CN113202789B - Impeller and centrifugal compressor for centrifugal compressor - Google Patents

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 in the vicinity of 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 and centrifugal compressor for 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 impeller.

Background technique

Centrifugal compressors are widely used in internal combustion engine turbochargers, aviation turbine engines, micro gas turbines, fuel cell engines, closed-cycle turbine power, industrial compressors and other power devices due to their small size, light weight and high efficiency. and fluid delivery devices.

Further, centrifugal compressors used in power plants generally use semi-open impellers. In this semi-open impeller, there is a gap between the tops of the blades and the casing. The pressure difference between the two sides of the blade will drive part of the fluid in the impeller channel to form a leakage flow through the above-mentioned gap, and a leakage vortex will be generated at the leading edge of the blade. The leakage vortex generated at the leading edge of the blade is mixed with the leakage flow in the downstream development process, so that the secondary flow in the impeller flow channel is enhanced, resulting in increased flow loss and reduced aerodynamic efficiency of the centrifugal compressor.

In the research of axial flow impeller machinery such as wind turbines, propellers and low-speed axial flow fans, the tip winglet (also known as tip winglet) technology is proposed to reduce the leakage flow loss at the top of the blade and improve the aerodynamic efficiency of the impeller. However, because the blade tip winglet will significantly increase the structural stress of the blade, it is not suitable for the impeller of a centrifugal compressor with a high speed. In order to apply tiplet technology in centrifugal compressors to improve aerodynamic efficiency, it is necessary to solve the problem of significant increase in the structural stress of the blade caused by the tiplet.

SUMMARY OF THE INVENTION

The present application is made based on the above-mentioned defects of the prior art. An object of the present application is to provide an impeller for a centrifugal compressor, which can suppress or even eliminate the generation of tip leakage vortices at the leading edge of a high-speed centrifugal impeller by using tip winglets, reduce tip leakage loss, and at the same time can significantly reduce the use of impellers. The problem of tip winglets increasing the structural stress of the blade. Another object of the present application is to provide a centrifugal compressor including the above-mentioned impeller for a centrifugal compressor.

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

The present application provides an impeller for a centrifugal compressor as follows, the impeller includes a main blade and a hub, a plurality of the main blades are fixed to the hub, and are distributed along the circumferential direction of the hub, two adjacent two A plurality of the main vanes are spaced in the circumferential direction, each of the main vanes comprising:

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

a main tip winglet, which is disposed on the blade tip edge from the blade leading edge and is located at a length from the blade leading edge that is 30% or more of the blade length of the main blade and In the area below 40%, the main blade tip winglets extend toward the pressure surface side and the suction surface side of the main blade body.

In an optional solution, each main blade body further has a blade trailing edge, and the circumferential width of the main blade tip winglets gradually decreases from the blade leading edge side toward the blade trailing edge side.

In another optional solution, the impeller further includes a splitter blade, the splitter blade is fixed on the hub, and a plurality of the main blades and a plurality of the splitter blades are alternately distributed in the circumferential direction.

In another optional solution, the splitter blade includes a splitter blade body and a splitter tip winglet, and the splitter blade tiplet is disposed on a blade of the splitter blade body from a leading edge of the splitter blade body on the sharp edge.

In another alternative, the splitter tiplet terminates at the same radial position as the main tiplet.

In another optional solution, the width of the main blade tip wing extending toward the pressure surface side at the blade leading edge is set to be Bp, and the main blade tip wing is at the blade leading edge. The width extending toward the suction surface side is Bs, then Bp=Bs.

其中α为常数且0.1≤α≤0.2。In another optional solution, if the radius of the inlet tip of the impeller is Rint, and the number of all blades is Zb, then

where α is a constant and 0.1≤α≤0.2.

In another optional solution, if the length of the main blade tip winglet is L1 and the blade length of the main blade is L, then 0.3×L≤L1≤0.4×L.

In another optional solution, the main blade body and the main blade tip winglet are integrally formed, and the connecting part of the main blade main body and the main blade tip winglet is formed as a curved transition area, and the The height of the curved surface transition region is h and the blade height of the main blade is H, then 1/10×H≤h≤1/8×H.

The present application also provides the following centrifugal compressor, which includes the compressor impeller described in any one of the above technical solutions.

