Turbine rotor with floating force collar and method of assembling same

Abstract

The application discloses a turbine rotor with a floating force-bearing hoop ring and an assembling method thereof, and belongs to the technical field of turbine rotors. The turbine rotor comprises a turbine disc, a plurality of turbine blades and an integrated floating force-bearing hoop ring. The outer edge of the turbine disc is provided with a plurality of mortise and tenon joints, and each turbine blade is installed in the mortise and tenon joint through a tenon. The floating force-bearing hoop ring surrounds all the turbine blades and is fixedly connected with the top parts of the blades. When working, the floating force-bearing hoop ring provides a radial inward constraint force for the blade top, so as to share and offset part of the tensile load generated by centrifugal force. The floating force-bearing hoop ring and the blade top are in interference fit, and the interference fit is formed through a hot assembling process: the hoop ring is sleeved on the blade top which is cooled and shrunk after expansion caused by heating, and the interference fit is formed after the temperature is restored. The application changes the load transmission path of the traditional rotor by introducing the floating force-bearing hoop ring, shares part of the centrifugal load to the hoop ring itself, realizes rational distribution of the blade root stress, and provides a new solution for the lightweight design of the turbine rotor.

Description

Technical Field

[0001] This invention belongs to the field of turbine rotor technology, specifically relating to a turbine rotor with a floating load-bearing hoop and its assembly method. Background Technology

[0002] As the crown jewel of industry, the performance level of an aero-engine is a concentrated reflection of a nation's scientific and industrial strength. The turbine, as the core hot-end component of the engine, operates under extremely harsh conditions of high temperature, high pressure, and high speed. Its performance directly determines the thrust-to-weight ratio, efficiency, and reliability of the entire engine. Turbine rotor blades are one of the key components of an aero-engine. Under operating conditions, they must withstand not only steady-state loads such as centrifugal and thermal loads, but also alternating aerodynamic loads, making turbine rotor blades one of the components with the highest failure rate in the engine. In aero-engine failure accidents, turbine rotor-related failures account for more than 70%, with blade root fracture being the primary cause.

[0003] To address this significant challenge, traditional designs increase load-bearing capacity by increasing the size and thickness of blades, blade roots, and corresponding areas of the turbine disk. However, this incremental design directly leads to a significant increase in turbine rotor weight, thereby impairing the engine's thrust-to-weight ratio and maneuverability. Therefore, with the ever-increasing performance requirements of aero engines, lightweight design has become an inevitable development direction.

[0004] Currently, the main technological approaches to achieving lightweight turbine rotors fall into two categories: one relies on advancements in materials science, employing next-generation high-temperature alloys or composite materials with higher specific strength; the other optimizes the local morphology of blades and rotor disks through optimization algorithms to remove redundant materials. While these methods have achieved some success, their inherent limitations are becoming increasingly apparent: material iteration cycles are long and extremely costly, and performance improvements have entered a phase of diminishing marginal returns; while local structural optimization is a limited adjustment within a given overall force transmission configuration, its weight reduction potential is approaching saturation, making it difficult to meet the breakthrough requirements of next-generation engines for turbine rotors in terms of higher thrust-to-weight ratio and longer lifespan. Fundamentally, existing technologies have failed to address the inherent defects in turbine rotor load transmission, namely severe stress concentration and uneven load distribution at the root of the tenon teeth, which is the mechanical root cause of blade root fracture.

[0005] Therefore, to fundamentally overcome existing limitations, solutions must be sought at the level of force transmission mechanism and configuration innovation. This invention proposes a novel turbine rotor configuration with a floating load-bearing hoop. The core of this design lies in introducing a floating load-bearing hoop assembly that works in conjunction with the blade-disk system to improve the load transmission path and optimize load distribution, thereby reducing the stress peak in the critical region of the blade root. This novel turbine rotor configuration with a floating load-bearing hoop makes it possible to reduce the thickness and mass of components such as blade tenons, blade crowns, and the disk while meeting structural strength and reliability requirements, providing a new solution for achieving lightweight turbine rotors. Summary of the Invention

