Flexible variable geometry turbine blades for reducing end region aerodynamic losses and variable geometry turbine

Abstract

The present disclosure provides a flexible variable geometry turbine blade and a variable geometry turbine for reducing end region aerodynamic loss, and relates to the technical field of variable geometry turbine blades for aeroengines and gas turbines. The flexible variable geometry turbine blade is installed between a casing and a hub of a turbine, and comprises an upper blade part, a lower blade part and a flexible component. An upper end of the upper blade part is rotatably installed on the casing; the lower blade part is oppositely arranged with the upper blade part along a blade height direction, and a lower end of the lower blade part is rotatably installed on the hub; and the flexible component is connected between the upper blade part and the lower blade part in a deformable manner along the blade height direction, and is suitable for absorbing a thermal deformation difference between the casing and the hub.

Description

Technical Field

[0001] This disclosure relates to the field of variable geometry turbine blades for aero engines and gas turbines, and more specifically, to a flexible variable geometry turbine blade and a variable geometry turbine for reducing end-area aerodynamic losses. Background Technology

[0002] Variable geometry turbine technology can effectively improve the efficiency and acceleration / deceleration performance of gas turbines under off-design conditions, and adjusting the turbine blade installation angle is the mainstream implementation scheme for this technology. In order to achieve blade installation angle adjustment and avoid excessive thermal stress under hot conditions, the upper and lower end walls of the blades need to be reserved with clearance, and the blade shaft adopts a design with one end fixed and the other end freely expanding. This requires a larger end clearance at the free end to prevent the blade from rubbing against the casing. At the same time, the end disks at both ends of the blades are prone to forming steps with the flow channel surface due to the free end design, which greatly increases aerodynamic losses.

[0003] In existing technologies, one approach is to accurately assess thermal deformation during the design phase, making the end-zone clearance and disk step as close to zero as possible. However, the internal flow of a gas turbine is unsteady and exhibits strong three-dimensional effects, and the contact thermal resistance of components is uncertain, making this approach difficult to implement. It can only guarantee steady-state operation under design conditions, while the risk of rubbing still exists under transient and non-design conditions. Another approach is to reduce the impact of leakage flow through new end-zone structures. While such structures can reduce end-zone leakage losses to some extent, their effectiveness is dominated by the clearance size; when the clearance is too large, their effectiveness decreases significantly.

[0004] Therefore, there is an urgent need for a variable geometry turbine blade that is compatible with variable geometry turbines, so as to fundamentally solve the problems of rubbing, aerodynamic loss and poor leakage control caused by end-section clearance. Summary of the Invention

[0005] In view of this, the present disclosure provides a flexible variable geometry turbine blade and a variable geometry turbine for reducing aerodynamic losses in the end region. By setting a flexible component in the middle of the blade, the thermal deformation difference between the blade and the inner and outer flow channel surfaces is absorbed, thus overcoming the technical problems caused by the blade end region.

[0006] One embodiment of this disclosure provides a flexible variable geometry turbine blade for reducing end-region aerodynamic losses, installed between the turbine casing and the hub, comprising: an upper blade portion, the upper end of which is rotatably mounted to the casing; a lower blade portion, disposed opposite to the upper blade portion along the blade height direction, the lower end of which is rotatably mounted to the hub; and a flexible assembly, deformably connected between the upper blade portion and the lower blade portion along the blade height direction, suitable for absorbing the thermal deformation difference between the casing and the hub.

[0007] According to an embodiment of this disclosure, the flexible component includes a first flexible body connected to the lower end of the upper part of the blade; and a second flexible body connected to the upper end of the lower part of the blade; wherein the first flexible body and the second flexible body are connected in the middle region of the blade.

[0008] According to an embodiment of this disclosure, the first end of the first flexible body is sleeved on the lower end of the upper part of the blade and extends outward along the outer surface of the upper part of the blade, and forms a first wing at the second end; the first end of the second flexible body is sleeved on the upper end of the lower part of the blade and extends outward along the outer surface of the lower part of the blade, and forms a second wing at the second end; wherein the first wing and the second wing abut against each other in the middle region of the blade.

[0009] According to embodiments of this disclosure, the profiles of the first wing and the second wing conform to the theoretical surface formed by the rotation of the circumferential average streamline at the corresponding blade height position around the turbine rotation axis.

