A front-mounted centrifugal impeller cover

Abstract

The present application relates to the technical field of small and medium-sized aero-engine compressor, and particularly discloses a front-mounted centrifugal impeller cover, which comprises a flared cover body, a mounting flange is arranged on the outer wall of the flared head of the cover body, a protrusion is arranged on the outer wall of the flared tail of the cover body, a limiting step is arranged on the protrusion close to the flared tail, and a stable-pressure anti-scratching concave cavity is arranged on the inner wall of the middle part of the cover body. The front-mounted centrifugal impeller cover is applicable to the application occasions with high requirements for the clearance of the centrifugal impeller of the small and medium-sized aero-engine compressor, high requirements for compactness and lightness, high requirements for convenience in assembly and disassembly, high requirements for process wrench space, high requirements for heat dissipation at the outlet of the centrifugal impeller, high requirements for deformation coordination control, and high requirements for safety and stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of small and medium-sized aero-engine compressor, in particular to a front-mounted centrifugal impeller cover. BACKGROUND

[0002] The impeller cover of the existing small and medium-sized aero-engine compressor adopts a structure form of middle-mounted installation or rear-mounted installation, such as Figure 11 and Figure 12 The structure form of middle-mounted installation has relatively uniform deformation along the flow passage, and has relatively good heat dissipation at the cold end and the hot end. However, under the same conditions, the inherent frequency is relatively low, and the risk of critical passage is relatively high. Due to the limitation of the matching connecting casing structure and other factors, the overall mass is generally relatively large, and the number of disassembly and assembly related parts is relatively large. The risk of scraping is relatively small compared with the structure form of rear-mounted installation, but it is relatively large compared with the structure form of front-mounted installation.

[0003] The structure form of rear-mounted installation has small outlet deformation and small equivalent error of outlet gap calculation. The heat dissipation at the cold end is good, and the heat dissipation at the hot end is poor. However, under the same conditions, the overall mass is also relatively large, and the risk of scraping is large. Therefore, a rear-mounted form with elastic structure is often used, as shown in Figure 13 . SUMMARY

[0004] The purpose of the present application is to provide a front-mounted centrifugal impeller cover, which can be applied to application occasions with relatively high requirements for the size of the tail part of the impeller cover, relatively compact and light structure, relatively convenient and flexible installation and disassembly, high heat dissipation requirements at the outlet of the centrifugal impeller, good deformation coordination control requirements, and high safety and reliability requirements.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] A front-mounted centrifugal impeller cover, comprising an expanded port-shaped cover body, an installation flange is arranged on the outer wall of the expanded port head of the cover body, a protrusion is arranged on the outer wall of the expanded port tail of the cover body, the protrusion is smoothly connected with the outer wall of the cover body near the end of the installation flange through a concave arc surface, a limiting step is arranged at the position close to the expanded port tail of the protrusion, and a stable pressure anti-scraping concave cavity is arranged on the inner wall of the middle part of the cover body.

[0007] In a further scheme, the height of the protrusion is less than the height of the limiting step.

[0008] In a further scheme, the protrusion is an arc-shaped protrusion or a trapezoidal protrusion, a concave arc surface is formed between one slope of the trapezoidal protrusion and the outer wall of the cover body, another slope of the trapezoidal protrusion is connected with the upper end surface of the limiting step, a concave arc surface is formed between one side of the arc-shaped protrusion and the outer wall of the cover body, and the other side of the arc-shaped protrusion is connected with the limiting step through an arc surface.

[0009] In a further aspect, the stable pressure anti-scratch concave cavity section layer comprises a wear-resistant scraping layer, a pre-warning layer and a base layer arranged in sequence, the wear-resistant scraping layer is used to rub against the turbine blade, and the pre-warning layer is used to give a warning after the wear-resistant scraping layer is worn.

[0010] In a further aspect, the thickness of the pre-warning layer is 0.02-0.15 mm, and the thickness of the wear-resistant scraping layer is 0.62±0.04 mm.

[0011] In a further aspect, the stable pressure anti-scratch concave cavity has a drainage surface near one end of the limiting step, and an included angle a is formed between the drainage surface and a vertical surface, and the included angle a is smaller than a tail angle b of the stable pressure anti-scratch concave cavity.

[0012] In a further aspect, the included angle a ranges from 10±2°.

[0013] In a further aspect, the cover body flared head outer wall has a limiting slot, and the limiting slot is located at an end of the cover body away from the limiting step.

[0014] In a further aspect, the mounting flange has a waist-shaped mounting hole, and the waist-shaped mounting hole has a larger hole diameter at one end than at the other end.

