Rotor blades of axial compressor and their design methods

Abstract

This invention discloses a rotor blade for an axial compressor and its design method. The stacking line of the rotor blade includes a first segment and a second segment connected in sequence. The second segment is an arc segment along the axial direction of the axial compressor, extending from one end near the first segment to the other end away from the first segment towards the leading edge of the rotor blade, with the center of the arc segment located on the side near the leading edge of the rotor blade. The plane containing the first segment is perpendicular to the axial direction of the axial compressor. The distance from the connection point of the first and second segments to the blade root is greater than half the height of the blade. The orthographic projection of the blade tip onto the axial direction of the axial compressor lies within the orthographic projection of the blade root onto the axial direction of the axial compressor. By setting the specific structure of the rotor blade, this invention achieves control over the shock wave and flow field in the blade tip region, reduces secondary flow in the blade tip region, thereby improving the efficiency and stable operating range of the rotor blade, while avoiding the risk of rubbing between adjacent rotor blades and stator blades.

Description

Technical Field

[0001] This invention relates to a rotor blade for an axial flow compressor and its design method. Background Technology

[0002] With the development of technology, modern aero engines face increasingly higher requirements for economy and reliability, posing unprecedented challenges to the performance of various components. The axial compressor is one of the core components of an aero engine, and its performance has a crucial impact on the entire engine. However, as aero engine performance indicators continue to improve, the internal temperature and pressure ratio of the engine gradually increase, leading to increasingly serious losses in the compressor's internal flow system. The severe internal flow losses in multi-stage, high-pressure-ratio axial compressors significantly affect their aerodynamic performance, and consequently, the overall engine performance.

[0003] The main sources of compressor losses are airfoil losses, endwall losses, and leakage losses. The flow in the endwall region of a high-load compressor is very complex, and endwall boundary layer losses and tip leakage losses are the main components of compressor rotor blade losses.

[0004] The compressor is the rotating component inside an aero-engine that experiences the greatest adverse pressure gradient, and achieving efficient airflow pressurization is a major challenge in compressor design. In the corner region formed by the rotor hub and the suction surfaces at the blade roots, separation easily occurs due to the influence of the hub boundary layer and gas undercurrent, resulting in aerodynamic losses and a decrease in compressor efficiency. In the blade tip region, a gap exists between the rotor and the outer casing. Airflow from the rotor blade pressure surface leaks through this gap to the blade suction surface, generating complex secondary flow characteristics such as leakage vortices. Furthermore, the high tangential velocity of the rotor blades generates shock waves at the tips of the compressor's leading-stage rotor blades. These shock waves, leakage vortices, and the outer casing boundary layer interfere with each other, making the flow in the blade tip gap region extremely complex, exhibiting various complex vortex structures. Numerous studies have shown that compressor stall typically occurs in the blade tip and hub regions.

[0005] Therefore, how to effectively control the shock wave and flow field in the blade tip region, thereby reducing the secondary flow in the blade tip region, is a problem that needs to be solved in this field. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defect of airflow loss in the rotor blades of axial compressors in the prior art, and to provide a rotor blade of axial compressor and its design method.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] A rotor blade for an axial compressor, characterized in that the rotor blade includes a blade root and a blade tip, and the rotor blade has a plurality of basic airfoil sections along the height direction from the blade root to the blade tip. The centroids of each basic airfoil section are used as accumulation points and superimposed along the height direction of the rotor blade to obtain an accumulation line.

[0009] The accumulation line, along the height direction of the rotor blade from the blade root to the blade tip, includes a first segment and a second segment connected in sequence. The second segment is an arc segment in the axial direction of the axial compressor, and the arc segment bends toward the leading edge of the rotor blade.

[0010] The plane containing the first segment is perpendicular to the axial direction of the axial compressor, and the distance from the connection point between the first segment and the second segment to the blade root is greater than half the height of the rotor blade.

[0011] The orthographic projection of the blade tip onto the axis of the axial compressor lies within the orthographic projection of the blade root onto the axis of the axial compressor.

[0012] In this technical solution, by setting the above-mentioned structure of the rotor blades, it is possible to control the shock wave and flow field in the blade tip region, reduce the secondary flow in the blade tip region, thereby improving the efficiency and stable operating range of the rotor blades of the axial compressor, while avoiding the risk of rubbing between adjacent rotor blades and stator blades.

[0013] Specifically, by setting the second section near the blade tip to be an arc segment along the axial direction of the axial compressor, and this arc segment curving towards the leading edge of the rotor blade, the intensity of the blade tip shock wave is weakened, thereby reducing the boundary layer separation loss caused by the shock wave and improving the rotor blade efficiency of the axial compressor. In other words, control of the shock wave and flow field in the blade tip region is achieved. On the other hand, compressor rotor stall typically occurs in the blade tip region. By setting an arc-shaped stack, a reverse pressure gradient is generated in the radial direction, which facilitates the migration of low-energy fluid from the blade tip region to the middle of the blade, thereby weakening the secondary flow effect in the blade tip region, improving the flow conditions at the blade tip, and extending the stable operating range of the compressor rotor blade.

[0014] By setting the plane containing the first segment perpendicular to the axial direction of the axial compressor, and ensuring that the distance from the connection point between the first and second segments to the blade root is greater than half the height of the rotor blade—that is, maintaining at least 50% of the blade height below the center section without axial offset—the risk of rubbing between adjacent rotor blades and stator blades is avoided. This is because, typically, to ensure blade strength, the axial chord length at the root of the rotor blade is relatively large, and its axial distance to the stator of the preceding row of blades is the shortest. If forward sweep is adopted in this case, there is a risk of rubbing between adjacent rotor blades and stator blades.