[0010] According to an embodiment of this disclosure, a first groove is formed at the lower end of the upper part of the blade, and the first end of the first flexible body is sleeved outside the first groove, so that the outer surface of the first end of the first flexible body is flush with the surface of the upper part of the blade; a second groove is formed at the upper end of the lower part of the blade, and the first end of the second flexible body is sleeved outside the second groove, so that the outer surface of the first end of the second flexible body is flush with the surface of the lower part of the blade.

[0011] According to embodiments of this disclosure, at least one release groove is provided in the region of the first flexible body and / or the second flexible body near the trailing edge of the blade, which is suitable for releasing the stress generated by the deformation of the first flexible body and / or the second flexible body.

[0012] According to an embodiment of the present disclosure, a torsion transmission structure is also included, disposed between the upper part of the blade and the lower part of the blade, the torsion transmission structure being configured to allow the upper part of the blade and the lower part of the blade to move relative to each other in the blade height direction while rotating synchronously in the blade circumferential direction.

[0013] According to an embodiment of the present disclosure, the torque transmission structure includes a plurality of torque transmission shaft hole groups, which are respectively formed on the opposite end faces of the upper part and the lower part of the blade. Each of the torque transmission shaft hole groups includes a torque transmission shaft extending radially along the turbine and a torque transmission hole that mates with the torque transmission shaft hole.

[0014] According to an embodiment of this disclosure, the upper end of the blade is rotatably mounted to the casing via a first rotating shaft, and the lower end of the blade is rotatably mounted to the hub via a second rotating shaft; the first rotating shaft and the second rotating shaft are coaxially arranged and extend radially along the turbine.

[0015] Another embodiment of this disclosure provides a variable geometry turbine, including a casing, a hub, and the aforementioned flexible variable geometry turbine blades. A plurality of the aforementioned flexible variable geometry turbine blades are evenly arranged along the circumference of the hub and are rotatably mounted between the casing and the hub.

[0016] According to embodiments of this disclosure, by rotatably mounting the upper and lower parts of the blade to the casing and hub respectively, the deformation capability of the flexible component along the blade height direction can effectively absorb the thermal deformation difference between the casing and hub. This avoids the risk of blade rubbing against the casing and hub under hot conditions without reserving an excessively large end-area gap, thereby reducing aerodynamic losses caused by the step formed between the end-area disk and the flow channel surface, improving the end-area leakage control effect, fundamentally alleviating a series of problems caused by end-area gaps in the prior art, and taking into account variable geometry adjustment performance, operational safety and aerodynamic efficiency. Attached Figure Description

[0017] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0018] Figure 1 A perspective view of the flexible variable geometry turbine blade of this disclosure is shown;

[0019] Figure 2 An exploded view of the flexible component of this disclosure is shown;

[0020] Figure 3 A cross-sectional view of the mid-section of the flexible variable geometry turbine blade of this disclosure is shown;

[0021] Figure 4 A perspective view of the upper part of the blade of this disclosure is shown;

[0022] Figure 5 A perspective view of the lower part of the blade of this disclosure is shown;

[0023] Figure 6 The flow field simulation analysis diagram of the initial blade of this disclosure is shown;

[0024] Figure 7 A schematic diagram of the profiles of the first and second wing portions of this disclosure is shown;

[0025] Figure 8 for Figure 1 An enlarged view of point A shown;

[0026] Figure 9 The limiting streamline diagram of the suction surface of the initial blade of this disclosure is shown;

[0027] Figure 10 The limiting streamline diagram of the suction surface of the flexible variable geometry turbine blade of this disclosure is shown.

[0028] In the accompanying drawings, the meanings of the reference numerals are as follows:

[0029] 1. Upper part of the blade; 11. First groove; 12. First disk; 2. Lower part of the blade; 21. Second groove; 22. Second disk; 3. Flexible component; 31. First flexible body; 311. First airfoil; 312. First connecting part; 32. Second flexible body; 321. Second airfoil; 322. Second connecting part; 33. Release groove; 4. Torque transmission structure; 41. Torque transmission shaft; 42. Torque transmission hole; 5. First rotation shaft; 6. Second rotation shaft; 7. Initial blade; C1. Circumferential average streamline; C2. Intersection line; C3. Offset curve; S1. Surface of revolution; S2. Initial profile; L1. Centerline. Detailed Implementation

[0030] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or mechanisms, but do not exclude the presence or addition of one or more other features, steps, operations, or mechanisms.

