Centrifugal impeller and centrifugal compressor

Abstract

The present application provides a centrifugal impeller and a centrifugal compressor. The centrifugal impeller comprises a wheel disc, a plurality of blades arranged on the wheel disc and distributed along the circumference of the wheel disc, and two adjacent blades are spaced apart, and a flap arranged on the trailing edge of each blade, the flap extending along the circumference of the wheel disc. By arranging the flap extending along the circumference of the wheel disc on the trailing edge of the blade, without changing the overall structural parameters of the original blade and the blade profile, the blade inlet to outlet fluid energy can be increased when the impeller rotates, the fluid flow direction is not affected, and the airflow is not disturbed, so that the fluid condition at the blade outlet can be effectively changed, the performance of the impeller is improved, and the manufacturing cost is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of compressor technology, and particularly relates to a centrifugal impeller and a centrifugal compressor. Background Technology

[0002] With the increasing demand for energy conservation and environmental protection, and the rapid development of hydrogen fuel cell technology, significant progress has been made in the research and development of vehicle fuel cell systems. Centrifugal compressors, as the "heart" of vehicle fuel cell systems, are also a current research hotspot. The performance of the centrifugal compressor directly determines the power generation efficiency and the choice of users.

[0003] The centrifugal impeller is the core component of a centrifugal compressor. Its high-speed rotation forces fluid (e.g., gas) from the inlet to the outlet. The blade structure and profile directly affect the fluid conditions at the outlet. Related technologies have attempted to improve fluid conditions and enhance impeller performance by modifying the overall blade structure; however, the results have been less than ideal, and the costs are high. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a centrifugal impeller and a centrifugal compressor.

[0005] The first aspect of the present invention provides a centrifugal impeller, comprising: a disk; a plurality of blades disposed on the disk and distributed along the circumference of the disk, with adjacent blades spaced apart; and a flap disposed at the trailing edge of each blade, the flap extending along the circumference of the disk.

[0006] In some embodiments, the flap extends from the trailing edge of the blade toward the suction side.

[0007] In some embodiments, the flap extends from the trailing edge of the blade toward the pressure surface side.

[0008] In some embodiments, the height θ of the flap is the angle formed between the line connecting the top of the flap to the center of the wheel axis and the line connecting the bottom of the flap to the center of the wheel axis, wherein the height θ is greater than 0° and less than or equal to 2°.

[0009] In some embodiments, the height θ is 0.5°.

[0010] In some embodiments, the thickness δ of the flap is the distance the flap extends in the radial direction of the wheel, wherein the ratio of the thickness δ to the thickness of the trailing edge of the blade in the circumferential direction of the wheel is greater than or equal to 40% and less than or equal to 100%.

[0011] In some embodiments, the flap extends a distance in the axial direction of the disk, wherein the ratio of the width h to the length of the trailing edge of the blade in the axial direction of the disk is greater than or equal to 50% and less than or equal to 100%.

[0012] In some embodiments, the flap is tilted toward the pressure surface side of the blade, and the tilt angle γ of the flap is the angle between the flap and the axis of the wheel, wherein the tilt angle γ is greater than or equal to 18° and less than or equal to 25°.

[0013] In some embodiments, the front section of the blade is inclined and the rear section is curved, the front section and the rear section are connected by a middle section, wherein the rear section is curved toward the suction side of the blade, and both the front and rear sections of the blade are inclined toward the pressure side of the blade, the connection point between the rear section of the blade and the flap is a first position, the tangent of the rear section at the first position is a first tangent, the tangent of the flap at the first position is a second tangent, wherein the angle between the first tangent and the second tangent is equal to the inclination angle γ of the flap, and wherein the middle section connects the front section and the rear section.

[0014] In some embodiments, the blade includes a plurality of main blades and a plurality of branch blades arranged circumferentially along the disk, the main blades and the branch blades being staggered, wherein a flap extending circumferentially along the disk is provided at the trailing edge of each main blade and / or at the trailing edge of each branch blade.