[0015] By setting the orthogonal projection of the blade tip onto the axis of the axial compressor to be within the orthogonal projection of the blade root onto the axis of the axial compressor, that is, the axial forward sweep offset of the blade tip position does not exceed the axial projection of the blade root position, and the axial position of the blade tip leading edge is located axially backward from the axial position of the blade root leading edge, the risk of rubbing between adjacent rotor blades and stator blades is avoided. This is because the design speed of the compressor is usually high, and the compressor blades and blade disk are connected together. At the design speed, the axial deformation at the blade root position can be understood as only the deformation of the disk itself, while the axial deformation at the blade tip position is the axial deformation of the blade plus the deformation of the compressor disk, thus the axial deformation at the blade tip position is larger. In this technical solution, by setting the axial position of the blade tip leading edge to be axially backward from the axial position of the blade root leading edge, it is beneficial to reduce the risk of axial rubbing between the leading edge of the rotor blade tip and the trailing edge of the previous row of stator blades.

[0016] Preferably, the second segment from the leaf root to the leaf tip includes at least a first control point and a second control point, the first control point being located at the connection point between the first segment and the second segment, and the second control point being located at the centroid of the basic leaf section of the leaf tip;

[0017] Along the axial direction of the axial flow air compressor, the coordinates of any point located between the first control point and the second control point are (x, y), and the coordinates of the center of the arc segment are (x, y). o y o The radius of the arc segment is R, where:

[0018] (xx o ) 2 +(yy o ) 2 =R 2

[0019] Wherein, the coordinate (x) of the center of the circle on the axial direction of the axial flow air compressor. o y o The axial sweep angle α of the arc segment at the second control point is obtained by the coordinates of the first control point on the axis of the axial flow compressor. The axial sweep angle α of the second segment at the second control point is 45 degrees to 90 degrees.

[0020] In this technical solution, the axial offset of the second segment of the rotor blade stacking line is controlled by constructing a simple equation, thereby achieving the parametric control design objective of rotor blade stacking; at the same time, the axial offset of other blade height positions is fitted with as few control points as possible, thereby improving the calculation efficiency of optimizing the blade profile.

[0021] Preferably, in the direction from the leaf root to the leaf tip, both the first segment and the second segment are linearly offset in the circumferential direction.

[0022] In this technical solution, both the first and second segments are linearly offset in the circumferential direction from the blade root to the blade tip. That is, the circumferential offset of the rotor blade's stacking line is added linearly. Specifically, the maximum circumferential offset of the blade tip relative to the blade root is given first, and the remaining circumferential offsets of the blade height are obtained through linear interpolation based on the blade height. Once the axial and circumferential offsets are determined, they are superimposed to determine the stacking profile of the basic airfoil. Extending the basic airfoil along the stacking profile to construct a set of curves yields a three-dimensional rotor blade.

[0023] Preferably, the axial projection chord length of the cross section at the tip of the rotor blade is 40%-70% of the axial projection chord length of the cross section at the root of the rotor blade; the axial projection chord length of the cross section at the middle of the rotor blade is 60%-80% of the axial projection chord length of the cross section at the root of the rotor blade; and the axial projection chord length of the cross section at 15% of the blade height of the rotor blade is not less than 90% of the axial projection chord length of the cross section at the root of the rotor blade.

[0024] The axial projection chord lengths of the cross section located between the blade tip and the middle of the rotor blade, the cross section located between the middle of the rotor blade and 15% of the blade height of the rotor blade, and the cross section located between 15% of the blade height of the rotor blade and the blade root all have smooth transitions.

[0025] In this technical solution, by setting the axial projection chord length of the cross-section at different positions of the rotor blade, it is beneficial to maintain a high compressor efficiency while ensuring that the rotor blade maintains a good strength level. By setting the projection length of the remaining cross-sections of the rotor blade to transition smoothly, it is beneficial to maintain a high compressor efficiency while further ensuring that the rotor blade maintains a good strength level.

[0026] Preferably, the distance between the leading edge of the rotor blade at its root and the adjacent stator blade along the axial direction of the axial compressor is greater than or equal to 6 mm and less than or equal to 30 mm; and / or,

[0027] The axial projection chord length of the cross section at the root of the rotor blade is 5%-20% of the inner diameter of the casing covering the outside of the rotor blade.

[0028] As mentioned earlier, compressor discs are subject to axial deformation. Based on experience, the axial deformation of a compressor disc typically does not exceed 6mm, but some larger compressor discs may experience deformation exceeding 6mm. In this technical solution, by setting the distance between the leading edge of the rotor blade root and the adjacent stator blade along the axial direction of the axial compressor to be greater than or equal to 6mm and less than or equal to 30mm, for some larger compressor discs, axial rubbing at the blade root can be more effectively avoided; that is, the risk of rubbing between adjacent rotor blades and stator blades can be more effectively prevented.

[0029] In this technical solution, by setting the axial projection chord length of the cross-section at the blade root of the rotor blade to 5%-20% of the inner diameter of the casing covering the outer side of the rotor blade, it is beneficial to maintain high blade efficiency and a stable operating range. This is because, from the perspective of blade aerodynamic performance, generally, the longer the blade chord length, the less likely the gas is to separate, and the wider the stable operating range of the compressor; however, the longer the blade, the greater the frictional loss of the gas. By setting the axial projection chord length of the cross-section at the blade root of the rotor blade to 5%-20% of the inner diameter of the casing covering the outer side of the rotor blade, the rotor blade with this structure can combine stability margin and efficiency, thereby helping to maintain high blade efficiency and a stable operating range, and thus having better aerodynamic performance.

