CN114623087A

CN114623087A - Blade and impeller for air compressor and air compressor

Info

Publication number: CN114623087A
Application number: CN202011451672.6A
Authority: CN
Inventors: 严骏
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-12-10
Filing date: 2020-12-10
Publication date: 2022-06-14
Also published as: DE102021213653A1

Abstract

The present application provides a blade for an air compressor, the blade comprising: a positive pressure face configured to receive a positive pressure of air as the blade rotates; a negative pressure surface configured to receive a negative pressure of air when the blade rotates, the negative pressure surface being disposed on an opposite side of the positive pressure surface; and a side surface configured to connect the positive pressure surface and the negative pressure surface; wherein at least the side surface comprises a non-smooth surface structure. The application also provides an impeller comprising the blade and an air compressor comprising the impeller. According to the application, the efficiency of the air compressor can be improved.

Description

Blade and impeller for air compressor and air compressor

Technical Field

The present application relates to the field of air compressors, and more particularly to a vane, impeller and air compressor for an air compressor.

Background

Air compressors have been widely used in various industries as air supply devices. For example, an electric air compressor is used in a vehicle as a braking air supply, a turbocharger air supply, a fuel cell air supply, or the like.

Air compressors typically include a housing, an impeller and a drive (e.g., an electric motor) that is driven by the drive to rotate at high speed, causing air entering the housing to be compressed as the impeller rotates. High speed movement of the impeller results in complex air movement patterns near the blades, due to the high rotational speeds of the impeller, which can be as high as hundreds of thousands of revolutions per minute. Specifically, at the vane surface, air contacting the smooth surface of the vane is easily turbulent due to a viscous effect, thereby causing energy loss to reduce the efficiency of the air compressor.

There are various proposals for improving the components of the air compressor, such as changing the curved shape and angular distribution of the blades, changing the configuration of the positive and negative pressure surfaces of the blades, etc., but the problem of reducing the turbulence losses has not been fully solved.

Disclosure of Invention

The application aims at providing an improved blade for an air compressor, an impeller comprising the blade and the air compressor comprising the impeller, so that energy loss is reduced, and efficiency is improved.

The concept of the present application is mainly derived from numerical simulation and analog calculation of turbulence loss at blades of the existing air compressor and observation of the external surface topography of the coleoptera of coleopteran insects (for example, dung beetle and the like).

In general, manufacturers or designers try to reduce the turbulence losses generated by the positive pressure surface (i.e., the surface subjected to the positive pressure of air during the rotation of the blade) and the negative pressure surface (i.e., the surface subjected to the negative pressure of air during the rotation of the blade, the negative pressure surface being disposed on the opposite side of the positive pressure surface), and therefore the design is also mostly concentrated on the positive pressure surface and the negative pressure surface of the blade. However, the applicant found, after numerical simulation and simulation calculation of the blade, that not only the positive pressure surface and the negative pressure surface of the blade but also the side surface connecting the positive pressure surface and the negative pressure surface (i.e., the surface on the one side in the thickness direction of the blade, which is substantially perpendicular to the positive pressure surface and the negative pressure surface) generate a large amount of turbulent loss. Therefore, reducing the turbulent losses at the sides of the vanes can further improve the efficiency of the air compressor. In order to reduce the turbulence loss of the side surface of the blade, the applicant researches the appearance of the outer surface of the coleoptera of coleoptera insects (such as dung beetles) and finds that the non-smooth surface structure of the outer surface of the coleoptera can effectively reduce the viscous effect of the side surface of the blade when the blade moves at a high speed, so that the turbulence loss is reduced, and the efficiency of the air compressor is improved.

To this end, according to an aspect of the present application, there is provided a blade for an air compressor, the blade comprising: a positive pressure face configured to receive a positive pressure of air as the blade rotates; a negative pressure surface configured to receive a negative pressure of air when the blade rotates, the negative pressure surface being disposed on an opposite side of the positive pressure surface; and a side surface configured to connect the positive pressure surface and the negative pressure surface; wherein at least the side surface comprises a non-smooth surface structure.

According to an embodiment of the application, the blade comprises a primary blade and a secondary blade, the length of the non-smooth surface structure of the primary blade in the radial direction being larger than the length of the non-smooth surface structure of the secondary blade in the radial direction.

According to an embodiment of the application, the blade further comprises a peripheral surface being a radially outermost surface of the blade, the non-smooth surface structure of the blade being provided in a portion of the side surface close to the peripheral surface.