[0032] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0033] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0034] Those skilled in the art will understand that the features described in the various embodiments of this disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments of this disclosure can be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0035] The following will refer to the appendix. Figures 1 to 8 The specific embodiments of the flexible variable geometry turbine blade and variable geometry turbine for reducing end-area aerodynamic losses of this disclosure are described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure. In the following description, descriptions of well-known structures and manufacturing techniques are omitted to avoid unnecessarily obscuring the technical concepts of this disclosure; the terms "blade height direction" as used herein refer to the extension direction of the turbine blade from the blade root to the blade tip, "turbine radial direction" refers to the radial direction from the turbine hub to the casing, and "blade circumferential direction" refers to the circumferential direction of the turbine. These directional definitions are for the convenience of describing the structural relationships of this disclosure and are not intended to limit the actual installation and operating direction of the turbine.

[0036] Figure 1 A perspective view of the flexible variable geometry turbine blade of this disclosure is shown.

[0037] Embodiments of this disclosure provide a flexible variable geometry turbine blade for reducing end-region aerodynamic losses, with reference to Figure 1 As shown, the flexible variable geometry turbine blade of this disclosure is installed between the turbine casing and the hub, and is a guide vane structure of the variable geometry turbine. The whole is composed of an upper blade 1, a lower blade 2, a flexible component 3, a first rotating shaft 5 and a second rotating shaft 6. The upper blade 1 and the lower blade 2 are arranged opposite to each other along the blade height direction. The flexible component 3 can be deformably connected between the two along the blade height direction to absorb the thermal deformation difference between the casing and the hub caused by thermal expansion and contraction.

[0038] In some embodiments, the first rotating shaft 5 and the second rotating shaft 6 extend radially along the turbine and are coaxially arranged. The upper end of the upper blade 1 is rotatably connected to the casing through the first rotating shaft 5, and the lower end of the lower blade 2 is rotatably connected to the hub through the second rotating shaft 6. The upper blade 1 and the lower blade 2 can rotate synchronously around the coaxial first and second rotating shafts to realize the adjustment of the turbine guide vane installation angle and meet the operating condition adjustment requirements of the variable geometry turbine.

[0039] Based on the above configuration, the large end gap required for adapting to thermal deformation in traditional variable geometry turbine blades is eliminated, thus avoiding the problem of blade rubbing against the casing and hub caused by the end gap from the root. At the same time, the aerodynamic losses caused by the large gap are also avoided. The rotatable design of the upper part 1 and the lower part 2 of the blade can still achieve flexible adjustment of the turbine guide vane installation angle, meeting the core requirements of the variable geometry turbine for operating condition adjustment.

[0040] In some embodiments, the first rotating shaft 5 is connected to the casing and the second rotating shaft 6 is connected to the hub by bearings. The bearings are high-temperature resistant rolling bearings, which can adapt to the high-temperature working environment of the turbine and reduce rotational friction resistance, making the adjustment of the blade installation angle smoother. The external drive mechanism is connected to the first rotating shaft 5 or the second rotating shaft 6, and the installation angle of the guide vane is adjusted by driving the rotation of the rotating shaft. The installation angle of the guide vane can be precisely adjusted according to different operating conditions of the gas turbine, thereby improving the efficiency and acceleration / deceleration performance of the turbine under non-design conditions.

[0041] In some embodiments, the upper end of the upper part 1 of the blade is integrally formed with a first disk 12, and the lower end of the lower part 2 of the blade is integrally formed with a second disk 22. The first disk 12 and the second disk 22 respectively cooperate with the flow channel surface of the casing and the hub, which can effectively reduce the leakage flow intensity in the turbine end area. Unlike the traditional variable geometry turbine blade design of "one end fixed and one end free", in this disclosure, the upper part 1 and the lower part 2 of the blade are rotatably connected and have no free end. There is no need to reserve too large a gap in the end area, which avoids the aerodynamic loss caused by the step formed between the end area disk and the flow channel surface from the root. At the same time, with the deformation compensation of the flexible component 3, the risk of collision and rubbing between the blade and the casing and hub under hot conditions is completely solved.