[0006] The present invention aims to solve the above problems and provides a turbine rotor with a floating load-bearing hoop and its assembly method.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0008] A turbine rotor with a floating load-bearing hoop, comprising:

[0009] A turbine disk with multiple tenons and slots circumferentially arranged on its outer edge;

[0010] Multiple turbine blades, each turbine blade being installed in a mortise in the turbine disk via a tenon connected to it;

[0011] An integral floating load-bearing hoop, which is a ring structure that surrounds all turbine blades and is fixedly connected to the tip of all turbine blades;

[0012] Among them, the floating load-bearing hoop is used to provide radially inward constraint force to the tip of the turbine blades when the turbine rotor is working, so as to share and offset part of the tensile load generated by centrifugal force.

[0013] Furthermore, the floating load-bearing ring and the tip of the turbine blade are interference fit.

[0014] Furthermore, the floating load-bearing ring is fitted onto the tip of the turbine blade when it is heated and expanded. After the temperature recovers, the floating load-bearing ring contracts and forms a tight interference fit with the tip of the blade.

[0015] Furthermore, the inner wall of the floating load-bearing hoop is provided with an inner surface groove for accommodating and fixing the tip of the turbine blade.

[0016] Furthermore, the inner surface groove consists of a groove and two bosses located on both sides of the groove, circumferentially surrounding it and protruding radially toward the center of the disk.

[0017] Furthermore, the top outer edge of the floating load-bearing hoop is provided with at least one circumferentially extending and radially protruding grating.

[0018] Furthermore, the floating load-bearing ring is made of a material whose radial outward deformation at the operating speed is less than the radial elongation at the tip of the turbine blade. The material includes titanium alloy, nickel-based high-temperature alloy or carbon fiber reinforced composite material.

[0019] Furthermore, the tenon is a dovetail tenon, and the mortise is a dovetail mortise that mates with the dovetail tenon.

[0020] Furthermore, the floating load-bearing hoop is equipped with:

[0021] Two rows of ferrules with the same height L4;

[0022] The width L3 of the inner surface groove is equal to or slightly less than the chord length b of the turbine blade, and the heights of the two inner surface bosses are equal, which is L6.

[0023] The total thickness of the floating load-bearing hoop is the sum of the grate tooth height L4, the hoop body thickness L5, and the boss height L6, and the thickness distribution of the three satisfies the ratio L4:L5:L6=3:4:1.

[0024] The distance between the first tooth and the leading edge of the turbine disk and the distance between the second tooth and the trailing edge of the turbine disk are equal, both being L1. Furthermore, L1 and the width L3 of the inner surface groove satisfy the distribution relationship of L1:L3=1:4.

[0025] A method for assembling a turbine rotor with a floating load-bearing ring includes the following steps:

[0026] Step 1: Insert the tenons of multiple turbine blades into the mortises of the turbine disk to complete the pre-assembly of the blade-disk assembly;

[0027] Step 2: Heat the floating load-bearing ring to increase its inner diameter, and at the same time cool the blade-disk assembly to reduce the diameter of the circle containing the blade tip;

[0028] Step 3: Fit the heated and expanded floating load-bearing ring onto the outer tip of all turbine blades after cooling and shrinking;

[0029] Step 4: Return the entire rotor assembly to room temperature after assembly, causing the floating load-bearing ring to shrink and the blade-disc assembly to expand, ultimately forming an interference fit between the ring and the blade tip.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. This invention innovatively alters the load transfer path of traditional rotors by introducing a floating load-bearing hoop. This hoop distributes some of the centrifugal load from the impeller and blade root regions to itself, effectively reducing blade root stress and rationally distributing turbine rotor stress. This allows the turbine rotor structure to break away from the traditional design approach of increasing the size and thickness of blades, blade roots, and corresponding impeller regions to enhance load-bearing capacity. While ensuring structural strength and fatigue life meet or even exceed design requirements, it allows for thinning and weight reduction designs of turbine blades and impellers, thereby reducing the overall mass of the rotor system and achieving lightweighting.

