Cross-split blade self-circulation treatment casing of centrifugal compressor and centrifugal compressor

Abstract

The present application proposes a cross-split blade self-circulation treatment casing of a centrifugal compressor and a centrifugal compressor, comprising: a main blade, the main blade including a main blade leading edge; a first splitter blade, the first splitter blade including a first splitter blade leading edge; a second splitter blade, the second splitter blade including a second splitter blade leading edge; the main blade leading edge is located on the front side of the first splitter blade leading edge, and the first splitter blade leading edge is located on the front side of the second splitter blade leading edge; a casing, the casing surrounds the main blade, the first splitter blade and the second splitter blade; and a casing treatment groove, the casing treatment groove surrounds the casing, the casing treatment groove is connected to the casing, and the axial ends of the casing treatment groove form openings on the casing, and in the axial direction of the centrifugal compressor, the two openings of the casing treatment groove on the casing are respectively located upstream and downstream of the leading edge of the second splitter blade.

Description

Technical Field

[0001] The present application belongs to the field of compressors, and in particular relates to a centrifugal compressor cross-split blade self-circulation processing casing and a centrifugal compressor. Background Art

[0002] The compressor is a key component in the aero-engine field, urgently in need of technological breakthroughs. Centrifugal compressors occupy a crucial position in small and medium-sized aero-engines due to their advantages, including high single-stage compression ratio, wide stable operating range, compact structure, and light weight. However, centrifugal compressors are technically challenging and require high investment. The internal flow of transonic centrifugal compressors is extremely complex, and the shock wave and vortex structures both lead to reduced stability margins and efficiency. The design requirements of high pressure ratio, high load, and high efficiency present numerous technical challenges for centrifugal compressor design.

[0003] Especially under the conditions of large flow (greater than 1kg / s) and high pressure ratio (greater than 10), the blade load is higher than that in the environment of small flow and low pressure ratio, resulting in complex interaction between shock waves and leakage vortices, making blockage and stall more likely to occur, so that the compressor can only support the aircraft engine to operate at full speed in the entire airspace within a narrow stable operating range.

[0004] Casing treatment, a simple, highly reliable compressor stabilization technology, has been widely used in axial and centrifugal compressor applications. Traditional casing treatment methods, such as casing vent holes and grooves, can generally increase the operating stability margin by approximately 10%.

[0005] At low flow rates and low pressure ratios, centrifugal compressors have a high margin of stable operation, and generally require no stabilization measures. However, as flow rates and pressure ratios increase, the compressor gradually enters transonic operation, where the shock wave and head gap leakage vortex strength gradually increase, increasing compressor instability.

[0006] The self-circulating casing of a centrifugal compressor can effectively suppress unstable flow near the stall point, delay the occurrence of stall, and thus improve the stable operating margin of the compressor. However, for large flow rates and ultra-high pressure ratios, there is still a lack of effective methods to further increase the margin on the basis of low efficiency loss.

[0007] The opening of a traditional centrifugal compressor's self-circulating casing is typically located after the impeller's throat. This is intended to draw airflow at both the blocked and stalled ends, thereby increasing the blocked flow rate and reducing the stall flow rate. However, for high-flow, ultra-high-pressure ratio centrifugal compressors, the impeller's work capacity is greater, and the pressure after the impeller's throat is higher than at the impeller's inlet, making traditional centrifugal compressor casings difficult to adapt to these high-flow, ultra-high-pressure ratio centrifugal compressors. Summary of the Invention

[0008] The present application aims to propose a centrifugal compressor cross-split blade self-circulation processing casing, which is suitable for centrifugal compressors with large flow and ultra-high pressure ratio, and effectively expands the stable operating margin of the compressor.

[0009] The present application also proposes a centrifugal compressor comprising a self-circulating processing casing with cross-split blades.