[0042] In some embodiments, the upper part 1 and the lower part 2 of the blade are both made of conventional high-temperature alloy material for turbine guide vanes, and the first disk 12 and the upper part 1 of the blade, and the second disk 22 and the lower part 2 of the blade are integrally forged structures.

[0043] Figure 2 An exploded view of the flexible component of this disclosure is shown; Figure 3 A cross-sectional view of the mid-section of the flexible variable geometry turbine blade of this disclosure is shown.

[0044] In one illustrative embodiment, reference is made to... Figure 2 and Figure 3 As shown, the flexible component 3 includes a first flexible body 31 and a second flexible body 32; the first flexible body 31 is connected to the lower end of the upper part 1 of the blade; the second flexible body 32 is connected to the upper end of the lower part 2 of the blade; wherein the first flexible body 31 and the second flexible body 32 are connected in the middle region of the blade.

[0045] Compared to an integrated flexible structure, the split flexible component 3 is easier to precisely assemble with the upper part 1 and the lower part 2 of the blade, and can make the flexible deformation evenly distributed in the blade height direction, avoiding the problem of local stress concentration in the flexible structure, and effectively improving the absorption effect of thermal deformation difference between the casing and the hub.

[0046] In one illustrative embodiment, reference is made to... Figures 1 to 3 As shown, the first end of the first flexible body 31 is sleeved on the lower end of the upper part 1 of the blade and extends outward along the outer surface of the upper part 1 of the blade, and forms a first wing 311 at the second end; the first end of the second flexible body 32 is sleeved on the upper end of the lower part 2 of the blade and extends outward along the outer surface of the lower part 2 of the blade, and forms a second wing 321 at the second end; wherein the first wing 311 and the second wing 321 abut against each other in the middle region of the blade.

[0047] Figure 4 A perspective view of the upper part of the blade of this disclosure is shown; Figure 5 A perspective view of the lower part of the blade of this disclosure is shown.

[0048] In one illustrative embodiment, reference is made to... Figure 4 and Figure 5 As shown, a first groove 11 is formed at the lower end of the upper part 1 of the blade, and the first end of the first flexible body 31 is sleeved outside the first groove 11, so that the outer surface of the first end of the first flexible body 31 is flush with the surface of the upper part 1 of the blade; a second groove 21 is formed at the upper end of the lower part 2 of the blade, and the first end of the second flexible body 32 is sleeved outside the second groove 21, so that the outer surface of the first end of the second flexible body 32 is flush with the surface of the lower part 2 of the blade.

[0049] In detail, a first groove 11 is provided on the lower end of the upper part 1 of the blade facing the lower part 2 of the blade. The first groove 11 is an annular groove extending along the circumference of the blade, and its depth is adapted to the thickness of the first flexible body 31 in the flexible component 3. A second groove 21 is provided on the upper end of the lower part 2 of the blade facing the upper part 1 of the blade. The second groove 21 is symmetrical to the first groove 11 and is also an annular groove extending along the circumference of the blade. Its depth is adapted to the thickness of the second flexible body 32.

[0050] In some embodiments, the first groove 11 and the second groove 21 are formed by CNC milling, and the surface roughness Ra is ≤1.6μm to ensure the fit with the flexible component.

[0051] In some embodiments, the first flexible body 31 includes an integrally formed first connecting portion 312 and a first wing portion 311. The first connecting portion 312 is an annular structure adapted to the first groove 11. The first wing portion 311 is formed by extending outward and downward from the outer edge of the first connecting portion 312 along the outer surface of the upper part 1 of the blade towards the middle region of the blade. The second flexible body 32 includes an integrally formed second connecting portion 322 and a second wing portion 321. The second connecting portion 322 is an annular structure adapted to the second groove 21. The second wing portion 321 is formed by extending outward and upward from the outer edge of the second connecting portion 322 along the outer surface of the lower part 2 of the blade towards the middle region of the blade.

