A passive gap control system with dynamically adjustable airflow area

Abstract

This application provides a passive clearance control system with dynamically adjustable bleed air flow area, comprising: a bleed air seat assembly, a gas collection box, and a cooling air pipe. The bleed air seat assembly is mounted on the gas collection box, which has multiple distribution holes. A cooling air pipe is installed on each distribution hole. The introduced cooling air is distributed through the distribution holes and flows out from the injection holes on the cooling air pipe to cool the turbine casing. The bleed air seat assembly includes a valve cylinder, a bleed air seat cylinder, a valve, a pressure adjusting nut, a spring, and a vent pipe. A cooling air flow channel is formed between the valve cylinder and the bleed air seat cylinder. The valve is mounted on the valve cylinder by the spring and the pressure adjusting nut. The vent pipe connects the valve cylinder and the bleed air seat cylinder to introduce external atmosphere. By ensuring that the spring stiffness, spring pre-compression, maximum valve opening, and valve pressure adjusting area satisfy a predetermined relationship, the valve is guaranteed to be fully open during cruise and closed during takeoff.

Description

Technical Field

[0001] This application belongs to the field of aero-engines, and specifically relates to a passive clearance control system with dynamically adjustable bleed air flow area. Background Technology

[0002] Existing high-bypass turbofan engine turbine components generally employ clearance control systems. These systems use fan or compressor gas to impinge-cool the turbine casing, reducing casing thermal deformation and minimizing turbine blade tip clearance, thereby improving turbine component efficiency. Clearance control systems are primarily divided into two types: active clearance control systems and passive clearance control systems. Active clearance control systems control valve opening and closing based on engine control principles, actively adjusting the bleed air source and flow rate to ensure the turbine blade tip clearance remains within design limits. Passive clearance control systems, on the other hand, lack control components and have a simpler structure. Because passive clearance control systems lack control components, their bleed air flow rate and pressure are uncontrollable, making it impossible to actively adjust casing thermal deformation and blade tip clearance. Under certain engine conditions, passive clearance control systems can cause blade tip clearance to deviate from design requirements, potentially leading to adverse effects. For example, when the engine is pushed from idle to takeoff, the rotor speed increases rapidly. Under the action of centrifugal force, the turbine disk and rotor blades elongate rapidly in the radial direction. At this time, the passive clearance control system continuously cools the casing, which reduces and delays the thermal deformation of the turbine casing. This results in excessively small blade tip clearance, severe rubbing between the rotor and stator, and severe wear of the outer ring honeycomb (or coating), which has an adverse effect on the engine's safety and performance maintenance capabilities.

[0003] While active clearance control systems can actively adjust blade tip clearance, their complexity, structural dimensions and weight, and manufacturing costs are significantly higher than those of passive clearance control systems. In certain situations, due to limitations in engine space, weight, or manufacturing costs, active clearance control systems cannot be applied, thus necessitating the use of passive clearance control systems. To overcome these drawbacks, a new passive clearance control system is needed. Summary of the Invention

[0004] The purpose of this application is to provide a passive gap control system with dynamically adjustable airflow area to solve or mitigate at least one of the problems in the prior art.

[0005] The technical solution of this application is: a passive gap control system with dynamically adjustable air bleed flow area, comprising: an air bleed seat assembly, an air collection box, and a cooling air pipe. The air bleed seat assembly is installed on the air collection box for introducing cooling air. The air collection box is provided with multiple distribution holes, and a cooling air pipe is installed on each distribution hole. The introduced cooling air is distributed through the distribution holes of the air collection box and flows out from the injection holes provided on the cooling air pipe to cool the turbine casing.

[0006] The air intake seat assembly includes a valve cylinder, an air intake seat cylinder, a valve, a pressure adjusting nut, a spring, and a vent pipe. A cooling air passage is formed between the valve cylinder and the air intake seat cylinder. The valve is installed on the valve cylinder by the spring and the pressure adjusting nut. The vent pipe connects the valve cylinder and the air intake seat cylinder to introduce external atmosphere.

[0007] By ensuring that the spring stiffness, spring pre-compression, maximum valve opening, and valve pressure adjustment area satisfy a predetermined relationship, the valve is guaranteed to be fully open during cruise and closed during takeoff.

[0008] In at least one embodiment of this application, the air intake seat assembly and the cooling air pipe are all fixed to the air collection box by corner seam welding.

[0009] In at least one embodiment of this application, the upper end of the valve cylinder is a spoke structure, and a plurality of air inlets are formed between the spoke structures to ensure the introduction of cooling air. The valve cylinder has a cylindrical structure at its center, and the cylindrical structure extends downward into the air intake seat cylinder.