[0032] 2. This invention utilizes the principle of load sharing through a hoop structure, reducing the strength requirements of the turbine rotor structure materials. This allows for greater flexibility in material selection while meeting design specifications, creating conditions for adopting more cost-effective material combinations or novel material systems. Through this approach of "structural design reinforcement" rather than purely "material performance stacking," manufacturing costs can be reduced while ensuring or improving load-bearing capacity, providing a solution for a leapfrog improvement in the performance of next-generation aero-engines.

[0033] 3. The floating load-bearing ring on the outer side of this invention connects all the blades at the top into a closed rigid ring, which significantly enhances the structural constraint and overall stiffness of the turbine disk. This design not only suppresses the bending deformation of the blades under high centrifugal force fields, but also increases the first-order bending critical speed of the rotor and optimizes its vibration modes. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of the turbine rotor with floating load-bearing ring of the present invention.

[0035] Figure 2 yes Figure 1 An enlarged view of one of the sectors in the structure.

[0036] Figure 3 yes Figure 2 Enlarged view of the left side of region I.

[0037] Figure 4 This is a cross-sectional view of the floating load-bearing hoop.

[0038] Figure 5 This is a schematic diagram of a traditional crownless turbine rotor and its single-sector force transmission.

[0039] Figure 6 This is a schematic diagram of a traditional crowned turbine rotor and its single-sector force transmission.

[0040] Figure 7 This is a schematic diagram of the turbine rotor with floating load-bearing ring and its single-sector force transmission according to the present invention.

[0041] The markings in the diagram are as follows: 1-Floating load-bearing hoop; 2-Turbine blade; 3-Dovetail tenon; 4-Turbine disk; 5-Dovetail tenon; 6-Drive shaft; 7-Inner surface groove. Detailed Implementation

[0042] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0043] like Figure 1 and Figure 2 As shown, this invention provides a novel turbine rotor configuration with a floating load-bearing ring. The structure includes a turbine disk 4, several turbine blades 2, and a floating load-bearing ring 1. The inner hole of the turbine disk connects to a drive shaft 6. A ring of dovetail tenons 5 is evenly spaced on the outer side of the turbine disk. Each dovetail tenon 5 contains a dovetail tenon 3 with a small gap. A turbine blade 2 is connected to the outer side of each dovetail tenon 3. The outer side of the tip of each turbine blade 2 is bound to the inner side of the floating load-bearing ring 1. The floating load-bearing ring 1 is a 360° integral ring with a certain thickness and rigidity. The structure of the floating load-bearing ring 1 is as follows: Figure 4 As shown. This integrated structure not only improves structural strength and rigidity, but also ensures that the hoop 1, turbine blade 2, dovetail tenon 3, and turbine disk 4 always rotate concentrically during operation.

[0044] To facilitate understanding the structure, the following is shown. Figure 2 A left view of a sector, such as Figure 3 As shown, the blade 2 is connected to the hoop via the inner surface buckle 7 of the floating load-bearing hoop, and there is a certain distance between the inner surface buckle 7 and the two sides of the floating load-bearing hoop.

[0045] The structural parameters of floating load-bearing hoop structure 1 are as follows: Figure 4 As shown, there are two rows of grates, both with the same height L4. The distance between the first grate and the leading edge of the turbine disk and the distance between the second grate and the trailing edge of the turbine disk are equal, L1, and the grate tip width is A. The width of the inner surface groove L3 is equal to (or slightly less than) the blade chord length b, and the heights of the two inner surface bosses are equal, L6, with a boss width of B. Both bosses are spaced L2 away from both sides of the floating load-bearing ring. The thickness of the floating load-bearing ring is the grate height L4 + thickness L5 + boss height L6, and the thickness distribution of these three components must satisfy the ratio L4:L5:L6 = 3:4:1. The distance L1 between the grate and the leading edge of the turbine must satisfy the distribution ratio L1:L3 = 1:4.

