Structural design method and manufacturing method of an aircraft engine intermediate casing

Abstract

The present invention discloses a structural design method and a manufacturing method for an intermediate casing of an aircraft engine, which belongs to the technical field of structural design and manufacturing of aircraft engines. The structural design method includes: a. establishing a Cartesian three-dimensional rectangular coordinate system of an engine; b. outputting the stress components of the intermediate casing under various unit overloads to obtain array 1; c. multiplying array 2 by array 1 to obtain the maximum equivalent stress of the intermediate casing under all overload coefficients within the flight envelope, to obtain array 3, and determining the most severe working condition of the intermediate casing; d. calculating the stress distribution; e. extracting the external loads of n support plates from the calculation results of step (d); f. performing radial topology optimization calculations on the n support plates 3 respectively; g. obtaining a support plate structure with a higher safety factor. The structural design is completed by using a topology optimization method to ensure that a support plate structure with a higher safety factor is obtained. The advantages of machining and additive manufacturing for processing complex cavities are combined to establish a manufacturing method for the intermediate casing.

Description

Technical Field

[0001] The invention relates to a structural design method and a manufacturing method of an intermediate casing of an aero-engine, belonging to the technical field of structural design and manufacturing of aero-engines. Background Art

[0002] The intermediate casing of an aircraft engine is the most important load-bearing component. The thrust bearings and main load-bearing pins in aircraft engines are usually designed on the intermediate casing, so the intermediate casing bears all aerodynamic loads and most of the inertial loads. Therefore, the intermediate casing is required to meet the strength and stiffness requirements while reducing its weight as much as possible.

[0003] The turbofan engine's intermediate casing is connected by several radial support plates, which connect the three rotating bearing rings (inner casing, diverter ring, and outer casing) into a single unit. Therefore, the radial support plates are a critical load-bearing structure of the intermediate casing. Currently, there are two main methods for manufacturing intermediate casings: one is to use plate weldments for the support plates, machine the rotating casing, and then assemble the various parts into the intermediate casing unit by welding; the other is to use a monolithic casting method to produce the intermediate casing.

[0004] However, both of the above two methods cannot produce support plate structures with complex cavities. The radial load-bearing support plate is required to meet the strength, stiffness and weight reduction requirements at the same time, which will make its internal structure very complicated to design. How to design the radial load-bearing support plate structure and manufacture the intermediate casing at low cost and high efficiency is a technical problem that needs to be solved urgently by technical personnel in this field. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a structural design method and a manufacturing method for an intermediate casing of an aero-engine.

[0006] The present invention is achieved through the following technical solutions:

[0007] A structural design method for an intermediate casing of an aircraft engine, the intermediate casing comprising an outer casing, a diverter ring, an inner casing, and a plurality of support plates, the outer casing being provided with a main load-bearing pin hole in a radial direction, the diverter ring being coaxially arranged within the outer casing, the inner casing being coaxially arranged within the diverter ring, the plurality of support plates connecting the outer casing, the diverter ring, and the inner casing into a whole, the plurality of support plates being evenly distributed and arranged radially along the outer casing;

[0008] The structural design method of the intermediate casing of the aircraft engine comprises the following main steps:

[0009] a. Establish a three-dimensional Cartesian coordinate system for the engine. This coordinate system takes the engine axis forward as +X, the direction to the right along the course as +Y, and +Z as determined by the right-hand rule. The origin is the intersection of the centerline of the main bearing pin hole and the centerline of the intermediate casing.

[0010] b. Calculate the external loads on the intermediate casing under several unit overloads, where unit overload means the engine is subjected to a load in a single direction, and output the stress components of the intermediate casing under various unit overloads to obtain array 1.

[0011] c. Array 2 is formed using the overload coefficients of the engine flight envelope. Array 2 is multiplied by array 1 to obtain the maximum equivalent stress of the intermediate casing under all overload coefficients within the flight envelope, thereby obtaining array 3. The most severe operating condition of the intermediate casing is then determined.

[0012] d. Multiplying the unit overload of the intermediate casing by the most severe working condition of the intermediate casing in step (c) to obtain the external load of the intermediate casing under the most severe working condition, and calculate the stress distribution;

[0013] e. Extract the external loads of the n support plates from the calculation results of step (d);

[0014] f. Using the support plate external loads extracted in step (e) as input, perform radial topology optimization calculations on each of the n support plates 3;

[0015] g. Based on the safety factor of the intermediate casing, repeat steps (d) to (f) to obtain the topologically optimized support plate structure under several overload factors of array 3. Then, superimpose the above several support plate structure models and merge them to obtain a support plate structure with a higher safety factor.

[0016] In the step (b), a finite element model of the intermediate casing is first established in a finite element calculation tool, and then several unit overloads are applied to the finite element model of the intermediate casing, and the stress components of the intermediate casing under various unit overloads are calculated.

