A test specimen of a variable geometry turbine sector blade cascade including a gear transmission mechanism for controlling the angle of adjustable guide vanes.

Abstract

The purpose of this invention is to provide a variable geometry turbine sector blade test piece including a gear transmission mechanism for controlling the adjustable guide vane angle. The test piece includes a test section rim, a test section hub front section, a test section hub rear section, an upper half of an adjustable guide vane shaft, and a lower half of an adjustable guide vane shaft. An upper bushing is mounted on the upper half of the adjustable guide vane shaft and fitted into a mounting hole in the test section rim. A lower bushing is mounted on the lower half of the adjustable guide vane shaft. The test section hub front section and test section hub rear section are respectively fitted with slots to fix the shaft. Test blades are installed and arranged in the test section flow channel between the test section rim and the test section hub front and rear sections. This invention can achieve effective and high-precision adjustment of the test blade angle. Simulation results show that the angle error between each test blade is controlled within 0.1°, and the guide vane angle can be controlled in real time, improving the accuracy of the experiment.

Description

Technical Field

[0001] The present invention relates to a test piece for realizing guide vane angle control, specifically a turbine fan-shaped blade cascade test piece. Background Technology

[0002] The variable geometry turbine is one of the most important components of a variable cycle engine. By changing the turbine geometry, the engine's flow rate, i.e., thrust, is controlled, and the engine's operating point is adjusted. Under different flight conditions, it can improve the thermodynamic cycle at maximum thrust, increasing thrust; improve the flow matching of the propulsion system; improve the engine's starting acceleration and deceleration performance; and improve or adjust the matching relationships between various components.

[0003] Marine gas turbines operate under partial load conditions for over 90% of their lifespan. Off-design point operation leads to changes in thermodynamic parameters, resulting in a sharp increase in fuel consumption. In the aerodynamic design of marine gas turbine power turbines, the use of variable geometry turbine technology effectively adjusts and optimizes the matching relationships between various components, thereby improving the acceleration / deceleration characteristics and low-temperature performance of the entire unit. The main reason for employing variable geometry turbine technology is that under partial load conditions, only the adjustable guide vanes need to be partially closed, reducing the guide vane throat area and thus decreasing the turbine's flow capacity and flow rate. This reduces the turbine's output power without lowering or only slightly lowering the turbine inlet gas temperature. Since the initial gas temperature remains high, the gas turbine efficiency can be maintained at a high level, resulting in better fuel economy than fixed geometry turbines.

[0004] While variable geometry turbine designs employing adjustable guide vanes can effectively regulate and optimize the matching characteristics between gas turbine components by altering the blade installation angle and thus the stator throat area, thereby controlling turbine flow, a certain clearance must be maintained at the tip of the adjustable stator to allow for free rotation of the stator, and a rotating shaft must be installed. This results in not only fluid leakage at the stator tip but also inherent unsteady-state problems such as flow around the rotating shaft, directly affecting the generation and development of the tip vortex structure. To investigate the flow field and loss characteristics in the tip region of the adjustable guide vane, an experimental study was conducted using a fan-shaped blade cascade with adjustable guide vane angles. The experimental setup required high-precision adjustment of the guide vane angle and realistic blade installation conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a variable geometry turbine fan-shaped blade cascade test piece that includes a gear transmission mechanism for controlling the rotation angle of the adjustable guide vane, for the purpose of studying the leakage flow characteristics and loss control of the endwall gap of the variable geometry turbine guide vane, in order to provide the most accurate reproduction of the actual installation of the variable geometry turbine adjustable guide vane.

[0006] The objective of this invention is achieved as follows:

[0007] This invention discloses a variable geometry turbine sector blade test piece including a gear transmission mechanism for controlling the rotation angle of adjustable guide vanes. The test piece comprises a test section rim, a test section hub front section, a test section hub rear section, an upper half of an adjustable guide vane shaft, and a lower half of an adjustable guide vane shaft. An upper bushing is mounted on the upper half of the adjustable guide vane shaft and fitted into a mounting hole in the test section rim. A lower bushing is mounted on the lower half of the adjustable guide vane shaft. The test section hub front section and test section hub rear section are respectively fitted with slots to fix the shaft. Test blades are installed and arranged in the test section flow channel between the test section rim and the test section hub front and rear sections.