[0010] The embodiments of the present application provide a centrifugal compressor cross-split blade self-circulation processing casing, comprising:

[0011] a main blade, the main blade comprising a main blade leading edge;

[0012] a first splitter blade, the first splitter blade comprising a first splitter blade leading edge;

[0013] a second splitter blade, the second splitter blade including a second splitter blade leading edge; a plurality of the main blades, the first splitter blades, and the second splitter blades are arranged spaced apart along the circumference of the centrifugal compressor, the main blade leading edge is located in front of the first splitter blade leading edge, and the first splitter blade leading edge is located in front of the second splitter blade leading edge;

[0014] a casing enclosing the main blade, the first splitter blade, and the second splitter blade; and

[0015] A casing processing groove surrounds the casing, the casing processing groove is connected to the casing, and openings are formed on the casing at both axial ends of the casing processing groove, so that the airflow in the casing can enter the casing processing groove through the opening at one axial end of the casing processing groove and then return to the casing from the opening at the other axial end of the casing processing groove.

[0016] In the axial direction of the centrifugal compressor, the two openings of the casing treatment groove on the casing are respectively located upstream and downstream of the leading edge of the second splitter blade.

[0017] In at least one possible embodiment, an opening of the upstream end of the casing processing slot on the casing is located between a leading edge of the first splitter blade and a leading edge of the second splitter blade.

[0018] In at least one possible embodiment, in the airflow direction of the centrifugal compressor, the two openings of the casing treatment slot on the casing are equidistant from the leading edge of the second splitter blade.

[0019] In at least one possible embodiment, the casing processing groove includes an arc segment and a connecting segment, the arc segment is connected to the casing through the connecting segment, and the connecting segment is perpendicular to a connection position between the casing and the connecting segment.

[0020] In at least one possible embodiment, the connecting section extends along a straight line.

[0021] In at least one possible embodiment, the two openings of the casing processing groove on the casing are located at 27% and 41% between the leading edge of the main blade and the trailing edge of the main blade, the position where the leading edge of the main blade is located is 0%, and the position where the trailing edge of the main blade is located is 100%.

[0022] In at least one possible implementation manner, the widths of the two openings of the casing processing groove on the casing are respectively 1 mm.

[0023] In at least one possible implementation, the casing processing tank includes an inner wall and an outer wall, and the inner wall and the outer wall are connected by a rigid support structure.

[0024] In at least one possible embodiment, the centrifugal compressor is used in an environment where the flow rate is greater than 4 kilograms per second and the compression ratio is greater than or equal to 10.

[0025] An embodiment of the present application further provides a centrifugal compressor, which includes the cross-split blade self-circulation processing casing of the centrifugal compressor described in any one of the above technical solutions.

[0026] By adopting the above technical solution, the casing of the present application enables the centrifugal compressor to be suitable for large flow and ultra-high pressure ratio, maintaining a relatively high stable operating margin. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a meridian flow passage of a centrifugal compressor according to an embodiment of the present application is shown.

[0028] Figure 2 A schematic structural diagram of a centrifugal compressor according to an embodiment of the present application is shown.

[0029] Figure 3 A schematic diagram of the internal structure of a centrifugal compressor according to an embodiment of the present application is shown.

[0030] Figure 4 A flow-efficiency curve of a centrifugal compressor according to an embodiment of the present application is shown.

[0031] Figure 5 A flow-pressure ratio curve diagram of a centrifugal compressor according to an embodiment of the present application is shown.

[0032] Description of Reference Numerals

[0033] 1 air intake

[0034] 2 Main blade 21 Main blade leading edge

[0035] 3 First splitter blade 31 First splitter blade leading edge

[0036] 4 Second splitter blade 41 Second splitter blade leading edge

[0037] 5. First diffuser

[0038] 6 Second diffuser

[0039] 7 Air outlet

[0040] 8 Receiver

[0041] 9 Casing processing groove 91 arc segment 92 connecting segment

[0042] A axial direction C circumferential direction DETAILED DESCRIPTION

[0043] In order to more clearly illustrate the above-mentioned purposes, features and advantages of the present application, this section describes in detail the specific embodiments of the present application in conjunction with the accompanying drawings. In addition to the various embodiments described in this section, the present application can also be implemented in other different ways. Without violating the spirit of the present application, those skilled in the art can make corresponding improvements, deformations and substitutions. Therefore, the present application is not limited to the specific embodiments disclosed in this section. The scope of protection of this application shall be based on the claims.