[0017] In the step (b), the external loads of the intermediate casing under six unit overloads, namely, nx, ny, nz, Ωy, Ωz, and aerodynamic load, are calculated respectively, where nx indicates that the engine is only subjected to an inertial overload in the +X direction, ny indicates that the engine is only subjected to an inertial overload in the +Y direction, nz indicates that the engine is only subjected to an inertial overload in the +Z direction, Ωy indicates that the engine is subjected to a gyroscopic torque generated by a rotor rotating at a constant speed of 1 rad / s in the +Y direction, Ωz indicates that the engine is subjected to a gyroscopic torque generated by a rotor rotating at a constant speed of 1 rad / s in the +Z direction, and the aerodynamic load indicates the aerodynamic axial force and torque borne by each component under the maximum aerodynamic operating condition of the engine.

[0018] In step (c), the operating condition when the aerodynamic load is maximum is selected as the most severe operating condition of the intermediate casing, that is, (nx, ny, nz, Ωy, Ωz, aerodynamic) = (X1, X2, X3, X4, X5, maximum).

[0019] The extraction position of the external load of the support plate in the step (e) is the intersection of the support plate and the rotating body casing, including the interface between the support plate and the outer casing, the interface between the support plate and the diverter ring, and the interface between the support plate and the inner casing; the external load of the support plate extracted in step (e) includes Fx, Fy, Fz, Mx, My, and Mz.

[0020] In step (e), the sub-model method provided by the finite element calculation tool can also be used to extract the displacement boundary. In step (f), the sub-model displacement boundary is used as input to perform radial topology optimization calculations on the n support plates respectively.

[0021] The variable area of ​​topology optimization in step (f) is all areas inside the intermediate casing except the flow path surface outside the support plate and the pipes designed for ventilation, power transmission, air ventilation, lubricating oil flow, and signal transmission functions.

[0022] A method for manufacturing an intermediate casing of an aircraft engine comprises the following main steps:

[0023] Step 1: machining the rotating parts in the intermediate casing;

[0024] Step 2: Producing the support plate using an additive manufacturing method;

[0025] Step 3: Position and weld the rotating parts and the support plate together to obtain the intermediate casing unit.

[0026] The rotating body parts in step 1 include an outer casing, a diverter ring and an inner casing.

[0027] The beneficial effects of the present invention are:

[0028] 1. A structural design method for the intermediate casing support plate was established, and the structural design was completed using topology optimization to ensure a support plate structure with a high safety factor and solve the problem of calculating the design load of the intermediate casing support plate.

[0029] 2. Rotating parts with simple structures are machined, and support plates with complex structures are processed by additive manufacturing. Combining the advantages of high efficiency and low cost of traditional machining with the advantages of additive manufacturing for processing complex cavities, a manufacturing method for intermediate casings is established, which improves the production efficiency of intermediate casings and reduces the production cost of intermediate casings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the three-dimensional structure of the intermediate casing of the present invention;

[0031] Figure 2 for Figure 1 Schematic diagram of the structure from another perspective;

[0032] Figure 3It is a schematic diagram of the main structure of the intermediate casing of the present invention;

[0033] Figure 4 for Figure 3 Cross-sectional view along AA;

[0034] Figure 5 This is a flow chart for designing the support plate structure of the intermediate casing of the present invention;

[0035] Figure 6 This is a schematic diagram of the intermediate casing load definition according to the second embodiment of the present invention;

[0036] Figure 7 This is a diagram showing the relationship between the maximum equivalent stress of the intermediate casing and the operating conditions within the flight envelope of the second embodiment of the present invention;

[0037] Figure 8 This is the displacement boundary diagram of the intermediate casing support plate model under the most severe working conditions of the second embodiment of the present invention;

[0038] Figure 9 This is a schematic diagram of the support plate structure of the intermediate casing according to the second embodiment of the present invention;

[0039] Figure 10 For the most severe working conditions Figure 9 The structural diagram of the support plate after topological optimization is shown;

[0040] Figure 11 This is a schematic diagram of the topology optimization results of the intermediate casing support plate under working condition 1 of the second embodiment of the present invention;

[0041] Figure 12 This is a schematic diagram of the topology optimization results of the intermediate casing support plate under working condition 2 of the second embodiment of the present invention;

[0042] Figure 13 This is a schematic diagram of the topology optimization results of the intermediate casing support plate under working condition 3 of the second embodiment of the present invention;

[0043] Figure 14 This is a schematic diagram of the topology optimization results of the intermediate casing support plate under working condition 4 of the second embodiment of the present invention;

[0044] Figure 15 This is a schematic diagram of the intermediate casing support plate structure after superposition of topology optimization structures for four assessment working conditions according to the second embodiment of the present invention.