[0052] Furthermore, the extension lengths of the first wing 311 and the second wing 321 are adapted to each other, and the two abut against each other in the blade region of the turbine. During cold assembly, a slight compression amount is reserved between the first wing 311 and the second wing 321 to ensure that they can always maintain the abutment state when they move relative to each other due to thermal deformation under hot conditions, thereby preventing leakage flow from passing through the contact gap between the two and further reducing end area leakage loss.

[0053] In some embodiments, the first connecting portion 312 of the first flexible body 31 is sleeved outside the first groove 11 of the upper blade 1, and the inner ring of the first connecting portion 312 is fixedly connected to the groove wall of the first groove 11 by brazing. After assembly, the outer surface of the first connecting portion 312 is flush with the outer surface of the upper blade 1. The second connecting portion 322 of the second flexible body 32 is sleeved outside the second groove 21 of the lower blade 2, and the inner ring of the second connecting portion 322 is also fixedly connected to the groove wall of the second groove 21 by brazing. After assembly, the outer surface of the second connecting portion 322 is flush with the outer surface of the lower blade 2.

[0054] According to the above configuration, there are no steps or protrusions between the flexible component 3 and the upper part 1 and the lower part 2 of the blade, ensuring the flatness of the blade flow channel surface and avoiding additional aerodynamic losses caused by uneven flow channel surface. This solves the problem of flow channel surface disturbance when traditional flexible structures are matched with blades.

[0055] Figure 6 The flow field simulation analysis diagram of the initial blade of this disclosure is shown; Figure 7 A schematic diagram of the profiles of the first and second wing portions of this disclosure is shown;

[0056] In one illustrative embodiment, reference is made to... Figure 6 and Figure 7 As shown, the profiles of the first wing 311 and the second wing 321 conform to the theoretical surface formed by the rotation of the circumferential average streamline at the corresponding blade height position around the turbine rotation axis.

[0057] In some embodiments, firstly, computational fluid dynamics is used to simulate and analyze the flow field of the initial blade 7 without the flexible component 3, and the circumferential average streamline C1 at the blade height position in the blade mid-region is obtained (e.g., ...). Figure 6 Using the turbine's centerline L1 as the axis of rotation, the circumferential average streamline C1 is rotated to form a surface of revolution S1; the surface of revolution S1 intersects with the side surface of the initial blade 7 to obtain an intersection line C2, and the intersection line C2 is offset by a preset distance along the circumferential direction of the blade on the surface of revolution S1 to form an offset curve C3; the surface of revolution S1 is trimmed with the offset curve C3, retaining the inner part, to obtain the initial airfoil profile S2 (e.g., ...). Figure 7 Then, according to the engineering processing requirements, the initial surface is rounded and trimmed to form the final surface of the first wing 311 and the second wing 321.

[0058] According to the above configuration, the initial profile S2 is configured so that the surfaces of the first wing 311 and the second wing 321 are in contact with the flow lines inside the turbine, which can effectively guide the airflow in the blade region, avoid aerodynamic losses caused by the wing blocking the airflow, and effectively block the leakage flow in the end region, further improving the aerodynamic efficiency of the turbine.

[0059] In some embodiments, the first flexible body 31 and the second flexible body 32 are both ultra-thin sheet metal parts, made of high-temperature resistant stainless steel, with a thickness of 0.05mm to 0.3mm, capable of elastic deformation along the blade height direction, and able to adapt to the high-temperature working environment of the turbine.

[0060] Figure 8 for Figure 1 An enlarged view of point A shown.

[0061] In one illustrative embodiment, reference is made to... Figure 8 As shown, at least one release groove 33 is provided in the region of the first flexible body 31 and / or the second flexible body 32 near the trailing edge of the blade, which is suitable for releasing the stress generated by the deformation of the first flexible body 31 and / or the second flexible body 32.

[0062] The release groove 33 can effectively release the deformation stress of the first flexible body 31 and the second flexible body 32 under hot conditions due to the thermal deformation difference between the casing and the hub, and prevent the flexible component 3 from buckling, cracking and other failures due to excessive stress. At the same time, the release groove 33 can increase the deformation freedom of the flexible component 3 along the blade height direction, so that the flexible component 3 can absorb the thermal deformation difference more smoothly and improve the structural reliability of the blade.