[0044] like Figures 1 to 3 As shown, an embodiment of the present application proposes a centrifugal compressor, which includes an air inlet 1, main blades 2, first splitter blades 3, second splitter blades 4, a first diffuser 5, a second diffuser 6, an air outlet 7 and a casing 8.

[0045] Figure 1 The left side is the upstream of the centrifugal compressor, and the right side is the downstream of the centrifugal compressor. The airflow flows from the upstream side to the downstream side.

[0046] The casing 8 can be surrounded by an air inlet duct 1 extending along the axial direction A of the centrifugal compressor. The main blades 2, the first splitter blades 3 and the second splitter blades 4 are connected to the impeller hub, and the impeller hub can rotate relative to the casing 8. The main blades 2, the first splitter blades 3 and the second splitter blades 4 are all rotatably arranged inside the casing 8 relative to the casing 8.

[0047] like Figure 2 and Figure 3As shown, a plurality of main blades 2, first splitter blades 3, and second splitter blades 4 are provided at intervals along the circumferential direction C of the centrifugal compressor. In the circumferential direction C of the centrifugal compressor, the first splitter blade 3 can be provided between two adjacent main blades 2, and the second splitter blade 4 can be provided between adjacent first splitter blades 3 and main blades 2. Along the circumferential direction C of the centrifugal compressor, the main blades 2, the second splitter blades 4, the first splitter blades 3, and the second splitter blades 4 can be periodically arranged in this order.

[0048] The upstream end of the main blade 2 is the main blade leading edge 21, the upstream end of the first splitter blade 3 is the first splitter blade leading edge 31, and the upstream end of the second splitter blade 4 is the second splitter blade leading edge 41. The main blade leading edge 21 is located forward of the first splitter blade leading edge 31, and the first splitter blade leading edge 31 is located forward of the second splitter blade leading edge 41.

[0049] It can be understood that the specific blade profiles of the main blade 2, the first splitter blade 3 and the second splitter blade 4 can be designed based on the basic theory of impeller machinery to meet the performance requirements of the centrifugal compressor.

[0050] The first splitter blades 3 and the second splitter blades 4 rotate together with the main blades 2 to perform work, which can improve the work capacity of the centrifugal compressor and reduce the possibility of compressor blockage.

[0051] The casing 8 is provided with a casing processing groove 9, which can surround the radial outer side of the casing 8, and the axial ends of the casing processing groove 9 can form annular openings on the casing 8, so that the casing processing groove 9 is connected to the interior of the casing 8.

[0052] The casing processing tank 9 includes an inner wall and an outer wall, wherein the inner wall is located radially inward of the outer wall, and the inner wall and the outer wall can form a channel. Figure 1 As shown, when viewed along the meridian plane of the centrifugal compressor, the casing processing groove 9 can be an arc-shaped channel.

[0053] In the axial direction A of the centrifugal compressor, the two openings of the casing treatment groove 9 on the casing 8 straddle the leading edge 41 of the second splitter blade. The casing treatment groove 9 can form a gas recirculation groove, forming a gas flow channel from the first splitter blade to the second splitter blade, allowing gas to flow through the casing treatment groove 9, thereby suppressing unstable flow near the stall point, delaying the onset of stall, and thereby improving the stable operating margin of the compressor.

[0054] The opening of the casing processing groove 9 is completely located on the casing 8. Under the condition of large flow and high pressure ratio, it is beneficial to regulate the development of the top gap leakage vortex upstream and downstream of the splitter blade, thereby effectively improving the stable working margin while avoiding excessive flow loss.

[0055] Furthermore, the opening of the upstream end of the casing processing tank 9 on the casing 8 is located between the first splitter blade leading edge 31 and the second splitter blade leading edge 41 .