According to an embodiment of the application, the non-smooth surface structure comprises a pit structure, a groove structure or a combination thereof.

According to an embodiment of the application, when the non-smooth surface structure comprises a pit structure, the pit structure is an array of a plurality of pits, and the pitch between adjacent pits gradually decreases outwards in the radial direction; and when the non-smooth surface structure comprises a groove structure, the groove structure comprises a plurality of grooves, and the distance between adjacent grooves gradually decreases outwards along the radial direction.

According to an embodiment of the application, the cross-sectional shape of the pit is a partial circle or a partial ellipse; and the cross-sectional shape of the groove is partially circular or partially elliptical.

According to an embodiment of the application, the pits have a depth of 5-100 microns, a length and/or width of 10-400 microns; and the depth of the groove is 5-100 microns, and the width is 10-400 microns.

According to another aspect of the present application, there is provided an impeller for an air compressor, wherein the impeller comprises: a hub configured to be coupleable with a drive device; and a blade as described above, wherein the blade is fixedly coupled to or integral with the hub.

According to an embodiment of the application, the impeller further comprises an end plate, which is arranged perpendicular to the direction of the axis of rotation of the impeller and fixedly coupled to or integral with the hub, wherein the blades are fixedly coupled to or integral with the end plate.

According to yet another aspect of the present application, there is provided an air compressor, wherein the air compressor includes: a drive device; and an impeller as described above, wherein the drive means is configured to cause the impeller to rotate.

Due to the non-smooth structure of the side face of the blade, the impeller and the air compressor provided by the application can reduce energy loss caused by turbulence near the side face of the blade, so that the efficiency of the air compressor can be further improved.

Drawings

Exemplary embodiments of the present application will now be described in detail with reference to the drawings, with the understanding that the following description of the embodiments is intended to be illustrative, and not limiting of the scope of the application, and in which:

FIG. 1 is a schematic perspective view illustrating an impeller for an air compressor according to an embodiment of the present application;

fig. 2 is a schematic enlarged view illustrating a region a in fig. 1;

FIG. 3 is a schematic perspective view illustrating a blade for an air compressor according to an embodiment of the present application.

Detailed Description

Preferred embodiments of the present application are described in detail below with reference to examples. In the embodiments of the present application, the present application is described by taking a centrifugal air compressor and its blades and impeller as examples. However, it should be understood by those skilled in the art that these exemplary embodiments are not meant to limit the present application in any way. Furthermore, the features in the embodiments of the present application may be combined with each other without conflict. Like components are designated by like reference numerals in the different drawings, and other components are omitted for the sake of brevity, which does not indicate that the vane, impeller, and air compressor of the present application may not include other components. It should be understood that the dimensions, proportions and numbers of elements in the drawings are not intended to limit the present application.

In this context, unless otherwise specified, "axial" denotes the direction of extension of the axis of rotation about which the blades or impellers of the air compressor rotate, "radial" denotes the radial direction with respect to the axis of rotation, and "circumferential" denotes the circumferential direction with respect to the axis of rotation, i.e. the direction around the axis of rotation.

Herein, unless otherwise specified, "positive pressure" means a pressure greater than normal pressure, and "negative pressure" means a pressure lower than normal pressure.

A blade and an impeller for an air compressor according to an embodiment of the present application are described below with reference to fig. 1-3. Fig. 1 schematically shows an impeller for an air compressor according to an embodiment of the application, fig. 2 is a schematic enlarged view showing a region a in fig. 1, and fig. 3 schematically shows a blade for an air compressor according to an embodiment of the application.

It should be noted that the air compressor may be of any type, and is illustrated herein as a centrifugal air compressor. Although not shown in the drawings, it is known that an air compressor generally comprises a housing, an impeller and a drive means, the impeller being housed within the housing and fixedly coupled with the drive means. When the driving device drives the impeller to rotate, air entering the shell is pushed by the blades rotating at high speed to do circumferential motion on the one hand and radial motion on the other hand. Under the action of the impeller, the pressure and the kinetic energy of the air are improved. When air flows out of the impeller and enters the diffuser, the air speed is gradually reduced, the pressure is continuously increased, and then the air flows out of the compressor and enters a storage container or a pipe network. In the case of the impeller 100 of the centrifugal air compressor shown in fig. 1, air enters in the axial direction and exits in the radial direction.