[0046] The turbine rotor of this invention adopts an interference fit thermal assembly process, the specific implementation process of which is as follows: The first step is to pre-assemble the turbine blades 2 and turbine disk 4: The dovetail tenons 3 of all turbine blades 2 are sequentially inserted into the dovetail tenons 5 on the outer edge of the turbine disk 4, adjusting all blades to be evenly distributed circumferentially to ensure that the blade tips of all blades form a coaxial complete cylindrical surface, thus completing the pre-assembly of the blade-disk assembly. The second step is to install the floating load-bearing ring 1: The floating load-bearing ring 1 is heated, causing it to expand radially and increase its inner diameter. Simultaneously, the assembly pre-assembled in the first step is cooled, causing it to contract radially and decrease its blade tip diameter. Utilizing the assembly gap created by thermal expansion and contraction, the expanded floating load-bearing ring 1 is fitted onto the outer side of the blade tips of all turbine blades 2, ensuring that the blade tips are completely embedded in the slot structure of the ring's inner wall, thus achieving precise axial and circumferential positioning. The third step is to complete the assembly and shaping: After the assembly is completed, the entire rotor assembly is placed in a normal temperature environment to naturally recover to room temperature. The floating load-bearing ring 1 shrinks as the temperature decreases, and the blade-disc assembly expands as the temperature rises. Finally, an interference fit is formed between the ring and the blade tip, forming a turbine rotor structure with a floating load-bearing ring in the rotor system.

[0047] With the above structure, during operation, the drive shaft 6 in the circular hole on the inner surface of the turbine disk 4 drives the turbine disk 4 to rotate. The dovetail tenon 5 of the turbine disk 4 engages with the dovetail tenon 3, and the rotation is transmitted to the dovetail tenon 3 through the contact surface between the dovetail tenon 5 and the dovetail tenon 3. The dovetail tenon 3 is fixed to the blade, and the rotation is transmitted to the blade along with the dovetail tenon 3. The tip of each blade is tightly engaged with the overall hoop through the groove 7 on the inner surface of the floating load-bearing hoop 1, and the rotation is transmitted to the hoop along with the blade assembly, finally realizing the rotation of the entire structure. During operation, the turbine disk 4, the dovetail tenon 3, and the blades are subjected to centrifugal force and centrifugal bending moment generated by rotation, and under the action of centrifugal force and centrifugal bending moment, a deformation occurs. This deformation increases the outer diameter of the blade, making close contact with the hoop. At this time, the outer hoop provides a clamping force to the blade, and the hoop distributes the centrifugal force and centrifugal bending moment generated by the turbine disk 4, the dovetail tenon 3, and the blade. The presence of the hoop changes the problem that traditional turbine rotor blades only bear tensile stress, thereby reducing the stress at the blade root and achieving a rational distribution of stress at the blade root.

[0048] In addition, to clearly demonstrate the working principle of the new configuration in improving the load transmission path and achieving a rational distribution of blade root stress, the attached figure provides a force transmission diagram of three turbine rotor structures for comparison, in which the black arrows represent the direction of force. Figure 5 It is a traditional crownless turbine rotor structure, in which the blades mainly bear unidirectional tensile stress caused by centrifugal force when rotating. Figure 6The rotor structure is a crowned turbine. Due to the centrifugal force generated by the added mass of the blade crown under high-speed rotation, the tensile stress on the blades and tenons is further increased. Figure 7 The turbine rotor structure with floating load-bearing ring 1 described in this invention provides a radially inward constraint on the blade tip during operation, offering a clamping force opposite to the centrifugal tension, thus subjecting the blade to both compressive and tensile stresses simultaneously. This mechanism can offset some of the pure tensile load acting on the blade root tenon, resulting in a more uniform and rational stress distribution in the blade root region, effectively reducing stress concentration levels in the tenon and rotor disk tenon. While ensuring that the structural strength and reliability meet design requirements, this design provides a mechanical basis for thinning and reducing the weight of the turbine blades 2 and turbine disk 4, thereby supporting the overall lightweighting of the structure.

