Steam turbine blade structure with firing pin frequency modulation function

Abstract

A steam turbine blade structure with a firing pin frequency modulation function belongs to the technical field of steam turbine blades, a step center hole is formed in the center line of a blade, the step center hole comprises a blade body center hole and a blade root top center hole which are different in diameter and coaxial, a firing pin is installed in the step center hole, and allowance is reserved in the depth direction. The firing pin head is in interference fit with a center hole in the top of the blade root, and the firing pin body is in clearance fit with a center hole of the blade body. The requirements for the vibration amplitude and the vibration frequency of the rotor blade under the wide-range operation rotating speed of the marine steam turbine can be met, and the safety performance of the marine steam turbine is improved.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbine blades, and in particular to a steam turbine blade structure with a striker frequency modulation function, which is suitable for mushroom-shaped blade roots. Background Art

[0002] Blade damage is one of the main causes of turbine failure, and vibration fatigue is the main cause of blade breakage. Blade vibration is a core issue related to its operational safety.

[0003] Existing blade anti-vibration designs usually achieve frequency modulation by changing the blade's own vibration frequency through measures such as blade profile design, blade height and width design.

[0004] Marine steam turbines are frequently started and stopped, have variable operating conditions, a wide range of speed changes, limited structural dimensions, and high difficulty in blade frequency modulation design. During the design process, the dimensions of the blade shape, flow axial length, and height must first meet the thermal scheme, and then the strength is assessed under the condition that the structural parameters are determined. Conventional blade frequency modulation design often requires multiple iterations of design to change the structural parameters and thermal scheme. The design is difficult under limited space conditions, and blade frequency modulation cannot meet the design requirements.

[0005] In summary, under the limited space conditions of existing marine steam turbines, blade frequency modulation cannot meet the design requirements. Summary of the invention

[0006] The present invention provides a steam turbine blade with a striker frequency modulation function to overcome the shortcomings of the prior art, and to solve the problem that the blade frequency modulation cannot meet the design requirements under the condition of limited space of a marine steam turbine. The steam turbine blade structure with a striker frequency modulation function can adjust the vibration frequency of the blade itself to meet the design requirements without changing the blade shape and flow size, thereby ensuring safe operation.

[0007] A steam turbine blade with a striker frequency modulation function, wherein a stepped center hole is opened on the center line of the blade, wherein the stepped center hole comprises a blade body center hole and a blade root top center hole of different diameters and coaxial, wherein the striker is installed in the stepped center hole, and a margin is left in the depth direction, wherein the striker head is interference fit with the blade root top center hole, and the striker body is clearance fit with the blade body center hole

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] The striker of the present application has a clearance fit with the inside of the blade body. During the design, the frequency modulation effect of changing the vibration frequency of the blade can be achieved by changing the size of the striker body without changing the key thermal scheme parameters such as the blade shape. At the same time, the striker itself can consume vibration energy during operation, reduce the blade's own amplitude, and realize anti-vibration design.

[0010] The present application can conveniently adjust the design scheme of marine steam turbine blades under the condition that the thermal scheme remains unchanged, meet the requirements for rotor blade vibration amplitude and vibration frequency under a wide range of operating speeds of the marine steam turbine, and improve the safety performance of the marine steam turbine.

[0011] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the structure of a steam turbine blade with a striker frequency modulation function according to the present application;

[0013] Figure 2 This is a schematic diagram of a firing pin structure of the present application.

[0014] Figure numerals: 1-blade body, 2-blade body center hole, 3-blade root top center hole, 4-striker head, 5-striker body, 6-knife back groove. DETAILED DESCRIPTION

[0015] The embodiments of the technical solution of the present application will be described in detail below in conjunction with the accompanying drawings. Unless otherwise specified, the technical terms or scientific terms used in the present application are generally understood by those skilled in the art to which the present invention belongs.

[0016] A steam turbine blade structure with a striker frequency modulation function, wherein a stepped center hole is opened on the center line of the blade, wherein the stepped center hole includes a blade body center hole 2 and a blade root top center hole 3 of different diameters and coaxial, and the striker is installed in the stepped center hole, with a margin in the depth direction, and the striker head 4 is interference fit with the blade root top center hole 3. During assembly, the striker head 4 is ground to an interference of 0.03, and the striker body 5 is clearance fit with the blade body center hole 2. During assembly, the striker is inserted into the blade from the center hole, and the head is ensured to be repaired with the interference amount. Each blade is equipped with a striker part, and the striker's outer dimensions are required to be able to fit into the stepped center hole opened in the blade, with an appropriate margin in the depth direction.

