CN113202789A

CN113202789A - Impeller for centrifugal compressor and centrifugal compressor

Info

Publication number: CN113202789A
Application number: CN202110642603.1A
Authority: CN
Inventors: 诸葛伟林; 陈昊翔; 张扬军; 钱煜平
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2021-06-09
Filing date: 2021-06-09
Publication date: 2021-08-03
Anticipated expiration: 2041-06-09
Also published as: CN113202789B

Abstract

The application provides an impeller and centrifugal compressor for centrifugal compressor. The impeller includes a hub and blades. Each blade includes a blade body and a winglet disposed in a region proximate a leading edge tip at a top of the blade body. The winglet extends towards the pressure and suction side of the blade body. Therefore, on one hand, by utilizing the winglet, the generation of tip leakage vortex at the front edge of the high-speed centrifugal impeller can be inhibited or even eliminated, the tip leakage loss is reduced, and the pneumatic performance of the centrifugal compressor is further improved. On the other hand, because the winglet is only positioned near the leading edge of the blade, i.e., in the low linear velocity region of the blade, the adverse effects of the winglet on the structural stresses in the blade are significantly reduced.

Description

Impeller for centrifugal compressor and centrifugal compressor

Technical Field

The present application relates to the field of centrifugal compressors, and more particularly, to an impeller for a centrifugal compressor and a centrifugal compressor including the same.

Background

Centrifugal compressors, because of their small size, light weight and high efficiency, are widely used in power plants and fluid handling devices such as internal combustion engine turbochargers, aircraft turbine engines, micro gas turbines, fuel cell engines, closed cycle turbine power, industrial compressors, and the like.

Further, centrifugal compressors used in power plants typically employ semi-open impellers. In such a semi-open impeller, a gap exists between the blade tip and the casing. The pressure differential across the vanes will drive a portion of the fluid in the impeller flowpath through the gap to create a leakage flow and create a leakage vortex at the leading edge of the vane. The leakage vortex generated at the leading edge of the blade is mixed with the leakage flow in the process of developing downstream, so that the secondary flow in the impeller flow passage is enhanced, and the flow loss of the centrifugal compressor is increased and the aerodynamic efficiency is reduced.

In the research of axial-flow type impeller machinery such as wind turbines, propellers, low-speed axial-flow fans and the like, a winglet (also called as a winglet) technology is provided for reducing the leakage flow loss at the top of a blade and improving the aerodynamic efficiency of the impeller. However, winglets are not suitable for impellers of centrifugal compressors with higher rotational speeds, since they significantly increase the structural stresses on the blades. In order to apply winglet technology to improve aerodynamic efficiency in centrifugal compressors, it is necessary to solve the problem of significant increase in structural stress of the blade caused by the winglet.

Disclosure of Invention

The present application has been made in view of the above-mentioned drawbacks of the prior art. An object of the present invention is to provide an impeller for a centrifugal compressor, which can suppress or even eliminate the generation of tip leakage vortex at the front edge of a high-speed centrifugal impeller by using a winglet, reduce tip leakage loss, and at the same time, can significantly reduce the problem of increasing the structural stress of a blade by using the winglet. Another object of the present application is to provide a centrifugal compressor comprising an impeller for a centrifugal compressor as described above.

In order to achieve the above object, the present application adopts the following technical solutions.

The present application provides an impeller for a centrifugal compressor, the impeller includes main blade and wheel hub, a plurality of the main blade is fixed in wheel hub, and along the circumference of wheel hub distributes, and adjacent two the main blade is in it is spaced apart to circumference, every the main blade includes:

a main blade body having a tip edge and a leading edge; and

a main tip winglet provided on the tip edge from the leading edge and located in a region having a length of 30% or more and 40% or less of a blade length of the main blade from the leading edge, the main tip winglet extending toward a pressure surface side and a suction surface side of the main blade body.

In one alternative, each of the main blade bodies further has a trailing edge, and the circumferential width of the main winglet gradually decreases from the leading edge side toward the trailing edge side.