[0030] A method for designing rotor blades for an axial compressor, characterized in that the rotor blade includes a root and a tip, and the rotor blade has a plurality of basic airfoil sections along the height direction from the root to the tip. The design method includes the following steps:

[0031] S1: The centroids of the cross sections of each basic blade are used as the accumulation points and superimposed along the height direction of the rotor blades to obtain the accumulation line;

[0032] S2: The accumulation line is configured to include a first segment and a second segment connected sequentially along the height direction of the rotor blade from the blade root to the blade tip. The second segment is an arc segment in the axial direction of the axial compressor, and the arc segment bends towards the leading edge of the rotor blade. The plane containing the first segment is perpendicular to the axial direction of the axial compressor. The distance from the connection point of the first segment and the second segment to the blade root is greater than half the height of the rotor blade. The orthographic projection of the blade tip on the axis of the axial compressor is located within the orthographic projection of the blade root on the axis of the axial compressor.

[0033] In this technical solution, by setting the above-mentioned structure of the rotor blades, it is possible to control the shock wave and flow field in the blade tip region, reduce the secondary flow in the blade tip region, thereby improving the efficiency and stable operating range of the rotor blades of the axial compressor, while avoiding the risk of rubbing between adjacent rotor blades and stator blades.

[0034] Specifically, by setting the second section near the blade tip to be an arc segment along the axial direction of the axial compressor, and this arc segment curving towards the leading edge of the rotor blade, the intensity of the blade tip shock wave is weakened, thereby reducing the boundary layer separation loss caused by the shock wave and improving the rotor blade efficiency of the axial compressor. In other words, control of the shock wave and flow field in the blade tip region is achieved. On the other hand, compressor rotor stall typically occurs in the blade tip region. By setting an arc-shaped stack, a reverse pressure gradient is generated in the radial direction, which facilitates the migration of low-energy fluid from the blade tip region to the middle of the blade, thereby weakening the secondary flow effect in the blade tip region, improving the flow conditions at the blade tip, and extending the stable operating range of the compressor rotor blade.

[0035] By setting the plane containing the first segment perpendicular to the axial direction of the axial compressor, and ensuring that the distance from the connection point between the first and second segments to the blade root is greater than half the height of the rotor blade—that is, maintaining at least 50% of the blade height below the center section without axial offset—the risk of rubbing between adjacent rotor blades and stator blades is avoided. This is because, typically, to ensure blade strength, the axial chord length at the root of the rotor blade is relatively large, and its axial distance to the stator of the preceding row of blades is the shortest. If forward sweep is adopted in this case, there is a risk of rubbing between adjacent rotor blades and stator blades.

[0036] By setting the orthogonal projection of the blade tip onto the axis of the axial compressor to be within the orthogonal projection of the blade root onto the axis of the axial compressor, that is, the axial forward sweep offset of the blade tip position does not exceed the axial projection of the blade root position, and the axial position of the blade tip leading edge is located axially backward from the axial position of the blade root leading edge, the risk of rubbing between adjacent rotor blades and stator blades is avoided. This is because the design speed of the compressor is usually high, and the compressor blades and blade disk are connected together. At the design speed, the axial deformation at the blade root position can be understood as only the deformation of the disk itself, while the axial deformation at the blade tip position is the axial deformation of the blade plus the deformation of the compressor disk, thus the axial deformation at the blade tip position is larger. In this technical solution, by setting the axial position of the blade tip leading edge to be axially backward from the axial position of the blade root leading edge, it is beneficial to reduce the risk of axial rubbing between the leading edge of the rotor blade tip and the trailing edge of the previous row of stator blades.

[0037] Preferably, step S2 includes:

[0038] The second segment is configured to include at least a first control point and a second control point in the direction from the leaf root to the leaf tip. The first control point is located at the connection point between the first segment and the second segment, and the second control point is located at the centroid of the basic leaf section of the leaf tip.

[0039] Along the axial direction of the axial flow air compressor, the coordinates of any point located between the first control point and the second control point are (x, y), and the coordinates of the center of the arc segment are (x, y). o y o The radius of the arc segment is R, where:

[0040] (xx o ) 2 +(yy o ) 2 =R 2

[0041] Wherein, the coordinate (x) of the center of the circle on the axial direction of the axial flow air compressor. o y o The axial sweep angle α of the arc segment at the second control point is obtained by the coordinates of the first control point on the axis of the axial flow compressor. The axial sweep angle α of the second segment at the second control point is 45 degrees to 90 degrees.

[0042] In this technical solution, the axial offset of the second segment of the rotor blade stacking line is controlled by constructing a simple equation, thereby achieving the parametric control design objective of rotor blade stacking; at the same time, the axial offset of other blade height positions is fitted with as few control points as possible, thereby improving the calculation efficiency of optimizing the blade profile.

[0043] Preferably, step S2 includes:

[0044] In the direction from the leaf root to the leaf tip, both the first segment and the second segment are linearly offset in the circumferential direction.

[0045] In this technical solution, both the first and second segments are linearly offset in the circumferential direction from the blade root to the blade tip. That is, the circumferential offset of the rotor blade's stacking line is added linearly. Specifically, the maximum circumferential offset of the blade tip relative to the blade root is given first, and the remaining circumferential offsets of the blade height are obtained through linear interpolation based on the blade height. Once the axial and circumferential offsets are determined, they are superimposed to determine the stacking profile of the basic airfoil. Extending the basic airfoil along the stacking profile to construct a set of curves yields a three-dimensional rotor blade.

