An adjustable split-flow slotted vane diffuser and centrifugal compressor thereof

Abstract

The application provides a slotted blade diffuser with adjustable flow distribution and a centrifugal compressor. The centrifugal compressor comprises a volute, an inlet cover, an impeller cover, a blade diffuser and a centrifugal impeller. The blade diffuser is divided into a diffuser casing, adjustable small blades and a diffuser back plate. The diffuser casing is provided with fixed large blades, and the fixed large blades are provided with large blade notches. The adjustable small blades are connected with the diffuser casing and the diffuser back plate through an adjusting structure. The blade diffuser provided by the application has simple structure and is convenient to process. The blade diffuser can expand the stable working flow range while maintaining the high aerodynamic performance of the centrifugal compressor.

Description

Technical Field

[0001] This invention relates to the field of compressor technology, and more particularly to an adjustable split-flow slotted blade diffuser and its centrifugal compressor. Background Technology

[0002] The diffuser is a key pneumatic component of a centrifugal compressor. It enables secondary pressurization of the high-pressure air from the centrifugal impeller and pre-rectification of the air discharged from the volute, playing a crucial role in connecting the two processes.

[0003] Based on the presence or absence of blades, diffusers can be classified into bladeless and bladed types. Compared to bladeless diffusers, the periodically arranged diffuser blades can constrain the flow direction, shorten the flow path, and achieve a smaller radial dimension under the same pressurization requirements. Similarly, under the same diffuser radial dimension, bladed diffusers have stronger pressurization capacity and higher operating efficiency. However, since most bladed diffusers are milled from castings, the diffuser blades and casing are an integral structure, making it impossible to adjust the blade installation angle. Furthermore, with only circumferentially distributed blades of a single chord length and a complete blade surface, positive or negative angles of attack can sometimes occur between the tangential direction of the blade's force surface and the airflow direction, even leading to increased flow separation at large radial positions downstream. This limits the flow range of this advantage to the vicinity of the design conditions. For other non-design conditions, it often exacerbates the aerodynamic performance of the centrifugal compressor, causing premature surge or blockage, thereby reducing the stable operating flow range of the centrifugal compressor.

[0004] In summary, while ensuring sufficient aerodynamic performance of the centrifugal compressor, how to achieve a wider stable operating flow range by delaying surge or blockage of the blade diffuser is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] Based on the aforementioned technical problems, since most conventional blade diffusers are milled from castings, the diffuser blades and casing are an integral structure, making it impossible to adjust the blade installation angle. Furthermore, the presence of only circumferentially distributed blades with a single chord length and complete surface can sometimes result in positive or negative angles of attack between the tangential direction of the blade's contact surface and the airflow direction, even exacerbating flow separation in the downstream radial direction. This limits the advantageous flow range to the vicinity of the design conditions, often worsening the aerodynamic performance of the centrifugal compressor under non-design conditions, leading to premature surge or blockage, thus narrowing the stable operating flow range of the centrifugal compressor. Therefore, this invention provides an adjustable split-flow slotted blade diffuser and its centrifugal compressor. This invention primarily utilizes fixed large blade slotting, taking advantage of the pressure difference between the two contact surfaces to allow part of the airflow to flow from the pressure surface to the suction surface through the slot, reducing the velocity of high Mach number fluids, improving the inlet airflow non-uniformity, and delaying rotational stall, thereby widening the stable operating flow range. By utilizing adjustable small blades that can rotate under different pressure differences on the stressed surfaces, the blade installation angle can be adjusted. This allows for the re-diversion and constraint of secondary flow caused by leakage flow at the large blade slot, reducing losses caused by airflow mixing. Simultaneously, it reduces airflow separation from the blades during flow, minimizing losses caused by boundary layer separation on the suction surface, and further widening the stable operating flow range. This invention features a simple structure and is easy to manufacture, effectively expanding the stable operating flow range while essentially maintaining the high aerodynamic performance of the centrifugal compressor.

[0006] The technical means employed in this invention are as follows:

[0007] An adjustable split-flow slotted blade diffuser includes: a diffuser housing, a plurality of adjustable small blades arranged in a circle, and a diffuser back plate. A receiving space is formed between the diffuser housing and the diffuser back plate. The diffuser housing is provided with a plurality of fixed large blades arranged in a circle within the receiving space. The fixed large blades are provided with large blade slots for airflow to pass through.