[0056] Furthermore, in the airflow direction of the centrifugal compressor (which can be understood as the axial direction A), the distances between the two axial ends of the casing processing groove 9 and the leading edge 41 of the second splitter blade are equal. Of course, the equality here can include being approximately equal, for example, the distance between the two openings and the leading edge 41 of the second splitter blade is less than or equal to 10%.

[0057] Specifically, the positions of the two openings of the casing processing slot 9 on the casing 8 are located at 27% and 41% between the main blade leading edge 21 and the main blade trailing edge, the position where the main blade leading edge 21 is located is 0%, and the position where the main blade trailing edge is located is 100%. Of course, there may be a slight position difference, for example, the error amount is plus or minus 3%.

[0058] The width of the openings at both ends of the casing processing groove 9 can be relatively small, for example, about 1 mm, to avoid excessive flow loss of gas in the casing processing groove 9. The widths of the openings at both ends of the casing processing groove 9 can be equal, and of course, the equal here can include being approximately equal, for example, the difference between the two openings is less than or equal to 10%.

[0059] The inner wall and outer wall of the casing processing tank 9 can be connected by a rigid support structure. The rigid support structure can include a support rod. The support rod can be nested in the outer wall. The support rod can be arranged between the inner wall and the outer wall to support and fix the inner wall.

[0060] like Figure 1 As shown, the casing processing groove 9 includes an arc segment 91 and a connecting segment 92 . The connecting segment 92 can be located at both ends of the arc segment 91 , and the connecting segment 92 is connected to the casing 8 .

[0061] The connection position of the connecting section 92 and the casing 8 is perpendicular. The gas flow near the casing is relatively complex. Under different working conditions, such as different speeds and flow rates, it is difficult to determine the direction of the gas flow near the casing. The gas may flow downstream or upstream. Making the connection position of the connecting section 92 and the casing 8 perpendicular can ensure that the opening of the casing treatment tank 9 is neither facing nor facing the air flow under different working conditions.

[0062] The connecting section of the casing treatment tank 9 can be a straight segment. This allows the connecting section 92 to intersect the casing 8 perpendicularly, regardless of the outer shape of the casing 8. This ensures a smooth transition between the arc section 91 of the casing treatment tank 9 and the casing 8. The length of the straight segment can be selected based on the specific shape of the casing, minimizing the length of the self-circulating treatment tank 9 along the axial direction A of the centrifugal compressor.

[0063] The first diffuser 5, the second diffuser 6 and the air outlet 7 can be sequentially arranged on the downstream side of the second splitter blade 4, with the second diffuser 6 being located radially outward of the first diffuser 5. The first diffuser 5 can be a tapered bladeless diffuser. The second diffuser 6 can be a wedge-shaped diffuser. Since the gas flow rate and pressure on the downstream side of the blade 4 are high, the use of a tapered bladeless diffuser contributes to the stable flow of the gas. Using a wedge-shaped diffuser on the downstream side of the tapered bladeless diffuser can further decelerate and diffuse the gas, giving the diffuser better diffusion capacity.

[0064] The gas outlet 7 can be bent 90 degrees as a whole, the upstream section of the gas outlet 7 can extend along the radial direction R, and the downstream section of the gas outlet 7 can extend along the axial direction A, so that the gas is discharged from the casing 8 along the axial direction A.

[0065] When a centrifugal compressor operates under conditions of high flow (greater than 4kg / s) and high pressure ratio (greater than 10), a gas flow channel is formed in the casing treatment tank 9 because its pressure ratio far exceeds that of a conventional compressor, and the gas flow speed far exceeds the flow speed near the casing and the intensity of the top gap leakage vortex. Therefore, a strong jet is formed at the upstream outlet of the casing treatment tank, which has a blocking effect on the top gap leakage vortex. At the same time, the static pressure in the flow channel before the casing treatment tank is increased, weakening the intensity of the shock wave at the leading edge of the main blade. The maximum flow speed before the shock wave at the leading edge of the main blade is reduced by 0.2 Mach compared to the case without the casing treatment tank.