[0015] In a further aspect, the larger hole diameter end of the waist-shaped mounting hole has a notch, the mounting flange and the flared head outer wall are smoothly connected through a circular arc, and the mounting flange and the flared head outer wall are smoothly connected through a circular arc.

[0016] Advantages of the present application:

[0017] The present application has the advantages that: the mounting flange is arranged in front, the rear end of the impeller cover is freely connected, the rear end (hot end) has good heat dissipation, the surge margin is increased to a certain extent, the flared design can effectively guide and expand the inlet air, the tail protrusion can effectively coordinate and control the overall thermal deformation of the cover body, the tail structure complexity is reduced, the dynamic characteristics of the impeller cover are optimized, the limiting step can abut against the corresponding structure on the matched casing, thereby limiting the rear movement of the entire centrifugal impeller cover and limiting the extension size of the tail end thermal deformation, the stable pressure anti-scratch concave cavity is arranged, the inter-blade clearance between the impeller cover and the impeller is appropriately increased, the clearance between the impeller cover and the centrifugal impeller at medium and low speeds is increased, the surge margin at medium and low speeds is improved, the medium and low speeds are ensured, especially the critical through pressure is stable, the design task speed is reached, the cavity disappears, and the preset (clearance state) performance at high speed is ensured. Moreover, when local friction occurs, the wear-resistant scraping layer of the stable pressure anti-scratch concave cavity can enhance the wear resistance. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 is a three-dimensional schematic view of a front-mounted centrifugal impeller cover in an embodiment of the present application;

[0020] Figure 2 is an axial cross-sectional schematic view of a front-mounted centrifugal impeller cover in an embodiment of the present application;

[0021] Figure 3 is an enlarged schematic view of the first and last parts of the stable pressure anti-scratching concave cavity in an embodiment of the present application;

[0022] Figure 4 is a connection schematic view at the drainage surface in an embodiment of the present application;

[0023] Figure 5 is a local cut schematic view at the stable pressure anti-scratching concave cavity in an embodiment of the present application;

[0024] Figure 6 is a schematic view when the mounting flange is installed in an embodiment of the present application;

[0025] Figure 7 is a front view schematic view of a front-mounted centrifugal impeller cover along the engine axial direction in an embodiment of the present application;

[0026] Figure 8 is a schematic view of a mounting flange with a notch in an equivalent example of the present application;

[0027] Figure 9 is a front view schematic view of a front-mounted centrifugal impeller cover along the engine axial direction in the related art;

[0028] Figure 10 is a local schematic view at two kinds of arc-shaped protrusions c and d in some embodiments of the present application;

[0029] Figure 11 is a schematic view of a rear-mounted centrifugal impeller cover in the related art;

[0030] Figure 12 is a schematic view of a centrally-mounted centrifugal impeller cover in the related art;

[0031] Figure 13 is a schematic view of a rear-mounted centrifugal impeller cover with an elastic structure in the related art;

[0032] Figure 14is an axial section view of a front-mounted centrifugal impeller cover in the related art;

[0033] In the figure: 1, mounting flange; 10, waist-shaped mounting hole; 101, notch; 2, protrusion; 3, limiting step; 4, stable pressure anti-scratch concave cavity; 41, wear-resistant scratch layer; 42, early warning layer; 43, base layer; 5, drainage surface; 6, limiting notch. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0035] As shown in Figure 1 , a front-mounted centrifugal impeller cover includes a flared cover body, a wear-resistant scratch layer, and an early warning layer. The flared head outer wall of the cover body has a mounting flange 1. The flared tail outer wall of the cover body has a protrusion 2. The protrusion 2 is smoothly connected to the outer wall of the cover body near the end of the mounting flange 1 through a concave surface, as shown in Figure 2 . The protrusion 2 has a limiting step 3 near the flared tail. The inner wall of the middle part of the cover body has a stable pressure anti-scratch concave cavity 4.