[0008] Multiple adjustable small blades are located within the housing space and are spaced and intersected with multiple fixed large blades. The adjustable small blades are connected to the diffuser casing and diffuser back plate through an adjustment structure. The adjustment structure is used to enable the adjustable small blades to rotate on their own under the action of pressure differences on different force surfaces.

[0009] Furthermore, the large blade groove is located on the axial end face of the fixed large blade, at 1 / 4 to 1 / 2 of the chord length, close to the leading edge of the fixed large blade; the depth of the large blade groove is no greater than 1 / 10 of the height of the fixed large blade; and the width of the large blade groove is no greater than 2 / 5 of the chord length of the fixed large blade.

[0010] Furthermore, the inlet cross-sectional area of ​​the large blade slot is larger than the outlet cross-sectional area; the inner and outer boundaries of the large blade slot are single-section straight edges; the downstream extension line of the inner boundary of the large blade slot is located on the pressure surface side of the adjustable small blade.

[0011] Furthermore, the adjustment structure includes a long pin, a housing mounting hole on the diffuser housing, a blade mounting hole on the adjustable blade, and a back plate mounting hole on the diffuser back plate. The blade mounting hole is located radially at the leading edge of the adjustable blade. The housing mounting hole, the blade mounting hole, and the back plate mounting hole are coaxially arranged. The long pin is sequentially inserted into the housing mounting hole, the blade mounting hole, and the back plate mounting hole for connection. The adjustable blade rotates around the long pin through the blade mounting hole.

[0012] Furthermore, the diffuser casing is provided with a limiting groove, and the adjustable blade is provided with a limiting pin near the bottom of the leading edge. The limiting pin is inserted into the limiting groove for connection and can slide back and forth in the limiting groove to form a limiting structure, which is used to limit the circumferential rotation angle range and axial tip clearance of the adjustable blade.

[0013] Furthermore, the casing mounting holes are located circumferentially at the inter-blade positions of the fixed large blades;

[0014] The radial boundary of the limiting groove is a concentric arc of the casing mounting hole, and the rotation angle limited by the limiting groove is no more than 20°.

[0015] The depth of the limiting groove is 0.1~0.2mm less than the height of the limiting pin, and it is used to adjust the axial assembly clearance between the adjustable small blade and the diffuser casing.

[0016] The limiting pin is located radially at 2 / 5 to 4 / 5 of the chord length of the adjustable blade.

[0017] Furthermore, the trailing edges of the fixed large blade and the adjustable small blade are located on the same circumference. The fixed large blade has a low-density airfoil shape and 7 to 9 blades, which are evenly distributed along the circumference.

[0018] The fixed large blade is a full-length blade, meaning the assembly clearance between the diffuser casing and the diffuser back plate is zero.

[0019] Furthermore, the adjustable blade has an airfoil-like shape; the adjustable blades are grouped into one set, with blades of the same type within the set, and the blade chord length is 0.6 to 0.8 times that of the fixed large blade.

[0020] Furthermore, gasket A and gasket B are respectively provided between the casing assembly hole and the blade assembly hole, and between the blade assembly hole and the back plate assembly hole, and the thickness of gasket A and gasket B is 0.1~0.2mm.

[0021] The present invention also provides a centrifugal compressor, including a volute, an inlet shroud, an impeller shroud, a centrifugal impeller, and a blade diffuser;

[0022] The centrifugal impeller is installed in the middle mounting hole of the blade diffuser. The air inlet shroud, impeller shroud and blade diffuser are installed on the volute from bottom to top, and the impeller shroud is fitted over the outside of the centrifugal impeller.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The adjustable-flow slotted blade diffuser and its centrifugal compressor provided by this invention address the issue that when the pressurized air exiting the centrifugal impeller has a super-Mach number velocity, uneven airflow can induce a strong compression wave effect in the downstream diffuser inlet, causing strong airflow discontinuity and further inducing diffuser rotational stall. By using fixed large-blade slotting, the pressure difference between the two pressure surfaces allows part of the airflow to flow from the pressure surface to the suction surface through the slot opening, reducing the velocity of the high-Mach number fluid, improving the inlet airflow unevenness, and delaying rotational stall, thereby widening the stable operating flow range. The adjustable small blades can rotate automatically under different pressure differences to adjust the blade installation angle, which can re-splitting and constrain the secondary flow caused by leakage from the large-blade slot opening, reducing losses caused by airflow mixing, and simultaneously reducing the separation of airflow from the blades during flow, reducing losses caused by boundary layer separation on the suction surface, and further widening the stable operating flow range. In summary, the blade diffuser provided by this invention has a simple structure and is easy to manufacture. It can broaden the stable operating flow range while basically maintaining the high aerodynamic performance of the centrifugal compressor.

