A rotor internal cooling structure, method and aircraft engine inner rotor

Abstract

The present invention discloses a rotor internal cooling structure, method and aircraft engine inner rotor, wherein the rotor internal cooling structure comprises a shaft barrel assembly positioned inside a center tie rod; an annular airflow channel is formed between the outer wall of the shaft barrel assembly and the inner wall of the center tie rod; the front end of the airflow channel is connected to a cooling medium supply system, and the rear end of the airflow channel is connected to the inside of a small tie rod. The present invention supplies cooling medium to the airflow channel, cools the inside of the center tie rod through the cooling medium, reduces the temperature of the center tie rod, and then changes the average temperature difference of the inner rotor, which can effectively reduce the installation preload of the aircraft engine rotor blade disk with end tooth centering or stopper centering, meet the strength design requirements, and effectively avoid the phenomenon of the rotor blade disk being disengaged during high-speed rotation.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a rotor internal cooling structure, method and an inner rotor of an aero-engine, which are applied to an aero-engine or a test piece having a tubular central tie rod structure inside the rotor. Background Art

[0002] The rotors of aircraft engines, especially small and medium-sized engines, need to rotate at high speeds during operation. In order to ensure the high reliability of the blades in each level of the rotor, stable centering and torque transmission between the blades at each level are required. The schematic diagram of the conventional rotor structure is shown in the figure. Figure 1 As shown. Currently, the arc end teeth or stopper are often used to ensure that the center line of the rotor blade disk is in the same axial direction. However, the rotor blade disk will generate relaxation force due to temperature and centrifugal force during high-speed rotation, which may cause the rotor blade disk to disengage. Therefore, it is usually necessary to apply a sufficiently large preload force through the center tie rod during the assembly process to prevent the rotor from axially disengaging.

[0003] With the continuous development of engine technology, the operating temperature of rotor blade disks is getting higher and higher, and the relaxation force generated during rotation is getting larger and larger, some of which have exceeded the strength limit of the preload force applied by the center tie rod. Therefore, reducing the preload force required for the center tie rod assembly has become an urgent problem to be solved. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the existing aircraft engine rotor blade disk is disengaged due to relaxation force during high-speed rotation, thereby providing a rotor internal cooling structure, method and aircraft engine inner rotor.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A rotor internal cooling structure includes a shaft barrel assembly positioned inside a center tie rod;

[0007] An annular airflow channel is formed between the outer wall of the shaft cylinder assembly and the inner wall of the central pull rod;

[0008] The front end of the airflow channel is connected to the cooling medium supply system, and the rear end of the airflow channel is connected to the inside of the small pull rod; the cooling medium supply system supplies cooling medium to the airflow channel to cool the center pull rod and reduce the preload required for assembling the center pull rod.

[0009] To further optimize the technical solution, the shaft-cylinder assembly includes a shaft-cylinder front joint, a shaft-cylinder and a shaft-cylinder rear joint which are sequentially connected thereto, the shaft-cylinder front joint is assembled to the inside of the front journal, and the shaft-cylinder rear joint is assembled to the inside of the center pull rod.

[0010] To further optimize the technical solution, the front joint of the shaft cylinder is clearance-matched with the inner wall of the front journal; the rear joint of the shaft cylinder is clearance-matched with the inner wall of the center pull rod and is positioned to prevent rotation through a positioning assembly.

[0011] To further optimize the technical solution, the air flow channel is connected to the cooling medium supply system via an air duct; at least one air duct is provided and is opened on the side wall of the front journal.

[0012] To further optimize the technical solution, the front joint of the shaft cylinder is a tapered cylinder joint; the side wall of the front joint of the shaft cylinder is a concave curved surface, an air intake channel is formed between the concave curved surface and the inner wall of the front journal, and the air intake channel is connected to the airflow channel.

[0013] To further optimize the technical solution, one or more shaft cylinder support rings are sleeved on the side wall of the shaft cylinder to prevent the shaft cylinder from vibrating;

[0014] A plurality of axial air guide grooves are provided on the shaft cylinder support ring.

[0015] To further optimize the technical solution, a plurality of ventilation holes are opened circumferentially on the outer side wall of the rear section of the shaft cylinder.

[0016] Further optimizing the technical solution, the air flow channel is 2 to 10 mm.