[0015] A second aspect of this disclosure also provides a centrifugal compressor, including a centrifugal impeller as described in any of the above embodiments.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0017] By setting flaps extending circumferentially toward the impeller along the trailing edge of the blade, without altering the original blade's overall structural parameters or blade profile, it is beneficial to increase the fluid energy from the blade inlet to the outlet when the impeller rotates, without affecting the fluid flow direction or causing airflow turbulence. This effectively changes the fluid condition at the blade outlet, improves impeller performance, and significantly reduces manufacturing costs.

[0018] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0020] Figure 1 This is a schematic diagram of a centrifugal impeller structure according to an exemplary embodiment of the invention;

[0021] Figure 2 This is a schematic diagram of a centrifugal impeller structure from another angle, according to an exemplary embodiment of the invention;

[0022] Figure 3 This is a schematic diagram of a centrifugal impeller structure according to another exemplary embodiment of the invention;

[0023] Figures 4-7 This is a schematic diagram showing the dimensions of various parameters of the flap according to some embodiments of the present invention;

[0024] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0025] In the description of this invention, it should be noted that the terms "inner" and "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "contact," and "communication" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] like Figures 1 to 3 As shown, the present invention provides a centrifugal impeller 100, which can be applied to centrifugal compressors, especially high-speed rotating centrifugal impellers for hydrogen fuel cell air compressors, and can significantly improve the performance of air compressors.

[0028] The centrifugal impeller 100 of the present invention may include a disc 10, a plurality of blades 20 and a flap 30.

[0029] Multiple blades 20 are fixed on the impeller 10 and are evenly arranged along the circumference (circumferential direction) of the impeller 10. Adjacent blades 20 are spaced apart in the circumferential direction to form an impeller channel for fluid (e.g., gas) to flow.

[0030] like Figure 1 As shown, each blade 20 may include a leading edge 211, a trailing edge 212, a pointed edge 213, and a root edge 214. The blade root edge 214 is the edge of the blade 20 that is fixedly connected to the impeller 10. The blade pointed edge 213 is the edge of the blade 20 that is away from the impeller 10 and opposite to the root edge 214. The blade leading edge 211 and the blade trailing edge 212 are both connected to the blade pointed edge 213 and the blade root edge 214, wherein the blade leading edge 211 is located at the blade inlet, which is also upstream in the direction of fluid flow in the impeller channel; the blade trailing edge 212 is located at the blade outlet, which is also downstream in the direction of fluid flow in the impeller channel.

[0031] A flap 30 is provided at the trailing edge 212 of each blade 20, and the flap 30 extends circumferentially along the disk 10. A step protruding from the trailing edge 212 of the blade 20 along the circumferential direction of the disk can be used as the flap 30, and the flap 30 can be integrally formed with the blade 20.

[0032] This invention, by setting a flap 30 extending circumferentially along the impeller at the trailing edge 212 of the blade, can increase the fluid energy from the blade inlet to the outlet when the impeller rotates without changing the original overall structural parameters and blade profile, and without affecting the flow direction of the fluid or causing airflow turbulence. This can effectively change the fluid condition at the blade outlet, improve impeller performance, and significantly reduce manufacturing costs.

[0033] The flap 30 can extend toward one side in the circumferential direction of the impeller. This avoids obstructing the impeller flow path and ensures an increase in fluid energy from the blade inlet to the outlet when the impeller rotates.

[0034] In some embodiments, such as Figure 3 As shown, the centrifugal impeller 100 of the present invention may include a disk 10, a plurality of blades 20, and a flap 30. The plurality of blades 20 are fixed to the disk 10 and are evenly arranged along the circumference of the disk 10. Adjacent blades 20 are spaced apart in the circumferential direction to form an impeller flow channel for fluid (e.g., gas) to flow through. A flap is provided at the trailing edge of each blade, extending along the circumference of the disk. The flap 30 extends circumferentially from the trailing edge 212 of the blade 20 toward the suction surface 215 towards the disk.