[0025] The centrifugal compressor provided by the present invention includes the aforementioned blade diffuser. Since the aforementioned blade diffuser has the aforementioned technical effects, the aforementioned centrifugal compressor should also have the same technical effects, which will not be described in detail here.

[0026] In summary, the technical solution of this invention can solve the problem in the prior art where most blade diffusers are milled from castings, and the diffuser blades and casing are an integral structure, making it impossible to adjust the blade installation angle. Moreover, the presence of only circumferentially distributed blades with a single chord length and complete blade surface can sometimes result in positive or negative angles of attack between the tangential direction of the blade's force surface and the airflow direction, and even exacerbate flow separation in the downstream radial direction. This limits the advantageous flow range to the vicinity of the design conditions, and often worsens the aerodynamic performance of the centrifugal compressor in other non-design conditions, leading to premature surge or blockage, thereby reducing the stable operating flow range of the centrifugal compressor.

[0027] Based on the above reasons, this invention can be widely applied in fields such as air compressors. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is an assembly cross-sectional view of the centrifugal compressor in an embodiment of the present invention. The compressor is a centrifugal compressor with an adjustable split-flow slotted blade diffuser.

[0030] Figure 2 This is another assembly cross-sectional view of the centrifugal compressor in an embodiment of the present invention, with the diffuser blade portion retained.

[0031] Figure 3 This is an assembly cross-sectional view of the blade diffuser in an embodiment of the present invention. The diffuser is a blade diffuser with large and small blades, the large blades being slotted and the small blades being adjustable.

[0032] Figure 4 This is a schematic diagram of the diffuser casing in an embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of the adjustable blade structure in an embodiment of the present invention.

[0034] Figure 6 This is a schematic diagram of the diffuser backplate in an embodiment of the present invention.

[0035] Figure 7 This is a schematic diagram illustrating the rotation method of the adjustable blade in an embodiment of the present invention.

[0036] Figure 8 This is a schematic diagram of the limiting groove in an embodiment of the present invention.

[0037] Figure 9 This is a schematic diagram of blade-related terminology in an embodiment of the present invention.

[0038] In the diagram: 1. Volute; 2. Inlet shroud; 3. Impeller shroud; 4. Blade diffuser; 5. Centrifugal impeller; 6. Diffuser casing; 7. Adjustable small blade; 8. Diffuser back plate; 9. Casing mounting hole; 10. Limiting groove; 11. Fixed large blade; 12. Large blade slot; 13. Limiting pin; 14. Small blade mounting hole; 15. Back plate mounting hole; 16. Gasket A; 17. Gasket B; 18. Long pin. Detailed Implementation

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] This invention provides an adjustable split-flow slotted blade diffuser and its centrifugal compressor, comprising an adjustable split-flow slotted blade diffuser and a centrifugal compressor equipped with the diffuser. The centrifugal compressor includes a volute, an inlet shroud, an impeller shroud, a blade diffuser, and a centrifugal impeller. This invention divides the blade diffuser into a diffuser casing, adjustable small blades, and a diffuser back plate. The diffuser casing has fixed large blades with large blade slots. When the pressurized air flowing out of the centrifugal impeller has a super-Mach number velocity, the uneven airflow will induce a strong compression wave effect in the downstream diffuser inlet channel, causing strong airflow discontinuity and further inducing the diffuser's rotational stall. By slotting the fixed large blades, the pressure difference between the two pressure surfaces allows part of the airflow to flow from the pressure surface to the suction surface through the large blade slots, reducing the velocity of the high-Mach number fluid, improving the unevenness of the inlet airflow, and delaying rotational stall, thereby widening the stable operating flow range. The adjustable small blades can rotate spontaneously under different pressure differences on the stressed surfaces, adjusting the blade installation angle within a certain range. This allows for the re-diversion and constraint of secondary flow caused by leakage flow from the large blade slots, reducing losses caused by airflow mixing. Simultaneously, it reduces airflow separation from the blades during flow, minimizing losses caused by boundary layer separation on the suction surface, and further widening the stable operating flow range. The blade diffuser provided by this invention has a simple structure and is easy to manufacture, maintaining the high aerodynamic performance of the centrifugal compressor while widening the stable operating flow range. This invention can be widely applied to widening the stable operating flow range of centrifugal compressors, especially diffuser stall type centrifugal compressors. To delay stall and maintain performance during unstable flow in the diffuser, this invention introduces a blade diffuser with large and small blades. The large blades are slotted, while the small blades are adjustable in rotation. The large blades utilize channel flow to reduce the high Mach number fluid velocity in front of the blades and delay diffuser stall. The adjustable small blades also reduce downstream mixing losses in the channel secondary flow. This allows the centrifugal compressor to maintain its aerodynamic performance while effectively widening its stable operating flow range.