Thus, the present application provides a novel impeller for a centrifugal compressor and a centrifugal compressor including the impeller. The impeller includes a hub and blades, a plurality of blades are fixed on the hub and distributed along the circumferential direction of the hub, and two adjacent blades are spaced apart in the circumferential direction. Each blade includes a blade body and a tip winglet. The tip winglet is provided on the tip edge of the leading edge of the blade body in the vicinity of the tip. The tip winglets extend toward the pressure side and the suction side of the blade body.

The tiplet of the novel centrifugal compressor with tiplet according to the present application only covers the region near the leading edge of the blade body (which may include an axial section and a partial transition section). This is because, according to the flow field analysis of the tip leakage flow, the tip leakage loss is mainly caused by the leakage vortex flowing in the mainstream direction generated at the tip of the blade leading edge and the circumferential flow generated at the downstream blade tip. Leakage flow is generated, so suppressing one of the leakage vortex at the leading edge of the blade or the downstream leakage flow can reduce the leakage loss; and because the radial section of the impeller for centrifugal compressors has a high linear velocity, increasing the number of blades in the radial section Tip winglets can have a significant adverse effect on impeller structural strength. Therefore, the present application adopts the above solution. On the one hand, the tip winglet can be used to suppress or even eliminate the generation of tip leakage vortices at the leading edge of the centrifugal impeller, thereby weakening the mixing flow loss caused by the leakage vortex at the leading edge of the blade and improving centrifugal compression. aerodynamic performance of the machine. On the other hand, since the tip winglets are only arranged in the region near the leading edge of the blade, that is, in the low linear velocity region near the leading edge of the top of the blade body, the effect of the tip winglets on the structural stress of the blade is significantly reduced. Negative Effects.

Description of drawings

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 a centrifugal compressor in FIG. 1A .

1D is a schematic plan view showing a main blade of the impeller for a centrifugal compressor in FIG. 1A , and the viewing direction of the view is the A direction in the axial projection view in FIG. 1C .

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

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

3A is a graph for explaining a change in isentropic efficiency with mass flow rate of the impeller for centrifugal compressors of the present application and the impeller for centrifugal compressors of the related art.

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

Description of reference numerals

1Main blade 11Main blade body 111Blade tip edge 112Blade bottom edge 113Blade leading edge 114Blade trailing edge 115Pressure surface 116Suction surface 12Main blade tip winglet

2 hubs

3 Splitter blade 31 Splitter blade body 311 Blade tip edge 32 Splitter blade tip winglet.

Detailed ways

Exemplary embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not used to exhaust all possible ways of the present application, nor to limit the scope of the present application.

The hub of the impeller for a centrifugal compressor according to the present application has a disk shape as a whole. In this application, unless otherwise specified, "axial direction", "radial direction" and "circumferential direction" respectively refer to the axial direction, radial direction and circumferential direction of the hub of the impeller for a centrifugal compressor.

The specific structure of the impeller for a centrifugal compressor according to the first embodiment of the present application will be described below with reference to the accompanying drawings.

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

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

In this embodiment, as shown in FIG. 1A , all the main blades 1 and the hub 2 are fixed together. A plurality of main blades 1 are evenly distributed along the circumferential direction of the hub 2, and two adjacent main blades 1 are spaced apart in the circumferential direction. All main blades 1 are the same in shape and size. Each main blade 1 includes a main blade body 11 and a main tip winglet 12 that are formed in one piece.

Specifically, as shown in FIG. 1A , each main blade body 11 is formed in a twisted shape, and has a blade tip edge 111 , a blade bottom edge 112 , a blade leading edge 113 and a blade trailing edge 114 . The blade bottom edge 112 is the edge where the main blade body 11 is connected to the hub 2 , and the blade tip edge 111 is the edge of the main blade body 11 away from the hub 2 and facing away from the blade bottom edge 112 . Both the leading edge 113 and the trailing edge 114 of the blade are connected to the tip edge 111 and the bottom edge 112 of the blade. The leading edge 113 of the vane is located at the inlet of the impeller channel for fluid inflow, and the trailing edge 114 of the vane is located at the outlet of the impeller channel for the fluid to flow out. That is, the vane leading edge 113 is located upstream of the vane trailing edge 114 in the flow direction of the fluid within the impeller channel. Further, the two sides of each main blade body 11 in the circumferential direction are the pressure surface 115 and the suction surface 116, respectively, the pressure surface 115 is the surface where the main blade body 11 exerts pressure on the fluid, and the suction surface 116 is the fluid impacting the main blade. that side of the main body 11.