[0017] A method for cooling the inside of a rotor, the method being performed based on the above-mentioned rotor internal cooling structure, comprising the following steps:

[0018] A shaft barrel assembly is added inside the central pull rod, and a ring-shaped air flow channel is formed between the central pull rod and the shaft barrel assembly;

[0019] The cooling medium enters the air flow channel from the front journal to cool the center tie rod, change the average temperature difference of the center tie rod, and reduce the preload required for center tie rod assembly;

[0020] Then the cooling medium flows out from the side of the small tie rod.

[0021] To further optimize the technical solution, the method controls the size of the airflow channel by controlling the radial gap between the central pull rod and the shaft cylinder assembly, so as to achieve the effect of controlling the airflow speed.

[0022] An internal rotor of an aero-engine comprises a front journal, a center tie rod and a small tie rod which are hollow inside and sequentially connected from front to back; a plugging cover is arranged at the front end of the front journal; and the rotor internal cooling structure is arranged inside the center tie rod.

[0023] The technical solution of the present invention has the following advantages:

[0024] 1. The present invention provides a rotor internal cooling structure, in which a cooling medium supply system supplies cooling medium to the air flow channel, and the cooling medium is used to cool the inside of the center tie rod, thereby reducing the temperature of the center tie rod, thereby changing the average temperature difference of the inner rotor, and can effectively reduce the installation preload force of the aircraft engine rotor blade disk with end tooth centering or stopper centering, meet the strength design requirements, and effectively avoid the phenomenon of the rotor blade disk being disengaged during high-speed rotation.

[0025] 2. The rotor internal cooling structure provided by the present invention does not change the material of the blade disk and does not affect the normal use of the blade disk.

[0026] 3. The present invention provides a rotor internal cooling structure, in which one or more shaft barrel support rings are sleeved on the side wall of the shaft barrel, and the shaft barrel is effectively supported inside the center pull rod by the shaft barrel support rings. The shaft barrel support rings are in contact with the inner wall of the center pull rod to radially limit the shaft barrel, thereby solving the problem of large vibration caused by the long span of the shaft barrel during operation.

[0027] 4. The present invention provides a method for cooling the inside of a rotor, which adjusts the cross-sectional area of ​​the airflow channel by controlling the radial gap between the central pull rod and the shaft cylinder assembly to achieve the effect of controlling the airflow velocity and meet the needs of different cooling effects.

[0028] 5. In an aircraft engine inner rotor provided by the present invention, a plugging cover is provided at the front end of the front journal to effectively prevent the cooling airflow from leaking from the front end of the rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a schematic diagram of the structure of a conventional engine rotor;

[0031] Figure 2 A schematic structural diagram of a rotor internal cooling structure provided by the present invention;

[0032] Figure 3 An exploded schematic diagram of a rotor internal cooling structure provided by the present invention;

[0033] Figure 4 It is a structural schematic diagram of the shaft cylinder support ring of the present invention;

[0034] Figure 5 is a cross-sectional view of the shaft cylinder support ring of the present invention;

[0035] Figure 6 A schematic diagram of the temperature field of a central pull rod of a rotor internal cooling structure provided by the present invention.

[0036] Reference numerals:

[0037] 1. Front bearing; 2. Front journal; 3. Blade disk; 4. Center tie rod; 5. Centrifugal impeller; 6. Small tie rod; 7. Balance disk; 8. Rear bearing; 9. Plug cover; 10. Front joint of shaft cylinder; 11. Shaft cylinder; 12. Shaft cylinder support ring; 121. Axial air groove; 13. Shaft cylinder stop pin; 14. Shaft cylinder rear joint; A, B, C, D. Assembly surface; M. Air hole; N. Vent hole; R. Rounded radius. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] The relaxation force during the operation of the rotor blade disk is mainly composed of temperature and centrifugal force, among which temperature plays a major role. The temperature relaxation force is determined by the thermal expansion incompatibility ΔL of the inner rotor (center tie rod 4) and the outer rotor (first-stage blade disk, second-, third- and fourth-stage blade disks, centrifugal impeller 5). ΔL can be simplified to:

[0043] ΔL=L×a×ΔT

[0044] Where: a is the linear expansion coefficient of the material, L is the length of the inner rotor and the outer rotor, and ΔT is the average temperature difference between the inner rotor and the outer rotor.

[0045] Therefore, the temperature relaxation force is mainly determined by the average temperature difference between the inner rotor (center tie rod) and the outer rotor (blade disk) and the linear expansion coefficient of the material.