[0066] The stabilization effect of the centrifugal compressor of the present application is mainly reflected in the near-stall end, while the impact on the near-blockage end is relatively small. However, when the speed is lower than the design speed, more low-speed fluid appears in the casing processing tank, and some flow is lost near the blockage end.

[0067] The aerodynamic performance of the centrifugal compressor of this application is analyzed using NUMECA software. First, NUMECA / Autogrid is used to divide the compressor, diffuser and self-circulating processing casing 8 into structured grids, and the wall grid satisfies Y+ less than 10. The SA turbulence model is used for calculation, and the fourth-order explicit Runge-Kutta time-marching method is used for time discretization, and the central difference format is used for spatial discretization. Given the total inlet temperature and total pressure under standard atmospheric conditions, the impeller wall is set as an adiabatic no-slip wall. In terms of outlet conditions, the small flow condition is the flow outlet, and the large flow condition is the pressure outlet. The multi-grid method and CPUbooster and other technologies are used to accelerate the calculation convergence.

[0068] ANSYS / Mechanical software was used to perform strength verification on the centrifugal impeller. TC11 titanium alloy for aviation was selected as the impeller material. Frictionless constraints were applied to both ends of the shaft, cylindrical constraints were applied to the inner surface of the shaft, and rotational angular velocity constraints were applied. The maximum stress was found to occur near the rim and blade tip, with a safety factor of 1.16.

[0069] Figure 4 The flow-efficiency curve of the centrifugal compressor of the present application is shown, wherein the horizontal axis represents the flow rate and the vertical axis represents the efficiency. Figure 5 The flow-pressure ratio curve of the centrifugal compressor of the present application is shown, wherein the horizontal axis represents the flow rate and the vertical axis represents the pressure ratio. Figure 4 and Figure 5 The n in represents the speed, Figure 4 and Figure 5 The working state of the centrifugal compressor at 5 speeds (90%n to 110%n) is shown. The two ends of the curve represent the stall end and the blocked end. Figure 4 and Figure 5 90%n to 110%n) compared to the original solution without casing processing slot ( Figure 4 and Figure 5 The original design in the middle) has a wider operating range, that is, the speed range corresponding to the curve of the present application on the horizontal axis is larger, which supports the full speed operation of the aircraft engine in the entire airspace. Especially at the stall end ( Figure 4 The centrifugal compressor of the present application has achieved a great improvement in surge margin, which can meet the requirements of modern aircraft engines for stable working margin and efficiency of the compressor.

[0070] Through performance comparison, it can be seen that the treatment casing of the centrifugal compressor using the present application is better than that without casing ( Figure 4 and Figure 5 In the original design), at the design speed ( Figure 4 and Figure 5 At 90% to 110% of the original speed (in the 90% to 110% range), the surge margin is significantly improved with minimal efficiency loss, meeting the stable operating margin and efficiency requirements of modern aircraft engines. Taking the highest efficiency point as the design point, the overall surge margin at various speeds is generally improved by more than 50% compared to the caseless design, approaching 10%. Under certain operating conditions, the overall surge margin exceeds 10%, meeting practical engineering requirements.

[0071] It should be understood that at least some aspects or features of the above-mentioned embodiments, examples or examples may be appropriately combined.

[0072] It is understood that in this application, when the number of parts or components is not specifically limited, the number may be one or more, and the term "plurality" herein refers to two or more. Where the number of parts or components is shown in the drawings and / or described in the specification as a specific number, such as two, three, or four, the specific number is generally illustrative and not restrictive, and may be understood as a plurality, i.e., two or more. However, this does not mean that this application excludes the case of one.

[0073] In this application, unless otherwise clearly stated or limited, terms such as "install", "assemble", "connect", "connect", "couple", "link", "abut", "connect", "interconnect", "communicate", "conduct", "fix", "fasten", etc. should be understood in a broad sense, for example, they can be direct or indirect. For example, with respect to connection, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly stated or limited. For example, with respect to connectivity / conduction, it can be direct connectivity / conduction or indirect connectivity / conduction through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0074] In the present application, unless otherwise clearly stated or limited, a component provided on / installed on / located on / accommodated on / placed in, within, inside, etc. another component may be any of the following two situations: a part or most of the one component is located in the other component; and the one component is completely accommodated in the other component.