As shown in fig. 1-3, an impeller 100 for an air compressor of the present application includes a hub 60, a blade 10, wherein the hub 60 is configured to be capable of being coupled with a driving device (not shown), and the blade 10 is fixedly coupled (e.g., by welding) or integrated with the hub 60, e.g., by a root 17 of the blade 10. In addition, in the impeller 100 of the centrifugal air compressor shown in fig. 1, an end plate 50 is further included, which is disposed perpendicular to the rotational axis direction of the impeller 100 and is fixedly coupled to or integrated with the hub 60, wherein the blades 10 are also fixedly coupled to or integrated with the end plate 50, for example, through the root portions 17 of the blades 10.

The blade 10 for an air compressor of the present application comprises a primary blade 11 and a secondary blade 12, both of similar construction, but of different size and shape. The main blades 11 and the sub-blades 12 are uniformly arranged in the circumferential direction of the impeller 100, and the sub-blades 12 are located between two adjacent main blades 11. Of course, the impeller 100 may have only the primary blades 11 and no secondary blades 12. The specific structure of the blade 10 will be described below taking the primary blade 11 as an example, and a repeated description of a similar structure of the secondary blade 12 will be omitted. Referring to fig. 3, the main blade 11 includes: a positive pressure surface 13 configured to receive a positive pressure of air when the main blade 11 rotates; a negative pressure surface 14 configured to receive a negative pressure of air when the main blade 11 rotates, and the negative pressure surface 14 is disposed on the opposite side of the positive pressure surface 13; and a side surface 15 configured to connect the positive pressure surface 13 and the negative pressure surface 14. In other words, the side surface 15 is a surface of one side of the main blade 11 in the thickness direction. According to an embodiment of the application, in the main blade 11, at least the side surface 15 comprises a non-smooth surface structure 16. Thus, when the main blade 11 is operated at a high speed, a viscous effect at the side surface 15 of the main blade 11 can be reduced, so that a turbulent loss can be reduced, and the efficiency of the air compressor can be improved.

According to an embodiment of the application, in addition to the side surface 15 of the main blade 11 being provided with a non-smooth surface structure 16, the positive pressure surface 13 and/or the negative pressure surface 14 of the main blade 11 may also be provided with a non-smooth surface structure 16 to further reduce turbulence losses.

It should be noted that the secondary blade 12 also has a positive pressure surface, a negative pressure surface and side surfaces as described above, and at least the side surfaces are provided with a non-smooth surface structure. In particular, as shown in fig. 3, in consideration of the difference in the air flow to which the main blade 11 and the sub-blade 12 are subjected, the length L1 in the radial direction of the non-smooth surface structure of the main blade 11 is greater than the length L2 in the radial direction of the non-smooth surface structure of the sub-blade 12 to emphasize the reduction of the turbulent loss on the main blade 11.

The primary vane 11 further comprises a peripheral surface 18, which peripheral surface 18 is the radially outermost surface of the primary vane 11, the non-smooth surface structure 16 of the primary vane 11 being provided in a portion of the side surface 15 near the peripheral surface 18. It was found during numerical simulations that there is a greater probability of greater turbulence losses occurring in a portion of the side surface 15 near the peripheral surface 18, and therefore that a non-smooth surface structure 16 may be provided near the peripheral surface 18. Of course, the peripheral surface 18 may also be provided with a non-smooth surface structure as described above to further improve the flow field structure of the gas flow.

The uneven surface structure 16 is a structure obtained by performing a biomimetic design with reference to the outer surface of a coleoptera of a dung beetle. The pit structure and the groove structure are of shapes and structures at different positions on the outer surface of a sheath fin of the dung beetle, and can change a gas flow field flowing through the vicinity of the structure.

According to an embodiment of the present application, as shown in fig. 2 and 3, the non-smooth surface structure 16 is a pit structure, wherein the pit structure is an array of a plurality of pits, and the spacing between adjacent pits gradually decreases outward in the radial direction. I.e. radially outwards, the dimples are arranged more and more densely to correspond to the turbulent loss distribution on the blade side 15.

According to another embodiment of the present application, the non-smooth surface structure 16 may also be a groove structure (not shown), wherein the groove structure comprises a plurality of grooves, and the spacing between adjacent grooves gradually decreases outward in the radial direction. Similarly, radially outward, the grooves are more and more densely arranged to correspond to the turbulent loss distribution on the blade sides 15.

Alternatively, the non-smooth surface structure 16 may also be a combination of a pit structure and a groove structure.