[0043] Specifically, the present invention provides an adjustable split-flow slotted blade diffuser 4, comprising a diffuser housing 6, multiple adjustable small blades 7, and a diffuser back plate 8. A receiving space is formed between the diffuser housing 6 and the diffuser back plate 8. The diffuser housing 6 is provided with multiple fixed large blades 11 arranged circumferentially within the receiving space. Multiple adjustable small blades 7 are located within the receiving space and are spaced apart from the multiple fixed large blades 11. The diffuser housing 6 is provided with a housing mounting hole 9, a limiting groove 10, and fixed large blades 11, with large blade slots 12 on the fixed large blades 11. The adjustable small blades 7 are multiple independent blades, each provided with a limiting pin 13 and a small blade mounting hole 14. The diffuser back plate 8 is provided with a back plate mounting hole 15.

[0044] Preferably, the casing mounting hole 9, the blade mounting hole 14, and the back plate mounting hole 15 are corresponding (coaxially arranged), spaced apart by shims A16 and B17, and then assembled by long pins 18. The adjustable blade 7 rotates around the long pins 18 through the blade mounting hole 14.

[0045] Preferably, the limiting groove 10 and the limiting pin 13 are in a mating relationship. The limiting pin 13 is inserted into the limiting groove 10 for mating and connection and can slide back and forth in the limiting groove 10 to form a limiting structure, which is used to limit the circumferential rotation angle range and axial tip clearance of the adjustable blade 7.

[0046] Preferably, the casing mounting hole 9 is located circumferentially at the inter-blade positions of the fixed large blade 11.

[0047] Preferably, the radial boundary of the limiting groove 10 is a concentric arc of the housing mounting hole 9, and the rotation angle limited by the limiting groove 10 is no more than 20°.

[0048] Preferably, the depth of the limiting groove 10 is 0.1~0.2mm less than the height of the limiting pin 13, and is used to adjust the axial assembly clearance between the adjustable small blade 7 and the diffuser casing 6.

[0049] Preferably, the fixed large blade 11 has an airfoil-like blade shape and is evenly distributed circumferentially. The fixed large blade 11 is a low-density blade with 7 to 9 blades.

[0050] Preferably, the fixed large blade 11 is a full-blade high blade, that is, the assembly gap between the diffuser casing 6 and the diffuser back plate 8 is zero.

[0051] Preferably, the large blade groove 12 is located on the axial end face of the fixed large blade. The large blade groove 12 is located at 1 / 4 to 1 / 2 of the chord length of the fixed large blade. The depth of the large blade groove 12 is not greater than 1 / 10 of the height of the fixed large blade 11; the width of the large blade groove 12 is not greater than 2 / 5 of the chord length of the fixed large blade 11.

[0052] Preferably, the inlet cross-sectional area of ​​the large blade groove 12 is larger than the outlet cross-sectional area; the inner and outer boundaries of the large blade groove 12 are single-section straight edges; the downstream extension line of the inner boundary of the large blade groove 12 is located on the pressure surface side of the adjustable small blade 7.

[0053] Preferably, the adjustable blade 7 has an airfoil-shaped blade; the adjustable blade 7 is in groups of one, with blades of the same type in each group, and the blade chord length is 0.6 to 0.8 times that of the fixed large blade 11.

[0054] Preferably, the blade assembly hole 14 is located radially at the leading edge of the adjustable blade 7.

