A fir-tree blade root structure, blade and steam turbine

Abstract

This utility model relates to the field of steam turbine technology, specifically to a fir-tree type blade root structure, blades, and a steam turbine. The fir-tree type blade root structure provided by this utility model includes a blade root with a first side and a second side arranged opposite to each other. The first side is located on the back arc side of the blade root, and the second side is located on the inner arc side of the blade root. The second side has a protruding structure, and the first side has grooves corresponding to the protruding structures. The blade roots of each pair of adjacent blades interlock through the protruding and groove structures. The interlocking of the blade roots between each pair of blades, through the protruding and groove structures, allows the blade roots to mutually restrain each other during operation, limiting the circumferential sway range of the blades, thereby solving the problem of blade swaying due to low centrifugal force when the blades are lightweight or operate at low speeds.

Description

Technical Field

[0001] This utility model relates to the field of steam turbine technology, specifically to a fir-shaped leaf root structure, blades, and steam turbine. Background Technology

[0002] With the large-scale grid connection of renewable energy sources such as wind power and photovoltaics, more and more thermal power units are frequently and deeply shaving peak loads to ensure the stability and economy of the power system. Thermal power units are operating under low load and rapidly changing load conditions for extended periods, which puts greater strain on the lifespan of turbine blades.

[0003] Currently, because the fir tree-shaped root grooves are axially installed, to ensure that the fir tree-shaped blades can be installed into the root grooves on the rotor rim and that each blade can ensure full contact between all contact surfaces during operation, a certain assembly gap must be maintained between the blade root and the rotor rim root groove, and also between every two blades. This characteristic causes the blades to wobble when their weight is light or at low speeds due to the small centrifugal force, resulting in slippage between the blade root and the rotor rim root groove. That is, during turbine operation, the rotating blades are impacted by the steam flow excitation force every time they pass through a stationary blade groove, causing the blades to vibrate. This causes the blade root to reciprocate tangentially along the rotor rim, resulting in oscillating friction. This leads to bidirectional, multi-source fatigue cracking at the contact area between the blade root and the rotor groove, which gradually expands and eventually causes the blade to break.

[0004] The use of fir-shaped leaf root structure, especially the shorter intermediate-stage blades, results in less centrifugal force during operation compared to the final and sub-final-stage blades. At low speeds, it is easier to excite the second-order resonance mode, which intensifies the alternating vibration load. The contact area between the blade root and the rotor groove is more prone to alternating fatigue, which can lead to fatigue cracks and fracture. Utility Model Content

[0005] (I) The problem to be solved by this utility model is that the rotating blade is subjected to the impact of the steam flow excitation force when it passes through a stationary blade channel, which causes the blade to vibrate, causing the blade root to reciprocate along the rotor wheel rim tangentially, swinging and rubbing. The contact part between the blade root and the rotor wheel groove forms a bidirectional multi-source fatigue crack, which gradually expands and leads to the final fracture of the blade.

[0006] (II) Technical Solution

[0007] A fir-shaped leaf-root structure includes a leaf root, the leaf root having a first side and a second side disposed opposite to each other, the first side being located on the dorsal arc side of the leaf root, and the second side being located on the inner arc side of the leaf root.

[0008] The second side has a raised structure, and the first side has a groove structure that corresponds to the raised structure. The roots of each pair of adjacent blades are interlocked by the raised structure and the groove structure.

[0009] According to one embodiment of the present invention, the protrusion structure includes at least one protrusion, and the groove structure includes at least one groove.

[0010] According to one embodiment of the present invention, the leaf root has a first end face and a second end face that are parallel to each other, the groove extends from the first end face of the leaf root to the second end face, and the direction from the first end face to the second end face is perpendicular to the direction from the first side face to the second side face.

[0011] According to one embodiment of the present invention, the protrusion extends from the first end face of the leaf root to the second end face.

