Adjustable centrifugal compressor impeller housing structure

Abstract

The invention discloses an adjustable centrifugal compressor impeller housing structure, which relates to the technical field of centrifugal compressors, and comprises an impeller body, an impeller housing and an air inlet bypass recirculation structure, the impeller housing comprises a front edge impeller housing and a tail edge impeller housing which are sequentially arranged in the axial direction, and an air inlet gap is formed between the front edge impeller housing and the tail edge impeller housing. The front edge impeller housing comprises a plurality of front edge impeller housing units which are evenly distributed in the circumferential direction, the air inlet bypass recirculation structure comprises a recirculation structure outer wall, and the tail edge of the recirculation structure outer wall is fixedly connected with the tail edge impeller housing. A front edge impeller housing fixing structure is fixedly arranged on the outer side wall of each front edge impeller housing unit, fixing structure cavities in one-to-one correspondence with the front edge impeller housing fixing structures are fixedly formed in the outer wall of the recirculation structure, and a radial adjusting mechanism is arranged on each front edge impeller housing fixing structure. According to the invention, the aerodynamic performance requirement can be met, and the aerodynamic noise can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of centrifugal compressors, and in particular to an adjustable impeller cover structure of a centrifugal compressor. Background Art

[0002] Turbocharging technology is widely used in the field of marine low-speed engines due to its advantages such as energy saving, noise reduction and improved economy. However, as turbocharged centrifugal compressors develop towards high pressure ratio and large flow, aerodynamic noise has become a key factor restricting its development.

[0003] The maximum sound power of aerodynamic noise of centrifugal compressor mainly occurs in the impeller. For semi-open centrifugal compressor, the components of aerodynamic noise in the impeller are different under different working conditions. Under low speed conditions, the main components of aerodynamic noise are dipole noise caused by dynamic-static interference between the impeller and the inlet pipe and between the impeller and the diffuser. Under high speed conditions, the main components of aerodynamic noise, in addition to dynamic-static interference noise, also include dipole noise caused by shock waves at the leading edge of the blade.

[0004] In existing research, increasing the tip clearance of the blades can weaken the shock wave at the leading edge of the blades, thereby reducing noise, but there are certain defects. First, it will reduce the performance of the compressor. The increase in the tip clearance will lead to an increase in the tip clearance leakage flow, aggravating the internal flow loss of the impeller, thereby reducing the performance of the compressor; second, the application conditions are limited. Increasing the tip clearance can only simply reduce the aerodynamic noise under high-speed conditions, while for low-speed conditions, it will increase the internal flow loss of the impeller and reduce the compressor performance, and the vortex noise of the compressor will also increase due to the increase in the tip clearance leakage flow.

[0005] Based on the above situation, we propose an adjustable centrifugal compressor impeller cover structure to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0006] The object of the present invention is to provide an adjustable centrifugal compressor impeller cover structure to solve the problems existing in the above-mentioned prior art, which can not only meet the aerodynamic performance requirements but also improve the aerodynamic noise.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides an adjustable impeller casing structure for a centrifugal compressor, comprising an impeller body, an impeller casing and an intake bypass recirculation structure;

[0009] The impeller casing circumferentially wraps the impeller body in the middle;

[0010] The impeller casing comprises a leading edge impeller casing and a trailing edge impeller casing arranged in sequence along the axial direction, an air intake gap is arranged between the leading edge impeller casing and the trailing edge impeller casing, and the gap between the impeller body and the leading edge impeller casing and the trailing edge impeller casing constitutes a centrifugal compressor blade tip gap;

[0011] The leading edge impeller cover shell comprises a plurality of leading edge impeller cover shell units uniformly distributed along the circumferential direction, each of the leading edge impeller cover shell units is sequentially connected end to end along the circumferential direction, and each adjacent two leading edge impeller cover shell units are connected via a labyrinth sealing structure;

[0012] The intake bypass recirculation structure comprises a recirculation structure outer wall, the recirculation structure outer wall is arranged around the outside of the impeller casing, the trailing edge of the recirculation structure outer wall is fixedly connected to the trailing edge impeller casing, a recirculation structure chamber is formed between the recirculation structure outer wall and the impeller casing, and the intake gap communicates with the centrifugal compressor blade tip gap and the recirculation structure chamber;