[0008] The present invention may also include:

[0009] 1. It also includes an output shaft, a driving cylindrical gear, and a cylindrical gear rack. One side of the output shaft is connected to the worm gear reducer of the geared motor, and the driving cylindrical gear is assembled to the shaft end on the other side. A first flat key is set between the output shaft and the driving cylindrical gear. A first screw is installed on the driving cylindrical gear. A first shaft end retaining ring is sleeved on the outside of the first screw. The fastening screw and the shaft end retaining ring fix the cylindrical gear to the shaft end.

[0010] 2. A keyway and a threaded hole are provided on the upper half of the adjustable guide vane shaft. A third screw is installed in the threaded hole. A second shaft end retaining ring is fitted on the outside of the third screw. The third screw restricts the radial displacement of the bevel gear. An angle sensor mating groove is machined at the end of the lower half of the adjustable guide vane shaft. It is connected to the measuring shaft of the angle sensor to measure the rotation angle change of the test blade.

[0011] 3. It also includes a rack connector, a bevel gear rack, a rack mounting guide rail, and a driven bevel gear. The cylindrical gear rack is connected to the bevel gear rack through the rack connector and is fastened by a second screw to form a rack assembly, which is assembled on the rack mounting guide rail. The cylindrical gear rack meshes with the driving cylindrical gear. The driven bevel gear is assembled on the upper half of the adjustable guide vane shaft and transmits torque through a second flat key in the keyway of the upper half of the adjustable guide vane shaft.

[0012] 4. It also includes a linkage rod, a linkage ring, and a shaft end linkage. The cylindrical gear rack is connected to the linkage ring by bolts and is assembled on the guide rail of the wheel rim. The torque is transmitted to the linkage ring through the meshing of the driving cylindrical gear and the cylindrical gear rack. The linkage rod is connected to the linkage ring by bolts and bushings. The shaft end linkage is connected to the linkage rod by bolts and bushings. The shaft end linkage is fixed to the upper half of the adjustable guide vane shaft by bolts.

[0013] 5. A Hall angle sensor is used to remotely monitor the rotation angle of the test blade in real time, with a monitoring error of no more than 0.1°.

[0014] 6. The test blades can be adjusted from -20° to 70°, and the rotation angle error between each test blade is within 0.1°.

[0015] 7. The connection point between the linkage ring and the linkage rod is point A, the connection point between the shaft end connecting rod and the linkage rod is point B, and the end point of the shaft end connecting rod fixed to the upper half of the adjustable guide vane shaft is point C. The initial angle of the shaft end connecting rod is α1. When the linkage ring rotates along the guide rail around the wheel rim, point A is displaced by a distance x to point A′. Similarly, point B on the linkage rod is also displaced to point B′, causing the shaft end connecting rod to rotate around point C. The angle of the shaft end connecting rod changes to α2. The test blade is fixed to the shaft end connecting rod and moves in unison, thus realizing the change in the rotation angle of the test blade. The change value Δα=α2-α1.

[0016] The advantages of this invention are:

[0017] 1. The meridional channel of the blade cascade in the test section is designed with a spherical end wall, and the blade cascade inlet and outlet smoothly transition to the cylindrical end wall, ensuring the rotational freedom of the blade in the blade cascade channel and ensuring that the gap between the blade and the upper and lower end walls is constant at all positions.

[0018] 2. Modular design: For turbine and compressor adjustable guide vane cascade tests with different designs, only the test section components and the test blades themselves need to be replaced, while other components can still be installed and used, saving test costs to the greatest extent.

[0019] 3. By using a combination of worm gear reducer motor and gear transmission, the high precision and high torque characteristics of gear meshing transmission are utilized to achieve effective and high-precision adjustment of the blade rotation angle. The self-locking design in the worm gear reducer can maintain the blade angle of attack stability during the test.