In another optional scheme, the impeller further includes splitter blades fixed to the hub, and the plurality of main blades and the plurality of splitter blades are alternately distributed in the circumferential direction.

In another alternative, the splitter blade includes a splitter blade body and a splitter winglet disposed on a tip edge of the splitter blade body from a leading edge of the splitter blade body.

In another alternative, the split winglet terminates at the same radial position as the main winglet.

In another alternative, Bp is greater than Bs when the main winglet extends towards the pressure side at the leading edge and Bs extends towards the suction side at the leading edge.

In another alternative, if the radius of the inlet tip of the impeller is Rint and the number of all the blades is Zb, then

Wherein alpha is a constant and is more than or equal to 0.1 and less than or equal to 0.2.

In another alternative, assuming that the length of the main winglet is L1 and the blade length of the main blade is L, then 0.3 XL ≦ L1 ≦ 0.4 XL.

In another optional scheme, the main blade main body and the main tip winglet are integrally formed, the connection part of the main blade main body and the main tip winglet is formed into a curved surface transition region, and if the height of the curved surface transition region is H and the height of the main blade is H, 1/10 × H is less than or equal to H, and less than or equal to 1/8 × H.

The application also provides a centrifugal compressor, which comprises the impeller for the compressor in any one of the technical schemes.

Therefore, the application provides a novel impeller for a centrifugal compressor and the centrifugal compressor comprising the impeller. The impeller comprises a hub and a plurality of blades, wherein the blades are fixed on the hub and distributed along the circumferential direction of the hub, and two adjacent blades are spaced in the circumferential direction. Each blade includes a blade body and a winglet. The winglet is disposed on a tip edge of the blade body in a region adjacent to a leading edge tip of the blade. The winglet extends towards the pressure and suction side of the blade body.

The winglet of the novel centrifugal compressor impeller with the winglet according to the application covers only the region (which may include an axial section and a partial transition section) near the leading edge tip of the blade body. The tip leakage loss is mainly generated by leakage vortexes which are generated at the blade tip of the front edge of the blade and flow along the main flow direction and leakage flows which are generated at the downstream blade tip and flow along the circumferential direction, so that the leakage loss can be reduced by inhibiting one of the leakage vortexes or the downstream leakage flows at the front edge of the blade; moreover, because the radial section of the impeller for the centrifugal compressor has higher linear speed, the addition of the winglet to the radial section can have a significant adverse effect on the structural strength of the impeller. By adopting the scheme, on one hand, the generation of tip leakage vortexes at the front edge of the fast centrifugal impeller can be inhibited or even eliminated by using the winglet, so that the blending flow loss caused by the leakage vortexes at the front edge of the blade is weakened, and the pneumatic performance of the centrifugal compressor is improved. On the other hand, since the winglet is only disposed in the vicinity of the leading edge of the blade, i.e., in the low linear velocity region near the leading edge at the top of the blade body, the adverse effects of the winglet on the structural stresses in the blade are significantly reduced.

Drawings

Fig. 1A is a schematic perspective view showing an impeller for a centrifugal compressor according to a first embodiment of the present application, the impeller including only main blades.

Fig. 1B is an enlarged schematic view showing a partial structure of a region S of the impeller for a centrifugal compressor in fig. 1A.

Fig. 1C is an axial projection view (two-dimensional meridional plane view) showing the impeller for the centrifugal compressor in fig. 1A.

Fig. 1D is a schematic top view showing the main blades of the impeller for a centrifugal compressor in fig. 1A, the view direction of which is the a direction in the axial projection view in fig. 1C.

Fig. 1E is a sectional view showing a blade of the impeller for the centrifugal compressor in fig. 1A, which is a sectional view taken along direction B-B of the axial projection in fig. 1C.

Fig. 2 is a perspective view schematically showing an impeller for a centrifugal compressor according to a second embodiment of the present application, the impeller including main blades and splitter blades.