[0046] Preferably, step S2 includes:

[0047] The axial projection chord length of the cross section at the tip of the rotor blade is set to 40%-70% of the axial projection chord length of the cross section at the root of the rotor blade; the axial projection chord length of the cross section at the middle of the rotor blade is set to 60%-80% of the axial projection chord length of the cross section at the root of the rotor blade; and the axial projection chord length of the cross section at 15% of the blade height of the rotor blade is not less than 90% of the axial projection chord length of the cross section at the root of the rotor blade.

[0048] The axial projection chord lengths of the cross section located between the blade tip and the mid-section of the rotor blade, the axial projection chord lengths of the cross section located between the mid-section of the rotor blade and 15% of the blade height of the rotor blade, and the axial projection chord lengths of the cross section located between 15% of the blade height of the rotor blade and the blade root are all smoothly transitioned.

[0049] In this technical solution, by setting the axial projection chord length of the cross-section at different positions of the rotor blade, it is beneficial to maintain a high compressor efficiency while ensuring that the rotor blade maintains a good strength level. By setting the projection length of the remaining cross-sections of the rotor blade to transition smoothly, it is beneficial to maintain a high compressor efficiency while further ensuring that the rotor blade maintains a good strength level.

[0050] Preferably, step S2 includes:

[0051] The distance between the leading edge of the rotor blade at its root and the adjacent stator blade along the axial direction of the axial compressor is greater than or equal to 6 mm and less than or equal to 30 mm; and / or,

[0052] The axial projection chord length of the cross section at the root of the rotor blade is set to 5%-20% of the inner diameter of the casing covering the outside of the rotor blade.

[0053] As mentioned above, by setting the distance between the leading edge of the rotor blade at the blade root and the adjacent stator blade along the axial direction of the axial compressor to be greater than or equal to 6 mm and less than or equal to 30 mm, it is beneficial to more effectively avoid axial rubbing at the blade root for some larger compressor disks, that is, to more effectively avoid the risk of rubbing between adjacent rotor blades and stator blades.

[0054] By setting the axial projection chord length of the cross section at the blade root of the rotor blade to 5%-20% of the inner diameter of the casing covering the outside of the rotor blade, it is beneficial to maintain the blade's high efficiency and stable operating range.

[0055] The positive and progressive effects of this invention are as follows:

[0056] By setting the specific structure of the rotor blades, this invention can control the shock wave and flow field in the blade tip region, reduce the secondary flow in the blade tip region, and thus improve the efficiency and stable operating range of the rotor blades of the axial compressor. At the same time, it can avoid the risk of rubbing between adjacent rotor blades and stator blades. Attached Figure Description

[0057] Figure 1 This is a partial structural schematic diagram of an axial flow compressor according to a preferred embodiment of the present invention.

[0058] Figure 2 This is a schematic diagram of the rotor blades of an axial compressor according to a preferred embodiment of the present invention.

[0059] Figure 3 This is a flowchart illustrating a preferred embodiment of the design method for rotor blades of an axial compressor according to the present invention.

[0060] Figure 4 A comparison diagram showing the pressure-flow characteristics of axial compressors formed by designing rotor blades of axial compressors that do not use the present invention and those that do.

[0061] Figure 5 A comparison chart showing the flow efficiency characteristics of rotor blades formed by the design method of axial compressors without and with the present invention. Detailed Implementation

[0062] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments.

[0063] like Figure 1 and Figure 2 As shown, this embodiment provides a rotor blade 10 of an axial compressor. The rotor blade 10 includes a blade root 11 and a blade tip 12. The rotor blade 10 has a number of basic airfoil sections along the height direction h from the blade root 11 to the blade tip 12. The centroids of each basic airfoil section are used as the stacking points and are stacked along the height direction h of the rotor blade 10 to obtain the stacking line 20.

[0064] The accumulation line 20, along the height direction h of the rotor blade 10 from the blade root 11 to the blade tip 12, includes a first segment 21 and a second segment 22 connected in sequence. The second segment 22 is an arc segment along the axial direction P of the axial compressor, curving towards the leading edge 13 of the rotor blade 10. That is, the arc segment extends from one end near the first segment 21 to the end away from the first segment 21 towards the leading edge 13 of the rotor blade 10, and the center O of the arc segment is located on the side near the leading edge 13 of the rotor blade 10. By setting the second segment 22 near the blade tip 12 to be an arc segment along the axial direction P of the axial compressor, and the arc segment curving towards the leading edge 13 of the rotor blade 10, it is beneficial to weaken the shock wave intensity at the blade tip 12, thereby reducing the boundary layer separation loss caused by the shock wave and improving the efficiency of the rotor blade 10 of the axial compressor. In other words, it achieves control over the shock wave and flow field in the blade tip region. On the other hand, compressor rotor stall usually occurs in the blade tip region. By setting an arc-shaped stack, a reverse pressure gradient is generated in the radial direction, which is conducive to the migration of low-energy fluid in the blade tip region to the middle of the blade, thereby reducing the influence of secondary flow in the blade tip region, improving the flow conditions at the blade tip 12, and increasing the stable operating range of the compressor rotor blade 10.