[0013] A leading edge impeller cover shell fixing structure is fixedly provided on the outer side wall of each leading edge impeller cover shell unit, a fixed structure cavity corresponding to each leading edge impeller cover shell fixing structure is fixedly provided on the outer wall of the recycling structure, the leading edge impeller cover shell fixing structure is nested and connected with the fixed structure cavity, and a radial adjustment mechanism is provided on each leading edge impeller cover shell fixing structure for adjusting the radial position of the leading edge impeller cover shell fixing structure.

[0014] In one embodiment, the leading edge impeller shell includes six leading edge impeller shell units evenly distributed along the circumferential direction.

[0015] In one embodiment, the radial adjustment mechanism includes a screw and a screw knob, the screw is rotatably connected to the outer wall of the recycling structure and is radially fixed relative to the outer wall of the recycling structure, the leading edge impeller cover fixing structure is provided with a threaded hole threadedly connected to the screw, and the screw knob is connected to the radially outward end of the screw and is used to rotate to drive the screw to rotate.

[0016] In one embodiment, a limiting convex ring is fixedly provided on the inner side of the fixed structure cavity, and an annular limiting groove corresponding to the limiting convex ring is provided on the leading edge impeller cover fixing structure, and the limiting convex ring is loosely fitted in the annular limiting groove.

[0017] In one embodiment, the leading edge impeller cover fixing structure comprises an axially inclined elliptical structure or a streamlined structure; the fixing structure cavity is a structural cavity adapted to the shape of the leading edge impeller cover fixing structure.

[0018] In one embodiment, the screw is rotatably connected to the outer wall of the recycling structure via a bearing.

[0019] In one embodiment, the screw knob is sleeved on the screw and connected to the screw via a flat key.

[0020] In one embodiment, the outer wall of the recirculation structure, the trailing edge impeller casing and the fixed structure cavity are an integrated structure.

[0021] In one embodiment, the leading edge impeller cover unit and the leading edge impeller cover fixing structure thereon are an integrated structure.

[0022] Compared with the prior art, the present invention has achieved the following technical effects:

[0023] The adjustable centrifugal compressor impeller cover structure provided by the present invention can change the impeller leading edge blade tip clearance as required, and can reduce the centrifugal compressor aerodynamic noise on the basis of meeting the aerodynamic performance requirements. Under high speed conditions, the leading edge blade tip clearance is increased, thereby weakening the leading edge shock wave and reducing aerodynamic noise. Under low speed conditions, the leading edge blade tip clearance is reduced, reducing the flow loss inside the impeller, improving the compressor performance, and also reducing the vortex noise of the compressor due to the reduction of the blade tip clearance leakage flow.

[0024] The adjustable centrifugal compressor impeller cover structure provided by the present invention can not only be used in high and low speed conditions, but also can be adjusted accordingly according to the change in blade tip clearance caused by deformation of the blades due to the influence of thermal load, centrifugal force and aerodynamic load during the operation of the compressor, so as to improve the performance of the compressor and increase the safety margin of the compressor.

[0025] The present invention starts from changing the blade tip clearance structure itself, adopts a mechanical transmission structure, is relatively safe and reliable, and provides a radial limiting structure (limiting convex ring and annular limiting groove), which can ensure the safe operation of the compressor without problems such as blade wear. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Schematic diagram of the structure of an adjustable centrifugal compressor impeller casing structure in an embodiment of the present invention;

[0028] Figure 2 for Figure 1A partial enlarged schematic diagram of part A;

[0029] Figure 3 for Figure 1 A partial enlarged schematic diagram of part B;

[0030] Figure 4 is a side view of a leading edge impeller casing in an embodiment of the present invention;

[0031] Figure 5 is a cross-sectional view of the outer wall of the recirculation structure and the trailing edge impeller casing in an embodiment of the present invention;

[0032] Figure 6 4 is a cross-sectional view of the radial adjustment mechanism in an embodiment of the present invention.