[0046] At present, the common practice is to replace the materials of the blade disk 3 and the center tie rod, replacing the blade disk 3 with a high expansion coefficient material and the center tie rod with a low expansion coefficient material, so as to reduce the thermal elongation incompatibility and thus reduce the preload required for assembly. However, this practice has the following defects:

[0047] 1) Generally, high expansion coefficient materials (such as high temperature alloys, etc.) have low specific strength. When used in blade disks, there is a risk of insufficient disk reserves, which makes it difficult to meet the life requirements;

[0048] 2) Generally, low expansion coefficient materials (such as titanium alloys, etc.) have high specific strength, but low operating temperatures, which makes it difficult to meet the requirements of the increasingly high operating temperature of the center tie rod;

[0049] 3) Changing the material has limited effect on improving the relaxation force and cannot fundamentally change the problem.

[0050] Example 1

[0051] Another effective way to reduce the preload of aircraft engine rotors is to change the average temperature difference between the inner and outer rotors. The average temperature of the outer rotor is determined by the design, and the inner rotor is mainly composed of a center tie rod.

[0052] like Figures 2 to 6 As shown, this embodiment discloses a rotor internal cooling structure, including a shaft cylinder assembly, and the shaft cylinder assembly is positioned inside the center tie rod 4.

[0053] An annular airflow channel is formed between the outer wall of the shaft cylinder assembly and the inner wall of the central pull rod 4, allowing a cooling medium to flow therein, wherein the cooling medium may be a cooling airflow or other medium. The front end of the airflow channel is connected to the cooling medium supply system, and the rear end of the airflow channel is connected to the inside of the small pull rod 6.

[0054] The above-mentioned rotor internal cooling structure is a method of changing the average temperature difference of the inner rotor. The cooling medium supply system supplies cooling medium to the air flow channel, and the cooling medium is used to cool the inside of the center pull rod 4, thereby reducing the temperature of the center pull rod 4, and then changing the average temperature difference of the inner rotor. It can effectively reduce the preload force required for assembly, meet the strength design requirements, and effectively avoid the phenomenon of rotor blade disc disengagement during high-speed rotation.

[0055] The shaft barrel assembly is installed in the center tie rod 4. The shaft barrel assembly includes a shaft barrel front joint 10, a shaft barrel 11 and a shaft barrel rear joint 14 which are connected in sequence. The shaft barrel front joint 10, the shaft barrel 11 and the shaft barrel rear joint 14 are welded / adhesively connected from front to back. When the shaft barrel assembly is installed, it is necessary to ensure that Figure 2 The runout of the assembly surfaces A, B, C and D with the front journal 2 and the center tie rod 4 is shown.

[0056] The shaft barrel front joint 10 is assembled to the inside of the front journal 2, the shaft barrel rear joint 14 is assembled to the inside of the center tie rod 4, and the shaft barrel 11 is located inside the center tie rod 4. More specifically, an air flow channel is formed between the outer wall of the shaft barrel 11 and the inner wall of the center tie rod 4 of the present invention.

[0057] The clearance between the shaft cylinder front joint 10 and the inner wall of the front journal 2 provides a certain thermal expansion space for the shaft cylinder front joint 10, ensuring that the shaft cylinder front joint 10 will not be deformed due to extrusion during thermal expansion. The shaft cylinder front joint 10 can move under the preload of the thread, and then close to the front journal 2.

[0058] The shaft cylinder rear joint 14 is clearance-matched with the inner wall of the center pull rod 4 to ensure that the shaft cylinder rear joint 14 will not be deformed due to extrusion when it is thermally stretched.

[0059] The shaft cylinder rear joint 14 and the inner wall of the center pull rod 4 are positioned and prevented from rotating by a positioning assembly. The positioning assembly includes shaft cylinder stop pins 13, which are arranged at three locations along the circumference to realize the positioning of the shaft cylinder rear joint 14 and prevent the shaft cylinder rear joint 14 from rotating.

[0060] The air flow channel is connected to the cooling medium supply system through an air intake hole. The air intake hole M is provided on the side wall of the front journal 2. The air intake holes M are evenly distributed at 2 to 8 locations on the front journal circumferentially, and have a diameter of 2 to 8 mm.