[0065] The plane containing the first segment 21 is perpendicular to the axial direction P of the axial compressor. The distance from the connection point of the first segment 21 and the second segment 22 to the blade root 11 is greater than half the height of the rotor blade 10. By setting the plane containing the first segment 21 to be perpendicular to the axial direction P of the axial compressor, and ensuring that the distance from the connection point of the first segment 21 and the second segment 22 to the blade root 11 is greater than half the height of the rotor blade 10, that is, ensuring that at least 50% of the blade height is below the center section without axial offset, the risk of rubbing between adjacent rotor blades 10 and stator blades 40 is avoided. This is because, usually, to ensure blade strength, the axial chord length at the root of the rotor blade 10 is relatively large, and its axial distance to the stator of the previous row of blades is the shortest. If forward sweep is adopted at this time, there is a risk of rubbing between adjacent rotor blades 10 and stator blades 40.

[0066] The orthographic projection of the blade tip 12 onto the axis p of the axial compressor lies within the orthographic projection of the blade root 11 onto the axis p of the axial compressor. That is, the axial forward sweep offset of the blade tip 12 does not exceed the axial projection of the blade root 11. In other words, the axial position of the leading edge 13 of the blade tip 12 is located further back than the axial position of the leading edge 13 of the blade root 11, thus avoiding the risk of rubbing between adjacent rotor blades 10 and stator blades 40. This is because the compressor's design speed is typically high. The compressor blades and blade disk are connected together. At the design speed, the axial deformation at the blade root can be understood as only the deformation of the disk itself, while the axial deformation at the blade tip is the sum of the blade's axial deformation and the compressor disk's deformation, resulting in a larger axial deformation at the blade tip. In this embodiment, the axial position of the leading edge 13 of the blade tip 12 is located further back than the axial position of the leading edge 13 of the blade root 11, which helps reduce the risk of axial rubbing between the leading edge of the rotor blade 10's blade tip 12 and the trailing edge of the previous row of stator blades 40.

[0067] In this embodiment, the direction of the second segment 22 from the leaf root 11 to the leaf tip 12 includes at least a first control point O1 and a second control point O2. The first control point O1 is located at the connection point between the first segment 21 and the second segment 22, and the second control point O2 is located at the centroid of the basic leaf section of the leaf tip 12.

[0068] Along the axial direction of the axial flow air compressor, the coordinates of any point located between the first control point O1 and the second control point O2 are (x, y), and the coordinates of the center O of the arc segment are (x, y). o y o The radius of the arc segment is R, where:

[0069] (xx o ) 2 +(yy o ) 2 =R 2

[0070] Wherein, the coordinate (x) of the center O on the axial direction of the axial flow air compressor is... o y o The axial sweep angle α of the arc segment at the second control point O2 and the coordinates of the first control point O1 along the axial direction of the axial flow compressor are obtained from... Figure 2 It can be seen that the height of the center O is the same as the height of the first control point O1. The axial sweep angle α at the second control point O2 in the second segment 22 is 45 degrees - 90 degrees. It should be noted that... Figure 2 As shown, the axial sweep angle α at the second control point O2 is the angle between the tangent at the second control point O2 and the axial direction P of the axial compressor.

[0071] In this way, the axial offset of the second segment 22 of the stacking line 20 of the rotor blade 10 can be controlled by constructing a simple equation, thereby achieving the parametric control design objective of the stacking of the rotor blade 10; at the same time, the axial offset of other blade height positions can be fitted with as few control points as possible, thereby improving the calculation efficiency of optimizing the blade profile.

[0072] In this embodiment, in the direction from the blade root 11 to the blade tip 12, both the first segment 21 and the second segment 22 are linearly offset in the circumferential direction. That is, the circumferential offset of the stacking line 20 of the rotor blade 10 is added in a linear manner. Specifically, the maximum circumferential offset of the blade tip 12 relative to the blade root 11 is given first, and the circumferential offset of the remaining blade height is obtained by linear interpolation based on the blade height. After the axial and circumferential offsets are determined, they are superimposed to determine the stacking profile of the basic blade shape. By extending the basic blade shape along the stacking profile to construct a set of curves, the three-dimensional rotor blade 10 can be obtained.

[0073] Preferably, the axial projection chord length A'B' of the section AB at the blade tip 12 of the rotor blade 10 is 40%-70% of the axial projection chord length C'D' of the section CD at the blade root 11 of the rotor blade 10; the axial projection chord length E'F' of the section EF at the blade midpoint of the rotor blade 10 is 60%-80% of the axial projection chord length C'D' of the section CD at the blade root 11 of the rotor blade 10; and the axial projection chord length I'J' of the section IJ at 15% blade height of the rotor blade 10 is not less than 90% of the axial projection chord length C'D' of the section CD at the blade root 11 of the rotor blade 10. In this way, by setting the axial projection chord lengths of the sections at different positions of the rotor blade 10, it is beneficial to maintain a high compressor efficiency while also ensuring that the rotor blade 10 maintains a good strength level.

[0074] It should be noted that the axial projection chord length of the rotor blade 10 cross section refers to the length of the projection of the cross section onto the axis p of the axial compressor.

[0075] Preferably, the axial projected chord lengths of the cross section between the blade tip 12 and the mid-section of the rotor blade 10, the cross section between the mid-section of the rotor blade 10 and 15% of the blade height of the rotor blade 10, and the cross section between 15% of the blade height of the rotor blade 10 and the blade root 11 all have smooth transitions. In this way, by setting the projected lengths of the remaining cross sections of the rotor blade 10 to have smooth transitions, it is beneficial to maintain a higher compressor efficiency while further maintaining a better strength level for the rotor blade 10.