[0017] The blade can be tuned by hollowing out the center to change its own rigidity and changing the design dimensions such as the center hole diameter and height, without changing the centrifugal stress of the blade, thus meeting the strength and rigidity requirements. The striker is fitted with clearance inside the blade, and the vibration energy is consumed by the vibration of the striker when the blade is running, thus reducing the blade's own amplitude and ensuring safe operation.

[0018] As an example:

[0019] See also Figure 1 As shown,

[0020] The root of the blade is designed as a mushroom-shaped leaf root structure.

[0021] Drill a circular hole at the center of the top of the leaf root head and the center of the blade body. The hole must be directly opposite the center line of the blade, and the hole depth deviation from the radial line should not exceed 0.15mm per 100mm.

[0022] The diameter of the center hole 3 at the top of the blade root is A, and the tolerance is allowed to be ±0.05.

[0023] The diameter of the blade center hole 2 is C, and the tolerance is allowed to be 0~+0.02.

[0024] The center hole 3 at the top of the blade root and the center hole 2 at the blade body are both round holes, and the concentricity is required to be within 0.04. The above data units are mm.

[0025] As another example:

[0026] See also Figure 2 As shown,

[0027] The diameter of the striker head 4 is A, with a repair margin, and it is ground during assembly. The height of the striker head 4 is D, and the tolerance is 0 to -0.04.

[0028] The diameter of the striker body 5 is C, and the tolerance is allowed to be 0 to -0.02.

[0029] The striker head 4 is provided with a chamfered right angle or a rounded corner.

[0030] A cutter recess 6 is provided at the connection between the striker head and the body.

[0031] The striker head 4 and the blade root center hole 3 are interference fit, and the striker head 4 is ground to an interference fit of 0.03 during assembly. The striker body 5 and the blade body center hole 2 are clearance fit. The above data units are mm.

[0032] In this embodiment, during assembly, the striker is inserted into the blade from the center hole to ensure that the head is fitted with an interference fit.

[0033] The steam turbine blade structure with the striker frequency modulation function provided in this embodiment can conveniently adjust the design scheme of the marine steam turbine blades under the condition that the thermal scheme remains unchanged, meet the requirements of the vibration amplitude and vibration frequency of the rotor blades under a wide range of operating speeds of the marine steam turbine, and improve the safety performance of the marine steam turbine.

[0034] The present invention has been disclosed as above with preferred implementation cases, but it is not intended to limit the present application. Any technician familiar with the profession can make slight changes or modifications to equivalent implementation cases with equivalent changes by using the above-disclosed structures and technical contents without departing from the scope of the technical solution of the present application, which still fall within the scope of the technical solution of the present application.

Claims

1. A steam turbine blade structure with a striker frequency modulation function, characterized in that: A stepped center hole is opened on the center line of the blade, and the stepped center hole includes a blade body center hole (2) and a blade root top center hole (3) with different diameters and coaxial. A striker is installed in the stepped center hole, with a margin left in the depth direction. The striker head (4) is interference-fitted with the blade root top center hole (3), and the striker body (5) is clearance-fitted with the blade body center hole (2).

2. A steam turbine blade structure with striker frequency modulation function according to claim 1, characterized in that: The root of the blade is designed as a mushroom-shaped leaf root structure.

3. The steam turbine blade structure with striker frequency modulation function according to claim 1, characterized in that: The hole depth deviation between the center line and radial line of the stepped center hole shall not exceed 0.15mm per 100mm.

4. The steam turbine blade structure with striker frequency modulation function according to claim 1, characterized in that: The center hole (3) at the top of the blade root is a circular hole with a diameter of A and a tolerance of ±0.05 mm.

5. The steam turbine blade structure with striker frequency modulation function according to claim 1, characterized in that: The blade center hole (2) is a circular hole with a diameter of C and a tolerance of 0-+0.02mm.

6. The steam turbine blade structure with striker frequency modulation function according to claim 1, characterized in that: The concentricity between the center hole (3) at the top of the blade root and the center hole (2) at the blade body is within 0.

04.

7. The steam turbine blade structure with striker frequency modulation function according to claim 1, characterized in that: The height of the striker head (4) is D, and its tolerance is 0 to -0.

04.

8. The steam turbine blade structure with striker frequency modulation function according to claim 1, characterized in that: The diameter of the striker body (5) is C, and its tolerance is allowed to be 0 to -0.

02.

9. The steam turbine blade structure with striker frequency modulation function according to claim 1, characterized in that: The striker head (4) is provided with a chamfered right angle or a rounded corner.

10. The steam turbine blade structure with striker frequency modulation function according to claim 1, characterized in that: A cutter recess (6) is provided at the connection between the striker head (4) and the striker body (5).

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