A turbine casing-shroud intersection coupling structure that reduces axial leakage flow

Abstract

The purpose of this invention is to provide a turbine casing-blade tip cross-coupling structure for reducing axial leakage flow, belonging to the field of gas turbine blades. Its specific structure is as follows: spaced-apart blade tip edge ribs are provided at the top of the blade body, and cross grooves are formed between adjacent blade tip edge ribs; casing ribs are provided at the bottom of the casing, and the casing ribs are installed in their corresponding blade tip edge rib cross grooves; a blade tip clearance exists between the casing and the blade body; and a blade tip groove is provided inside the blade body below the blade tip clearance. This invention can significantly reduce the axial leakage velocity at the blade tip and improve aerodynamic efficiency; the efficient blocking effect of the cross-coupling structure reduces the material required for traditional grooved blade tips, achieving a lightweight blade tip design and reducing the centrifugal load on rotating components; the design parameters of this invention are highly adjustable and can be flexibly optimized according to different operating conditions, possessing wide applicability.

Description

Technical Field

[0001] The present invention relates to a gas turbine, specifically a gas turbine blade. Background Technology

[0002] Gas turbines are a strategic industry for nations, hailed as the crown jewel of modern industry. To ensure safe turbine operation, a certain gap must be maintained between the rotor and the casing; this radial gap is called the tip clearance. Some of the mainstream gas flows across the blade tip under the influence of the pressure difference across the rotor blades, forming a gap leakage flow. This unworked gap leakage flow affects the flow in the channel near the casing. To suppress tip clearance leakage and reduce tip heat load, a groove structure with sealing characteristics is widely used in the design of the rotor blade tip, known as a tip groove. Tip grooves not only achieve good results in suppressing leakage and reducing tip heat transfer, but also reduce rotor mass while decreasing the contact area that may be affected by rubbing, thus gaining widespread application in research and practical use.

[0003] However, existing blade tip grooves still face the following technical bottlenecks in engineering applications: 1. With the continuous increase in pressure ratio and turbine inlet temperature of new gas turbines, their leakage flow control efficiency is gradually approaching its physical limit, making it difficult to further meet the performance requirements of the next generation of high-efficiency, high-load turbines; 2. Blade tip groove structures mainly suppress leakage caused by pressure difference across the blade, and have limited effectiveness against leakage caused by axial pressure difference; 3. Blade tip groove structures are sensitive to operating conditions, and changes in blade tip clearance under different operating conditions will significantly affect the effectiveness of suppressing leakage and reducing blade tip thermal load. Therefore, it is urgent to propose an improved structure to overcome the technical bottlenecks of existing turbine blade tip grooves. Summary of the Invention

[0004] The purpose of this invention is to provide a turbine casing-tip cross-coupling structure that reduces axial leakage flow, thereby enabling control of axial leakage in the blade tip clearance and thus improving aerodynamic efficiency while extending blade life.

[0005] The objective of this invention is achieved as follows: This invention discloses a turbine casing-blade tip cross-coupling structure for reducing axial leakage flow, comprising a blade body, a casing, a rim plate, and a tenon. The casing is installed above the blade body, and the rim plate and tenon are installed below the blade body. The structure is characterized by: spaced-apart blade tip edge ribs at the top of the blade body, with blade tip edge rib cross grooves formed between adjacent blade tip edge ribs; casing ribs at the bottom of the casing, which are installed in their corresponding blade tip edge rib cross grooves; a blade tip gap between the casing and the blade body; and a blade tip groove inside the blade body below the blade tip gap.

[0006] The present invention may also include: 1. The blade tip edge rib cross grooves are arranged in pairs on the front and rear sides of the blade body. Each casing rib is located in its corresponding pair of blade tip edge rib cross grooves, thus forming a set of casing-blade tip cross coupling structure.

[0007] 2. The casing-blade tip cross-coupling structure comprises at least two sets, arranged in series.

[0008] 3. The casing-blade tip cross-coupling structure includes three or four sets arranged in series.

[0009] 4. The width of the casing ribs is 3% to 5% of the axial chord length of the blade body.

[0010] 5. The height of the casing ribs is 50% to 80% of the height of the blade tip edge ribs.

[0011] 6. The cross-section of the casing ribs is a forward-inclined trapezoidal structure, and the shape of the cross grooves of the blade tip edge ribs corresponds to it.

[0012] 7. The maximum forward tilt angle of the forward-tilting trapezoidal structure shall not exceed 60°.