[0033] In the figure: 1-impeller body, 2-impeller cover, 3-intake bypass recirculation structure, 4-leading edge impeller cover, 5-trailing edge impeller cover, 6-intake gap, 7-leading edge impeller cover unit, 8-labyrinth seal structure, 9-recirculation structure outer wall, 10-recirculation structure chamber, 11-leading edge impeller cover fixing structure, 12-fixed structure cavity, 13-radial adjustment mechanism, 14-screw, 15-screw knob, 16-threaded hole, 17-limiting convex ring, 18-annular limiting groove. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The purpose of the present invention is to provide an adjustable centrifugal compressor impeller cover structure to solve the problems existing in the prior art, which can not only meet the aerodynamic performance requirements but also improve the aerodynamic noise.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 1-Figure 6 As shown, this embodiment provides an adjustable centrifugal compressor impeller cover structure, including an impeller body 1, an impeller cover 2 and an intake bypass recirculation structure 3;

[0038] The impeller casing 2 wraps the impeller body 1 circumferentially in the middle;

[0039] The impeller casing 2 comprises a leading edge impeller casing 4 and a trailing edge impeller casing 5 which are arranged in sequence along the axial direction, an air intake gap 6 is arranged between the leading edge impeller casing 4 and the trailing edge impeller casing 5, and the gap between the impeller body 1 and the leading edge impeller casing 4 and the trailing edge impeller casing 5 constitutes a centrifugal compressor blade tip gap;

[0040] The leading edge impeller cover 4 includes a plurality of leading edge impeller cover units 7 uniformly distributed along the circumferential direction, each leading edge impeller cover unit 7 is sequentially connected end to end along the circumferential direction, and each two adjacent leading edge impeller cover units 7 are connected via a labyrinth sealing structure 8; the labyrinth sealing structure 8 can not only ensure the air tightness of the leading edge impeller cover 4, but also utilize the gap margin of the labyrinth sealing structure 8 to provide space for radial movement of each part of the leading edge impeller cover 4;

[0041] In this embodiment, the leading edge impeller cover 4 includes six leading edge impeller cover units 7 evenly distributed along the circumferential direction, so that the leading edge blade tip clearance changes as evenly as possible in the circumferential direction, and the error between the change of the central leading edge blade tip clearance of each part of the leading edge impeller cover unit 7 and the change of the leading edge blade tip clearance on the labyrinth seal side is only 13.3%;

[0042] The intake bypass recirculation structure 3 includes a recirculation structure outer wall 9, which is arranged around the outside of the impeller casing 2, and the trailing edge of the recirculation structure outer wall 9 is fixedly connected to the trailing edge impeller casing 5, and a recirculation structure chamber 10 is formed between the recirculation structure outer wall 9 and the impeller casing 2, and the intake gap 6 communicates with the centrifugal compressor blade tip gap and the recirculation structure chamber 10;

[0043] The gas enters the compressor impeller flow channel axially through the leading edge impeller cover 4, and the rotating shaft drives the impeller body 1 to rotate. Under the action of centrifugal force and the restriction of the trailing edge impeller cover 5, the blades compress the gas entering the impeller flow channel, converting the mechanical energy into kinetic energy and pressure energy of the gas, and then the gas is discharged at the trailing edge of the impeller.

[0044] The gas blocked between the impeller body 1 and the leading edge impeller cover 4 and the trailing edge impeller cover 5 flows back from the intake gap 6 into the recirculation structure chamber 10, and then mixes with the normal intake air and enters the centrifugal compressor impeller flow channel axially through the leading edge impeller cover 4.

[0045] A leading edge impeller cover shell fixing structure 11 is fixedly provided on the outer side wall of each leading edge impeller cover shell unit 7, and a fixed structure cavity 12 corresponding to each leading edge impeller cover shell fixing structure 11 is fixedly provided on the outer wall 9 of the recycling structure. The leading edge impeller cover shell fixing structure 11 is nested and connected with the fixed structure cavity 12. The nested connection structure is adopted to fix the circumferential position of the leading edge impeller cover shell unit 7, but does not limit the radial movement of the leading edge impeller cover shell unit 7. A radial adjustment mechanism 13 is provided on each leading edge impeller cover shell fixing structure 11 for adjusting the radial position of the leading edge impeller cover shell fixing structure 11.