Further, as shown in FIGS. 1A to 1C , the main blade tip winglet 12 (also known as the blade tip winglet) is disposed at the blade tip edge 111 of the region near the leading edge of the main blade body 11 from the blade leading edge 113 (it can also be said to be provided in the region of the blade body 11 including the axial section and part of the transition section, wherein the transition section is the part of the main blade body 11 located between the axial section and the meridional section). During the rotation of the impeller, the linear velocity of the leading edge portion of the blade tip of the main blade body 11 is smaller than the linear velocity of other parts of the main blade body 11 . For each main blade 1 , the area near the leading edge tip refers to the area of the main blade 1 whose length from the blade leading edge 113 is 30% or more and 40% or less of the blade length of the main blade 1 .

其中α为常数且0.1≤α≤0.2。在上述具体尺寸设定下，主叶尖小翼12能够发挥更好的改善叶尖泄漏导致的高速离心压缩机性能下降的效果。In order to enable the main blade tip winglet 12 to better improve the performance degradation of the high-speed centrifugal compressor caused by the blade tip leakage. The main blade tiplet 12 extends toward the pressure surface 115 side and the suction surface 116 side of the main blade 1 by a certain width. As shown in FIG. 1D , it is assumed that the width of the main blade tip winglet 12 extending toward the pressure surface 115 side at the blade leading edge 113 is Bp, and the main blade tip winglet 12 extending toward the suction surface 116 side at the blade leading edge 113 . The width of is Bs, then Bp=Bs. It has been proved by experiments that if the radius of the inlet tip of the impeller is Rint, and the number of main blades 1 is Zb, then

where α is a constant and 0.1≤α≤0.2. Under the above specific dimension setting, the main blade tip winglet 12 can better improve the performance degradation of the high-speed centrifugal compressor caused by the blade tip leakage.

In addition, in order to reduce the adverse effect of the main blade tip winglet 12 on the structural stress of the main blade 1 , the width of the main blade tip winglet 12 gradually decreases from the blade leading edge 113 side to the blade 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 main tiplet 12 extends, the width of the tiplet on the pressure surface 115 side and the width on the suction side The width of the side 116 decreases linearly and finally converges to the tip edge 111 . In order to reduce the adverse effect of the main blade tip winglet 12 on the structural stress of the main blade 1, as shown in FIG. 1D, if the length of the main blade tip winglet 12 is L1 and the blade length of the main blade 1 is L, then 0.3× L≤L1≤0.4×L.

In addition, as shown in FIG. 1E , the main blade tip winglet 12 and the main blade body 11 are integrally formed, and the connection portion between the main blade tip winglet 12 and the main blade body 11 is formed as a curved transition area (which can be regarded as a rounded corner). In the cross-sectional view shown in FIG. 1E , the height h of the curved transition region is 1/10×H≦h≦1/8×H of the blade height H in the cross-section of the main blade 1 .

By adopting the above technical solution, the blade tip winglet can be used to improve the performance degradation of the high-speed centrifugal compressor caused by the tip leakage caused by the gap between the impeller tip and the casing, and at the same time, it can be greatly alleviated. Adverse effects of tip winglets on blade structural stress.

The specific configuration of the impeller for a centrifugal compressor according to the second embodiment of the present application will be described below.

(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 between the two are mainly described below.

As shown in FIG. 2 , the impeller for a centrifugal compressor according to the second embodiment of the present application includes not only a main blade 1 and a hub 2 , but also a splitter blade 3 . The plurality of splitter vanes 3 are fixed to the hub 2 . The plurality of splitter vanes 3 and the plurality of main vanes 1 are alternately and uniformly distributed in the circumferential direction, that is, each splitter vane 3 is located between adjacent main vanes 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 that of the main blade 1 . Each splitter blade 3 includes a splitter main blade body 11 and a splitter tip winglet 32 . The splitter tiplet 32 is arranged on the tip edge 311 in the region near the leading edge of the splitter main blade body 11 , the length of the splitter tiplet 32 is smaller than that of the main blade tip 12 , and the splitter tip is smaller. The axial and radial cut-off positions of the airfoils 32 are the same as the axial and radial cut-off positions of the main tip winglets 12 . It can also be said that the splitter tiplet 32 of the splitter blade 3 terminates at the same radial position (the same position of the blade in the airflow direction) as the main tiplet 12 of the main blade 1 .