[0036] As shown in Figure 1 and Figure 2 , the flared cover body can facilitate air flow drainage. The mounting flange 1 can be used for quick mounting at the front end of the cover body. This front-mounted fixing can make the rear end free and not be limited by fixing, increase the deformation compensation space, and increase the surge margin to a certain extent. The rear end can be prevented from moving too much by the limiting step 3. The main dimensions of the tail part, such as the mounting size and the working size, are limited, which can avoid the occurrence of scratching between the tail part and the impeller when the centrifugal impeller cover is deformed by heat. The strength of the tail part of the cover body can be enhanced by the protrusion 2, and the deformation amount of the tail part of the cover body can be reduced, without affecting other dynamic characteristics. The thrust characteristics can also be increased to a certain extent. The stable pressure anti-scratch concave cavity 4 can increase the deformation margin of the middle part of the impeller cover and increase the distance from the impeller. At the same time, the stable pressure anti-scratch concave cavity 4 can also strengthen the air intake. Once the impeller is scratched, the wear-resistant coating can also improve the wear-resistant characteristics. The stable pressure anti-scratch concave cavity is arranged in the middle part. When working at high temperature, the middle part of the cover body is limited by the mounting flange 1 and the limiting step 3 at both ends, and the gap between the middle part of the cover body and the impeller is reduced. The stable pressure anti-scratch concave cavity 4 can compensate for the reduced gap value to the maximum extent.

[0037] Those skilled in the art should also realize that the cross-sectional view of the front-mounted centrifugal impeller cover can also be as shown in Figure 14As shown, the tail end is wedge-shaped, but the shape has insufficient limiting ability and the tail end has insufficient diffuser effect.

[0038] According to the working principle described above, some embodiments or implementations are provided, in which the height of the protrusion 2 is less than the height of the limiting step 3. In this way, when the tail of the cover body deforms or moves backward, the limiting step 3 and the corresponding structure on the casing first contact to limit the deformation size of the tail, preventing the gap from increasing. Since the limiting step 3 is L-shaped, the deformation direction of the impeller cover can be well limited to the vertical direction or away from the impeller direction, thereby maximizing the avoidance of friction with the impeller.

[0039] In some embodiments, the protrusion 2 can be an arc-shaped protrusion, such as Figure 10 As shown in the two arc-shaped protrusion local example diagrams represented by c and 10d, one side of the arc-shaped protrusion forms a concave arc surface with the outer wall of the cover body, and the other side of the arc-shaped protrusion is connected to the limiting step 3 through an arc surface, such as Figure 2 As shown, the protrusion 2 is a trapezoidal protrusion, one side of the trapezoidal protrusion forms a concave arc surface with the outer wall of the cover body through a rounded corner, and the other side of the trapezoidal protrusion is connected to the upper end surface of the limiting step 3 through the other side of the trapezoidal protrusion. This can well facilitate the flow of air and avoid turbulence.

[0040] As shown in the two arc-shaped protrusion local example diagrams represented by c and 10d, one side of the arc-shaped protrusion forms a concave arc surface with the outer wall of the cover body, and the other side of the arc-shaped protrusion is connected to the limiting step 3 through an arc surface, such as Figure 5 As shown, the cross-sectional layer of the stable pressure anti-scratch concave cavity 4 includes a wear-resistant scraping layer 41, a pre-warning layer 42, and a base layer 43 arranged in sequence, the wear-resistant scraping layer 41 is used to rub against the turbine blade, and the pre-warning layer 42 is used to issue a warning after the wear-resistant scraping layer 41 is worn. The wear-resistant scraping layer 41 is used to improve its wear resistance, and the pre-warning layer 42 is arranged to facilitate observation and timely warning. In order to improve the installation of the impeller cover, accommodate accumulated errors, and insufficient concentricity, this three-layer structure is more conducive to coordinating deformation and uniformity, and is also conducive to sulfuric acid anodic hardening of the coating.

[0041] The thickness of the pre-warning layer 42 is 0.02-0.15mm, and the thickness of the wear-resistant scraping layer 41 is 0.62±0.04mm. This thickness can not affect the weight of the cover body, and can cause the cover body to have a controlled benign deformation.

[0042] As shown in the two arc-shaped protrusion local example diagrams represented by c and 10d, one side of the arc-shaped protrusion forms a concave arc surface with the outer wall of the cover body, and the other side of the arc-shaped protrusion is connected to the limiting step 3 through an arc surface, such as Figure 4 As shown, the stable pressure anti-scratch concave cavity 4 has a flow guide surface 5 near one end of the limiting step 3, and the flow guide surface 5 has a wide angle a with the vertical surface, and the wide angle a is less than the tail angle b of the stable pressure anti-scratch concave cavity 4. The structure of the wide angle a has a certain contraction and rectification, and has a diffuser effect, which can enhance the dynamic characteristics of the compressor.

[0043] The angular range of the wide angle a is 10 ± 2°. This angular range has a good pressure expansion effect, which can avoid the problem that when the wide angle is too large, the clearance between the limiting step 3 and the impeller is too small, and excessive deformation is likely to occur after high temperature, resulting in wear between the impeller and the limiting step. When the wide angle is too small, the effect of flow guiding and pressure expansion cannot be achieved.