[0035] Each blade 20 has a suction surface 215 and a pressure surface 216, wherein the pressure surface 216 is the surface of the blade 20 that applies pressure to the fluid, and the suction surface 215 is the surface of the blade that impacts the fluid and is opposite to the pressure surface 216. A suction surface flap is formed by a flap structure that protrudes 30 from the trailing edge 212 of each blade 20 toward the suction surface 215 and circumferentially toward the disk 20.

[0036] Because the wake jet and Mach number at the blade exit are relatively large after the gas flows into the impeller channel and performs work through the impeller, they affect impeller performance and generate noise. This invention addresses this by extending the trailing edge 212 of the blade 20 towards the suction surface 215 to form a suction surface flap. This effectively suppresses the gas wake jet and the blade exit Mach number, improves the gas flow environment within the impeller channel, and enhances impeller performance. Simultaneously, due to the reduced mixing of the suppressed wake and jet, the unsteady effect at the impeller exit is reduced, and impeller noise is effectively suppressed.

[0037] In other embodiments, such as Figure 1 and Figure 2 As shown, the centrifugal impeller 100 of the present invention may include a disk 10, a plurality of blades 20, and a flap 30. The plurality of blades 20 are fixed to the disk 10 and are evenly arranged along the circumference of the disk 10. Adjacent blades 20 are spaced apart in the circumferential direction to form an impeller flow channel for fluid (e.g., gas) to flow through. A flap is provided at the trailing edge of each blade, extending along the circumference of the disk. Specifically, the flap 30 extends circumferentially from the trailing edge 212 of the blade toward the pressure surface 216 toward the disk.

[0038] Unlike the suction-surface flaps in the above embodiments, a pressure-surface flap is formed by a flap 30 structure that protrudes from the trailing edge 212 of each blade 20 toward the pressure surface 216 and extends circumferentially toward the impeller 20. This pressure-surface flap effectively increases the installation angle of the blades 20, essentially without changing the main structural parameters of the impeller 20 or the blade profile, and can effectively improve the impeller pressure ratio, thereby improving impeller performance.

[0039] In some embodiments, the blades may include a plurality of main blades 21 and a plurality of diverter blades 22 arranged circumferentially along the wheel disk 10, with the main blades 21 and diverter blades 22 arranged alternately. The structure of the diverter blades 22 may be similar to that of the main blades 21. For example, the diverter blades 22 may also consist of a leading edge, a trailing edge, a pointed edge, and a root edge. The leading section of the diverter blades 22 may be shorter than the leading section of the main blades 21, that is, the leading edge of the diverter blades 22 may be downstream of the leading edge of the main blades 21, and the trailing edge of the diverter blades 22 may be on the same circumferential surface as the trailing edge of the main blades 21. A flap 30 extending circumferentially along the wheel disk 10 is provided at the trailing edge 212 of each main blade 21 and / or the trailing edge (not shown) of each diverter blade 22.

[0040] In one example, the flap 30 described above may be formed only on the main blade 21, for example, a pressure surface flap or a suction surface flap may be formed on the main blade 21.

[0041] In another example, the aforementioned flap 30 may be formed only on the splitter blade 22, for example, a pressure-side flap or a suction-side flap may be formed on the splitter blade 22.

[0042] In another example, the flaps 30 described above can also be formed on both the main blade 21 and the splitter blade 22, for example, pressure surface flaps can be formed on both the main blade 21 and the splitter blade 22, or suction surface flaps can be formed on both the main blade 21 and the splitter blade 22.

[0043] The blade 20 described above is not limited to including a main blade 21 and a splitter blade 22. In other possible embodiments, the blade 20 may also include only the main blade 21, without the splitter blade 22. In this case, only a pressure surface flap or a suction surface flap needs to be provided on the main blade 21.

