An aero-engine and a wheel disc mortise unloading method thereof

Abstract

The application provides an aero-engine wheel disc mortise unloading method, which comprises the following steps: determining stress concentration positions of a mortise of an aero-engine wheel disc, wherein the stress concentration positions comprise a rim lug throat radial stress concentration position and two end circumferential stress concentration positions of a mortise bottom; extending downward at a circumferential middle position of the mortise bottom to form a lower groove bottom, so that the circumferential concentrated stress at the two ends of the mortise bottom is transferred to the lower groove bottom at the circumferential middle position of the mortise, and two circular arc transitions are used to connect the rim lug throat radial stress concentration position and the lower groove bottom of the mortise. The aero-engine wheel disc mortise unloading method provided by the application can avoid the superposition of radial stress and circumferential stress of the mortise by redesigning the geometric structure of the mortise, effectively reduce the local combined stress of the mortise, improve the low-cycle fatigue life of the wheel disc, and improve the design efficiency of the mortise without affecting the strength of the blade tenon.

Description

Technical Field

[0001] This application belongs to the field of aero-engine technology, and specifically relates to an aero-engine and its wheel disk tenon groove unloading method. Background Technology

[0002] like Figure 1 As shown, the blade 1 and the disk 2 of the compressor rotor of the aero-engine are usually connected by a dovetail tenon 11 and a tenon 21. The processing method of the tenon 21 is: to draw out the axial (or at a certain angle with the axial) dovetail tenon on the rim of the disk with a broach.

[0003] like Figure 2 As shown, when designing the mortise and tenon 21, the geometric structure of the mortise and tenon 21 is usually designed in conjunction with the assembly relationship of the blade 1. The dimensions of the mortise and tenon 21 mainly focus on the reasonable distribution of the width B1 of the blade tenon throat and the width B2 of the wheel flange protrusion throat, so that the load-bearing capacity of the tenon-mortise and tenon connection structure meets the design requirements of the blade 1 and the wheel disc 2, and ensures that the tenon 11 and the wheel flange protrusion do not undergo tensile fracture failure under the engine working load.

[0004] In existing tenon structure designs, the average stress of critical sections is reduced by adjusting the ratio of the blade tenon throat width B1 to the rim protrusion throat width B2. However, this method is not effective for designing local stress in the wheel disc's tenon groove. High local stress in the tenon groove may affect the wheel disc's service life, and the wheel disc, as a critical component in the engine, will affect the engine's operational safety due to fracture. Furthermore, due to the circumferential space limitation of the rim, increasing the rim protrusion throat width B2 to improve the tenon groove strength will lead to a decrease in the blade tenon throat width B1, which is detrimental to the strength of blade 1.

[0005] Therefore, a method is needed to effectively reduce the local stress in the wheel disc tenon without affecting the strength of the blade tenon. Summary of the Invention

[0006] The purpose of this application is to provide a method for unloading the tenon groove of an aircraft engine wheel to solve or alleviate at least one of the problems in the prior art.

[0007] The technical solution of this application is: a method for unloading the tenon groove of an aero-engine wheel disc, the method comprising:

[0008] The stress concentration points of the tenon groove of the aircraft engine wheel disk are identified, including the radial stress concentration point at the throat of the wheel flange protrusion and the circumferential stress concentration points at both ends of the bottom of the tenon groove;

[0009] The groove extends downwards from the circumferential center of the bottom of the tenon to form a lower groove bottom, which transfers the circumferential stress concentrated at both ends of the bottom of the tenon to the lower groove bottom in the circumferential center of the tenon. The radial stress concentration part of the throat of the wheel flange protrusion is connected to the lower groove bottom of the tenon through two arc transitions.

[0010] Furthermore, the lower bottom of the tenon groove is a straight section.

[0011] Furthermore, the method also includes:

[0012] After determining the geometry of the tenon, the key dimensions for unloading the tenon are determined based on the stress distribution characteristics of the tenon.

[0013] Using the key dimensions as design variables, the required local stress level of the tenon groove is obtained by adjusting the size of the key dimensions, thereby obtaining the geometric dimensions of the tenon groove.

[0014] Furthermore, the key dimensions include:

[0015] The mortise throat width and the mortise rim protrusion throat width are matched to the tenon throat width and the mortise rim protrusion throat width.

[0016] The lengths of the lower and upper circular arcs of the radial stress concentration region, and the straight sections of the radial stress concentration region, which affect the level of radial local stress.