[0076] Preferably, the distance G between the leading edge 13 at the root 11 of the rotor blade 10 and the adjacent stator blade 40 along the axial direction P of the axial compressor is greater than or equal to 6 mm and less than or equal to 30 mm. As mentioned above, compressor disks will have axial deformation. Based on experience, the axial deformation of compressor disks generally does not exceed 6 mm, but the axial deformation of some larger compressor disks may exceed 6 mm. In this embodiment, by setting the distance G between the leading edge 13 at the root 11 of the rotor blade 10 and the adjacent stator blade 40 along the axial direction P of the axial compressor to be greater than or equal to 6 mm and less than or equal to 30 mm, for some larger compressor disks, it is beneficial to more effectively avoid axial rubbing at the blade root, that is, to more effectively avoid the risk of rubbing between adjacent rotor blades 10 and stator blades 40.

[0077] The axial projection chord length C'D' of the cross section CD at the blade root 11 of the rotor blade 10 is 5%-20% of the inner diameter of the casing 30 covering the outer side of the rotor blade 10. This is beneficial for maintaining high blade efficiency and a stable operating range. This is because, from an aerodynamic performance perspective, generally, the longer the blade chord length, the less likely the gas is to separate, and the wider the compressor's stable operating range. However, the longer the blade, the greater the frictional loss of the gas. By setting the axial projection chord length C'D' of the cross section CD at the blade root 11 of the rotor blade 10 to 5%-20% of the inner diameter of the casing 30 covering the outer side of the rotor blade 10, the rotor blade 10 with this structure can combine stability margin and efficiency, thus helping to maintain high blade efficiency and a stable operating range, resulting in better aerodynamic performance.

[0078] This embodiment also provides a design method for the rotor blade 10 of an axial flow compressor, for designing the aforementioned rotor blade 10. Please refer to the documentation for the structure of the rotor blade 10. Figure 1 and Figure 2 The rotor blade 10 includes a blade root 11 and a blade tip 12. The rotor blade 10 has several basic blade profile sections along the height direction h from the blade root 11 to the blade tip 12.

[0079] like Figure 3 As shown, the design method includes the following steps:

[0080] Step 100: The centroids of the cross sections of each basic blade are used as the stacking points and stacked along the height direction of the rotor blade to obtain the stacking line;

[0081] Step 200: The stacking line is set to include a first segment and a second segment connected sequentially along the height direction of the rotor blade from the blade root to the blade tip. The second segment is an arc segment in the axial direction of the axial compressor, and the arc segment bends towards the leading edge of the rotor blade. The plane containing the first segment is perpendicular to the axial direction of the axial compressor. The distance from the connection point of the first segment and the second segment to the blade root is greater than half the height of the rotor blade. The orthographic projection of the blade tip on the axis of the axial compressor is located within the orthographic projection of the blade root on the axis of the axial compressor.

[0082] In this way, by setting the rotor blades in the above-mentioned structure, it is possible to control the shock wave and flow field in the blade tip region, reduce the secondary flow in the blade tip region, thereby improving the efficiency and stable operating range of the rotor blades of the axial compressor, while avoiding the risk of rubbing between adjacent rotor blades and stator blades.

[0083] For details, please refer to the following: Figure 1 and Figure 2 By setting the second segment 22 near the blade tip 12 as an arc segment along the axial direction P of the axial compressor, and bending the arc segment towards the leading edge 13 of the rotor blade 10, the shock wave intensity at the blade tip 12 is weakened, thereby reducing the boundary layer separation loss caused by the shock wave and improving the efficiency of the rotor blade 10 of the axial compressor. In other words, the control of the shock wave and flow field in the blade tip region is achieved. On the other hand, compressor rotor stall usually occurs in the blade tip region. By setting the arc-shaped stacking, a reverse pressure gradient is generated in the radial direction, which is conducive to the migration of low-energy fluid in the blade tip region to the middle of the blade, thereby weakening the influence of secondary flow in the blade tip region, improving the flow conditions at the blade tip 12, and increasing the stable operating range of the compressor rotor blade 10.

[0084] By setting the plane containing the first segment 21 to be perpendicular to the axial direction P of the axial compressor, and ensuring that the distance from the connection point between the first segment 21 and the second segment 22 to the blade root 11 is greater than half the height of the rotor blade 10, that is, maintaining at least 50% of the blade height below the center section without axial offset, the risk of rubbing between adjacent rotor blades 10 and stator blades 40 is avoided. This is because, typically, to ensure blade strength, the axial chord length at the root of the rotor blade 10 is relatively large, and its axial distance to the stator of the previous row of blades is the shortest. If forward sweep is adopted at this point, there is a risk of rubbing between adjacent rotor blades 10 and stator blades 40. This is because the design speed of the compressor is usually high, and the compressor blades and blade disk are connected together. At the design speed, the axial deformation at the blade root can be understood as only the deformation of the disk itself, while the axial deformation at the blade tip is the axial deformation of the blade plus the deformation of the compressor disk, thus the axial deformation at the blade tip is larger. In this embodiment, the axial position of the leading edge 13 of the blade tip 12 is located behind the axial position of the leading edge 13 of the blade root 11, which helps to reduce the risk of axial rubbing between the leading edge of the blade tip 12 of the rotor blade 10 and the trailing edge of the previous row of stator blades 40.

[0085] By setting the orthogonal projection of the blade tip 12 on the axis p of the axial compressor to be within the orthogonal projection of the blade root 11 on the axis p of the axial compressor, that is, the axial forward sweep offset of the blade tip 12 does not exceed the axial projection of the blade root 11, that is, the axial position of the leading edge 13 of the blade tip 12 is behind the axial position of the leading edge 13 of the blade root 11, the risk of rubbing between adjacent rotor blades 10 and stator blades 40 is avoided.