Fig. 3A is a graph for explaining isentropic efficiency of the impeller for a centrifugal compressor of the present application and the impeller for a centrifugal compressor of the related art as a function of mass flow.

Fig. 3B is a graph for explaining a total pressure ratio of the impeller for the centrifugal compressor of the present application and the impeller for the centrifugal compressor of the related art as a function of a mass flow rate.

Description of the reference numerals

1 main blade 11 main blade body 111 tip edge 112 blade base edge 113 blade leading edge 114 blade trailing edge 115 pressure side 116 suction side 12 main tip winglet

2 wheel hub

3 splitter blade 31 splitter blade body 311 tip edge 32 splitter winglet.

Detailed Description

Exemplary embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that the detailed description is only intended to teach one skilled in the art how to practice the present application, and is not intended to be exhaustive or to limit the scope of the application.

The impeller for a centrifugal compressor according to the present application has a hub that is generally disk-shaped. In the present application, "axial direction", "radial direction" and "circumferential direction" refer to the axial direction, radial direction and circumferential direction, respectively, of a hub of an impeller for a centrifugal compressor, unless otherwise specified.

A specific configuration of an impeller for a centrifugal compressor according to a first embodiment of the present application is explained below with reference to the drawings.

(impeller for centrifugal compressor according to the first embodiment of the present application)

As shown in fig. 1A, an impeller for a centrifugal compressor according to a first embodiment of the present application includes a plurality of main blades 1 and a hub 2 fixed together.

In the present embodiment, all the main blades 1 are fixed to the hub 2 as shown in fig. 1A. A plurality of main blades 1 are uniformly distributed along the circumferential direction of the hub 2, and adjacent two main blades 1 are spaced apart in the circumferential direction. All the main blades 1 are identical in shape and size. Each main blade 1 comprises a main blade body 11 and a main tip winglet 12 formed in one piece.

Specifically, as shown in fig. 1A, each main blade body 11 is formed in a twisted shape, and has a tip edge 111, a base edge 112, a leading edge 113, and a trailing edge 114. The bottom edge 112 is an edge of the main blade body 11 connected to the hub 2, and the tip edge 111 is an edge of the main blade body 11 away from the hub 2 and facing away from the bottom edge 112. Leading edge 113 and trailing edge 114 are each connected to tip edge 111 and base edge 112. The leading edge 113 is located at the inlet of the wheel channel for fluid inflow and the trailing edge 114 is located at the outlet of the wheel channel for fluid outflow. That is, the leading edge 113 is located upstream of the trailing edge 114 in the flow direction of the fluid in the impeller channel. Further, both side surfaces of each main blade body 11 in the circumferential direction are a pressure surface 115 and a suction surface 116, respectively, the pressure surface 115 being the surface of the main blade body 11 that applies pressure to the fluid, and the suction surface 116 being the surface of the main blade body 11 that the fluid impacts.

Further, as shown in fig. 1A to 1C, the main tip winglet 12 (also called "winglet") is disposed from the leading edge 113 on the tip edge 111 of the main blade body 11 in the vicinity of the leading edge tip (also referred to as "winglet") thereof (i.e., in the region of the blade body 11 including the axial section and a partial transition section between the axial section and the radial section of the main blade body 11). During the rotation of the impeller, the linear velocity of the main blade body 11 in the area of the tip leading edge portion is lower than that of the other portions of the main blade body 11. The leading edge tip vicinity region means a region of the main blade 1 in which the length from the leading edge 113 is 30% to 40% of the blade length of the main blade 1, for each main blade 1.

In order to enable the main tip winglet 12 to exert a better effect of improving the performance degradation of a high-speed centrifugal compressor caused by tip leakage. The main tip winglet 12 extends over a certain width towards the pressure surface 115 side and the suction surface 116 side of the main blade 1. As shown in fig. 1D, if Bp is a width of the main winglet 12 extending toward the pressure surface 115 at the leading edge 113, and Bs is a width of the main winglet 12 extending toward the suction surface 116 at the leading edge 113, Bp is Bs. Tests prove that if the radius of the inlet blade tip of the impeller is Rint and the number of the main blades 1 is Zb, the impeller is provided with a blade tip with a radius of Rint

Wherein alpha is a constant and is more than or equal to 0.1 and less than or equal to 0.2. With the above specific sizing, the main tip winglet 12 is able to exert a better effect of improving the performance degradation of high-speed centrifugal compressors caused by tip leakage.

