Blade, blade tip clearance control system and blade length self-adjustment control method
By designing a blade with a deformed member with thermal expansion characteristics, the deformation amount of the deformation member drives the displacement of the first blade body, and realizes self-regulation of the blade length, solving the problem of reasonably adjusting the gap between the tips in different flight conditions, achieving efficient fuel consumption and exhaust temperature control, extending the engine life and reducing pollution emissions.
Patent Information
- Application Number
- CN202311069002.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-23
- Publication Date
- 2025-02-25
AI Technical Summary
How to minimize the gap between the tips as much as possible without grinding, especially during the cruising phase of the engine, especially since the entire range is in a cruise state for about 75% of the time, the clearance needs to be adjusted reasonably in different flight states.
A blade is designed, including an edge plate, a first leaf body, a second leaf body and a deformation member. The second leaf body is fixedly arranged on the edge plate. The first leaf body is retractably arranged in the groove of the second leaf body. The deformation member passes through the second leaf body and is fixedly connected to the first leaf body, and has thermal expansion characteristics. The deformation amount of the deformation member drives the first leaf body to move, change its protrusion length relative to the groove, thereby realizing self-adjustment of the blade length.
It realizes that the tip gap can be spontaneously adjusted without electrical signal control in different flight states, meets the gap requirements of different stages of the engine, has high safety and reliability, can significantly reduce fuel consumption and exhaust temperature, extend engine life, and reduce pollution emissions.
Smart Images
Figure CN119507996A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of engines, and in particular to the field of blade tip clearance adjustment. Background Art
[0002] Tip clearance generally refers to the gap between the outer ring and the rotor. For example, for high-pressure turbine parts, a gap is formed between the outer ring of the high-pressure turbine casing of the engine and the high-pressure turbine guide vane. Data show that during the cruising stage of the engine, a 1% increase in turbine clearance will cause the efficiency of the turbine to drop by 1.5%, while a 0.254mm reduction in the clearance of the high-pressure turbine can reduce the fuel consumption rate by 1%, reduce the engine exhaust temperature by 10K, and significantly improve the engine life. In addition, the emission of nitrogen oxides, carbon monoxide and carbon dioxide is also greatly reduced.
[0003] For the clearance system, the clearance needs to be reasonably adjusted in different flight states, such as take-off and cruising. Since about 75% of the entire flight is in cruising state, effectively reducing the clearance in the cruising stage in the throttle state can greatly reduce fuel consumption while taking into account safety and reliability.
[0004] Therefore, how to control and reduce the blade tip clearance as much as possible, especially without causing collision and wear, is an urgent problem to be solved. Summary of the invention
[0005] An object of the present invention is to provide a blade capable of self-adjusting the length of the blade under different engine conditions.
[0006] A blade for achieving the above-mentioned purpose includes an edge plate, a first blade body, a second blade body and a deformation member, wherein the second blade body is fixedly arranged on the edge plate and includes a groove, and the first blade body is telescopically arranged in the groove; the deformation member passes through the second blade body and is fixedly connected to the first blade body, and has a thermal expansion characteristic; wherein the deformation member is configured to be able to drive the first blade body to move by virtue of its own deformation amount, so as to change the extension length of the first blade body relative to the groove.
[0007] In one or more embodiments, the blade further includes a limiting protrusion arranged on the first blade body, and a limiting portion is provided on the inner wall forming the groove, and the limiting portion is used to limit the displacement of the limiting protrusion, thereby limiting the displacement of the first blade body.
[0008] In one or more embodiments, the first blade body includes a blade tip, and the axial direction of the deformation member is consistent with the radial direction of the blade, so as to push the blade tip to move radially by virtue of its own axial deformation.
[0009] In one or more embodiments, the length of the deformation member when there is no deformation is set so that the blade tip does not protrude from the groove.
[0010] In one or more embodiments, cooling holes and cooling cavities are provided on the first blade body and the second blade body for introducing cooling airflow.
[0011] In one or more embodiments, the deformation member is further configured to be stretched and deformed by centrifugal force.
[0012] In one or more embodiments, the second blade part includes a hollow cavity and one or more pairs of connection layer walls located in the hollow cavity, and the deformation member is disposed in the hollow cavity and located between the one or more pairs of connection layer walls.
[0013] In one or more embodiments, one end of one or more pairs of the connecting layer walls is connected to the first blade body or the second blade body, and the other end is suspended.
