / or substantially equivalents, whether known or currently or soon to be foreseen, will likely be apparent to those skilled in the art. Furthermore, the technical effects and / or technical problems described herein are exemplary and not limiting; therefore, the disclosures herein may be used to solve other technical problems and have other technical effects and / or can solve other technical problems. Accordingly, the examples of embodiments of this disclosure as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit or scope of this disclosure. Therefore, this disclosure is intended to include all known or previously developed alternatives, modifications, variations, improvements, and / or substantially equivalents.

Claims

1. A diffuser for a centrifugal compressor, characterized in that: The diffuser includes: At least one diffuser channel (132) outputs fluid radially from the centrifugal compressor and is configured to diffuse fluid entering the diffuser, each of the at least one diffuser channel (132) being defined by an upstream wall (201) and a downstream wall (203) disposed opposite to each other perpendicular to the axis of the centrifugal compressor shown; The upstream wall (201) is provided with at least two rings of first recesses (212), each ring of first recesses (212) is formed by recessing from the surface of the upstream wall (201) and is arranged around the axis of the centrifugal compressor; The downstream wall (203) is provided with at least two rings of second recesses (214), each ring of the second recesses (214) is formed by recessing from the surface of the downstream wall (203) and is arranged around the axis of the centrifugal compressor; The first recess (212) and the second recess (214) are arranged radially offset from each other in the centrifugal compressor.

2. The diffuser for a centrifugal compressor according to claim 1, characterized in that: The at least two first recesses (212) and the at least two second recesses (214) are arranged alternately in the radial direction of the centrifugal compressor.

3. The diffuser for a centrifugal compressor according to claim 1, characterized in that: The surface of each of the at least two rings of the first recess (212) and the surface of each of the at least two rings of the first recess (212) include a curved portion (302) and a straight portion (304), the curved portion (302) and the straight portion (304) being connected, the curved portion (302) being closer to the axis of the centrifugal compressor than the straight portion (304); On the radial cross-section of the centrifugal compressor, the curved section (302) is arc-shaped, and the straight section (304) is straight.

4. The diffuser for a centrifugal compressor according to claim 3, characterized in that: The surface of each of the at least two rings of first recesses (212) and the surface of each of the at least two rings of first recesses (212) further include an additional straight section (306), the curved section (302) being disposed between the straight section (304) and the additional straight section (306) and connected to the straight section (304) and the additional straight section (306); In the radial cross-section of the centrifugal compressor, the additional straight section (306) is a straight line.

5. The diffuser for a centrifugal compressor according to claim 1, characterized in that: The inlet (122) of each of the diffuser channels (132) is located at the center of the upstream wall (201), and the outlet (124) of each of the diffuser channels (132) is located at the point where the diameter of the upstream wall (201) and the downstream wall (203) is at its maximum.

6. The diffuser for a centrifugal compressor according to claim 1, characterized in that: The at least one diffuser channel (132) is a diffuser channel (132); The diffuser further includes a first diffuser plate (116) and a second diffuser plate (118) disposed opposite to each other, the first diffuser plate (116) forming the upstream wall (201) and the second diffuser plate (118) forming the downstream wall (203).

7. The diffuser for a centrifugal compressor according to claim 1, characterized in that: The at least one diffuser channel (132) is at least two diffuser channels (132); The diffuser further includes a first diffuser plate (116), a second diffuser plate (118), and at least one partition plate (402). The first diffuser plate (116) and the second diffuser plate (118) are arranged opposite to each other. The first diffuser plate (116) forms the upstream wall surface (201), and the second diffuser plate (118) forms the downstream wall surface (203). The at least one partition (402) is disposed between the first diffuser plate (116) and the second diffuser plate (118) to form the at least two diffuser channels (132); The side of the at least one partition (402) near the first diffuser plate (116) forms the downstream wall (203), and the side of the at least one partition (402) near the second diffuser plate (118) forms the upstream wall (201). The upstream wall (201) is provided with at least two rings of first recesses (212), and the downstream wall (203) is provided with at least two rings of second recesses (214).

8. A diffuser for a centrifugal compressor, characterized in that: The diffuser includes: First diffuser plate (116); A second diffuser plate (118) is disposed on one side of the first diffuser plate (116) and spaced apart from the first diffuser plate (116) by a certain distance; and At least three blades (502) are disposed between the first diffuser plate (116) and the second diffuser plate (118) and abut against the first diffuser plate (116) and the second diffuser plate (118); Two adjacent blades (502), the first diffuser plate (116) and the second diffuser plate (118) define a diffuser channel (132), each of the diffuser channels (132) having an inlet (122) close to the axis of the centrifugal compressor and an outlet (124) away from the axis of the centrifugal compressor. The diffuser channel (132) has at least two first recesses (512) and at least two second recesses (514) on its two opposite walls. The at least two first recesses (512) are arranged along the direction from the inlet (122) to the outlet (124), and the at least two second recesses (514) are arranged along the direction from the inlet (122) to the outlet (124).

9. The diffuser for a centrifugal compressor according to claim 8, characterized in that: The at least three blades (502) are evenly arranged along the circumference of the centrifugal compressor, and the arrangement direction of each of the at least three blades (502) is inclined to the radial direction of the centrifugal compressor.

10. The diffuser for a centrifugal compressor according to claim 8, characterized in that: The at least two first recesses (512) and at least two second recesses (514) are respectively disposed on the first diffuser plate (116) and the second diffuser plate (118) forming the diffuser channel (132), and the at least two first recesses (512) and at least two second recesses (514) extend circumferentially along the centrifugal compressor. The first recess (212) and the second recess (214) are arranged radially offset from each other in the centrifugal compressor; The surface of each of the first recess (512) and the second recess (514) includes a curved portion (302) and a straight portion (304) connected to each other, wherein the curved portion (302) is closer to the axis of the diffuser than the straight portion (304); On the radial cross section of the diffuser, the curved section (302) is arc-shaped, and the straight section (304) is straight.

11. The diffuser for a centrifugal compressor according to claim 10, characterized in that: The surface of each of the first recess (512) and the second recess (514) further includes an additional straight section (306), and the curved section (302) is disposed between the straight section (304) and the additional straight section (306) and connected to the straight section (304) and the additional straight section (306); On the radial cross section of the diffuser, the additional straight section (306) is a straight line.

12. The diffuser for a centrifugal compressor according to claim 8, characterized in that: The at least two first recesses (512) and the at least two second recesses (514) are respectively disposed on the two opposite wall surfaces of the two adjacent blades (502); The surface of each of the first recess (512) and the second recess (514) includes a curved portion (302) and a straight portion (304) connected to each other, wherein the curved portion (302) is closer to the axis of the centrifugal compressor than the straight portion (304); In the axial cross-section of the centrifugal compressor, the curved section (302) is arc-shaped, and the straight section (304) is straight.

13. The diffuser for a centrifugal compressor according to claim 12, characterized in that: The surface of each of the first recess (512) and the second recess (514) further includes an additional straight section (306), and the curved section (302) is disposed between the straight section (304) and the additional straight section (306) and connected to the straight section (304) and the additional straight section (306); In the axial section of the centrifugal compressor, the additional straight section (306) is a straight line.

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