[0044] As Figure 2 shown, there is a limiting notch 6 on the outer wall of the flared head of the cover body. The limiting notch 6 is located at one end of the cover body far from the limiting step 3. The limiting notch 6 can be used for further assembly and limiting with the casing and other components.

[0045] As Figure 7 shown, the mounting flange 1 has an oval mounting hole 10, and the aperture at one end of the oval mounting hole 10 is larger than that at the other end. The aperture of the larger-diameter end is larger than the maximum size of the mounting surface of the mounting bolt. After the larger-diameter end passes through the maximum size of the mounting surface of the mounting bolt or the maximum size of the mounting tool, the cover body can be rotated so that the screw part is located at the smaller-diameter end, and then the nut can be tightened by a tool. This can avoid the need to use a specific tool to drive the screw to align with the mounting hole on the casing, facilitating the assembly of the cover body.

[0046] As Figure 8 , there is a notch 101 at the larger-diameter end of the oval mounting hole 10; the mounting flange 1 and the outer wall of the flared head are smoothly connected by an arc. The notch 101 can make it more convenient for the nut or the pin part to enter.

[0047] Refer to Figure 7 shown, the mounting flange can be integrally arranged with the cover body itself in a uniformly distributed or non-uniformly distributed form. Generally, the radial edge thickness dm satisfies 2 < dm < 2R, where R is the radius of the smaller-diameter end of the oval mounting hole. In addition, the oval mounting hole is convenient for alignment and has a good misalignment prevention effect, and more base material with mass can be cut and removed.

[0048] When using the conventional impeller cover mounting edge as Figure 9 shown, it is often limited by the structure of the impeller cover itself, and often requires the use of shorter mounting bolts, or as Figure 6 shown, a professional special tool is used for disassembly and assembly. When disassembling and assembling, the current position indicated by the dotted line contour needs to be moved backward to the solid line part to avoid interference of the mounting bolt, but the moving limit is very small. The short bolts not only reduce the connection strength, but the disassembly and assembly operations of the special tool complicate the relevant technological processes.

[0049] By adopting the solution of the present invention, the bolt can be installed first, then the impeller cover can be screwed in, and then the bolt can be tightened. This not only ensures the connection strength but also simplifies the use of the special tool.

[0050] To ensure that there are no reverse steps between adjacent parts of the flow channel impeller, when adjusting the clearance of the compressor impeller, it is often necessary to move the installation position of the impeller cover backward by a certain amount. However, excessive backward movement may cause a certain degree of scraping risk, while adopting the solution of the present invention as Figure 2The tail-end limiting step 3 shown in the diagram has a one-way limiting function, which effectively prevents excessive displacement during impeller shroud installation and avoids the risk of insufficient flatness and impeller scraping and jamming caused by calculation and machining errors. Furthermore, because this structure uses a one-way limiting structure, sufficient deformation margin is maintained in the forward axial direction. Even in the event of minor surges or eccentric scraping that have not yet occurred, the entire compressor still maintains high safety and reliability.

[0051] Because the temperature varies along the airflow direction and increases gradually with the flow path, the deformation of each micro-element segment differs under the same expansion coefficient. If a non-uniform wall thickness design is used to prevent deformation, the cumulative error in deformation calculation is large, and the calculation and machining processes are complex. However, the protrusion at the tail of this invention not only better controls the overall deformation but also optimizes the dynamic characteristics of the impeller cover to a certain extent.

[0052] The voltage-stabilizing and scratch-resistant cavity structure involved in this invention, such as... Figure 3 As shown. At low and medium speeds, it improves the surge margin to a certain extent and enhances the smoothness of critical passage. For centrifugal compressors, under otherwise identical conditions, a larger clearance results in a higher surge margin and smoother passage to the critical point. The inlet height of the pressure-stabilizing and anti-scraping cavity is generally taken as D1 = 0.13 ± 0.02 mm, and the outlet height is generally taken as D2 = 0.33 ± 0.02 mm. The dimensions of the substrate layer 43 depend on the design requirements; the bottom warning layer 42 is generally taken as 0.02-0.15 mm, and the scraping containment layer is generally taken as 0.62 ± 0.04 mm.