[0014] Another object of the present invention is to provide a blade tip clearance control system, comprising an outer ring and the above-mentioned blade; a preset gap is provided between the blade and the outer ring, and the preset gap is set to be larger than the maximum displacement of the first blade body.
[0015] In one or more embodiments, the system further comprises a cooling assembly for introducing a cooling airflow to the blade.
[0016] Another object of the present invention is to provide a method for self-regulating blade length, comprising the following steps: introducing cooling airflows of different temperatures into the blades as described in any one of claims 1-7 at different engine stages to control the deformation amount of the deformation member.
[0017] The above-mentioned blade, by virtue of the design of the first blade body part, the second blade body part and the deformable part, enables the length of the blade to be spontaneously adjusted under different flight conditions with the help of the material properties of the deformable part and the blade structure, without the need for any electrical signal control, thereby meeting the requirements for tip clearance at different stages of the engine and having high safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:
[0019] Figure 1 is a schematic cross-sectional view of an aircraft engine turbine unit;
[0020] Figure 2A It is a cross-sectional schematic diagram of the clearance system of the high-pressure turbine of an aircraft engine;
[0021] Figure 2Bis a schematic diagram of the leakage flow in the gap;
[0022] Figure 3 It is a general schematic diagram of the design of passive clearance control of adjustable blades;
[0023] Figure 4 is a three-dimensional schematic diagram of one embodiment of a blade;
[0024] Figure 5 is a cross-sectional view of one embodiment of a blade (provided without AA);
[0025] Fig. 6A It is a cross-section of the leaf in its natural state;
[0026] Figure 6B is the cross-sectional view of the first blade at the maximum displacement state;
[0027] Figure 7 It is a schematic diagram of the working process of the high-pressure turbine clearance control system under takeoff and cruise conditions. DETAILED DESCRIPTION
[0028] The present invention is further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.
[0029] It should be noted that these and other subsequent drawings are only examples and are not drawn to scale, and should not be used to limit the actual scope of protection required by the present invention.
[0030] Figure 1 The cross-sectional view of the turbine unit of an aircraft engine is shown, and the direction O1 is the axial direction of the aircraft engine. The turbine system of a conventional aircraft engine can be roughly divided into a cooling pipe 101 , a turbine casing 102 , a suspension 103 , an outer ring 104 and high-pressure turbine blades 105 .
[0031] Figure 2A A cross-sectional schematic diagram of a clearance system of a high-pressure turbine of an aircraft engine is shown, wherein a blade tip clearance is provided between an outer ring 104 of a high-pressure turbine casing of the engine and a high-pressure turbine blade 105, wherein CL represents the size of the clearance. Figure 2BThe principle of gas flow leakage is shown. Due to the different surface pressures of various components inside the turbine, high-temperature gas flows from the high-pressure area to the low-pressure area. The fluid in the tip area of the pressure surface 61 (Pressure Surface) of the blade 105 flows into the suction surface 62 (Suction Surface) along the tip gap, causing gas flow leakage. In the figure, arrow 21 indicates the moving direction of the turbine casing 102, arrow 22 indicates the axial direction of the turbine 100, arrow 23 indicates the span direction, arrow 25 indicates the leakage flow, and arrow 24 indicates the second airflow near the casing.
[0032] For the clearance system, it is hoped that the tip clearance can be reasonably adjusted according to different flight conditions, such as reducing the clearance during the cruise phase and preventing friction during the take-off phase.
[0033] At present, there are three common gap control methods, namely passive control, semi-active control, and active control. Refer to Table 1 to understand that the basic method is through displacement and deformation, which can be roughly divided into mechanical, thermal, hydraulic, and expansion methods.
[0034] Table 1 Methods for implementing blade tip clearance changes
[0035]
[0036]
[0037] Specifically, passive control is mainly divided into the sealing layer design method and the method of open-loop control of the air flow path valve opening according to the speed. Among them, honeycomb seals have been widely used. Its function is to prevent the leakage of the gas flow at the blade tip by scraping the sealing layer of the turbine blade. The key point of semi-active control is to calculate the size of the gap by establishing an accurate gap model, and indirectly control the gap by open-loop control of the air flow path valve opening. The difficulty lies in accurately calculating the gap. The main difference between active gap control and semi-active gap control is the introduction of closed-loop feedback control. The method with a higher degree of recognition in the field of active gap control is thermal control. Specifically, it is to control the cooling airflow to exchange heat with the casing by setting an air bleed line, and change the expansion of the turbine casing by changing the temperature to adjust the size of the gap.