[0010] In at least one embodiment of this application, the air inlet is fan-shaped and evenly arranged in the circumferential direction.

[0011] In at least one embodiment of this application, the air intake cylinder includes a mounting section with a larger diameter and a ventilation section with a smaller diameter. The mounting section and the ventilation section are connected by a transition section. The mounting section is fixedly connected to the valve cylinder by a connector. The mounting section encloses the cylinder structure to form a space for cooling air to pass through and flows out from the ventilation section.

[0012] In at least one embodiment of this application, the transition section is a tapered structure.

[0013] In at least one embodiment of this application, the valve includes a rod and a blocking portion located at the end of the rod. The other end of the rod is provided with a threaded section for connecting with a pressure adjusting nut having a pressure adjusting portion. The rod and spring are installed in the cylindrical structure of the valve body. The blocking portion is located at the lower end of the rod and inside the air intake seat cylinder. The pressure adjusting portion is located at the upper end of the rod and inside the cylindrical structure of the valve body. The pressure adjusting nut, which cooperates with the threaded section of the rod, limits the spring and compresses the spring to a preset load.

[0014] In at least one embodiment of this application, the sealing part of the valve is provided with a number of pressure equalization holes to eliminate the pressure difference between the upper and lower parts of the sealing part.

[0015] In at least one embodiment of this application, the vent pipe is connected to the root of the cylindrical structure.

[0016] In at least one embodiment of this application, the predetermined relation includes:

[0017] Cruise status: K×h0≥(P' 引气 -P' 大气 )×(S1-S2)

[0018] Takeoff status: K×(h0+Δh) max )≤(P” 引气 -P” 大气 )×(S1-S2)

[0019] In the formula, P' 引气 P' is the bleed air pressure during cruise. 大气 The atmospheric pressure during cruise is given by S1, the pressure regulating section area is given by S2, and the rod area is given by F. 弹簧 For the spring force, P” 引气 The bleed air pressure at takeoff, P” 大气 The atmospheric pressure at takeoff is given by K, where K is the spring stiffness, h0 is the spring pre-compression, and Δh is the spring pre-compression. max This represents the maximum opening of the valve.

[0020] The passive clearance control system provided in this application can dynamically adjust the bleed air volume by adding a bleed air flow area adjustment mechanism, thereby controlling the thermal deformation of the turbine casing according to the changes in engine operating conditions, so that the rotor blade tip clearance always meets the design requirements. Moreover, the entire passive clearance control system has low manufacturing cost, small structural size changes, and can ensure the system's assembly interchangeability. Attached Figure Description

[0021] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0022] Figure 1 This is a schematic diagram of the passive clearance control system of this application.

[0023] Figure 2 This is a schematic diagram of the air intake seat assembly in this application.

[0024] Figure 3 This is a schematic diagram of the air intake seat assembly in this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0026] To overcome the shortcomings of the prior art, this application provides a passive gap control system with dynamically adjustable airflow area.

[0027] like Figure 1 As shown, the passive clearance control system 100 with dynamically adjustable bleed air flow area provided in this application includes: a bleed air seat assembly 10, a gas collection box 20, and a cooling air pipe 30. The gas collection box 20 has an inlet at its upper end, and the bleed air seat assembly 10 is installed on the inlet of the gas collection box 20. The gas collection box 20 has multiple distribution holes, and a cooling air pipe 30 is installed on each distribution hole. The cooling air pipe 30 has multiple injection holes. Cooling bleed air enters the gas collection box 20 from the bleed air seat assembly 10, is distributed by the distribution holes of the gas collection box 20, and then divided into several streams that enter the cooling air pipe 30. Afterward, it is ejected from a series of injection holes on the surface of the cooling air pipe 30 to perform impact cooling on the turbine casing (not shown). In some embodiments of this application, the bleed air seat assembly 10 and the cooling air pipe 30 installed with the gas collection box 20 are both fixed by fillet weld.

[0028] The air intake seat assembly 10 of this application is equipped with a differential pressure control valve, which can automatically control the valve opening according to the pressure difference between the air intake and the outside atmosphere to adjust the air intake flow area.

[0029] like Figure 2 As shown, the air intake seat assembly 10 includes: a valve cylinder 11, an air intake seat cylinder 12, a valve 13, a pressure adjusting nut 14, a spring 15, a vent pipe 16, a bolt 17, a self-locking nut 18, and a washer 19.