[0055] Preferably, the limiting pin 13 is located radially at 2 / 5 to 4 / 5 of the chord length of the adjustable blade 7.

[0056] Preferably, the trailing edges of the fixed large blade 11 and the adjustable small blade 7 are located on the same circumference.

[0057] Preferably, the thickness of gasket A16 and gasket B17 is 0.1~0.2mm.

[0058] Example 1

[0059] This invention discloses an adjustable split-flow slotted blade diffuser and its centrifugal compressor. It has a simple structure and is easy to manufacture, effectively widening its stable operating flow range while essentially maintaining the high aerodynamic performance of the centrifugal compressor.

[0060] The structure of the centrifugal compressor in this embodiment of the invention is as follows: Figure 1 , Figure 2 As shown. It includes a volute 1, an intake shroud 2, an impeller shroud 3, a blade diffuser 4, and a centrifugal impeller 5.

[0061] The structure of the blade diffuser 4 is as follows Figure 3 As shown, the blade diffuser 4 includes a diffuser casing 6, adjustable small blades 7, and a diffuser back plate 8.

[0062] The structure of diffuser casing 6 is as follows Figure 4 As shown, the diffuser casing 6 is provided with casing assembly hole 9, limit groove 10, fixed large blade 11, and large blade slot 12, wherein the large blade slot is located on the fixed large blade 11.

[0063] The structure of the adjustable small blade 7 is as follows Figure 5 As shown, the adjustable blade 7 is equipped with a limit pin 13 and a blade assembly hole 14.

[0064] The structure of diffuser backplate 8 is as follows Figure 6 As shown, the diffuser backplate 8 is provided with a backplate mounting hole 15.

[0065] The rotation method of the adjustable small blade 7 is as follows Figure 7 As shown, the long pin 18 sequentially connects the casing mounting hole 9, the small blade mounting hole 14, and the back plate mounting hole 15, allowing the adjustable small blade 7 to rotate around the long pin 18, and the two sides of the small blade mounting hole 14 are spaced apart by the shims 16 and 17.

[0066] The structure of the limiting groove 10 is as follows Figure 8 As shown, the rotation range of the adjustable blade 7 is limited by the cooperation of the limiting groove 10 and the limiting pin 13.

[0067] Related terms for blades, such as Figure 9As shown, the blade has two surfaces: a pressure surface and a suction surface. The pressure on the pressure surface is greater than the pressure on the suction surface. Following the gas flow direction, the intersection of the first pressure surface encountered is the leading edge, and the intersection of the last pressure surface encountered is the trailing edge. The slot on the pressure surface is the inlet, and the slot on the suction surface is the outlet. In the large blade slot 12, the boundary closer to the leading edge is the inner boundary, and the boundary farther from the leading edge is the outer boundary. After the fixed large blade 11 is equipped with the large blade slot 12, the airflow flows into the large blade slot 12 from the inlet on its pressure surface and then flows out from the outlet on its suction surface. The adjustable small blade can automatically adjust its blade installation angle according to the difference in distribution between the upstream mainstream airflow and the secondary airflow at the slot.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An adjustable split-flow slotted blade diffuser, characterized in that, include: The diffuser housing (6), multiple adjustable small blades (7) arranged in a circle, and a diffuser back plate (8) are provided. A receiving space is formed between the diffuser housing (6) and the diffuser back plate (8). Multiple fixed large blades (11) are arranged in a circle within the receiving space. Large blade slots (12) are provided on the fixed large blades (11). Through the large blade slots (12), the pressure difference between the two force surfaces is used to make part of the airflow flow from the pressure surface to the suction surface through the slots, thereby reducing the flow velocity of high Mach number fluids, improving the non-uniformity of the inlet airflow, delaying the rotational stall, and thus widening the stable working flow range. Multiple adjustable small blades (7) are located in the accommodating space and are arranged intermittently with multiple fixed large blades (11). The adjustable small blades (7) are connected to the diffuser casing (6) and the diffuser back plate (8) through the adjustment structure. The adjustment structure is used to enable the adjustable small blades (7) to rotate on their own under the action of pressure difference on different force surfaces, so as to adjust the blade installation angle, re-divide and constrain the secondary flow caused by leakage flow from the large blade slot (12), reduce the loss caused by airflow mixing, reduce the separation of airflow and blade in the flow, reduce the loss caused by boundary layer separation on the suction surface, and further broaden the stable working flow range. The large blade slot (12) is located on the axial end face of the fixed large blade (11), and the large blade slot (12) is located at 1 / 4 to 1 / 2 of the chord length of the fixed large blade (11), close to the leading edge of the fixed large blade (11); the cross-sectional area of ​​the air inlet of the large blade slot (12) is larger than the cross-sectional area of ​​the air outlet; the inner and outer boundaries of the large blade slot (12) are straight edges in one section; the downstream extension line of the inner boundary of the large blade slot (12) is located on the pressure surface side of the adjustable small blade (7); The adjustment structure includes a long pin (18), a housing assembly hole (9) provided on the diffuser housing (6), a small blade assembly hole (14) provided on the adjustable small blade (7), and a back plate assembly hole (15) provided on the diffuser back plate (8). The small blade assembly hole (14) is located radially at the leading edge of the adjustable small blade (7). The housing assembly hole (9), the small blade assembly hole (14), and the back plate assembly hole (15) are coaxially arranged. The long pin (18) is inserted into the housing assembly hole (9), the small blade assembly hole (14), and the back plate assembly hole (15) in sequence for connection. The adjustable small blade (7) rotates around the long pin (18) through the small blade assembly hole (14). The casing mounting hole (9) is located circumferentially at the inter-blade position of the fixed large blade (11); The trailing edges of the fixed large blade (11) and the adjustable small blade (7) are located on the same circumference.