[0038] Generally, it is difficult and expensive to measure and monitor the gap in real time. It is difficult to establish a data-driven gap estimation model due to the lack of basic data such as air systems, so model-based active gap control is difficult. In addition, the implementation of active gap control involves multidisciplinary coupling, which is also difficult.
[0039] In addition to controlling the gap and reducing leakage losses through control means, leakage can also be directly reduced by optimizing the blade and casing structure.
[0040] The blades described in the present disclosure are length-adjusting blades. Figures 3 to 5 It is understood that the blade 10 is arranged on the wheel disk 30 , and includes an edge plate 13 and a blade root 14 , and also includes a first blade body 11 , a second blade body 12 and a deformation member 15 .
[0041] Further references Figures 4 to 6B It is understood that the second blade body 12 is fixedly arranged on the edge plate 13 as a blade body base, and a groove 120 is provided thereon. The first blade body 11 is telescopically arranged in the groove 120, and the moving direction is the radial direction of the blade, that is, the attached Figure 5 Up and down directions shown.
[0042] The deformable member 15 has thermal expansion characteristics and is a metal member based on memory alloy material. It can have a certain memory at different temperatures. Its stretching length is theoretically determined by temperature and centrifugal force, which are determined by the rotation speed of the rotating parts. Both temperature and rotation speed can be measured and designed for verification. The deformable member 15 passes through the second blade 12 and is fixedly connected to the first blade 11. Therefore, the deformable member 15 pushes the first blade 11 to move by its own deformation to change the extension length of the first blade 11 relative to the groove 120.
[0043] When the first blade body 11 is retracted in the groove 120 , it has no protruding length. When the top of the first blade body 11 is flush with the notch of the groove 120 , the protruding length is defined as 0.
[0044] In some embodiments, the second blade 12 includes a hollow cavity 125 and one or more pairs of connecting layer walls 126 located in the hollow cavity 125. The rod-shaped deformation member 15 is disposed in the hollow cavity 125 and is located between the one or more pairs of connecting layer walls 126. Figure 5 As shown. The function of the connecting layer wall 126 is to reinforce the hollow blade and guide the cold airflow. Preferably, one end of the connecting layer wall 126 is fixedly connected to the first blade body 11 or the second blade body, and the other end is suspended, so that the other end of each connecting layer wall defines a gap to provide a flow channel for the cooling airflow.
[0045] As in Figure 5 In the illustrated embodiment, the first blade body 11 includes a blade tip 118, and the deformation member 15 is arranged along the radial direction of the blade 10 to push the blade tip 118 to move in the radial direction by virtue of its own axial deformation along the a direction, thereby changing the length of the first blade body 11 extending out of the groove 120, thereby changing the overall blade body length of the blade 10, and realizing the function of adjusting the blade tip clearance.
[0046] In some embodiments, the shape of the blade tip 118 includes but is not limited to Figure 5 The plane shown can also be designed into other shapes such as an arc-shaped pressure surface, thereby achieving the purpose of reducing leakage flow or more.
[0047] In some embodiments, the blade further includes a limiting protrusion arranged on the first blade body 11, such as Figure 5 The bottom plate 110 shown at the bottom of the first blade body 11 has a limiting portion 121 on the inner wall of the groove 120 , and the limiting portion 121 is used to limit the displacement of the bottom plate 110 , thereby limiting the displacement of the first blade body 11 .
[0048] As reference Fig. 6A As shown, the limiting portion 121 may be a limiting groove 122 provided on the inner wall of the groove 120, and the bottom plate 110 has the maximum width of the first blade body 11. The bottom plate 110 is allowed to move in the limiting groove 122 until the bottom plate 110 moves to the limit position. Figure 6B The position shown in the figure further limits the further displacement of the first blade 11, thereby controlling the overall length of the blade and ensuring that the blade tip 118 does not rub against the outer ring. The length of the limiting groove 122 is the margin gap, which determines the extension amount of the first blade 11.
[0049] In other embodiments, the extension amount of the first blade body 11 may also be achieved by controlling the maximum deformation amount of the deformation member 15 , thereby controlling the size of the blade tip clearance.
[0050] It should be noted that the maximum displacement of the first blade 11 is preferably less than 2 mm, so that the tip clearance is slightly reduced. Since the fuel consumption rate can be reduced by 1% and the engine exhaust temperature can be reduced by 10K for every 0.254 mm reduction in the clearance of the high-pressure turbine, only a relatively small deformation of the clearance can bring great benefits. The adjustment of a shorter displacement can be achieved by different expansion degrees of the material.