[0030] The upper end of the valve cylinder 11 has a spoke structure, with several air inlets 111 formed between the spokes to ensure the introduction of cooling air. In this embodiment of the application, the air inlets 111 are fan-shaped and evenly arranged in the circumferential direction. A cylindrical structure 112 is provided at the center of the valve cylinder 11, and the cylindrical structure 112 extends downward into the air intake seat cylinder 12.

[0031] The upper part of the air intake cylinder 12 is a larger diameter mounting section, which encloses the cylinder structure 112, with a certain space between them for the passage of cooling gas. The mounting section is fixedly connected to the valve cylinder 11 by bolts 17, self-locking nuts 18, and washers 19. The lower end of the air intake cylinder 12 is a smaller diameter ventilation section 122, which is connected to the mounting section by a transition section 121. In this application, the transition section 121 is a conical structure.

[0032] The valve 13 includes a rod and a sealing part 131 located at the end of the rod. The upper end of the rod of the valve 13 has a threaded section. The rod and spring 15 are installed in the cylindrical structure 112 of the valve body 11. The sealing part 131 is located at the lower end of the rod and inside the air intake seat cylinder 12. Its size is adapted to the transition section 121. The pressure adjusting nut 14 has a pressure adjusting part 141 integrated with its body. It is located inside the cylindrical structure 112 and its size is adapted to the cylindrical structure 112. The pressure adjusting nut 14 is engaged with the threaded section of the rod and screwed into the cylindrical structure 112 to a suitable depth, so that the spring 15 is compressed to a preset load. The sealing part 131 of the valve 13 has a number of pressure equalizing holes 132 to eliminate the pressure difference between the upper and lower parts of the sealing part 131 and to ensure the minimum cold air flow of the passive clearance control system 100 when the valve 13 is closed.

[0033] In this application, the top of the pressure adjusting nut 14 has a hexagonal self-locking structure.

[0034] The vent pipe 16 passes through the side wall of the air intake seat cylinder 12 and the valve cylinder 11, and is used to introduce outside air into the cylinder structure 112 of the valve cylinder 11. In a preferred embodiment of this application, the vent pipe 16 connects to the root or bottom of the cylinder structure 112, between the root of the cylinder structure 112 that can introduce outside air into the valve cylinder 11 and the pressure regulating part 141, thereby pushing the valve 13 to move up and down.

[0035] like Figure 3 As shown, the internal pressure differential control valve of the air intake seat assembly 10 has the following force balance relationship:

[0036] P 引气 ×S1=F 弹簧 +P 大气 ×(S1-S2)+P 引气 ×S2

[0037] In the formula, P 引气 For bleed air pressure, P 大气 Where S1 is the atmospheric pressure, S2 is the area of ​​the pressure regulating section, and F is the area of ​​the rod section. 弹簧 This is the spring force.

[0038] At this point, the spring force can be written as: F 弹簧 =(P 引气 -P大气 )×(S1-S2)

[0039] According to the formula for calculating spring force, stiffness, and compression: F 弹簧 =K×(h0+Δh)

[0040] In the formula, h0 is the spring pre-compression amount, and Δh is the change in spring compression during operation, which is equal to the change in valve opening.

[0041] Therefore, the valve opening Δh and bleed pressure P are established. 引气 With atmospheric pressure P 大气 The pressure differential relationship is used to control the valve opening by varying the pressure differential, thereby adjusting the bleed air flow. According to design requirements, the bleed air volume should be maximized when the valve is fully open during engine cruise to reduce turbine casing thermal deformation; during takeoff, the bleed air volume should be minimized when the valve is closed to improve the turbine casing's thermal response rate and deformation.

[0042] Based on performance calculations, the bleed air pressure P 引气 With atmospheric pressure P 大气 The pressure difference increases with the engine operating state; to ensure the valve is fully open during cruise and closed during takeoff, the forces acting on the valve in the two states have the following relationship:

[0043] Cruise status: K×h0≥(P' 引气 -P' 大气 )×(S1-S2)

[0044] Takeoff status: K×(h0+Δh) max )≤(P” 引气 -P” 大气 )×(S1-S2)

[0045] In the formula, P' 引气 P' is the bleed air pressure during cruise. 大气 The atmospheric pressure during cruise, P” 引气 The bleed air pressure at takeoff, P” 大气 This refers to the atmospheric pressure during takeoff.

[0046] In valve design, the spring stiffness K, spring pre-compression h0, and maximum valve opening Δh are all important parameters. max The selection of valve pressure regulating areas S1 and S2 must meet the above relationship requirements to ensure that the bleed air flow area adjustment law of the passive clearance control system meets the design requirements.