In addition, in order to reduce the adverse effect of the main tip winglet 12 on the structural stress of the main blade 1, the width of the main tip winglet 12 is gradually reduced from the leading edge 113 side toward the trailing edge 114 side. More specifically, as shown in fig. 1D, from the leading edge 113 of the main blade body 11 to the position where the extension of the main winglet 12 ends, both the width of the winglet on the pressure surface 115 side and the width of the winglet on the suction surface 116 side decrease linearly and eventually converge at the tip edge 111. In order to reduce the adverse effect of the main tip winglet 12 on the structural stress of the main blade 1, when the length of the main tip winglet 12 is L1 and the blade length of the main blade 1 is L, 0.3 × L ≦ L1 ≦ 0.4 × L, as shown in fig. 1D.

As shown in fig. 1E, the main winglet 12 is formed integrally with the main blade body 11, and the connecting portion between the main winglet 12 and the main blade body 11 is formed as a curved transition region (which may be regarded as a rounded corner). In the sectional view shown in FIG. 1E, the height H of the curved transition region is 1/10 XH ≦ H ≦ 1/8 XH of the blade height H in the cross-section of the main blade 1.

By adopting the technical scheme, the problem of performance reduction of the high-speed centrifugal compressor caused by blade tip leakage due to the gap between the blade tip and the casing of the impeller of the high-speed centrifugal compressor can be solved by utilizing the winglet, and meanwhile, the adverse effect of the winglet on the stress of the blade structure can be greatly reduced.

The following describes a specific configuration of an impeller for a centrifugal compressor according to a second embodiment of the present application.

(impeller for centrifugal compressor according to the second embodiment of the present application)

The basic structure of the impeller for a centrifugal compressor according to the second embodiment of the present application is substantially the same as that of the impeller for a centrifugal compressor according to the first embodiment of the present application, and the differences therebetween will be mainly described below.

As shown in fig. 2, an impeller for a centrifugal compressor according to a second embodiment of the present application includes not only main blades 1 and a hub 2 but also splitter blades 3. A plurality of splitter blades 3 are fixed to the hub 2. The plurality of splitter blades 3 and the plurality of main blades 1 are uniformly distributed in the circumferential direction alternately, that is, each splitter blade 3 is located between adjacent main blades 1. The length of the region near the leading edge tip of the splitter blade 3 is smaller than the length of the region near the leading edge tip of the main blade 1, so that the blade length of the splitter blade 3 is smaller than the blade length of the main blade 1. Each splitter blade 3 includes a splitter main blade body 11 and a splitter winglet 32. The split winglet 32 is disposed on the tip edge 311 in the vicinity of the leading edge tip of the split main blade body 11, the split winglet 32 has a length that is less than the length of the main tip winglet 12, and the split winglet 32 has the same axial and radial cutoff position as the main tip winglet 12. It can also be said that the splitter winglet 32 of the splitter blade 3 ends at the same radial position (the same position of the blade in the direction of flow of the airflow) as the main winglet 12 of the main blade 1.

In addition, in the present embodiment, when the following equation is utilized

The width of the main winglet 12 is calculated with the other parameters being of constant significance, but Zb is the sum of the number of main blades 1 and splitter blades 3.

In this way, in the present embodiment, the splitter blade 3 can split the fluid flowing between the main blades 1. Further, the main winglet 12 is provided on the main blade 1, and the splitter winglet 32 is provided on the splitter blade 3, whereby the same effects as those of the first embodiment can be achieved in the present embodiment.