[0017] The factors affecting the circumferential local stress level include the arc at the bottom of the groove, the height of the groove bottom, and the length of the straight section of the groove bottom.

[0018] Furthermore, the process for determining the width of the tenon throat within the mortise and the width of the rim protrusion throat within the mortise is as follows:

[0019] After determining the tenon throat width and the wheel rim protrusion throat width according to the existing design method, the values ​​of the tenon throat width and the wheel rim protrusion throat width in the mortise that match the tenon throat width and the wheel rim protrusion throat width are obtained.

[0020] Through finite element simulation analysis, the design values ​​of the tenon throat width in the mortise and the wheel rim protrusion throat width in the mortise are made to be slightly higher than the average tensile stress value of the tenon throat caused by the centrifugal force of the blade. Thus, the tenon throat width in the mortise and the wheel rim protrusion throat width in the mortise are obtained.

[0021] Furthermore, the process for determining the lower circular arc of the radial stress concentration region, the upper circular arc of the radial stress concentration region, and the length of the straight segment of the radial stress concentration region is as follows:

[0022] Through finite element simulation analysis, the design values ​​of the lower arc, the upper arc, and the straight section length of the radial stress concentration region are determined to meet the engine life design requirements for the local radial stress level. This results in the determination of the lower arc, the upper arc, and the straight section length of the radial stress concentration region.

[0023] Furthermore, the process for determining the arc at the bottom of the groove, the thickness of the groove bottom, and the length of the straight section of the groove bottom is as follows:

[0024] Through finite element simulation analysis, the design values ​​of the upper arc of the bottom of the groove, the thickness of the bottom of the groove, and the length of the straight section of the bottom of the groove are made so that the local circumferential stress level meets the engine life design requirements, thereby obtaining the upper arc of the bottom of the groove, the thickness of the bottom of the groove, and the length of the straight section of the bottom of the groove.

[0025] In addition, this application also provides an aero-engine, which includes rotor blades and a disk for mounting the rotor blades. The disk is provided with a tenon, which is obtained by the aero-engine disk tenon unloading method described above.

[0026] The engine wheel disc tenon unloading method provided in this application redesigns the geometry of the tenon, avoiding the superposition of radial and circumferential stresses, effectively reducing the local combined stress in the tenon. By identifying and adjusting key dimensions, stress concentration in the tenon is reduced, thereby lowering the local stress level and improving the low-cycle fatigue life of the wheel disc, without affecting the strength of the blade tenon. This method improves the design efficiency of the tenon and has excellent engineering application results. Attached Figure Description

[0027] 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.

[0028] Figure 1 This is a schematic diagram of a dovetail tenon-mortise connection structure in the prior art.

[0029] Figure 2 This is a schematic diagram of the throat width of the tenon and the rim protrusion in the prior art.

[0030] Figure 3 This is a schematic diagram of the force state of the wheel rim in this application.

[0031] Figure 4 This is a schematic diagram of the stress state of the wheel rim in this application.

[0032] Figure 5 This is a schematic diagram of the stress concentration area in the wheel groove of this application.

[0033] Figure 6This is a schematic diagram of the geometric design of the tenon and groove structure in this application.

[0034] Figure 7 This is a schematic diagram of stress concentration in the wheel groove of this application.

[0035] Figure 8 This is a schematic diagram showing the key dimensions of the tenon and mortise structure in this application.

[0036] Figure label:

[0037] 1-blade, 11-tenon

[0038] 2-Disc, 21-Tongue and Groove Detailed Implementation

[0039] 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.

[0040] The rotor disc of an aero-engine operates under the combined effects of centrifugal and thermal loads. The tenon joint exhibits geometric discontinuities and uneven stress distribution, placing it in a multiaxial stress state. For example... Figure 3 and Figure 4 As shown, the main stress state of the wheel is a high radial stress σ. r and circumferential stress σ θ The stress distribution around the tenon is uneven, with obvious stress concentration, which can easily generate local high stress and affect the service life of the wheel.

[0041] Based on the stress state of the wheel, the stress distribution characteristics of the tenon groove are analyzed. Radial stress concentration exists at the throat section of the rim protrusion, and circumferential stress concentration exists at both ends of the bottom of the tenon groove. Furthermore, the stress distribution at these concentration points is characterized by high stress distribution in a small, localized area. Because the radial and circumferential stress concentration points are close to each other, they are prone to overlap and intersection, generating excessively high stress in localized areas. This is often a significant limiting factor for the low-cycle fatigue life of the wheel.