[0047] The passive clearance control system provided in this application can dynamically adjust the bleed air volume by adding a bleed air flow area adjustment mechanism, thereby controlling the thermal deformation of the turbine casing according to the changes in engine operating conditions, so that the rotor blade tip clearance always meets the design requirements. Moreover, the entire passive clearance control system has low manufacturing cost, small structural size changes, and can ensure the system's assembly interchangeability.

[0048] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A passive gap control system with dynamically adjustable airflow area, characterized in that, include: The air intake seat assembly (10), the air collection box (20), and the cooling air pipe (30) are provided. The air intake seat assembly (10) is installed on the air collection box (20) to introduce cooling air. The air collection box (20) is provided with multiple distribution holes, and a cooling air pipe (30) is installed on each distribution hole. The introduced cooling air is distributed through the distribution holes of the air collection box (20) and flows out from the injection holes provided on the cooling air pipe (30) to cool the turbine casing. The air intake seat assembly (10) includes a valve cylinder (11), an air intake seat cylinder (12), a valve (13), a pressure adjusting nut (14), a spring (15), and a vent pipe (16). A cooling air passage is formed between the valve cylinder (11) and the air intake seat cylinder (12). The valve (13) is installed on the valve cylinder (11) by the spring (15) and the pressure adjusting nut (14). The vent pipe (16) connects the valve cylinder (11) and the air intake seat cylinder (12) to introduce external atmosphere. By ensuring that the spring stiffness, spring precompression, maximum valve opening, and valve pressure adjustment area satisfy a predetermined relationship, the valve is guaranteed to be fully open during cruise and closed during takeoff. The predetermined relationship includes: Cruise status: K×h0≥(P' 引气 -P' 大气 )×(S1-S2) Takeoff status: K×(h0+Δh) max )≤(P” 引气 -P” 大气 )×(S1-S2) In the formula, P' 引气 P' is the bleed air pressure during cruise. 大气 The atmospheric pressure during cruise is given by S1, the pressure regulating section area is given by S2, and the rod area is given by P. 引气 The bleed air pressure at takeoff, P” 大气 The atmospheric pressure at takeoff is given by K, where K is the spring stiffness, h0 is the spring pre-compression, and Δh is the spring pre-compression. max This represents the maximum opening of the valve.

2. The passive gap control system with dynamically adjustable airflow area as described in claim 1, characterized in that, The air intake seat assembly (10) and cooling air pipe (30) are all fixed to the air collection box (20) by corner seam welding.

3. The passive gap control system with dynamically adjustable airflow area as described in claim 1, characterized in that, The upper end of the valve cylinder (11) is a spoke structure, and several air inlets (111) are formed between the spoke structures to ensure the introduction of cooling air. The valve cylinder (11) has a cylinder structure (112) at its center, and the cylinder structure (112) sinks down and extends into the air intake seat cylinder (12).

4. The passive gap control system with dynamically adjustable airflow area as described in claim 3, characterized in that, The air inlet (111) is fan-shaped and evenly arranged in the circumferential direction.

5. The passive gap control system with dynamically adjustable airflow area as described in claim 3, characterized in that, The air intake cylinder (12) includes a larger diameter installation section and a smaller diameter ventilation section (122). The installation section and the ventilation section (122) are connected by a transition section (121). The installation section is fixedly connected to the valve cylinder (11) by a connector. The installation section encloses the cylinder structure (112) to form a space for cooling air to pass through and flows out from the ventilation section (122).

6. The passive gap control system with dynamically adjustable airflow area as described in claim 5, characterized in that, The transition section (121) has a conical structure.

7. The passive gap control system with dynamically adjustable airflow area as described in claim 5, characterized in that, The valve (13) includes a rod and a sealing part (131) located at the end of the rod. The other end of the rod is provided with a threaded section for connecting with a pressure adjusting nut (14) having a pressure adjusting part (141). The rod and the spring are installed in the cylindrical structure (112) of the valve body (11). The sealing part (131) is located at the lower end of the rod and inside the air intake seat cylinder (12). The pressure adjusting part (133) is located at the upper end of the rod and inside the cylindrical structure (112) of the valve body (11). The pressure adjusting nut (14) that cooperates with the threaded section of the rod limits the spring (15) and compresses the spring (15) to a preset load.

8. The passive gap control system with dynamically adjustable airflow area as described in claim 7, characterized in that, The valve (13) has a number of pressure equalization holes (132) on its sealing part (131) to eliminate the pressure difference between the upper and lower parts of the sealing part (131).

9. The passive gap control system with dynamically adjustable airflow area as described in claim 7, characterized in that, The vent pipe (16) connects to the root of the cylindrical structure (112).

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