[0044] In some embodiments, the front section 21a of the blade 20 (taking the main blade 21 as an example) is inclined, and the rear section 21c is curved, wherein the rear section 21c is curved toward the suction surface 215 of the blade. Figure 2 and Figure 6 As shown, taking the main blade 21 as an example, the main blade 21 may include a front section 21a, a middle section 21b, and a rear section 21c connected in sequence. The front section 21a and the rear section 21c of the main blade 21 are both inclined towards the pressure surface 216 of the blade. The angle between the tangent at the connection point of the rear section 21c with the flap 30 and the tangent at the connection point of the flap 30 with the rear section is the flap's tilt angle γ, which can be 18° to 30°, for example, 25°. In other words, the position at the connection point of the rear section 21c with the flap 30 is the first position (…). Figure 6 (Position of S in the middle), the tangent of the rear segment 21c at the first position S is the first tangent L1, and the tangent of the flap 30 at the first position S is the second tangent L2, wherein the included angle α between the first tangent L1 and the second tangent L2 is equal to the flap's tilt angle γ.

[0045] When the blade 20 includes a main blade 21 and a splitter blade 22, the structural profile of the splitter blade 22 can be similar to that of the main blade 21, and it can also be inclined. The inclination angle can be 18° to 30°, for example, 25°.

[0046] In the above embodiments, regardless of whether the flap 30 is a pressure-side flap or a suction-side flap, the flap 30 is tilted towards the pressure surface 216 of the blade 20, and the tilt angle (also called the inclination angle) of the flap 30 is γ. This tilt angle is the angle between the flap 30 and the axis o of the wheel 10, and the flap tilt angle γ is greater than or equal to 18° and less than or equal to 25°, for example, 25°. That is, the flap tilt angle γ is consistent with the blade tilt angle. It is worth noting that when the flap tilt angle γ is consistent with the blade tilt angle, the blade profile is not limited to the aforementioned inclined front section 21a and curved rear section 21c shape. In other possible embodiments, the blade profile can also be other shapes.

[0047] This invention, by setting a flap that is inclined toward the pressure surface side of the blade, and an inclined flap at the blade outlet, can effectively suppress the intensity of secondary flow in the impeller channel and improve impeller performance.

[0048] The flap 30 is inclined and is applicable to the above embodiments. For example, an inclined pressure surface flap or an inclined suction surface flap is provided on the main blade 21, or an inclined pressure surface flap or an inclined suction surface flap is provided on the splitter blade 22.

[0049] In some embodiments, such as Figure 5 and Figure 6 As shown, regardless of whether flap 30 is a pressure-side flap or a suction-side flap, the height θ of the flap can be expressed as the angle formed between the line connecting the top (free end) of flap 30 to the axis o of the wheel 10, and the line connecting the bottom (edge ​​connected to the trailing edge 212 of the blade) of flap to the axis o of the wheel 10. The height θ is greater than 0° and less than or equal to 2°, for example, 0.5°. When the flap is on the pressure side (pressure-side flap), it can be represented as +θ; when the flap is on the suction side (suction-side flap), it can be represented as -θ. For example, a pressure-side flap can be represented as +0.5°, and a suction-side flap can be represented as -0.5°. The sign of the angle θ is artificially set to facilitate distinguishing between the height of the pressure-side flap and the suction-side flap. In fact, the extension length of flap 30 is an arc length extending along the circumference of the wheel 10. This arc length increases as the angle θ increases and decreases as the angle θ decreases.

[0050] The flap height θ can be selected within a suitable range based on the diameter of the impeller 10. Through calculation experiments, this invention has found that by setting the flap height θ within a range greater than 0° and less than or equal to 2°, such a centrifugal impeller is more suitable for use in hydrogen fuel cell air compressors. It will not obstruct gas flow and can also improve the performance of the impeller and air compressor.

[0051] In some embodiments, such as Figure 5 and Figure 6As shown, regardless of whether the flap 30 is a pressure-side flap or a suction-side flap, the thickness δ of the flap 30 is the extension distance of the flap 30 in the radial direction of the disk 10, wherein the ratio of the thickness δ to the thickness of the trailing edge 212 of the blade in the circumferential direction of the disk 10 is greater than or equal to 40% and less than or equal to 100%, for example, the ratio can be 40%.