[0051] In order to ensure that there is enough clearance during the takeoff phase, Fig. 6A In the embodiment of FIG. 1 , the length of the deformation member 15 when there is no deformation is set so that the blade tip 118 does not extend out of the groove 120, such as making the blade tip 118 flush with the radial outer end of the second blade body 12, which is convenient for initial installation of the blade. At this time, the blade tip clearance is at a maximum value.
[0052] In addition, the deformable member 15 is also configured to be stretched and deformed by centrifugal force. Since the deformable member 15 is driven by centrifugal force when the aircraft engine is in operation, the centrifugal force may also have a certain degree of influence on the deformation of the deformable member. Under the combined influence of centrifugal force and thermal expansion, the deformable member 15 deforms.
[0053] Generally, the blade body will also be deformed due to heat. Fig. 6AThe turbine blade is shown in a natural state, in which the blade is not subjected to centrifugal force and thermal force, and the first blade body 11 with the blade tip 118 is retracted in the groove 120 of the second blade body 12, wherein x represents the length of the first blade body 11 in the natural state, y represents the length of the second blade body in the natural state, and z represents the length of the deformation member 15 in the natural state. In the natural state, the length of the blade is the sum of the length of the edge plate 13, the length of the tenon 14, and the length of the second blade body 12.
[0054] When the aircraft is in cruising mode, the blades are deformed and stretched by the combined effects of centrifugal force and thermal force. The sum of the thermal expansion of the deformable member 15 and the deformation caused by the centrifugal force is greater than the sum of the deformations of the first blade body 11 and the second blade body 12, causing the first blade body 11 to move radially outward until the margin gap of the limit groove 122 is completely swallowed up, and the bottom plate 110 abuts against the end of the limit groove 122 and cannot move forward. Figure 6B As shown, after being subjected to the combined action of centrifugal force and thermal force, the length of the first blade body 11 is x'=x+Δx, the length of the second blade body 12 is y'=y+Δy, and the length of the deformation member 15 is z'=z+Δz.
[0055] At this time, the length of the blade ignores the changes in the edge plate 13 and the tenon 14, and the blade length change △L is mainly the length change of the blade. Among them, the expansion △x of the first blade 11 and the expansion △y of the second blade 12 are much smaller than the deformation △z of the deformation member 15, that is, △x+△y<<△z. Therefore, the elongation of the blade length △L is mainly related to the deformation △z of the deformation member 15. When in the cruising state, the deformation of the deformation member 15 is significantly greater than the deformation of the first blade 11 and the second blade 12, thereby pushing the first blade 11 to move upward until the margin gap is completely swallowed up, the first blade 11 extends out of the groove 120, and the blade no longer moves.
[0056] Therefore, the deformation amount Δz of the deformable member 15 is limited by the margin gap of the limiting groove 122. In other embodiments, cooling holes 14 and cooling cavities 16 may be provided on the first blade body 11 and the second blade body 12 to introduce cooling airflow, thereby affecting the ambient temperature of the deformable member 15 and further controlling the deformation amount Δz of the deformable member 15.
[0057] Specifically, the combustion gas flows through the surface of the blade body. Since the second blade body 12 includes a hollow cavity 125, the blade is a hollow blade and has air holes for film cooling. The cooling airflow C from the bottom of the tenon can ensure that the blade is not burned by the combustion gas, resulting in thermal stress reduction and blade breakage. By adjusting the temperature of the cooling airflow C, the temperature of the deformable part 15 can be controlled, thereby controlling the deformation amount of the deformable part, and then controlling the displacement amount of the blade tip of the first blade body 11, thereby controlling the size of the blade tip gap.
[0058] In combination with the above introduction, a method for self-regulating blade length control can be understood. This method introduces cooling airflows of different temperatures into the above blades according to different stages of the engine to control the deformation amount of the deformation member and thus control the blade length.
[0059] For example, the cooling airflow is introduced from the fan to the compressor area, and the temperature of the cooling airflow is changed by introducing the airflow from the interstage casing at different positions to control the deformation amount of the deformable member 15. It can be understood by those skilled in the art that the cooling airflow has different sources according to different engine air bleed schemes, and can also be bleed from the fan duct or the 3-6th stage of the compressor.