[0063] In some embodiments, a release groove 33 is provided on the first flexible body 31 and the second flexible body 32. The release groove 33 is a long strip-shaped through groove extending along the blade height direction, with a width of 1mm to 2mm and a depth of 1 / 2 to 2 / 3 of the thickness of the flexible body. The two ends of the release groove 33 are rounded to avoid stress concentration.

[0064] Figure 9 The limiting streamline diagram of the suction surface of the initial blade of this disclosure is shown; Figure 10 The limiting streamline diagram of the suction surface of the flexible variable geometry turbine blade of this disclosure is shown.

[0065] In some embodiments, refer to Figure 9 and Figure 10 As shown, the aerodynamic performance of the flexible variable geometry turbine blade of this disclosure was compared and verified with that of the initial blade. Among them, Figure 9 The initial blade suction surface limit streamlines without the use of flexible component 3 are shown. Figure 10 The suction surface limit streamline of the flexible variable geometry turbine blade of this disclosure is shown.

[0066] Numerical simulation results show that after redesigning the first-stage variable geometry turbine guide vanes of a certain type of gas turbine using the technical solution of this invention, the total pressure loss coefficient of the guide vanes significantly decreased from 7.2% in the traditional design to 3.8%, resulting in a significant improvement in aerodynamic performance. From the perspective of flow field structure, Figure 9 The initial suction surface corner region of the blade exhibits significant convergence and deflection of limiting streamlines, displaying a typical corner separation phenomenon induced by end-region leakage flow. This separation region is the core reason for the persistently high aerodynamic losses in traditional designs. In stark contrast, Figure 10 After adopting the scheme disclosed herein, the corner separation phenomenon caused by leakage flow on the suction surface of the blade completely disappears, and the streamlines are smoothly distributed along the blade surface; at the same time, the flow trajectory near the flexible component 3 is smooth and continuous, with no signs of flow separation, and the flow field quality is excellent.

[0067] The limiting streamline refers to the actual trajectory of a fluid particle moving along a solid wall. It is the line where the streamlines and the pathline coincide at the wall under steady flow, and can intuitively reflect the direction and distribution of fluid flow near the wall. It is usually obtained through computational fluid dynamics simulation or experimental flow visualization. In turbine blade flow field analysis, the distribution characteristics of the limiting streamline are an important basis for judging whether flow separation occurs at the blade wall, evaluating the degree of influence of end-zone leakage flow, and the aerodynamic performance of the blade. Smooth and continuous limiting streamlines indicate no flow separation at the wall and low aerodynamic losses, while bends, convergences, or backflows of the limiting streamlines indicate flow separation at the wall, which will significantly increase aerodynamic losses.

[0068] In one illustrative embodiment, reference is made to... Figure 4 and Figure 5As shown, it also includes a torsion transmission structure 4, which is disposed between the upper part 1 and the lower part 2 of the blade. The torsion transmission structure 4 is configured to allow the upper part 1 and the lower part 2 of the blade to move relative to each other along the blade height direction while rotating synchronously in the circumferential direction of the blade.

[0069] According to the above configuration, it is ensured that the flexible component 3 can smoothly absorb the thermal deformation difference between the casing and the hub, and that the torque transmission between the upper part 1 and the lower part 2 of the blade can be realized. This ensures that when the turbine guide vane is adjusted at the installation angle, the upper part 1 and the lower part 2 of the blade can rotate synchronously, thus ensuring the effectiveness and synchronicity of the variable geometry adjustment.

[0070] In one illustrative embodiment, reference is made to... Figure 4 and Figure 5 As shown, the torque transmission structure 4 includes multiple torque transmission shaft hole groups, which are formed on the opposite end faces of the upper part 1 and the lower part 2 of the blade, respectively. Each torque transmission shaft hole group includes a torque transmission shaft 41 extending radially along the turbine and a torque transmission hole 42 that mates with the shaft hole of the torque transmission shaft 41.

[0071] In some embodiments, the number of torsion transmission shaft hole groups is two, which are evenly spaced along the circumference of the blade to ensure the stability of torque transmission and avoid the problem of uneven force distribution that occurs with single shaft hole mating.