[0061] The shaft cylinder front joint 10 is a conical cylinder joint. The side wall of the shaft cylinder front joint 10 is a concave curved surface, and an air intake channel is formed between the concave curved surface and the inner wall of the front journal 2, and the air intake channel is connected to the air flow channel. In this embodiment, an air intake hole and an air intake channel are provided so that the air intake position of the cooling medium can be located on the front journal 2. The cooling medium can enter the air intake channel through the air intake hole, and then enter the air flow channel.

[0062] In order to prevent the problem of large vibration caused by the long span of the shaft cylinder 11 during operation, one or more shaft cylinder support rings 12 are sleeved on the side wall of the shaft cylinder 11. The shaft cylinder 11 is effectively supported inside the center pull rod 4 through the shaft cylinder support rings 12. The shaft cylinder support rings 12 are in contact with the inner wall of the center pull rod 4 to radially limit the shaft cylinder 11.

[0063] The outer diameter φ1 of the shaft cylinder support ring 12 is matched with the center rod 4 in the shaft cylinder assembly to ensure a clearance of 0.02 to 0.1 with the inner diameter of the center rod; the inner diameter φ2 of the shaft cylinder support ring 12 is matched with the shaft cylinder 11 to ensure a clearance of 0.02 to 0.1 with the shaft cylinder. The outer diameter surface is rounded, and the radius R of the rounding is 2 to 8 mm.

[0064] A plurality of axial air guide grooves 121 are provided on the shaft cylinder support ring 12, so that the cooling medium can pass through the axial air guide grooves 121 on the shaft cylinder support ring 12, thereby ensuring the normal transmission of the cooling medium in the air flow channel. The axial air guide grooves are evenly distributed at 2 to 8 locations, the width of the air guide grooves is 2 to 10 mm, and the depth of the air guide grooves is not greater than 1 / 2 of the thickness of the shaft cylinder support ring.

[0065] A plurality of vent holes N are provided circumferentially on the outer wall of the rear section of the shaft cylinder 11, and the gas in the air flow channel enters the shaft cylinder 11 through the vent holes, then enters the small tie rod 6, and finally is discharged through the small tie rod 6. There are 2 to 15 vent holes evenly distributed circumferentially on the side wall of the shaft cylinder 11, with a total of 1 to 5 rows, and the diameter is 2 to 8 mm.

[0066] The air flow channel L between the central rod 4 and the shaft cylinder 11 is the difference between the inner radius R1 of the central rod 4 and the outer radius R2 of the shaft cylinder 11, L=R1-R2, and the value of L is 2-10 mm.

[0067] Example 2

[0068] An internal rotor of an aircraft engine comprises a front journal 2, a central tie rod 4, a small tie rod 6 and the rotor internal cooling structure of embodiment 1.

[0069] The front journal 2, the center tie rod 4 and the small tie rod 6 are hollow inside and connected in sequence from front to back. The front journal 2 is provided with a front bearing 1 on its periphery, the small tie rod 6 is provided with a balancing disc 7 on its periphery, and the balancing disc 7 is provided with a rear bearing 8 on its periphery.

[0070] A rotor internal cooling structure is arranged inside the central tie rod 4 , and the center line of the shaft cylinder of the rotor internal cooling structure coincides with the center line of the central tie rod 4 .

[0071] Since the front end of the shaft cylinder assembly in this embodiment is open, in order to prevent the cooling airflow from leaking from the front end of the rotor, a plug cover 9 is provided at the front end of the front journal 2 in this embodiment.

[0072] Example 3

[0073] A method for cooling the inside of a rotor comprises the following steps:

[0074] A shaft cylinder assembly is added inside the central pull rod, and a ring-shaped air flow channel (i.e., a ring cavity structure) is formed between the central pull rod and the shaft cylinder assembly, through which a cooling medium can flow.

[0075] The cooling medium introduced from the stator is introduced through the air inlet hole M at the front journal 2 (see Figure 2 ) enters the rotor, the airflow passes through the shaft cylinder front joint 10 into the airflow channel, and then passes through the axial air inlet groove 121 on the shaft cylinder support ring 12 (see Figure 4 ), the center tie rod 4 is cooled, the average temperature difference of the center tie rod 4 is changed, and the preload force required for assembling the center tie rod 4 is reduced. That is, the center tie rod 4 is assembled with a smaller preload force, which can ensure the normal operation of the rotor and prevent the rotor from being disengaged during rotation.