[0020] 4. The application of Hall angle sensors enables real-time monitoring of guide vane rotation angle and allows for remote control of rotation angle changes, thus improving the accuracy of the experiment. Attached Figure Description

[0021] Figure 1 This is an assembly diagram of the adjustable guide vane blades for implementation method one;

[0022] Figure 2 This is an assembly drawing of the gear and rack meshing transmission according to Embodiment 1;

[0023] Figure 3 This is a triaxial projection of implementation method one;

[0024] Figure 4 This is a right view of implementation method one;

[0025] Figure 5a The image shows the motion simulation results of the UG model in Implementation Method 1 (0-10 seconds). Figure 5b The image shows the motion simulation results of the UG model in Implementation Method 1 (0-0.5 seconds).

[0026] Figure 6 This is a triaxial projection of implementation method two;

[0027] Figure 7 This is a top view of implementation method two;

[0028] Figure 8 This is a schematic diagram of the linkage mechanism in Implementation Method 2;

[0029] Figure 9 The image shows the motion simulation results of the UG model in Implementation Method 2. Detailed Implementation

[0030] The invention will now be described in more detail with reference to the accompanying drawings:

[0031] Combination Figure 1-9 This invention relates to a variable geometry turbine sector blade test specimen, including a gear transmission mechanism for controlling the adjustable guide vane angle. The invention comprises five parts: a test section assembly, a gear transmission mechanism, multiple test blades, an angle measurement assembly, and a motor drive assembly. Its basic unit structure is as follows: Figure 3 , Figure 4 As shown.

[0032] Implementation Method 1

[0033] This invention is primarily used for testing the fan-shaped blade cascade of adjustable guide vanes for variable geometry turbines. Combined with... Figure 1 The meridional section view of the blade assembly shows that the upper half 6 of the adjustable guide vane shaft is fitted with a bushing 7 and assembled into the mounting hole of the test section rim 1; at the same time, the lower half 9 of the adjustable guide vane shaft is fitted with a lower bushing 10. The front section 2 and the rear section 3 of the test section hub are respectively fitted with slots to fix the shaft, and the front and rear sections are connected and tightened with bolts; the test blade 8 is finally installed in the flow channel of the test section, with a spherical end wall design, and the blade inlet and outlet smoothly transition to the cylindrical end wall, ensuring the rotational freedom of the blade in the blade channel and ensuring that the gap between the blade and the upper and lower end walls is constant at all positions; the bevel gear that controls the rotation of the test blade is connected to the keyway 5 of the upper half of the shaft through a flat key, and the screw is installed in the threaded hole 4 to fix the shaft end retaining ring and thus limit the radial displacement of the bevel gear; an angle sensor mating groove 11 is machined at the end of the lower half 9 of the adjustable guide vane shaft to connect with the measuring shaft of the angle sensor to measure the rotation angle change of the test blade 8.

[0034] The transmission mechanism consists of two types of gear meshing: one is a cylindrical gear that transmits motion between two parallel shafts; the other is used for transmission between two perpendicular shafts, and can be either a bevel gear or a face gear. The bevel gear scheme is used to explain this type of transmission. The cylindrical gear meshing transmits torque to the adjusting ring, which is assembled by cutting the driven cylindrical gear and the driving bevel gear to appropriate sizes and adding connecting parts. The bevel gear meshing ultimately transmits the torque to the test blade shaft. Figure 2 An assembly diagram of the gear and rack assembly is provided. The left side of the output shaft 12 is connected to the worm gear reducer of the geared motor, and the right side is where the driving cylindrical gear 13 is assembled to the shaft end. The cylindrical gear transmits torque through the flat key 14, and the fastening screw 16 and the shaft end retaining ring 15 fix the cylindrical gear 13 to the shaft end. The cylindrical gear rack 17 is connected to the bevel gear rack 20 through the rack connector 18 and is fastened with screws 19 to form a rack assembly, which is assembled on the rack mounting guide rail 22. The driven bevel gear 21 is assembled on the upper half 6 of the adjustable guide vane shaft and transmits torque through the flat key 25. The fastening screw 24 at the shaft end is fixed to the shaft end retaining ring 23, ultimately forming a bevel gear rack mesh. The motor output torque is transmitted to the test blade through the cylindrical gear rack mesh and the bevel gear rack mesh to achieve the adjustment of the rotation angle.