[0049] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0050] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A turbine rotor with a floating load-bearing hoop, characterized in that, include: A turbine disk (4) has multiple tenons (5) arranged circumferentially on its outer edge; Multiple turbine blades (2), each of the turbine blades (2) is installed in the mortise (5) of the turbine disk (4) by means of a tenon (3) connected thereto; An integral floating load-bearing hoop (1) is a ring structure that surrounds all turbine blades (2) and is fixedly connected to the tip of all turbine blades (2). The floating load-bearing ring (1) is used to provide radially inward constraint force to the tip of the turbine blade (2) when the turbine rotor is working, so as to share and offset part of the tensile load generated by centrifugal force.

2. A turbine rotor with a floating load-bearing hoop according to claim 1, characterized in that, The floating load-bearing ring (1) and the tip of the turbine blade (2) are interference fit.

3. A turbine rotor with a floating load-bearing hoop according to claim 2, characterized in that, The floating load-bearing ring (1) is fitted onto the tip of the turbine blade (2) when it is heated and expanded. After the temperature recovers, the floating load-bearing ring (1) shrinks and forms a tight interference fit with the tip of the blade.

4. A turbine rotor with a floating load-bearing hoop according to claim 1, characterized in that, The inner wall of the floating load-bearing hoop (1) is provided with an inner surface groove (7) for accommodating and fixing the tip of the turbine blade (2).

5. A turbine rotor with a floating load-bearing hoop according to claim 4, characterized in that, The inner surface groove (7) consists of a groove and two bosses located on both sides of the groove, circumferentially surrounding it and radially protruding toward the center of the disk.

6. A turbine rotor with a floating load-bearing hoop according to claim 4, characterized in that, The top outer edge of the floating load-bearing hoop (1) is provided with at least one circumferentially extending and radially protruding comb tooth.

7. A turbine rotor with a floating load-bearing hoop according to claim 1, characterized in that, The floating load-bearing ring (1) is made of a material whose radial outward deformation at the operating speed is less than the radial elongation at the tip of the turbine blade (2). The material includes titanium alloy, nickel-based high-temperature alloy or carbon fiber reinforced composite material.

8. A turbine rotor with a floating load-bearing hoop according to claim 1, characterized in that, The tenon (3) is a dovetail tenon, and the mortise (5) is a dovetail mortise that matches the dovetail tenon.

9. A turbine rotor with a floating load-bearing hoop according to claim 6, characterized in that, The floating load-bearing hoop (1) is provided with: Two rows of ferrules with the same height L4; The width L3 of the inner surface groove (7) is equal to or slightly smaller than the chord length b of the turbine blade (2), and the heights of the two inner surface bosses are equal, which is L6. The total thickness of the floating load-bearing hoop (1) is the sum of the tooth height L4, the hoop body thickness L5, and the boss height L6, and the thickness distribution of the three satisfies the ratio of L4:L5:L6=3:4:

1. The distance between the first tooth and the leading edge of the turbine disk and the distance between the second tooth and the trailing edge of the turbine disk are equal, both being L1. Furthermore, L1 and the width L3 of the inner surface groove satisfy the distribution relationship of L1:L3=1:

4.

10. A method for assembling a turbine rotor with a floating load-bearing ring as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Step 1: Insert the tenons (3) of multiple turbine blades (2) into the mortises (5) of the turbine disk (4) to complete the pre-assembly of the blade-disk assembly; Step 2: Heat the floating load-bearing hoop (1) to increase its inner diameter, and at the same time cool the blade-wheel assembly to reduce the diameter of the circle where the blade tip is located; Step 3: Fit the heated and expanded floating load-bearing ring (1) onto the outer tip of all the turbine blades (2) after cooling and shrinking; Step 4: Return the entire rotor assembly to room temperature after assembly, causing the floating load-bearing ring (1) to shrink and the blade-disc assembly to expand, ultimately forming an interference fit between the ring and the blade tip.

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