2. The adjustable split-flow slotted blade diffuser according to claim 1, characterized in that, The depth of the large blade groove (12) is not greater than 1 / 10 of the height of the fixed large blade (11); the width of the large blade groove (12) is not greater than 2 / 5 of the chord length of the fixed large blade (11).

3. The adjustable split-flow slotted blade diffuser according to claim 1, characterized in that, The diffuser casing (6) is provided with a limiting groove (10), and the adjustable blade (7) is provided with a limiting pin (13) near the bottom of the leading edge. The limiting pin (13) is inserted into the limiting groove (10) for connection and can slide back and forth in the limiting groove (10) to form a limiting structure, which is used to limit the circumferential rotation angle range and axial blade tip clearance of the adjustable blade (7).

4. The adjustable split-flow slotted blade diffuser according to claim 3, characterized in that, The radial boundary of the limiting groove (10) is the concentric arc of the casing mounting hole (9), and the rotation angle limited by the limiting groove (10) is no greater than 20°. The depth of the limiting groove (10) is 0.1~0.2mm less than the height of the limiting pin (13), and is used to adjust the axial assembly clearance between the adjustable small blade (7) and the diffuser casing (6). The limiting pin (13) is located radially at 2 / 5 to 4 / 5 of the chord length of the adjustable blade (7).

5. The adjustable split-flow slotted blade diffuser according to claim 1, characterized in that, The fixed large blade (11) has a low-density airfoil shape, with 7 to 9 blades evenly distributed along the circumference; The fixed large blade (11) is a full-blade high blade, that is, the assembly gap between the diffuser casing (6) and the diffuser back plate (8) is zero.

6. The adjustable split-flow slotted blade diffuser according to claim 1, characterized in that, The adjustable blade (7) has an airfoil-shaped blade; the adjustable blade (7) is in groups of one, with blades of the same type in each group, and the chord length of the adjustable blade (7) is 0.6 to 0.8 times that of the fixed blade (11).

7. The adjustable split-flow slotted blade diffuser according to claim 1, characterized in that, Gasket A (16) and gasket B (17) are respectively provided between the casing assembly hole (9) and the blade assembly hole (14), and between the blade assembly hole (14) and the back plate assembly hole (15). The thickness of gasket A (16) and gasket B (17) is 0.1~0.2mm.

8. A centrifugal compressor, characterized in that, It includes a volute (1), an air intake shroud (2), an impeller shroud (3), a centrifugal impeller (5), and a blade diffuser (4) as described in any one of claims 1-7; The centrifugal impeller (5) is installed in the middle mounting hole of the blade diffuser (4). The air inlet shroud (2), impeller shroud (3) and blade diffuser (4) are installed on the volute (1) from bottom to top. The impeller shroud (3) is fitted over the centrifugal impeller (5).

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