[0052] The smaller the flap thickness δ is within the strength allowable range, the better. Through calculation experiments, this invention found that by taking the ratio of flap thickness δ to blade trailing edge 212 thickness as 40%, the centrifugal impeller is more suitable for use in hydrogen fuel cell air compressors. This not only ensures flap strength but also does not obstruct gas flow, thereby improving flap reliability and air compressor performance.

[0053] In some embodiments, such as Figure 4 and Figure 7 As shown, regardless of whether the flap 30 is a pressure-side flap or a suction-side flap, the width h of the flap can be expressed as the extension distance of the flap 30 in the axial direction of the disk 10. The ratio of the flap width h to the length of the trailing edge 212 of the blade in the axial direction of the disk 10 (which is also the width at the blade exit) is greater than or equal to 50% and less than or equal to 100%. For example, the ratio can be 100%, that is, the flap width h is equal to the width at the blade exit.

[0054] Based on the same inventive concept, this invention also provides a centrifugal compressor, including a centrifugal impeller 100 as described in any of the above embodiments. The centrifugal compressor can be a hydrogen fuel cell air compressor. Because the centrifugal impeller of a hydrogen fuel cell air compressor operates in an ultra-high-speed environment, airflow loss is significant, resulting in low compressor efficiency and high noise. By configuring the centrifugal impeller provided by this invention, the impeller pressure ratio can be increased, improving compressor performance while simultaneously reducing noise.

[0055] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A centrifugal impeller, characterized in that, include: Roulette; Multiple blades are disposed on the wheel and distributed along the circumference of the wheel, with adjacent blades spaced apart. The flaps are provided at the trailing edge of each of the blades and extend circumferentially along the disk; Wherein, the flap is tilted toward the pressure surface side of the blade, and the tilt angle γ of the flap is the angle between the flap and the axis of the wheel, wherein the tilt angle γ is greater than or equal to 18° and less than or equal to 30°; The blade has an inclined front section and a curved rear section. The front section and the rear section are connected by a middle section. The rear section is curved toward the suction side of the blade. Both the front and rear sections of the blade are inclined toward the pressure side of the blade. The connection point between the rear section of the blade and the flap is a first position. The tangent of the rear section at the first position is a first tangent. The tangent of the flap at the first position is a second tangent. The angle between the first tangent and the second tangent is equal to the inclination angle γ of the flap. The thickness δ of the flap is the distance the flap extends in the radial direction of the wheel disk, wherein the ratio of the thickness δ to the thickness of the trailing edge of the blade in the circumferential direction of the wheel disk is greater than or equal to 40% and less than or equal to 100%. The width h of the flap is the extension distance of the flap in the axial direction of the wheel disk, wherein the ratio of the width h to the length of the trailing edge of the blade in the axial direction of the wheel disk is greater than or equal to 50% and less than or equal to 100%.

2. The centrifugal impeller according to claim 1, characterized in that, The flap extends from the trailing edge of the blade toward the suction side.

3. The centrifugal impeller according to claim 1, characterized in that, The flap extends from the trailing edge of the blade toward the pressure surface side.

4. The centrifugal impeller according to any one of claims 1-3, characterized in that, The angle θ formed between the line connecting the top of the flap to the center of the wheel axis and the line connecting the bottom of the flap to the center of the wheel axis is greater than 0° and less than or equal to 2°, wherein the top of the flap is the free end of the flap and the bottom of the flap is the edge connected to the trailing edge of the blade.

5. The centrifugal impeller according to any one of claims 1-3, characterized in that, The blade includes a plurality of main blades and a plurality of branch blades arranged circumferentially along the wheel disk, the main blades and the branch blades being staggered, wherein a flap extending circumferentially along the wheel disk is provided at the trailing edge of each main blade and / or at the trailing edge of each branch blade.

6. A centrifugal compressor, characterized in that, include: The centrifugal impeller as described in any one of claims 1 to 5.

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