[0042] To address the aforementioned problems, this application proposes a method for unloading the tenon groove of an aero-engine wheel disc, the method comprising:

[0043] S11. Determine the stress concentration points of the engine wheel disc tenon groove, wherein the stress concentration points are the radial stress concentration points at the throat of the wheel flange protrusion and the circumferential stress concentration points at both ends of the bottom of the tenon groove;

[0044] S12. A lower groove bottom is formed by extending downwards from the center of the circumferential direction at the bottom of the tenon groove, transferring the circumferential stress at both ends of the bottom of the tenon groove to the groove bottom in the center of the circumferential direction. The radial stress concentration area of ​​the throat of the wheel flange protrusion is connected to the lower groove bottom of the tenon groove by two rounded transitions. The newly formed groove bottom is a straight section.

[0045] like Figure 5 As shown, the stress concentration of the tenon groove 21 designed according to the existing method is concentrated in the radial stress concentration region A1 at the throat section of the wheel flange protrusion and the circumferential stress concentration region A2 at both ends of the bottom of the tenon groove. In this application, the radial stress concentration region A1 and the circumferential stress concentration region A2 are separated to avoid the overlap of the radial stress concentration region A1 and the circumferential stress concentration region A2.

[0046] Since the radial stress concentration area A1 is located at the throat section of the rim protrusion, it is difficult to adjust the radial stress concentration location given a fixed rim protrusion throat width B2. The circumferential stress concentration area is located at the lowest point of the tenon 21. Therefore, in this application, by extending the lowest point of the tenon 21 towards the circumferential center of the tenon bottom to form a lower groove bottom, the circumferential stress concentration area is shifted to the circumferential center of the groove bottom, thus avoiding the radial stress concentration area. Furthermore, the lowest point of the groove bottom of the tenon 21 is designed as a straight section with a length of L to avoid excessive circumferential stress concentration leading to high circumferential stress. The two ends of the downward-extending groove bottom of the tenon 21 transition with the radial stress concentration area A1 of the rim protrusion throat on both sides of the tenon using at least two arcs to avoid abrupt transitions that could cause new stress concentration problems. The radii of these two arcs are typically different. See the improved wheel mortise stress concentration area for reference. Figure 7 As shown.

[0047] S21. After determining the geometry of the tenon groove in the unloading design, determine the key dimensions of the unloading design based on the stress distribution characteristics of the tenon groove.

[0048] S22. Define the critical dimensions as design variables. By adjusting the size of the critical dimensions, obtain an acceptable local stress level in the tenon groove to ensure that the stress and life of the wheel disc tenon groove meet the engine life requirements.

[0049] The critical dimensions of a mortise and tenon structure are those that affect the local radial and circumferential stresses within the mortise and tenon. The process for determining these critical dimensions is as follows:

[0050] 1) After determining the tenon throat width B1 and the rim protrusion throat width B2 according to the existing design method, the values ​​of the tenon throat width L1 and the rim protrusion throat width L2 in the mortise can be obtained, which match the tenon throat width B1 and the rim protrusion throat width B2. Through finite element simulation analysis, the design values ​​of the tenon throat width L1 and the rim protrusion throat width L2 in the mortise are made so that the average tensile stress of the tenon throat caused by the centrifugal force of the blade is slightly higher than the average tensile stress value of the rim protrusion throat. Thus, the tenon throat width L1 and the rim protrusion throat width L2 in the mortise are obtained.

[0051] 2) The dimensions near the radial stress concentration region affect the radial stress level. The key dimensions affecting the local radial stress level are the lower arc R1, the upper arc R3, and the length L4 of the straight section of the radial stress concentration region. Increasing the values ​​of the lower arc R1, the upper arc R3, and the length L4 of the straight section of the radial stress concentration region can reduce radial stress concentration, thereby reducing the local radial stress level. Through finite element simulation analysis, the design values ​​of the lower arc R1, the upper arc R3, and the length L4 of the straight section of the radial stress concentration region are determined to meet the engine life design requirements for the local radial stress level. Thus, the dimensions of the lower arc R1, the upper arc R3, and the length L4 of the straight section of the radial stress concentration region are obtained.