[0053] like Figure 5 As shown, this pressure-stabilizing and anti-scratch cavity structure can also adjust the gap between the impeller shroud and the impeller by changing the shape of the different materials in the wear-resistant layer 41, the warning layer 42 and the substrate layer 43 at its cross-section, which have different coefficients of linear expansion. For example, the material of the wear-resistant layer 41 can be an aluminum-silicon layer and the material of the substrate layer 43 can be stainless steel. The two materials have different coefficients of linear expansion. At low speeds, a tiny annular cavity is formed between the impeller shroud and the impeller, which improves the surge margin and the smoothness of critical passage. As the speed increases, due to the difference in the coefficients of linear expansion, the cavity gradually decreases. When the design target speed is reached, the cavity disappears, thus ensuring the preset (gap state) performance at high speeds.

[0054] like Figure 4 As shown, this invention relates to a wide-angle 'a' structure for the tail drainage surface 5. It has a certain effect of contraction rectification and pressure diffusion. Generally, the wide angle A is taken as 10 ± 2°, and the chosen tail drainage wide angle A should be smaller than the tail angle of the voltage-stabilizing and anti-scratching cavity structure.

[0055] Through the above comparison and explanation, it can be concluded that the present invention has the following significant advantages:

[0056] 1. More compact and lightweight structural design features;

[0057] 2. Easier and more convenient disassembly and assembly features;

[0058] 3. Limit control for scraping caused by process errors, etc., and the front-mounted installation method results in a smaller flange mounting radius and better rigidity;

[0059] 4. Higher one-way security margin;

[0060] 5. Higher deformation control margin;

[0061] 6. Meets certain requirements for improved safety in terms of surge and anti-scraping properties;

[0062] 7. Meets certain requirements for stable flow and improved performance;

[0063] 8. Certain deformation coordination and stability characteristics of multi-layered structure.

[0064] It should be noted that the terms "first," "second," etc., used in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein.

[0065] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0066] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A front-mounted centrifugal impeller cover, characterized in that, The cover includes a flared head with a mounting flange (1) on the outer wall of the flared head and a protrusion (2) on the outer wall of the flared tail. The protrusion (2) is smoothly connected to the outer wall of the cover near the mounting flange (1) through a concave arc surface. The protrusion (2) has a limiting step (3) near the tail of the flared head. The inner wall of the middle part of the cover has a pressure-stabilizing and anti-scratch cavity (4). The height of the protrusion (2) is less than the height of the limiting step (3).

2. The front-mounted centrifugal impeller cover according to claim 1, characterized in that, The protrusion (2) is an arc-shaped protrusion or a trapezoidal protrusion. One inclined surface of the trapezoidal protrusion forms a concave arc surface with the outer wall of the cover through a rounded corner. The upper end face of the trapezoidal protrusion is connected to the upper end face of the limiting step (3) through another inclined surface of the trapezoidal protrusion. One side of the arc-shaped protrusion forms a concave arc surface with the outer wall of the cover. The other side of the arc-shaped protrusion is connected to the limiting step (3) through an arc surface.

3. The front-mounted centrifugal impeller cover according to claim 1, characterized in that, The pressure-stabilizing and anti-scratching cavity (4) cross-sectional layer includes a wear-resistant scraping layer (41), an early warning layer (42) and a substrate layer (43) arranged in sequence. The wear-resistant scraping layer (41) is used to generate friction with the turbine blades, and the early warning layer (42) is used to issue a warning after the wear-resistant scraping layer (41) is worn.

4. A front-mounted centrifugal impeller cover according to claim 3, characterized in that, The thickness of the warning layer (42) is 0.02-0.15mm, and the thickness of the wear-resistant scraping layer (41) is 0.62±0.04mm.

5. A front-mounted centrifugal impeller cover according to claim 1, characterized in that, The pressure-stabilizing and anti-scratching cavity (4) has a drainage surface (5) at one end near the limiting step (3). The drainage surface (5) and the vertical surface have a wide angle a, which is smaller than the tail angle b of the pressure-stabilizing and anti-scratching cavity (4).

6. A front-mounted centrifugal impeller cover according to claim 5, characterized in that, The angle range of the wide-angle a is 10±2°.

7. A front-mounted centrifugal impeller cover according to claim 1, characterized in that, The outer wall of the flared head of the cover has a limiting groove (6), which is located at the end of the cover away from the limiting step (3).

8. A front-mounted centrifugal impeller cover according to claim 1, characterized in that, The mounting flange (1) has a waist-shaped mounting hole (10), the diameter of one end of the waist-shaped mounting hole (10) being larger than the diameter of the other end.

9. A front-mounted centrifugal impeller cover according to claim 8, characterized in that, The waist-shaped mounting hole (10) has a notch (101) at the larger end; the mounting flange (1) is smoothly connected to the outer wall of the flared head by a circular arc.

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