计算主叶尖小翼12的宽度时，其它参数的含义不变，但是Zb为主叶片1和分流叶片3的数量之和。In addition, in this embodiment, when using the following equation

When calculating the width of the main blade tip winglet 12 , the meanings of other parameters remain unchanged, but Zb is the sum of the number of the main blade 1 and the splitter blade 3 .

In this way, in this embodiment, the splitter vanes 3 can play a role of splitting the fluid flowing between the main vanes 1 . In addition, by providing the main blade tip 12 on the main blade 1 and providing the splitter tiplet 32 on the splitter blade 3, the same effect as that of the first embodiment can be achieved in this embodiment.

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

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 functions and effects as the impeller described above. In an optional but non-limiting solution, 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 30,000 rpm.

ii. The centrifugal compressor impeller according to the present application mainly refers to a semi-open impeller, especially a rear semi-open impeller.

iii. The inventor compares the two parameters of isentropic efficiency and total pressure ratio through experiments to illustrate the performance improvement effect of the centrifugal compressor impeller of the present application relative to the centrifugal compressor impeller of the prior art. Specifically, as shown in FIG. 3A , it can be seen that the introduction of the tip winglets 12 and 32 effectively improves the isentropic efficiency of the impeller, and the highest efficiency is increased from 87.28% to 90.48%, an increase of 3.2%. As shown in Fig. 3B, it can be seen that the introduction of the tip winglets 12 and 32 effectively increases the working capacity of the impeller, and the total pressure ratio at the operating point of the same mass flow rate on the same rotational speed line is improved, and the maximum point is increased by approximately 0.03.

Claims (7)

1. An impeller for a centrifugal compressor, characterized in that the impeller comprises a main blade (1), a hub (2) and a splitter blade (3), and a plurality of the main blades (1) are fixed on the hub ( 2), and distributed along the circumferential direction of the hub (2), two adjacent main blades (1) are spaced apart in the circumferential direction, and the splitter blades (3) are fixed on the hub ( 2), a plurality of the main vanes (1) and the plurality of the splitter vanes (3) are alternately distributed in the circumferential direction, Each of said main blades (1) includes: a main blade body (11) having a tip edge (111) and a leading edge (113); and The main blade tip winglet (12), the main blade tip winglet (12) is provided on the blade tip edge (111) from the blade leading edge (113), and is located from the blade leading edge (113) on the blade tip edge (111). 113) from the region whose length is 30% or more and 40% or less of the blade length of the main blade (1), the main blade tip winglet (12) faces the pressure surface (115) of the main blade body (11) ) side and the suction side (116) side, The splitter blade (3) includes a splitter blade body (31) and a splitter tip winglet (32), and the splitter tip winglet (32) is provided at the leading edge of the splitter blade body (31). On the tip edge of the splitter blade body (31), the splitter tiplet (32) and the main tiplet (12) terminate at the same radial position. 2. The impeller for a centrifugal compressor according to claim 1, characterized in that, each main blade body (11) further has a blade trailing edge (114), and the circumference of the main blade tip winglet (12) is The width gradually decreases from the blade leading edge (113) side toward the blade trailing edge (114) side. 3. The impeller for centrifugal compressor according to claim 1 or 2, characterized in that, the main blade tip winglet (12) is set to face the pressure surface (115) at the blade leading edge (113) The width of the side extension is Bp, and the width of the main blade tip winglet (12) extending toward the suction surface (116) side at the blade leading edge (113) is Bs, then Bp=Bs. 4. The impeller for centrifugal compressor according to claim 3, characterized in that, if the inlet tip radius of the impeller is Rint, and the number of all blades (1, 3) is Zb, then

where α is a constant and 0.1≤α≤0.2. 5. The impeller for centrifugal compressor according to claim 1 or 2, characterized in that, let the length of the main blade tip winglet (12) be L1 and the blade length of the main blade (1) be L, Then 0.3×L≤L1≤0.4×L. The impeller for a centrifugal compressor according to claim 1 or 2, characterized in that, the main blade body (11) and the main blade tip winglet (12) are integrally formed, and the main blade main body ( 11) The connection part with the main blade tip winglet (12) is formed as a curved surface transition area. If the height of the curved surface transition area is h and the blade height of the main blade (1) is H, then 1/10 ×H≤h≤1/8×H. 7 . A centrifugal compressor, characterized in that the centrifugal compressor comprises the impeller for a compressor according to any one of claims 1 to 6 .

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