[0052] 3) Dimensions near the circumferential stress concentration area affect the circumferential stress level. The key dimensions affecting the local circumferential stress level are determined to be the upper arc R2 of the groove bottom, the groove bottom height L3, and the length of the straight section of the groove bottom L5. Reducing the groove bottom height L3 increases the separation between the radial and circumferential stress concentration areas, thereby reducing the combined stress level. Increasing the upper arc R2 and the length of the straight section of the groove bottom L5 reduces circumferential stress concentration, thereby reducing the local circumferential stress level. Through finite element simulation analysis, the design values ​​of the upper arc R2, groove bottom height L3, and straight section length L5 are determined to ensure that the local circumferential stress level meets the engine life design requirements, thus obtaining the upper arc R2, groove bottom thickness L3, and straight section length L5.

[0053] The engine wheel disc tenon unloading method provided in this application redesigns the geometry of the tenon, avoiding the superposition of radial and circumferential stresses, effectively reducing the local combined stress in the tenon. By identifying and adjusting key dimensions, stress concentration in the tenon is reduced, thereby lowering the local stress level and improving the low-cycle fatigue life of the wheel disc, without affecting the strength of the blade tenon. This method improves the design efficiency of the tenon and has excellent engineering application results.

[0054] 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 method for unloading the tenon groove of an aero-engine wheel disc, characterized in that, The method includes: The stress concentration points of the tenon groove of the aircraft engine wheel disk are identified, including the radial stress concentration point at the throat of the wheel flange protrusion and the circumferential stress concentration points at both ends of the bottom of the tenon groove; The groove extends downwards from the circumferential center of the bottom of the tenon to form a lower groove bottom, so that the circumferential stress concentrated at both ends of the bottom of the tenon is transferred to the lower groove bottom in the circumferential center of the tenon. The lower groove bottom is a straight section, which is connected to the radial stress concentration part of the throat of the wheel flange protrusion and the lower groove bottom of the tenon through two arc transitions. After determining the geometry of the tenon groove, the key dimensions for unloading the tenon groove are determined based on the stress distribution characteristics of the tenon groove. These key dimensions include the tenon throat width B1 and the rim protrusion throat width B2 within the tenon groove, which match the tenon throat width and the rim protrusion throat width; the lower arc R1 and upper arc R3 of the radial stress concentration area affecting the radial local stress level; the straight section length L4 of the radial stress concentration area; and the upper arc R2 of the groove bottom affecting the circumferential local stress level, the groove bottom height L3, and the straight section length L5 of the groove bottom. Wherein: The process of determining the tenon throat width B1 and the wheel rim protrusion throat width B2 within the mortise is as follows: After determining the tenon throat width and wheel rim protrusion throat width according to existing design methods, the values ​​of the tenon throat width and wheel rim protrusion throat width within the mortise matching the tenon throat width and wheel rim protrusion throat width are obtained; through finite element simulation analysis, the design values ​​of the tenon throat width and wheel rim protrusion throat width within the mortise are made such that the average tensile stress of the tenon throat caused by the centrifugal force of the blade is slightly higher than the average tensile stress value of the wheel rim protrusion throat, thus obtaining the tenon throat width and wheel rim protrusion throat width within the mortise; the radial stress concentration area is connected to the lower arc R1, the radial stress concentration area is connected to the upper arc R3, and the radial stress concentration area... The process for determining the length L4 of the straight section is as follows: Through finite element simulation analysis, the design values ​​of the lower arc of the radial stress concentration region, the upper arc of the radial stress concentration region, and the length of the straight section of the radial stress concentration region are determined to meet the engine life design requirements for the local radial stress level, thereby obtaining the length of the lower arc of the radial stress concentration region, the upper arc of the radial stress concentration region, and the length of the straight section of the radial stress concentration region; The process for determining the upper arc R2 of the groove bottom, the groove bottom thickness L3, and the length of the straight section L5 of the groove bottom is as follows: Through finite element simulation analysis, the design values ​​of the upper arc of the groove bottom, the groove bottom thickness, and the length of the straight section of the groove bottom are determined to meet the engine life design requirements for the local circumferential stress level, thereby obtaining the upper arc of the groove bottom, the groove bottom thickness, and the length of the straight section of the groove bottom; Using the key dimensions as design variables, the required local stress level of the tenon groove is obtained by adjusting the size of the key dimensions, thereby obtaining the geometric dimensions of the tenon groove.

2. An aircraft engine, characterized in that, The aero-engine includes rotor blades and a disk for mounting the rotor blades. The disk is provided with a tenon, which is obtained by the aero-engine disk tenon unloading method as described in claim 1.

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