[0035] The test piece is assembled as follows Figure 3 and Figure 4 As shown, combined with Figure 3 The worm gear reducer 26 is fixed to the top of the test section rim 1 with screws. The driving cylindrical gear 13 meshes with the cylindrical gear rack 17. The cylindrical gear rack 17, together with the rack connector 18 and the bevel gear rack 20, is mounted on the guide rail at the top of the test section rim. The bevel gear rack 20 simultaneously meshes with nine driven bevel gears 21, which are also simultaneously mounted on the shaft ends of their respective test blades. The nine test blades 8 are mounted in the test section housing, which consists of the test section rim 1, the test section hub, and side baffles. The test section hub consists of two sections (front section 2 and rear section 3) and is fixed by bolts. Figure 4 Angle sensor 27 is installed at the lower end of the side blade, the measuring shaft is connected to the mating groove, and the sensor body is fixed to the test section hub screws through the mounting flange.

[0036] To verify the design of the variable geometry turbine adjustable guide vane fan-shaped blade cascade test piece, the models of each test component were assembled, and motion simulation was performed using UG. The rim hub was fixed to the angle sensor, and a revolute joint was set between the driving cylindrical gear and the rack assembly. Each blade and its connected bevel gear were designed to move in the same direction, and a revolute joint was also set. To better and more accurately simulate the transmission accuracy of the gear set, the gear pair function was not used; instead, 3D contact was set between each meshing gear. A drag torque was set on the blade revolute joint to simulate the influence of aerodynamic forces on the adjustment angle of the mechanism. Simultaneously, interference analysis was performed between different blades, between different driven bevel gears, and between the blade and the test section casing. The simulation results showed no interference between the components. The total transmission ratio of the transmission gear set was 5:6, and a constant speed of 2.4° / s was set for the driving cylindrical gear revolute joint. The following is an example of motion simulation with a 20° increase in rotation angle, setting a 10-second motion calculation with 240 total steps. The analysis results show the change in blade rotation angle over time as follows: Figure 5a , Figure 5b The rotation angle changes almost linearly with time. During the simulation period from 0s to 0.5s, the angle initially decreases and then increases. This is attributed to initial errors in the 3D contact motion simulation of the gears. Under the influence of the resistance torque, the driven gear is forced to rotate in the opposite direction before contacting the driving gear rack. Furthermore, the initial lateral tooth clearance between each pinion and the rack varies, resulting in different error values. After eliminating the influence of these initial errors during data processing, the analysis shows that the absolute change in angle for different blades is between 19.66° and 19.76°, with a maximum error of 0.1° between individual blades and an overall error of less than 0.5°, meeting the experimental error requirements. Therefore, the feasibility of this variable geometry turbine adjustable guide vane fan-shaped blade cascade experimental design can be confirmed.

[0037] Implementation Method 2

[0038] Reference Figure 6 and Figure 7 The second implementation method is described below. The assembly method of the test blade and the rim hub is the same as that of the first implementation method. The adjustment mechanism still uses a low-speed motor and a worm gear reducer 26 as the drive source. The cylindrical gear rack 17 and the linkage ring 28 are connected by bolts and are assembled on the guide rail of the rim 1. The torque is transmitted to the linkage ring 28 through the meshing of the driving cylindrical gear 13 and the cylindrical gear rack 17. The linkage rod 30 is connected to the linkage ring 28 by bolts and bushings. The shaft end connecting rod 29 is connected to the linkage rod 30 by bolts and bushings. The shaft end connecting rod 29 is fixed to the upper half 6 of the adjustable guide vane shaft with bolts and secured with a locking pin to prevent the connecting rod 29 from rotating around the blade shaft.