[0072] Specifically, the torsion transmission structure 4 includes multiple torsion transmission shaft hole groups extending radially along the turbine. Each torsion transmission shaft hole group consists of a torsion transmission shaft 41 and a torsion transmission hole 42. The torsion transmission shaft 41 is integrally formed on the upper end face of the lower part 2 of the blade, and the torsion transmission hole 42 is correspondingly opened on the lower end face of the upper part 1 of the blade. The torsion transmission shaft 41 and the torsion transmission hole 42 are clearance fit, ensuring that the torsion transmission shaft 41 can slide relative to each other in the blade height direction within the torsion transmission hole 42.

[0073] In some embodiments, the free end of the torsion shaft 41 is provided with a chamfer, the angle of which is 30° to 45°, as an assembly guide structure, which facilitates the quick and accurate insertion of the torsion shaft 41 into the torsion hole 42, thereby improving the assembly efficiency of the blade.

[0074] In some embodiments, after the torsion shaft 41 is inserted into the torsion hole 42, a thermal expansion gap is reserved between the end face of the torsion shaft 41 and the root of the torsion hole 42 to prevent the torsion shaft 41 from being squeezed by the root of the torsion hole 42 due to thermal expansion under hot conditions, which would cause excessive thermal stress at the shaft-hole mating point.

[0075] The core function of the torsion transmission structure 4 is to allow the upper part 1 and the lower part 2 of the blade to move relative to each other along the blade height direction while simultaneously achieving synchronous rotation of the two parts in the circumferential direction of the blade: when the casing and hub generate thermal deformation difference, the upper part 1 and the lower part 2 of the blade move relative to each other along the blade height direction, and the torsion transmission shaft 41 slides axially in the torsion transmission hole 42, which, together with the deformation of the flexible component 3, completes thermal deformation compensation; when it is necessary to adjust the installation angle of the turbine guide vane, the external drive mechanism drives the upper part 1 of the blade to rotate around the first rotating shaft 5, and the upper part 1 of the blade abuts against the torsion transmission shaft 41 circumferentially through the torsion transmission hole 42, transmitting torque to the lower part 2 of the blade, so that the lower part 2 of the blade rotates synchronously around the second rotating shaft 6, thereby realizing the overall adjustment of the guide vane installation angle and ensuring the adjustment performance of the variable geometry turbine.

[0076] When the flexible variable geometry turbine blade of this disclosure is in hot operation, after the gas turbine is ignited and started, the turbine enters the hot operating condition. Due to the increase in temperature, the casing and hub generate a thermal deformation difference in the blade height direction. The upper part 1 and the lower part 2 of the blade move relative to each other in the blade height direction under the action of this thermal deformation difference. The torsion transmission shaft 41 slides axially in the torsion transmission hole 42 with this relative movement. The first flexible body 31 and the second flexible body 32 of the flexible component 3 undergo elastic deformation in the blade height direction simultaneously, realizing the effective absorption of the thermal deformation difference between the casing and the hub. At the same time, the release groove 33 on the first flexible body 31 and / or the second flexible body 32 can release the internal stress generated by the deformation of the flexible body in time, avoiding stress concentration, buckling or cracking failure of the flexible body. The cold pre-compression between the first wing 311 and the second wing 321 can compensate for the relative displacement of the two caused by thermal deformation, so that the two always keep in close contact and effectively block the leakage flow from passing through the wing contact gap.

[0077] During operating condition adjustment, when the gas turbine needs to adjust the turbine guide vane installation angle according to operating requirements, the external drive mechanism drives the first rotating shaft 5 to rotate radially around the turbine, causing the upper part 1 of the blade to rotate synchronously. The rotational torque of the upper part 1 of the blade is stably transmitted to the lower part 2 of the blade through the circumferential contact relationship of the shaft hole of the torque transmission structure 4, driving the lower part 2 of the blade to rotate synchronously around the second rotating shaft 6, thereby achieving overall precise adjustment of the turbine guide vane installation angle. Throughout the angle adjustment process, the flexible component 3 maintains good elastic deformation compensation capability, which can adapt to the small deformation during the adjustment process in real time, and the torque transmission structure 4 continuously ensures stable torque transmission. At the same time, the blade adopts a design without free ends, and there is no excessive end gap between it and the casing and hub, which can effectively avoid the blade from rubbing and interfering with the casing and hub.