[0086] Specifically, step S200 includes:

[0087] Please refer to the following: Figure 2 The direction of the second segment 22 from the leaf root 11 to the leaf tip 12 includes at least a first control point O1 and a second control point O2. The first control point O1 is located at the connection point between the first segment 21 and the second segment 22, and the second control point O2 is located at the centroid of the basic blade section of the leaf tip 12.

[0088] Along the axial direction of the axial flow air compressor, the coordinates of any point located between the first control point O1 and the second control point O2 are (x, y), and the coordinates of the center O of the arc segment are (x, y). o y o The radius of the arc segment is R, where:

[0089] (xx o ) 2 +(yy o ) 2 =R 2

[0090] Wherein, the coordinate of the center of the circle on the axial direction of the axial flow air compressor is (x) o y o The axial sweep angle α of the arc segment at the second control point O2 and the coordinates of the first control point O1 along the axial direction of the axial flow compressor are obtained from... Figure 2 It can be seen that the height of the center O is the same as the height of the first control point O1. The axial sweep angle α at the second control point O2 in the second segment 22 is 45 degrees - 90 degrees. It should be noted that... Figure 2 As shown, the axial sweep angle α at the second control point O2 is the angle between the tangent at the second control point O2 and the axial direction P of the axial compressor.

[0091] In this way, the axial offset of the second segment 22 of the stacking line 20 of the rotor blade 10 can be controlled by constructing a simple equation, thereby achieving the parametric control design objective of the stacking of the rotor blade 10; at the same time, the axial offset of other blade height positions can be fitted with as few control points as possible, thereby improving the calculation efficiency of optimizing the blade profile.

[0092] Specifically, step S200 includes:

[0093] Please refer to the following: Figure 2 The axial projection chord length A'B' of the section AB at the tip 12 of the rotor blade 10 is set to be 40%-70% of the axial projection chord length C'D' of the section CD at the root 11 of the rotor blade 10; the axial projection chord length E'F' of the section EF at the middle of the rotor blade 10 is set to be 60%-80% of the axial projection chord length C'D' of the section CD at the root 11 of the rotor blade 10; and the axial projection chord length I'J' of the section IJ at 15% blade height of the rotor blade 10 is not less than 90% of the axial projection chord length C'D' of the section CD at the root 11 of the rotor blade 10. In this way, by setting the axial projection chord lengths of the sections at different positions of the rotor blade 10, it is beneficial to maintain a high compressor efficiency while also ensuring that the rotor blade 10 maintains a good strength level.

[0094] It should be noted that the axial projection chord length of the rotor blade 10 cross section refers to the length of the projection of the cross section onto the axis p of the axial compressor.

[0095] Preferably, the axial projected chord lengths of the cross section between the blade tip 12 and the mid-section of the rotor blade 10, the cross section between the mid-section of the rotor blade 10 and 15% of the blade height of the rotor blade 10, and the cross section between 15% of the blade height of the rotor blade 10 and the blade root 11 all have smooth transitions. In this way, by setting the projected lengths of the remaining cross sections of the rotor blade 10 to have smooth transitions, it is beneficial to maintain a higher compressor efficiency while further maintaining a better strength level for the rotor blade 10.

[0096] Preferably, the distance G between the leading edge 13 at the blade root 11 of the rotor blade 10 and the adjacent stator blade 40 along the axial direction P of the axial compressor is greater than or equal to 6 mm and less than or equal to 30 mm. This helps to more effectively avoid axial rubbing at the blade root for some larger compressor discs, that is, it can more effectively avoid the risk of rubbing between adjacent rotor blades 10 and stator blades 40.

[0097] The axial projection chord length C'D' of the cross section CD at the blade root 11 of the rotor blade 10 is 5%-20% of the inner diameter of the casing 30 covering the outside of the rotor blade 10, so as to help maintain the blade's high efficiency and stable operating range.

[0098] Figure 4 This is a comparison chart showing the pressure ratio-flow characteristics of rotor blades for axial compressors designed using the method of this invention, with and without employing this invention. Figure 5 This chart compares the flow efficiency characteristics of rotor blades in axial compressors designed using and without the present invention. For a specific single-stage axial compressor, CFD software was used for mesh generation and 3D calculation, with a total mesh size of approximately 1.6 million. Single-channel steady-state calculations were performed using the SA model. The calculation results can be found from... Figure 4 and Figure 5 As can be seen, this invention patent broadens the effective operating range of axial flow compressors, manifested in the following ways: Figure 4 The minimum dimensionless flow rate of the leftmost rotor blade 10 of the present invention is smaller than that of the leftmost rotor blade 10' without the present invention, resulting in a higher pressure ratio. This means it can operate within a smaller flow range, expanding its stable operating range. Simultaneously, the peak efficiency of the compressor is improved, manifested as... Figure 5 The peak efficiency of the rotor blade 10 of the present invention is higher than that of the rotor blade 10' without the present invention.

[0099] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A rotor blade for an axial flow compressor, characterized in that, The rotor blade includes a blade root and a blade tip. The rotor blade has several basic blade profile sections along the height direction from the blade root to the blade tip. The centroids of each basic blade profile section are used as accumulation points and are superimposed along the height direction of the rotor blade to obtain an accumulation line. The accumulation line, along the height direction of the rotor blade from the blade root to the blade tip, includes a first segment and a second segment connected in sequence. The second segment is an arc segment in the axial direction of the axial compressor, and the arc segment bends toward the leading edge of the rotor blade. The plane containing the first segment is perpendicular to the axial direction of the axial compressor, and the distance from the connection point between the first segment and the second segment to the blade root is greater than half the height of the rotor blade. The orthographic projection of the blade tip onto the axis of the axial compressor lies within the orthographic projection of the blade root onto the axis of the axial compressor.