[0012] According to one embodiment of the present invention, the outer edge of the protruding cross-section has a first arc segment, a first straight segment, a second arc segment, a third arc segment, a fourth arc segment, a second straight segment, and a fifth arc segment connected in sequence.

[0013] Both the first arc segment and the fifth arc segment are connected to the second side surface.

[0014] According to one embodiment of the present invention, the central angles corresponding to the first arc segment and the fifth arc segment are the same, and the central angles corresponding to the second arc segment and the fourth arc segment are the same.

[0015] According to one embodiment of the present invention, the first straight line segment and the second straight line segment are parallel, and the first straight line segment is perpendicular to the second side.

[0016] A leaf, including the aforementioned fir-type leaf-root structure.

[0017] A steam turbine comprising one type of blade as described above.

[0018] The beneficial effects of this utility model are:

[0019] After the blades with this fir-tree-shaped root structure are assembled into the root grooves on the rotor rim, the roots of every two blades interlock through protrusions and grooves. This allows the roots to mutually restrain each other during operation, limiting the circumferential range of blade wobble. This solves the problem of blade wobble caused by low centrifugal force when the blade is lightweight or operates at low speeds. In other words, because the circumferential wobble of the blade roots (tangentially along the rotor rim) is reduced, the relative motion between the blade roots and the root grooves of the rotor rim is reduced, and the oscillating friction is weakened. This reduces the likelihood of bidirectional multi-source fatigue cracking at the contact point between the blade roots and the rotor grooves, helping to prevent the blades from ultimately breaking due to fatigue cracking. This improves the reliability and safety of the blades during operation, extends their service life, and does not affect the original ease of installation and disassembly of the fir-tree-shaped blade root structure, demonstrating good compatibility.

[0020] Furthermore, this design scheme only adds groove and protrusion structures to the original fir-shaped leaf root, without making complex modifications to the entire leaf root structure. Therefore, it is relatively simple and easy to implement in terms of manufacturing process, and will not significantly increase production costs and manufacturing difficulty. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of Embodiment 1 of the present utility model;

[0023] Figure 2 This is a partial schematic diagram of Embodiment 1 of the present utility model;

[0024] Figure 3 This is a schematic diagram showing the assembly of multiple fir-shaped leaf and root structures provided in this embodiment of the utility model.

[0025] Icons: 1. Leaf root; 101. First side; 102. Second side; 103. Protrusion; 104. Groove; 105. First arc segment; 106. First straight segment; 107. Second arc segment; 108. Third arc segment; 109. Fourth arc segment; 110. Second straight segment; 111. Fifth arc segment. Detailed Implementation

[0026] The technical solution of this utility model will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] Example 1:

[0028] like Figures 1-3 As shown, Embodiment 1 of this utility model provides a fir-shaped leaf root structure, including a leaf root 1. The leaf root 1 has a first side surface 101 and a second side surface 102 that are parallel to each other. The first side surface 101 is located on the back arc side of the leaf root 1, and the second side surface 102 is located on the inner arc side of the leaf root 1. The second side surface 102 is provided with a protruding structure, and the first side surface 101 is provided with a groove structure that corresponds one-to-one with the protruding structure. The leaf roots 1 of each pair of leaves are interlocked with each other through the protruding structure and the groove structure.

[0029] It should be noted that in this embodiment, by designing groove structures and protrusion structures on both sides of the radial plane (the first side 101 and the second side 102 mentioned above) of the blade root 1, considering that the steam outlet side is subjected to greater force, the protrusion structure is set on the inner arc side, which can specifically strengthen the steam outlet side and conforms to the force characteristics, while the groove structure is set on the back arc side where the force is less, so it will not affect the load-bearing capacity of the blade.