[0076] Then the cooling medium flows into the small tie rod 6 through the vent hole N at the rear section of the shaft cylinder 11 .

[0077] The cooling medium passing through the central tie rod 4 flows out from the side of the small tie rod 6 .

[0078] The method of the present invention controls the size of the airflow channel by controlling the radial gap between the central tie rod and the shaft cylinder assembly to achieve the effect of controlling the airflow velocity and meet the needs of different cooling effects. The cross-sectional area of ​​the cooling airflow channel inside the central tie rod 4 is reduced through the shaft cylinder front joint 10, the shaft cylinder 11, and the shaft cylinder support ring 12. Under the same air bleed state, the airflow velocity is increased, thereby improving the heat exchange efficiency of the cooling airflow.

[0079] The present invention has been subjected to numerical simulation analysis, and the results are shown in Table 1 and Figure 6 , indicating that the temperature of the center tie rod can be greatly reduced, thereby achieving the purpose of greatly reducing the preload force required for center tie rod assembly.

[0080] Table 1 Cooling effect and relaxation force of center tie rod

[0081]

[0082] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A rotor internal cooling structure, characterized in that: It includes a shaft barrel assembly positioned inside the central pull rod (4); An annular air flow channel is formed between the outer wall of the shaft cylinder assembly and the inner wall of the central pull rod (4); The front end of the airflow channel is connected to a cooling medium supply system, and the rear end of the airflow channel is connected to the inside of the small tie rod (6); the cooling medium supply system supplies cooling medium to the airflow channel to cool the central tie rod (4) and reduce the preload required for assembling the central tie rod (4); The shaft cylinder assembly comprises a shaft cylinder front joint (10), a shaft cylinder (11) and a shaft cylinder rear joint (14) which are sequentially connected to each other, the shaft cylinder front joint (10) is assembled into the interior of the front journal (2), and the shaft cylinder rear joint (14) is assembled into the interior of the center tie rod (4); One or more shaft cylinder support rings (12) are sleeved on the side wall of the shaft cylinder (11) to prevent the shaft cylinder (11) from vibrating; The shaft cylinder support ring (12) is provided with a plurality of axial air guide grooves (121).

2. A rotor internal cooling structure according to claim 1, characterized in that: The shaft cylinder front joint (10) is clearance-matched with the inner wall of the front journal (2); the shaft cylinder rear joint (14) is clearance-matched with the inner wall of the center pull rod (4) and is positioned to prevent rotation through a positioning assembly.

3. A rotor internal cooling structure according to claim 1, characterized in that: The air flow channel is connected to the cooling medium supply system via an air inlet hole; at least one air inlet hole is provided and is opened on the side wall of the front journal (2).

4. A rotor internal cooling structure according to claim 3, characterized in that: The shaft cylinder front joint (10) is a conical cylinder joint; the side wall of the shaft cylinder front joint (10) is a concave curved surface, an air intake passage is formed between the concave curved surface and the inner wall of the front journal (2), and the air intake passage is connected to the air flow passage.

5. The rotor internal cooling structure according to claim 1, characterized in that: A plurality of ventilation holes are circumferentially formed on the outer side wall of the rear section of the shaft cylinder (11).

6. A rotor internal cooling structure according to claim 1, characterized in that: The air flow channel is 2 to 10 mm.

7. A method for cooling the inside of a rotor, characterized in that: The method is carried out based on the rotor internal cooling structure according to any one of claims 1 to 6, and comprises the following steps: A shaft barrel assembly is added inside the central pull rod, and a ring-shaped air flow channel is formed between the central pull rod and the shaft barrel assembly; The cooling medium enters the air flow channel from the front journal (2) to cool the center tie rod (4), thereby changing the average temperature difference of the center tie rod (4) and reducing the preload force required for assembling the center tie rod (4); The cooling medium then flows out from one side of the small tie rod (6).

8. A method for cooling the inside of a rotor according to claim 7, characterized in that: The method controls the size of the airflow channel by controlling the radial gap between the central pull rod and the shaft cylinder assembly, so as to achieve the effect of controlling the airflow speed.

9. An inner rotor of an aircraft engine, characterized in that: It comprises a front journal (2) which is hollow inside and connected in sequence from front to back, a center tie rod (4) and a small tie rod (6); a plug cover (9) is provided at the front end of the front journal (2); and the rotor internal cooling structure according to any one of claims 1 to 6 is provided inside the center tie rod (4).

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