The dimple structures and the groove structures may also be arranged differently, such as uniformly along the radial direction, randomly along the radial direction, or more and more sparsely outward along the radial direction, depending on the operating parameters of the blade. It should also be noted that the grooves in the groove structure may be arranged parallel to each other, or may cross or converge with each other.

The cross-sectional shape of the pits can be partially circular or partially elliptical, and the cross-sectional shape of the grooves can also be partially circular or partially elliptical to facilitate the airflow of the boundary layer. It should be understood that the pits and grooves may have other cross-sectional shapes as well, such as triangular, rectangular, trapezoidal, etc.

The pits can have a depth of 5-100 microns, a length and/or width of 10-400 microns, and the grooves can have a depth of 5-100 microns and a width of 10-400 microns, as determined by ANSYS simulations and finite element calculations. Of course, the parameters of the pits and grooves may also be adjusted according to different blade sizes, rotation speeds, etc.

In further embodiments of the present application, the length of the non-smooth surface structure of the secondary blade 12 may also be greater than or equal to the length of the non-smooth surface structure of the primary blade 11, or may even not have a non-smooth surface structure.

According to embodiments of the present application, the non-smooth surface structure of the blade may be formed by machining (e.g., laser machining), chemical etching, and the like.

The present application is described in detail above with reference to specific embodiments. It is to be understood that both the foregoing description and the embodiments shown in the drawings are to be considered exemplary and not restrictive of the application. For example, the present application is described in the preferred embodiment with reference to a blade and impeller for a centrifugal air compressor, but may find application not only in a centrifugal air compressor, but also in an axial air compressor or other fluid machine having blades rotating at high speeds. It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit of the application, and these changes and modifications do not depart from the scope of the application.

Claims

1. A blade (10) for an air compressor, the blade (10) comprising:

a positive pressure face (13) configured to receive a positive pressure of air as the blade (10) rotates;

a negative pressure surface (14) configured to receive a negative pressure of air when the blade (10) rotates, the negative pressure surface (14) being disposed on an opposite side of the positive pressure surface (13); and

a side surface (15) configured to connect the positive pressure surface (13) and the negative pressure surface (14);

characterized in that at least the side face (15) comprises a non-smooth surface structure (16).

2. Blade (10) according to claim 1, characterized in that the blade (10) comprises a primary blade (11) and a secondary blade (12), the length (L1) in the radial direction of the non-smooth surface structure of the primary blade (11) being larger than the length (L3) in the radial direction of the non-smooth surface structure of the secondary blade (12).

3. Blade (10) according to claim 1 or 2, characterized in that the blade (10) further comprises an outer edge surface (18), the outer edge surface (18) being the radially outermost surface of the blade (10), the non-smooth surface structure (16) of the blade (10) being provided in a part of the side surface (15) close to the outer edge surface (18).

4. The blade (10) of claim 1, wherein the non-smooth surface structure (16) comprises a dimple structure, a groove structure, or a combination thereof.

5. The blade (10) of claim 4, wherein when the non-smooth surface structure (16) comprises a dimple structure, the dimple structure is an array of a plurality of dimples, and the spacing between adjacent dimples tapers outwardly in the radial direction; and when the non-smooth surface structure (16) comprises a groove structure, the groove structure comprises a plurality of grooves, and the spacing between adjacent grooves gradually decreases outwardly in the radial direction.

6. The blade (10) of claim 5, wherein the cross-sectional shape of the pocket is a partial circle or a partial oval; and the cross-sectional shape of the groove is partially circular or partially elliptical.

7. Blade (10) according to claim 5 or 6, characterized in that the depth of the pits is 5-100 microns, the length/width is 10-400 microns; and the depth of the groove is 5-100 micrometers, and the width of the groove is 10-400 micrometers.

8. An impeller (100) for an air compressor, the impeller (100) comprising:

a hub (60) configured to be coupleable with a drive device; and

blade (10) according to any of claims 1 to 7, wherein the blade (10) is fixedly coupled to or integral with the hub (60).

9. The impeller (100) according to claim 8, wherein the impeller (100) further comprises an end plate (50), the end plate (50) being arranged perpendicular to the direction of the axis of rotation of the impeller (100) and being fixedly coupled to or integral with the hub (60), wherein the blades (10) are fixedly coupled to or integral with the end plate (50).

10. An air compressor, comprising:

a drive device; and

impeller (100) according to claim 8 or 9,

wherein the drive device is configured to drive the impeller (100) in rotation.