2. The rotor blades of the axial compressor as described in claim 1, characterized in that, The second segment, from the leaf root to the leaf tip, includes at least a first control point and a second control point. The first control point is located at the connection point between the first segment and the second segment, and the second control point is located at the centroid of the basic leaf section of the leaf tip. Along the axial direction of the axial flow air compressor, the coordinates of any point located between the first control point and the second control point are (x, y), and the coordinates of the center of the arc segment are (x, y). o y o The radius of the arc segment is R, where: (x-x o ) 2 +(y-y o ) 2 =R 2 Wherein, the coordinate (x) of the center of the circle on the axial direction of the axial flow air compressor. o y o The axial sweep angle α of the arc segment at the second control point is obtained by the coordinates of the first control point on the axis of the axial flow compressor. The axial sweep angle α of the second segment at the second control point is 45 degrees to 90 degrees.

3. The rotor blades of the axial compressor as described in claim 1, characterized in that, In the direction from the leaf root to the leaf tip, both the first segment and the second segment are linearly offset in the circumferential direction.

4. The rotor blades of the axial compressor as described in claim 1, characterized in that, The axial projection chord length of the cross section at the tip of the rotor blade is 40%-70% of the axial projection chord length of the cross section at the root of the rotor blade; the axial projection chord length of the cross section at the middle of the rotor blade is 60%-80% of the axial projection chord length of the cross section at the root of the rotor blade; the axial projection chord length of the cross section at 15% of the blade height of the rotor blade is not less than 90% of the axial projection chord length of the cross section at the root of the rotor blade. The axial projection chord lengths of the cross section located between the blade tip and the middle of the rotor blade, the cross section located between the middle of the rotor blade and 15% of the blade height of the rotor blade, and the cross section located between 15% of the blade height of the rotor blade and the blade root all have smooth transitions.

5. The rotor blades of the axial compressor as described in claim 1, characterized in that, The distance between the leading edge of the rotor blade at its root and the adjacent stator blade along the axial direction of the axial compressor is greater than or equal to 6 mm and less than or equal to 30 mm; and / or, The axial projection chord length of the cross section at the root of the rotor blade is 5%-20% of the inner diameter of the casing covering the outside of the rotor blade.

6. A method for designing rotor blades for an axial flow compressor, characterized in that, The rotor blade includes a blade root and a blade tip, and the rotor blade has a plurality of basic airfoil sections along the height direction from the blade root to the blade tip. The design method includes the following steps: S1: The centroids of the cross sections of each basic blade are used as the accumulation points and superimposed along the height direction of the rotor blades to obtain the accumulation line; S2: The accumulation line is configured to include a first segment and a second segment connected sequentially along the height direction of the rotor blade from the blade root to the blade tip. The second segment is an arc segment in the axial direction of the axial compressor, and the arc segment bends towards the leading edge of the rotor blade. The plane containing the first segment is perpendicular to the axial direction of the axial compressor. The distance from the connection point of the first segment and the second segment to the blade root is greater than half the height of the rotor blade. The orthographic projection of the blade tip on the axis of the axial compressor is located within the orthographic projection of the blade root on the axis of the axial compressor.

7. The method for designing rotor blades of an axial compressor as described in claim 6, characterized in that, Step S2 includes: The second segment is configured to include at least a first control point and a second control point in the direction from the leaf root to the leaf tip. The first control point is located at the connection point between the first segment and the second segment, and the second control point is located at the centroid of the basic leaf section of the leaf tip. Along the axial direction of the axial flow air compressor, the coordinates of any point located between the first control point and the second control point are (x, y), and the coordinates of the center of the arc segment are (x, y). o y o The radius of the arc segment is R, where: (x-x o ) 2 +(y-y o ) 2 =R 2 Wherein, the coordinate (x) of the center of the circle on the axial direction of the axial flow air compressor. o y o The axial sweep angle α of the arc segment at the second control point is obtained by the coordinates of the first control point on the axis of the axial flow compressor. The axial sweep angle α of the second segment at the second control point is 45 degrees to 90 degrees.

8. The method for designing rotor blades of an axial compressor as described in claim 6, characterized in that, Step S2 includes: In the direction from the leaf root to the leaf tip, both the first segment and the second segment are linearly offset in the circumferential direction.

9. The method for designing rotor blades of an axial compressor as described in claim 6, characterized in that, Step S2 includes: The axial projection chord length of the cross section at the tip of the rotor blade is set to 40%-70% of the axial projection chord length of the cross section at the root of the rotor blade; the axial projection chord length of the cross section at the middle of the rotor blade is set to 60%-80% of the axial projection chord length of the cross section at the root of the rotor blade; and the axial projection chord length of the cross section at 15% of the blade height of the rotor blade is not less than 90% of the axial projection chord length of the cross section at the root of the rotor blade. The axial projection chord lengths of the cross section located between the blade tip and the mid-section of the rotor blade, the axial projection chord lengths of the cross section located between the mid-section of the rotor blade and 15% of the blade height of the rotor blade, and the axial projection chord lengths of the cross section located between 15% of the blade height of the rotor blade and the blade root are all smoothly transitioned.

10. The method for designing rotor blades of an axial compressor as described in claim 6, characterized in that, Step S2 includes: The distance between the leading edge of the rotor blade at its root and the adjacent stator blade along the axial direction of the axial compressor is greater than or equal to 6 mm and less than or equal to 30 mm; and / or, The axial projection chord length of the cross section at the root of the rotor blade is set to 5%-20% of the inner diameter of the casing covering the outside of the rotor blade.

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