[0075] While the present application has been described in detail using the above-described embodiments, it will be apparent to those skilled in the art that the present application is not limited to the embodiments described in this specification. The present application can be modified and implemented as modified embodiments without departing from the subject matter and scope of the present application as defined by the claims. Therefore, the descriptions in this specification are for illustrative purposes only and do not have any limiting meaning with respect to the present application.

Claims

1. A centrifugal compressor cross-split blade self-circulation processing casing, characterized in that: include: A main blade (2), the main blade (2) comprising a main blade leading edge (21); A first splitter blade (3), the first splitter blade (3) comprising a first splitter blade leading edge (31); a second splitter blade (4), the second splitter blade (4) including a second splitter blade leading edge (41); a plurality of the main blade (2), the first splitter blade (3) and the second splitter blade (4) are arranged spaced apart along the circumferential direction (C) of the centrifugal compressor, the main blade leading edge (21) is located in front of the first splitter blade leading edge (31), and the first splitter blade leading edge (31) is located in front of the second splitter blade leading edge (41); a casing (8), the casing (8) surrounding the main blade (2), the first splitter blade (3) and the second splitter blade (4); as well as A casing processing groove (9), the casing processing groove (9) surrounds the casing (8), the casing processing groove (9) is connected to the casing (8), and the axial ends of the casing processing groove (9) form annular openings on the casing (8), so that the airflow in the casing (8) can enter the casing processing groove (9) through the opening at one axial end of the casing processing groove (9), and then return to the casing (8) from the opening at the other axial end of the casing processing groove (9). In the axial direction (A) of the centrifugal compressor, the two openings of the casing treatment groove (9) on the casing (8) are respectively located upstream and downstream of the leading edge (41) of the second splitter blade. The opening of the upstream end of the casing processing slot (9) on the casing (8) is located between the leading edge (31) of the first splitter blade and the leading edge (41) of the second splitter blade. In the airflow direction of the centrifugal compressor, the two openings of the casing treatment slot (9) on the casing (8) are equidistant from the leading edge (41) of the second splitter blade.

2. The centrifugal compressor cross-split blade self-circulation processing casing according to claim 1, characterized in that: The casing processing groove (9) comprises an arc segment (91) and a connecting segment (92), wherein the arc segment (91) is connected to the casing (8) via the connecting segment (92), and the connecting segment (92) is perpendicular to the connection position between the casing (8) and the connecting segment (92).

3. The centrifugal compressor cross-split blade self-circulation processing casing according to claim 2, characterized in that: The connecting section (92) extends along a straight line.

4. The centrifugal compressor cross-split blade self-circulation processing casing according to claim 1, characterized in that: The two openings of the casing processing groove (9) on the casing (8) are located at 27% and 41% between the leading edge (21) of the main blade and the trailing edge of the main blade (2), the position where the leading edge (21) of the main blade is located is 0%, and the position where the trailing edge of the main blade (2) is located is 100%.

5. The centrifugal compressor cross-split blade self-circulation processing casing according to claim 1, characterized in that: The widths of the two openings of the casing processing groove (9) on the casing (8) are respectively 1 mm.

6. The centrifugal compressor cross-split blade self-circulation processing casing according to claim 1, characterized in that: The casing processing tank (9) comprises an inner wall and an outer wall, and the inner wall and the outer wall are connected by a rigid support structure.

7. The centrifugal compressor cross-split blade self-circulation processing casing according to claim 1, characterized in that: The centrifugal compressor is used in an environment where the flow rate is greater than 4 kilograms per second and the compression ratio is greater than or equal to 10.

8. A centrifugal compressor, characterized in that: The centrifugal compressor comprises the cross-split blade self-circulation processing casing of the centrifugal compressor according to any one of claims 1 to 7.

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