[0013] 8. The rear part of the casing rib is provided with a casing rib groove.

[0014] 9. The blade body is provided with air film pores.

[0015] The advantages of this invention are: 1. This invention can significantly reduce the axial leakage velocity at the blade tip and improve aerodynamic efficiency; 2. The efficient blocking effect of the cross-coupling structure reduces the material of traditional grooved blade tips, achieving a lightweight design of the blade tip and reducing the centrifugal load on rotating components; 3. The design parameters of this invention have strong adjustability and can be flexibly optimized according to different operating conditions, possessing wide applicability. Therefore, this invention, by introducing a casing-blade tip cross-coupling structure into the turbine blade crown, achieves axial leakage flow control, breaking through the limitations of traditional blades relying solely on blade tip geometric blocking, significantly improving aerodynamic performance, and has broad engineering application prospects.

[0016] This invention exhibits significant advantages in aerodynamic performance and structural optimization. First, the structure effectively reduces axial clearance leakage at the blade tip, significantly improving the aerodynamic load and overall efficiency of the blade. Second, the casing-blade tip cross-coupling structure creates a high-resistance environment in the blade tip clearance, reducing the clearance velocity and suppressing unsteady phenomena such as flow separation, backflow, and reattachment in the blade tip region, thus reducing the blade tip thermal load and extending blade service life. Finally, the casing-blade tip cross-coupling structure not only facilitates lightweight design of the overall blade structure but also provides new ideas and feasible paths for the development of future high-efficiency, long-life turbine blades. In summary, this invention has significant advantages in improving aerodynamic performance and optimizing structural weight, and has broad engineering application prospects. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention (Embodiment 1); Figure 2 This is a schematic diagram of the structure of Implementation Method 2; Figure 3 This is a structural schematic diagram of implementation method three; Figure 4 This is a structural schematic diagram of implementation method four; Figure 5 This is a structural diagram of implementation method five; Figure 6 This is a schematic diagram of the structure of Implementation Method Six; Figure 7 This is a structural diagram of implementation method seven; Figure 8 This is a schematic diagram of a traditional turbine blade with a tip groove. Detailed Implementation

[0018] The invention will now be described in more detail with reference to the accompanying drawings: Implementation Method 1 Combination Figure 1 The turbine blade of the present invention, with its casing-tip cross-coupling structure, comprises a blade body 4, blade film perforations 5, a rim plate 6, and a tenon 7. The casing-tip cross-coupling structure is located at the top of the blade body 4. Figure 8 Unlike traditional blade tip groove structures, this invention features several intersecting grooves in the blade tip clearance channel, which is composed of intersecting grooves 10 between the casing ribs 8 and the blade tip edge ribs. This arrangement allows the blade tip leakage flow to exhibit extremely high flow resistance along the axial direction, thereby achieving axial restriction of the leakage flow. When high-temperature combustion gas passes through the turbine stage flow channel and acts on the blade body 4, blade tip clearance leakage flow inevitably occurs. After entering the upper part of the blade tip edge rib 9, the leakage flow enters the casing-blade tip cross-coupling structure flow channel. For leakage airflow flowing from the axial direction backward, this structure provides a flow path with extremely high resistance. Due to the presence of the casing ribs 8, the airflow is blocked and forced to form vortices behind the ribs, generating additional flow resistance and energy loss, significantly weakening its axial penetration capability, and achieving efficient control of the axial leakage flow.

[0019] Implementation Method 2 Combination Figure 2Based on Embodiment 1, the width and height of the casing ribs 8 in the casing-blade tip cross-coupling structure are adjusted to control the leakage flow resistance in the gap, thereby achieving a better leakage flow suppression effect. In this invention, the width of the casing ribs 8 is 3% to 5% of the axial length of the turbine blade, which ensures both circumferential leakage at the blade tip and the strength requirements of the casing ribs 8. The height of the casing ribs 8 is 50% to 80% of the height of the blade tip edge ribs 9 to ensure the degree of overlap of the cross structure.

[0020] Implementation Method 3 Combination Figure 3 Based on implementation method two, the height of the casing ribs is reduced.

[0021] Implementation Method 4 Combination Figure 4 Based on implementation method two, the width of the casing ribs is increased.

[0022] Implementation Method 5 Combination Figure 5 Based on Embodiment 1, the casing-blade tip cross-coupling structure adopts a multi-stage series arrangement. For the multi-stage series arrangement, each stage consists of a set of blade tip edge rib cross grooves 10 and casing ribs 8. When the leaking airflow passes through each stage, its energy loss is superimposed, and the obstruction effect is significantly enhanced. While ensuring sufficient blade tip space, this embodiment sets 3-4 sets of cross-coupling series structures.