[0046] In this embodiment, the radial adjustment mechanism 13 includes a screw 14 and a screw knob 15. The screw 14 is rotatably connected to the outer wall 9 of the recycling structure and is radially fixed relative to the outer wall 9 of the recycling structure. A threaded hole 16 threadedly connected to the screw 14 is provided on the leading edge impeller cover fixing structure 11. The screw knob 15 is connected to the radially outward end of the screw 14 and is used to rotate and drive the screw 14 to rotate. The radial position of the leading edge impeller cover unit 7 can be fine-tuned by rotating the screw 14, thereby changing the tip clearance of the leading edge of the blade. Since the tip clearance is a tiny structure, most of them are around 0.65 mm, so the range of variation of the tip clearance is also relatively small. In order to achieve fine radial movement of the leading edge impeller cover unit 7, the thread pitch of the threaded hole 16 and the screw 14 can be reduced, thereby achieving fine radial movement.

[0047] The intake bypass recirculation structure 3 is a fixed structure, which plays the role of fixing the screw 14 and the screw knob 15 in the radial direction, and realizes the function of the radial adjustment mechanism 13. The role of gas recirculation is to use the pressure difference principle to suck the high-pressure and low-speed flow blocked in the blade tip area into the recirculation structure chamber 10 through the intake gap 6, and then mix with the normal intake air and enter the centrifugal compressor impeller flow channel axially through the leading edge impeller shell 4, which can effectively alleviate the surge of the centrifugal compressor, thereby widening the stable operation range of the centrifugal compressor.

[0048] In this embodiment, a limiting convex ring 17 is fixedly provided on the inner side of the fixed structure cavity 12, and an annular limiting groove 18 corresponding to the limiting convex ring 17 is provided on the leading edge impeller cover fixed structure 11, and the limiting convex ring 17 is provided with a clearance fit in the annular limiting groove 18. Through the matching structure of the limiting convex ring 17 and the annular limiting groove 18, the radial movement distance of the leading edge impeller cover unit 7 can be controlled within the safety margin, and the size of the matching clearance can be determined through experiments, which can prevent the blade wear and collision caused by too small leading edge blade tip clearance, and can also prevent the compressor efficiency from being significantly reduced due to too large leading edge blade tip clearance.

[0049] In order not to hinder the flow of gas in the recirculation structure chamber 10, the leading edge impeller cover fixed structure 11 includes an axially inclined elliptical structure or a streamlined structure; the fixed structure cavity 12 is a structural cavity adapted to the shape of the leading edge impeller cover fixed structure 11. In this embodiment, the leading edge impeller cover fixed structure 11 is an elliptical structure. Among them, the streamlined structure includes a wing-shaped structure. The shape of the leading edge impeller cover fixed structure 11 is not limited to the above shape, and is based on the basis of being able to meet the functions of the present invention.

[0050] In this embodiment, the screw rod 14 is rotatably connected to the outer wall 9 of the recycling structure via a bearing.

[0051] In this embodiment, the screw knob 15 is sleeved on the screw 14 and connected to the screw 14 via a flat key.

[0052] In this embodiment, the recirculation structure outer wall 9, the trailing edge impeller casing 5 and the fixed structure cavity 12 are an integrated structure.

[0053] In this embodiment, the leading edge impeller cover unit 7 and the leading edge impeller cover fixing structure 11 thereon are an integrated structure.

[0054] The present invention has six screw knobs 15, and they are controlled by the controller to rotate simultaneously. When the speed sensor detects that the speed of the centrifugal compressor is reduced, it will give a signal to the controller, and the controller will control the six screw knobs 15 to rotate at the same time. The controller can control the rotation of the screw knobs 15 by controlling a rotating motor or a rotating cylinder and other devices, so that the six-part leading edge impeller cover unit 7 moves radially inward at the same time, reducing the leading edge blade tip clearance, thereby reducing the flow loss inside the impeller, improving the performance of the compressor, and also reducing the eddy current noise of the compressor due to the reduction of the blade tip clearance leakage flow. When the speed sensor detects that the speed of the centrifugal compressor increases, it will give a signal to the controller, and the controller will control the six screw knobs 15 to rotate at the same time, so that the six-part leading edge impeller cover unit 7 moves radially outward at the same time, increasing the leading edge blade tip clearance, thereby weakening the leading edge shock wave and reducing the aerodynamic noise.