[0060] Figure 7 The design process of adjustable blade length is shown. First, the two specific states of the aircraft, namely the take-off state and the cruising state, are determined by the aircraft engine controller FADEC. When the aircraft is in the take-off state, the blades are initialized, verified and calibrated before the aircraft takes off to ensure that the first blade 11 is completely retracted into the groove of the second blade 12, the blade tip 118 is flush with the end of the second blade 12, and the first blade can be displaced upward without obstruction.
[0061] When the aircraft is taking off, in order to avoid collision and wear, sufficient tip clearance must be ensured to allow the blades to deform rapidly under the influence of centrifugal force.
[0062] If the aircraft is in a cruising state, the first blade 11 may be spontaneously deformed by the centrifugal force and thermal expansion of the deformation member 15, and pushed to extend radially outward but limited by the limiting part. The reduction of the tip clearance can significantly improve the efficiency of the turbine.
[0063] Combined with the above introduction to the blade, we can also understand a tip clearance control system, including an outer ring and the above blade, wherein a preset gap is provided between the blade and the outer ring, and the preset gap is set to be larger than the maximum displacement of the first blade body to avoid collision and wear. A cooling assembly including a cooling pipe can also be provided to introduce cooling airflow from the interstage casing to the blade to adjust the deformation of the deformation member 15. Change the size of the tip clearance.
[0064] The above blade and tip clearance control system does not need to design complex pipelines to guide cooling airflow for casing temperature control. By designing a structure with adjustable blade length, the tip clearance is adjusted by controlling the blade length. Different materials are naturally affected by centrifugal force and thermal expansion in different flight states to self-adjust the blade length to maximize the turbine working efficiency; and a reasonable clearance is designed in combination with the needs of different control states (such as takeoff and cruise), taking into account the needs of takeoff and cruise stages for clearance, meeting the requirements of takeoff to prevent friction, and reducing the tip clearance in the cruise state, thereby achieving the purpose of saving fuel. The adjustment of the entire blade does not introduce any electrical signal control, does not require real-time measurement of the clearance, and does not require the establishment of a clearance model. The tip clearance is adjusted spontaneously through material properties and blade structure, which is safe and reliable.
[0065] The present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or multiple times in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.
[0066] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.
Claims
1. A blade, comprising an edge plate, characterized in that: Also includes: First leaf body; A second blade body, fixedly disposed on the edge plate, comprises a groove, and the first blade body is telescopically disposed in the groove; as well as A deformation member, passing through the second blade body and fixedly connected to the first blade body, having a thermal expansion characteristic; The deformation member is configured to drive the first blade to move by virtue of its own deformation, so as to change the extension length of the first blade relative to the groove.
2. The blade according to claim 1, characterized in that The blade further comprises a limiting protrusion arranged on the first blade body, and a limiting portion is arranged on the inner wall forming the groove, and the limiting portion is used to limit the displacement of the limiting protrusion, thereby limiting the displacement of the first blade body.
3. The blade according to claim 1, characterized in that The first blade body includes a blade tip, and the axial direction of the deformation member is consistent with the radial direction of the blade, so as to push the blade tip to move radially by virtue of its own axial deformation.
4. The blade according to claim 3, characterized in that The length of the deformation member when there is no deformation is set so that the blade tip does not extend out of the groove.
5. The blade according to claim 3, characterized in that The blade tip is a cambered surface.
6. The blade according to claim 1, characterized in that The first blade body and the second blade body are provided with cooling holes and cooling cavities for introducing cooling airflow.
7. The blade according to claim 1, characterized in that The deformation member is also configured to be stretched and deformed by centrifugal force.
8. The blade according to claim 1, characterized in that The second blade part includes a hollow cavity and one or more pairs of connection layer walls located in the hollow cavity. The deformation member is arranged in the hollow cavity and located between the one or more pairs of connection layer walls.
9. The blade according to claim 1, characterized in that One end of one or more pairs of the connection layer walls is connected to the first blade body or the second blade body, and the other end is suspended.
10. A blade tip clearance control system, characterized in that: include: Outer ring; as well as The blade according to any one of claims 1 to 9; A preset gap is arranged between the blade and the outer ring, and the preset gap is arranged to be larger than the maximum displacement of the first blade body.
11. The tip clearance control system according to claim 10, characterized in that: The system also includes a cooling assembly for introducing a cooling airflow to the blade.
12. A blade length self-adjusting control method, characterized in that: The steps include: Introducing cooling air of different temperatures into the engine at different stages A blade as described in any one of claims 1 to 9, so as to control the deformation amount of the deformable member.