Of course, the present application is not limited to the above-described embodiments, and those skilled in the art can make various modifications to the above-described embodiments of the present application without departing from the scope of the present application under the teaching of the present application. The following supplementary explanation is further made.

i. The present application also provides a centrifugal compressor including the impeller for a centrifugal compressor according to the present application, which has the same action and effect as the above-described impeller. In an alternative, but non-limiting aspect, the centrifugal compressor of the present application may be used in a vehicle, in which the rotational speed of the impeller is greater than or equal to 30000 rpm.

A centrifugal compressor impeller according to the present application is primarily intended to mean a semi-open impeller, in particular a semi-open impeller.

The inventor compares two parameters of isentropic efficiency and total pressure ratio through experiments to illustrate the performance improvement effect of the impeller for the centrifugal compressor relative to the impeller of the centrifugal compressor in the prior art. Specifically, as shown in FIG. 3A, it can be seen that the introduction of the

winglets

12, 32 effectively increases the isentropic efficiency of the impeller, with the maximum efficiency increasing from 87.28% to 90.48% by 3.2%. As shown in fig. 3B, it can be seen that the introduction of the

winglets

12 and 32 effectively increases the power capability of the impeller, and the total pressure ratio of the operating point with the same mass flow on the same rotational speed line is increased, and the maximum point is increased by about 0.03.

Claims

1. An impeller for a centrifugal compressor, characterized in that it comprises a plurality of main blades (1) and a hub (2), a plurality of said main blades (1) being fixed to said hub (2) and being distributed along the circumference of said hub (2), two adjacent main blades (1) being spaced apart in said circumference, each of said main blades (1) comprising:

a main blade body (11), the main blade body (11) having a tip edge (111) and a leading edge (113); and

a main winglet (12), wherein the main winglet (12) is provided on the tip edge (111) from the leading edge (113) and is located in a region having a length of 30% or more and 40% or less of a blade length of the main blade (1) from the leading edge (113), and wherein the main winglet (12) extends toward a pressure surface (115) side and a suction surface (116) side of the main blade body (11).

2. The impeller for a centrifugal compressor as claimed in claim 1, wherein each of the main blade bodies (11) further has a trailing edge (114), and a circumferential width of the main winglet (12) is gradually reduced from the leading edge (113) side toward the trailing edge (114) side.

3. The impeller for a centrifugal compressor according to claim 1 or 2,

the impeller further comprises splitter blades (3), the splitter blades (3) are fixed to the hub (2), and the plurality of main blades (1) and the plurality of splitter blades (3) are alternately distributed in the circumferential direction.

4. The impeller for a centrifugal compressor as claimed in claim 3, wherein the splitter blade (3) comprises a splitter blade body (31) and a splitter winglet (32), the splitter winglet (32) being provided on a tip edge of the splitter blade body (31) from a leading edge of the splitter blade body (31).

5. Impeller for a centrifugal compressor according to claim 4, characterized in that the diverging winglet (32) ends at the same radial position as the main winglet (12).

6. The impeller of claim 3, wherein Bp is Bs when the width of the main winglet (12) extending toward the pressure surface (115) at the leading edge (113) is Bp and Bs is the width of the main winglet (12) extending toward the suction surface (116) at the leading edge (113).

7. Impeller according to claim 6, characterized in that, given an inlet tip radius of the impeller of Rint and a number of all blades (1, 3) of Zb, then

8. The impeller according to claim 3, wherein, assuming that the length of the main tip winglet (12) is L1 and the blade length of the main blade (1) is L, 0.3 xL ≦ L1 ≦ 0.4 xL.

9. The impeller according to claim 3, wherein the main blade body (11) and the main blade tip winglet (12) are integrally formed, and a connecting portion between the main blade body (11) and the main blade tip winglet (12) is formed as a curved transition region, and wherein 1/10 x H ≦ H ≦ 1/8 x H, where H represents a height of the curved transition region and H represents a height of the main blade (1).

10. A centrifugal compressor comprising an impeller for a compressor according to any one of claims 1 to 9.