[0039] Figure 8 A schematic diagram of the linkage mechanism is provided. Point A is the connection point between the linkage ring 28 and the linkage rod 30, point B is the connection point between the shaft end linkage 29 and the linkage rod 30, and point C is the end point of the shaft end linkage 29 fixed to the upper half of the adjustable guide vane shaft 6. The initial angle of the shaft end linkage 29 is α1. When the linkage ring 28 rotates along the guide rail around the wheel rim, point A is displaced by a distance x to point A′. Similarly, point B on the linkage rod 30 is also displaced to point B′, causing the shaft end linkage 29 to rotate around point C. The angle of the shaft end linkage 29 changes to α2. Since the test blade 8 is fixed to the shaft end linkage and moves in unison, the rotation angle of the test blade 8 is changed, with a change value Δα = α2 - α1.

[0040] For the second implementation method, UG motion simulation was performed to simulate the change in the blade angle under motor drive. The rim hub and reducer were fixed; the cylindrical gear rack and linkage ring were set as the same revolute joint; the driving cylindrical gear was also set as a revolute joint; 3D contact was established between the driving cylindrical gear and the cylindrical gear rack to more accurately simulate the meshing between the gear and rack; the shaft end connecting rod and the test blade were set as the same revolute joint around the blade's rotation axis; the linkage rod was set as having 3D contact with both the linkage ring and the shaft end connecting rod to simulate the linkage motion; a resistance torque was set on the blade revolute joint to simulate the influence of aerodynamic forces on the mechanism's adjustment angle. A constant speed of 2.4° / s was set for the driving cylindrical gear revolute joint, with a motion calculation of 9.5s and a total of 228 steps. The analysis results show the change in blade angle over time as follows: Figure 9 The angle change showed the same phenomenon as the simulation results of Scheme 1: it first decreased and then increased. Subsequently, the angle change was close to linear, and the angle values ​​between the blades did not differ by more than 0.1°, which met the error requirements for the experiment.

[0041] This invention discloses a variable geometry turbine sector blade test specimen comprising a gear transmission mechanism for controlling the adjustable guide vane angle. Multiple adjustable guide vane test blades with stepped shafts are uniformly assembled circumferentially in the mounting holes of a sector-shaped rim hub. A low-speed motor and a worm gear reducer drive a gear and rack transmission mechanism mounted on the rim guide rail. This gear transmission mechanism drives the test blades to rotate around their own shafts. An angle sensor mounted on the end of the rotating shaft monitors and adjusts the blade angle in real time. The test specimen is used for experimental research on the aerodynamic performance of turbomachinery, specifically for studying the leakage flow characteristics and loss control of variable geometry turbine guide vane endwall clearance. The test blades utilize adjustable guide vanes for gas turbines based on similarity principle modeling.

[0042] The angle of the adjustable guide vane is adjusted by using bevel gear meshing.

[0043] The angle of the adjustable guide vane is adjusted by using end face gear meshing.

[0044] The angle of the adjustable guide vane is adjusted using a linkage structure.

[0045] The cylindrical gear is made into a rack, and the adjustment ring mounted on the wheel rim guide is controlled by the meshing of the cylindrical gear, thereby adjusting the rotation angle of the test blade.

[0046] The adjusting ring is assembled from a rack made of cylindrical gears and bevel gears or face gears using bolts and locating pins. Alternatively, the adjusting ring is assembled from a rack made of cylindrical gears and a connecting rod linkage ring using bolts and locating pins.

[0047] The inner wall of the test section adopts a spherical end wall design to keep the gap between the blade and the hub rim uniform.

[0048] The test blade's rotating shaft adopts a stepped shaft design and is installed in the mounting hole of the test piece's rim hub with a bushing.

[0049] The drive source for the guide vane angle adjustment mechanism consists of a reversible low-speed motor and a worm gear reducer.

[0050] A Hall angle sensor was used to remotely monitor the blade rotation angle in the test piece in real time, with a monitoring error of no more than 0.1°.

[0051] By using a drive source and angle monitoring, remote monitoring and adjustment of the positive and negative directions of the test blade's rotation angle can be achieved.

[0052] The test blades can be adjusted from -20° to 70°, and the rotation angle error between each test blade is controlled within 0.1°.