[0030] In this embodiment, after the blades with the fir-shaped leaf root structure are assembled into the root grooves on the rotor rim, the leaf roots 1 of every two blades interlock through protrusion and groove structures, allowing the leaf roots 1 to mutually restrain each other during operation. This limits the circumferential sway range of the blades, thus solving the problem of swaying caused by low centrifugal force when the blades are lightweight or operate at low speeds. In other words, because the circumferential sway of the leaf root 1 (the tangential direction of the leaf root 1 along the rotor rim) is reduced, the relative motion between the leaf root 1 and the root groove of the rotor rim is reduced, and the oscillating friction is weakened. This reduces the possibility of bidirectional multi-source fatigue cracking at the contact point between the leaf root 1 and the rotor groove, helping to avoid the eventual breakage of the blade due to fatigue cracking. This improves the reliability and safety of the blades during operation, extends the service life of the blades, and does not affect the original convenient installation and disassembly characteristics of the fir-shaped leaf root, exhibiting good compatibility.

[0031] Furthermore, this design scheme only adds groove and protrusion structures to the original fir-shaped leaf root, without making complex modifications to the entire leaf root structure. Therefore, it is relatively simple and easy to implement in terms of manufacturing process, and will not significantly increase production costs and manufacturing difficulty.

[0032] In this embodiment, the protrusion structure includes at least one protrusion 103, and the groove structure includes at least one groove 104. The leaf root 1 has a first end face 112 and a second end face that are parallel to each other. The first end face 112 and the second end face are the end faces of the leaf root 1, and the direction from the first end face 112 to the second end face is... Figure 1 The paper faces inward. The protrusion 103 extends from the first end face 112 of the leaf root 1 to the second end face, and the groove 104 extends from the first end face 112 of the leaf root 1 to the second end face. That is, the groove 104 completely penetrates the leaf root 1, and the distance from the first end face 112 to the second end face is the same as the length of the protrusion 103.

[0033] Specifically, when installing blades with the fir-shaped leaf root structure, simply insert the fir-shaped leaf root structure of the first blade into the root groove of the rotor rim along the rotor's axial direction. Then install the second blade, continuing to insert the fir-shaped leaf root structure of the second blade into the root groove of the rotor rim along the rotor's axial direction. At this time, the protrusion 103 of the first blade is inserted into the groove 104 of the second blade, ultimately forming... Figure 3 The state shown.

[0034] Because the blade roots 1 of these two blades interact and restrict each other during operation, the circumferential sway range of the blades is limited, thus solving the problem of blades swaying due to low centrifugal force when their own weight is light or their speed is low.

[0035] It should be noted that when the blade with the fir-shaped leaf root structure is installed on the root groove of the rotor rim, the height direction of the leaf root 1 is the same as the radial direction of the rotor rim.

[0036] In this embodiment, as Figure 2 As shown, the outer edge of the cross-section of the protrusion 103 has a first arc segment 105, a first straight line segment 106, a second arc segment 107, a third arc segment 108, a fourth arc segment 109, a second straight line segment 110, and a fifth arc segment 111 connected in sequence.

[0037] In this configuration, the first arc segment 105 and the fifth arc segment 111 are both connected to the second side surface 102. The central angles corresponding to the first arc segment 105 and the fifth arc segment 111 are the same, and the central angles corresponding to the second arc segment 107 and the fourth arc segment 109 are the same. The first straight line segment 106 and the second straight line segment 110 are parallel, have the same length, and the first straight line segment 106 is perpendicular to the second side surface 102.

[0038] It should be noted that in this embodiment, the corners of the protrusion 103 are rounded to make the stress distribution more uniform and avoid stress concentration at the sharp edges of the protrusion 103. Compared with the sharp protrusion 103, the smooth transition surface can effectively reduce the local stress peak, thereby reducing the risk of fatigue crack initiation and propagation caused by stress concentration, and improving the fatigue strength and service life of the blade.

[0039] Furthermore, when the smoothly transitioned protrusions 103 and grooves 104 engage with each other, they can more effectively transmit circumferential and tangential forces between the blades. When the blades are subjected to external loads such as airflow excitation forces, the smooth protrusions 103 and grooves 104 structure allows the force to be distributed and transmitted more evenly between the blades, avoiding excessive local stress, enhancing the mutual restraint between the blades, reducing the circumferential sway amplitude of the blades, and improving the overall stiffness and stability of the blade assembly.