[0055] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An adjustable centrifugal compressor impeller casing structure, characterized in that: It includes an impeller body, an impeller casing and an intake bypass recirculation structure; The impeller casing circumferentially wraps the impeller body in the middle; The impeller casing comprises a leading edge impeller casing and a trailing edge impeller casing arranged in sequence along the axial direction, an air intake gap is arranged between the leading edge impeller casing and the trailing edge impeller casing, and the gap between the impeller body and the leading edge impeller casing and the trailing edge impeller casing constitutes a centrifugal compressor blade tip gap; The leading edge impeller cover shell comprises a plurality of leading edge impeller cover shell units uniformly distributed along the circumferential direction, each of the leading edge impeller cover shell units is sequentially connected end to end along the circumferential direction, and each adjacent two leading edge impeller cover shell units are connected via a labyrinth sealing structure; The intake bypass recirculation structure comprises a recirculation structure outer wall, the recirculation structure outer wall is arranged around the outside of the impeller casing, the trailing edge of the recirculation structure outer wall is fixedly connected to the trailing edge impeller casing, a recirculation structure chamber is formed between the recirculation structure outer wall and the impeller casing, and the intake gap communicates with the centrifugal compressor blade tip gap and the recirculation structure chamber; A leading edge impeller cover shell fixing structure is fixedly provided on the outer side wall of each leading edge impeller cover shell unit, a fixed structure cavity corresponding to each leading edge impeller cover shell fixing structure is fixedly provided on the outer wall of the recycling structure, the leading edge impeller cover shell fixing structure is nested and connected with the fixed structure cavity, and a radial adjustment mechanism is provided on each leading edge impeller cover shell fixing structure for adjusting the radial position of the leading edge impeller cover shell fixing structure.

2. The adjustable centrifugal compressor impeller casing structure according to claim 1, characterized in that: The leading edge impeller casing includes six leading edge impeller casing units evenly distributed along the circumferential direction.

3. The adjustable centrifugal compressor impeller casing structure according to claim 1, characterized in that: The radial adjustment mechanism includes a screw and a screw knob. The screw is rotatably connected to the outer wall of the recycling structure and is radially fixed relative to the outer wall of the recycling structure. A threaded hole threadedly connected to the screw is provided on the leading edge impeller cover fixing structure. The screw knob is connected to the radially outward end of the screw and is used to rotate to drive the screw to rotate.

4. The adjustable centrifugal compressor impeller casing structure according to claim 1, characterized in that: A limiting convex ring is fixedly provided on the inner side of the fixed structure cavity, and an annular limiting groove corresponding to the limiting convex ring is provided on the leading edge impeller cover fixing structure, and the limiting convex ring is arranged in the annular limiting groove with a clearance fit.

5. The adjustable centrifugal compressor impeller casing structure according to claim 1, characterized in that: The leading edge impeller cover fixed structure comprises an axially inclined elliptical structure or a streamlined structure; the fixed structure cavity is a structural cavity adapted to the shape of the leading edge impeller cover fixed structure.

6. The adjustable centrifugal compressor impeller casing structure according to claim 3, characterized in that: The screw rod is rotatably connected to the outer wall of the recycling structure through a bearing.

7. The adjustable centrifugal compressor impeller casing structure according to claim 3, characterized in that: The screw rod knob is sleeved on the screw rod and connected to the screw rod through a flat key.

8. The adjustable centrifugal compressor impeller casing structure according to claim 1, characterized in that: The outer wall of the recirculation structure, the trailing edge impeller casing and the fixed structure cavity are an integrated structure.

9. The adjustable centrifugal compressor impeller casing structure according to claim 1, characterized in that: The leading edge impeller cover unit and the leading edge impeller cover fixing structure thereon are an integrated structure.

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