[0023] Implementation Method Six Combination Figure 6 Based on the first implementation method, the casing rib 8 in the casing-blade tip cross coupling structure is set as a forward-inclined trapezoidal structure. While ensuring the control of axial leakage flow, the resistance loss caused by the structure to the main flow channel is reduced. The forward inclination angle of the trapezoidal structure does not exceed 60°.

[0024] Implementation Method Seven Combination Figure 7 Based on the first embodiment, a casing rib groove 11 is additionally arranged at the rear of the casing rib 8. When the airflow passes through the casing rib, not only will the energy be dissipated due to the vortex structure generated by the flow, but also additional backflow vortices will be generated at the groove due to the circumferential movement of the blades, further dissipating the energy and enhancing the control effect of axial leakage flow.

[0025] In terms of manufacturing processes, the turbine blade with the casing-tip cross-coupling structure of this invention can be realized in various ways. For integral casting, the geometry of the casing-tip cross-coupling structure can be pre-set during the wax pattern design stage, and an integral structure can be formed after casting. In addition, with the rapid development of additive manufacturing technology, the casing-tip cross-coupling structure of this invention can also be realized through metal 3D printing.

[0026] In summary, the casing-tip cross-coupling structure turbine blade of this invention breaks through the limitations of traditional single geometric obstruction with tip grooves. Utilizing the strong fluid resistance characteristics of the casing-tip cross-coupling structure, and through rational design of geometric parameters and arrangement, it can effectively suppress the adverse effects of axial tip clearance leakage flow on mainstream aerodynamic performance, thereby significantly improving the aerodynamic efficiency of the turbine blade. This invention not only has theoretical innovation significance at the academic research level but also demonstrates broad prospects at the engineering application level, applicable to the efficient design of various advanced aero-engines and gas turbines.

Claims

1. A turbine casing-blade tip cross-coupling structure for reducing axial leakage flow, comprising a blade body, a casing, a rim plate, and a tenon, wherein the casing is installed above the blade body, and the rim plate and tenon are installed below the blade body, characterized in that: the blade... The top of the body is provided with spaced blade tip edge ribs, and blade tip edge rib cross grooves are formed between adjacent blade tip edge ribs. The bottom of the casing is provided with casing ribs, which are installed in their corresponding blade tip edge rib cross grooves. There is a blade tip gap between the casing and the blade body, and a blade tip groove is provided inside the blade body below the blade tip gap.

2. The turbine casing-blade tip cross-coupling structure for reducing axial leakage flow according to claim 1, characterized in that: The blade tip edge rib cross grooves are arranged in pairs on the front and rear sides of the blade body. Each casing rib is located in its corresponding pair of blade tip edge rib cross grooves, thus forming a set of casing-blade tip cross coupling structure.

3. The turbine casing-blade tip cross-coupling structure for reducing axial leakage flow according to claim 2, characterized in that: The casing-blade tip cross-coupling structure comprises at least two sets arranged in series.

4. A turbine casing-blade tip cross-coupling structure for reducing axial leakage flow according to claim 2, characterized in that: The casing-blade tip cross-coupling structure includes three or four sets arranged in series.

5. A turbine casing-blade tip cross-coupling structure for reducing axial leakage flow according to claim 1, characterized in that: The width of the casing ribs is 3% to 5% of the axial chord length of the blade body.

6. The turbine casing-blade tip cross-coupling structure for reducing axial leakage flow according to claim 1, characterized in that: The height of the casing ribs is 50% to 80% of the height of the blade tip edge ribs.

7. A turbine casing-blade tip cross-coupling structure for reducing axial leakage flow according to claim 1, characterized in that: The cross-section of the casing ribs is a forward-inclined trapezoidal structure, and the shape of the cross grooves of the blade tip edge ribs corresponds to it.

8. A turbine casing-blade tip cross-coupling structure for reducing axial leakage flow according to claim 7, characterized in that: The maximum forward tilt angle of the forward-tilting trapezoidal structure is no more than 60°.

9. A turbine casing-blade tip cross-coupling structure for reducing axial leakage flow according to claim 1, characterized in that: The rear part of the casing rib is provided with a casing rib groove.

10. A turbine casing-blade tip cross-coupling structure for reducing axial leakage flow according to claim 1, characterized in that: The blade body is provided with air film pores.

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