[0040] In some embodiments, the protrusion 103 and the blade root 1 are integrally formed. Specifically, the protrusion 103 and the groove 104 are machined onto the blade root 1.

[0041] In some embodiments, the straight-line distance between the second side 102 and the middle position of the third arc segment 108 is 2.9±0.05mm, and the straight-line distance between the first straight-line segment 106 and the second straight-line segment 110 is 3.0±0.05mm.

[0042] Example 2:

[0043] Embodiment 2 of this utility model provides a leaf blade, the leaf root 1 of which is the fir-type leaf root structure of Embodiment 1 above.

[0044] When assembling the blades, simply insert the fir-tree-shaped root structure of the first blade into the root groove of the rotor rim along the rotor axis. Then install the second blade and continue to insert the fir-tree-shaped root structure of the second blade into the root groove of the rotor rim along the rotor axis, so that the protrusion 103 of the first blade is inserted into the groove 104 of the second blade.

[0045] Because the blade roots 1 interact and restrict each other during operation, the circumferential range of blade movement is limited. The relative movement between the blade roots 1 and the rotor wheel rim root groove is reduced, and the oscillating friction is weakened. This reduces the possibility of bidirectional multi-source fatigue cracking at the contact point between the blade roots 1 and the rotor wheel groove, which helps to avoid the eventual breakage of the blade due to fatigue cracking.

[0046] Example 3:

[0047] Embodiment 2 of this utility model provides a steam turbine, wherein the blades of the rotor rim of the steam turbine are the blades in Embodiment 2 above.

[0048] In the description of this utility model, it should be noted that the terms "upper" and "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model 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 limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. Furthermore, in the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0050] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A fir-type leaf-root structure, characterized in that, Includes a leaf root (1), the leaf root (1) having a first side (101) and a second side (102) disposed opposite to each other, the first side (101) being located on the dorsal arc side of the leaf root (1), and the second side (102) being located on the inner arc side of the leaf root (1); The second side (102) is provided with a protruding structure, and the first side (101) is provided with a groove structure corresponding to the protruding structure. The leaf roots (1) of each two adjacent blades are interlocked by the protruding structure and the groove structure.

2. The fir-type leaf-root structure according to claim 1, characterized in that, The protrusion structure includes at least one protrusion (103), and the groove structure includes at least one groove (104).

3. The fir-type leaf-root structure according to claim 2, characterized in that, The leaf root (1) has a first end face (112) and a second end face that are parallel to each other, and the groove (104) extends from the first end face (112) of the leaf root (1) to the second end face; the direction from the first end face (112) to the second end face is perpendicular to the direction from the first side face (101) to the second side face (102).

4. The fir-type leaf-root structure according to claim 3, characterized in that, The protrusion (103) extends from the first end face (112) of the leaf root (1) to the second end face.

5. The fir-type leaf-root structure according to claim 4, characterized in that, The outer edge of the cross-section of the protrusion (103) has a first arc segment (105), a first straight segment (106), a second arc segment (107), a third arc segment (108), a fourth arc segment (109), a second straight segment (110), and a fifth arc segment (111) connected in sequence. The first arc segment (105) and the fifth arc segment (111) are both connected to the second side surface (102).

6. The fir-type leaf-root structure according to claim 5, characterized in that, The central angles corresponding to the first arc segment (105) and the fifth arc segment (111) are the same, and the central angles corresponding to the second arc segment (107) and the fourth arc segment (109) are the same.

7. A fir-type leaf-root structure according to claim 6, characterized in that, The first straight line segment (106) and the second straight line segment (110) are parallel, and the first straight line segment (106) is perpendicular to the second side surface (102).

8. A blade, characterized in that, Includes a fir-type leaf-root structure as described in any one of claims 1-7.

9. A steam turbine, characterized in that, Includes a blade as described in claim 8.

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