[0078] This disclosure also provides a variable geometry turbine, including a casing, a hub, and multiple flexible variable geometry turbine blades as described above. The multiple flexible variable geometry turbine blades are evenly spaced along the circumference of the hub, and each flexible variable geometry turbine blade is rotatably mounted between the casing and the hub. The multiple blades can simultaneously adjust their mounting angles, and each blade absorbs the thermal deformation difference between the casing and the hub through a flexible component 3. This eliminates the large free-end clearance and flow channel step problems found in traditional designs, thus reducing the end-area aerodynamic losses and leakage losses of the variable geometry turbine overall. This effectively improves the turbine's aerodynamic efficiency and structural reliability under all operating conditions. Other unmentioned structures of this variable geometry turbine can all adopt conventional variable geometry turbine structure designs from the fields of aero-engines and gas turbines.

[0079] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A flexible variable geometry turbine blade for reducing end-region aerodynamic losses, installed between the turbine casing and hub, characterized in that, include: The upper part of the blade is rotatably mounted to the casing; The lower part of the blade is disposed opposite to the upper part of the blade along the blade height direction, and the lower end of the lower part of the blade is rotatably mounted to the hub; A flexible component, deformably connected between the upper and lower parts of the blade along the blade height direction, is suitable for absorbing the thermal deformation difference between the casing and the hub.

2. The flexible variable geometry turbine blade according to claim 1, characterized in that, The flexible component includes: A first flexible body is connected to the lower end of the upper part of the blade; The second flexible body is connected to the upper end of the lower part of the blade; The first flexible body and the second flexible body are connected in the leaf region.

3. The flexible variable geometry turbine blade according to claim 2, characterized in that, The first end of the first flexible body is sleeved on the lower end of the upper part of the blade and extends outward along the outer surface of the upper part of the blade, and forms a first wing at the second end; The first end of the second flexible body is sleeved on the upper end of the lower part of the blade and extends outward along the outer surface of the lower part of the blade, and forms a second wing at the second end; The first wing and the second wing abut against each other in the leaf region.

4. The flexible variable geometry turbine blade according to claim 3, characterized in that, The profiles of the first and second wing sections conform to the theoretical surfaces formed by rotating the circumferential average streamlines at the corresponding blade height positions around the turbine rotation axis.

5. The flexible variable geometry turbine blade according to claim 3, characterized in that, A first groove is formed at the lower end of the upper part of the blade, and the first end of the first flexible body is sleeved outside the first groove, so that the outer surface of the first end of the first flexible body is flush with the surface of the upper part of the blade. A second groove is formed at the upper end of the lower part of the blade, and the first end of the second flexible body is sleeved outside the second groove, so that the outer surface of the first end of the second flexible body is flush with the surface of the lower part of the blade.

6. The flexible variable geometry turbine blade according to claim 2, characterized in that, At least one release groove is provided in the region of the first flexible body and / or the second flexible body near the trailing edge of the blade, which is suitable for releasing the stress generated by the deformation of the first flexible body and / or the second flexible body.

7. The flexible variable geometry turbine blade according to claim 1, characterized in that, It also includes a torsion transmission structure disposed between the upper part of the blade and the lower part of the blade, the torsion transmission structure being configured to allow the upper part of the blade and the lower part of the blade to move relative to each other along the blade height direction while rotating synchronously in the blade circumferential direction.

8. The flexible variable geometry turbine blade according to claim 7, characterized in that, The torque transmission structure includes multiple torque transmission shaft hole groups, which are respectively formed on the opposite end faces of the upper and lower parts of the blade. Each torque transmission shaft hole group includes a torque transmission shaft extending radially along the turbine and a torque transmission hole that mates with the torque transmission shaft hole.

9. The flexible variable geometry turbine blade according to claim 1, characterized in that, The upper end of the blade is rotatably mounted to the casing via a first rotating shaft, and the lower end of the blade is rotatably mounted to the hub via a second rotating shaft; the first rotating shaft and the second rotating shaft are coaxially arranged and extend radially along the turbine.

10. A variable geometry turbine, characterized in that, It includes a casing, a hub, and a plurality of flexible variable geometry turbine blades as described in claim 1, wherein the plurality of flexible variable geometry turbine blades are evenly arranged along the circumference of the hub and are rotatably mounted between the casing and the hub.

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