Claims

1. A variable geometry turbine cascade test piece comprising a gear mechanism for controlling the angle of the adjustable vanes, characterised in that: It includes a test section rim, a test section hub front section, a test section hub rear section, an adjustable guide vane shaft upper half section, and an adjustable guide vane shaft lower half section. The upper half section of the adjustable guide vane shaft is fitted with an upper bushing and assembled into the mounting hole of the test section rim. The lower half section of the adjustable guide vane shaft is fitted with a lower bushing. The test section hub front section and test section hub rear section are fixed with slots. The test blades are installed and arranged in the test section flow channel between the test section rim and the test section hub front section and test section hub rear section. It also includes an output shaft, a driving cylindrical gear, and a cylindrical gear rack. One side of the output shaft is connected to the worm gear reducer of the geared motor, and the driving cylindrical gear is assembled to the shaft end on the other side. A first flat key is set between the output shaft and the driving cylindrical gear. A first screw is installed on the driving cylindrical gear. A first shaft end retaining ring is sleeved on the outside of the first screw. The first screw and the first shaft end retaining ring fix the driving cylindrical gear to the shaft end. The upper half of the adjustable guide vane shaft is provided with a keyway and a threaded hole. A third screw is installed in the threaded hole, and a second shaft end retaining ring is fitted on the outside of the third screw. An angle sensor mating groove is machined at the end of the lower half of the adjustable guide vane shaft. It is connected to the measuring shaft of the angle sensor to measure the rotation angle change of the test blade. The inner wall of the test section adopts a spherical end wall design to keep the gap between the test blade and the hub rim uniform. If bevel gear meshing is used to achieve the angle adjustment of the adjustable guide vane, it also includes a rack connector, a bevel gear rack, a rack mounting guide rail, and a driven bevel gear. The cylindrical gear rack is connected to the bevel gear rack through the rack connector and is fastened by a second screw to form a rack assembly, which is assembled on the rack mounting guide rail. The cylindrical gear rack meshes with the driving cylindrical gear. The driven bevel gear is assembled on the upper half of the adjustable guide vane shaft and transmits torque through a second flat key in the keyway of the upper half of the adjustable guide vane shaft. A third screw limits the radial displacement of the driven bevel gear. If a linkage structure is used to achieve the angle adjustment of the adjustable guide vane, it also includes a linkage link, a linkage ring, and a shaft end link. The cylindrical gear rack is connected to the linkage ring by bolts and is assembled on the guide rail of the wheel rim. The torque is transmitted to the linkage ring through the meshing of the driving cylindrical gear and the cylindrical gear rack. The linkage link is connected to the linkage ring by bolts and bushings. The shaft end link is connected to the linkage link by bolts and bushings. The shaft end link is fixed to the upper half of the adjustable guide vane shaft by bolts.

2. A variable geometry turbine cascade test piece comprising a gear mechanism for controlling the angle of the adjustable vanes according to claim 1, characterized in that: A Hall angle sensor was used to remotely monitor the rotation angle of the test blade in real time, with a monitoring error of no more than 0.1°.

3. A variable geometry turbine sector blade test specimen according to claim 1, comprising a gear transmission mechanism for controlling the adjustable guide vane angle, characterized in that: The test blades can be adjusted from -20° to 70°, and the rotation angle error between each test blade is within 0.1°.

4. A variable geometry turbine sector blade test specimen according to claim 1, comprising a gear transmission mechanism for controlling the adjustable guide vane angle, characterized in that: Point A is the connection point between the linkage ring and the linkage rod; point B is the connection point between the shaft end connecting rod and the linkage rod; point C is the endpoint of the shaft end connecting rod fixed to the upper half of the adjustable guide vane shaft; and the initial angle of the shaft end connecting rod is... When the linkage ring rotates along the guide rail around the wheel flange, the connection point between the linkage ring and the linkage rod shifts from point A by a distance x to... Similarly, point B on the linkage will also move accordingly, displacing to... Point C causes the connecting rod at the shaft end to rotate around point C, and the angle of the connecting rod at the shaft end changes as follows: The test blade is fixed to the shaft end connecting rod and moves in unison, thus achieving an angle change in the test blade, with the change value being... .

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