[0045] In the figure: 1-outer casing, 2-diverter ring, 3-support plate, 4-inner casing. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0047] Example 1:

[0048] like Figures 1 to 5 As shown, the present invention discloses a structural design method for an intermediate casing of an aircraft engine. The intermediate casing includes an outer casing 1, a diverter ring 2, an inner casing 4, and a plurality of support plates 3. The outer casing 1 is radially machined with a main load-bearing pin hole 10. The diverter ring 2 is coaxially arranged within the outer casing 1, and the inner casing 4 is coaxially arranged within the diverter ring 2. The plurality of support plates 3 connect the outer casing 1, the diverter ring 2, and the inner casing 4 into one. The plurality of support plates 3 are evenly distributed and arranged radially along the outer casing 1. When in use, the number of engine support plates 3 is determined by the overall structural design of the engine. The outer surface of the support plates 3 is a blade-shaped structure with streamlined features. The interior of the support plates 3 is a hollow structure. The interior of the support plates 3 is designed with channels for ventilation, power transmission, air flow, lubricating oil flow, signal transmission, and other functions.

[0049] The structural design method of the intermediate casing of an aircraft engine (specifically, the structural design method of the intermediate casing middle support plate) includes the following main steps:

[0050] a. Establish a three-dimensional Cartesian coordinate system for the engine, with the engine axis forward as +X, the direction to the right along the course as +Y, and +Z determined by the right-hand rule. The origin of the coordinate system is the intersection of the center axis of the main bearing pin hole 10 and the center axis of the intermediate casing.

[0051] b. Calculate the external loads on the intermediate casing under several unit overloads, where unit overload means the engine is subjected to a load in a single direction, and output the stress components of the intermediate casing under various unit overloads to obtain array 1.

[0052] c. Array 2 is formed using the overload coefficients of the engine flight envelope. Array 2 is multiplied by array 1 to obtain the maximum equivalent stress of the intermediate casing under all overload coefficients within the flight envelope, thereby obtaining array 3. The most severe operating condition of the intermediate casing is then determined.

[0053] d. Multiplying the unit overload of the intermediate casing by the most severe working condition of the intermediate casing in step (c) to obtain the external load of the intermediate casing under the most severe working condition, and calculate the stress distribution;

[0054] e. Extract the external loads of the n support plates 3 from the calculation results of step (d);

[0055] f. Using the external loads of the support plates 3 extracted in step (e) as input, perform radial topology optimization calculations on each of the n support plates 3;

[0056] g. Based on the safety factor of the intermediate casing, repeat steps (d) to (f) to obtain the topologically optimized support plate 3 structure under several overload factors of array 3, and then superimpose the above several support plate 3 structure models to obtain a support plate 3 structure with a higher safety factor.

[0057] In the step (b), a finite element model of the intermediate casing is first established in a finite element calculation tool, and then several unit overloads are applied to the finite element model of the intermediate casing, and the stress components of the intermediate casing under various unit overloads are calculated.

[0058] In the step (b), the external loads of the intermediate casing under six unit overloads, namely, nx, ny, nz, Ωy, Ωz, and aerodynamic load, are calculated respectively, where nx indicates that the engine is only subjected to an inertial overload in the +X direction, ny indicates that the engine is only subjected to an inertial overload in the +Y direction, nz indicates that the engine is only subjected to an inertial overload in the +Z direction, Ωy indicates that the engine is subjected to a gyroscopic torque generated by a rotor rotating at a constant speed of 1 rad / s in the +Y direction, Ωz indicates that the engine is subjected to a gyroscopic torque generated by a rotor rotating at a constant speed of 1 rad / s in the +Z direction, and the aerodynamic load indicates the aerodynamic axial force and torque borne by each component under the maximum aerodynamic operating condition of the engine.

[0059] In step (c), the operating condition when the aerodynamic load is maximum is selected as the most severe operating condition of the intermediate casing, that is, (nx, ny, nz, Ωy, Ωz, aerodynamic) = (X1, X2, X3, X4, X5, maximum).

[0060] The extraction position of the external load of the support plate 3 in the step (e) is the intersection of the support plate 3 and the rotating body casing, including the interface between the support plate 3 and the outer casing 1, the interface between the support plate 3 and the diverter ring 2, and the interface between the support plate 3 and the inner casing 4; the external load of the support plate 3 extracted in step (e) includes Fx, Fy, Fz, Mx, My, and Mz.

[0061] In step (e), the sub-model method provided by the finite element calculation tool can also be used to extract the displacement boundary. In step (f), the sub-model displacement boundary is used as input to perform radial topology optimization calculations on the n support plates 3 respectively.

[0062] The variable area of ​​topology optimization in step (f) is all areas inside the intermediate casing except the flow path surface outside the support plate and the pipes designed for ventilation, power transmission, air ventilation, lubricating oil flow, and signal transmission functions.

[0063] A method for manufacturing an intermediate casing of an aircraft engine comprises the following main steps:

[0064] Step 1: Use machining (such as turning and milling) to process the rotating parts in the intermediate casing.

[0065] Step 2: Produce support plate 3 using additive manufacturing. Additive manufacturing (AM), commonly known as 3D printing, integrates computer-aided design, material processing, and molding technologies. Based on digital model files, AM utilizes software and numerical control systems to layer specialized metal materials, non-metal materials, and medical biomaterials through methods such as extrusion, sintering, melting, photocuring, and spraying to create physical objects. AM technology is currently available and will not be further elaborated here.

[0066] Step 3: Position and weld the rotating body parts and the support plate 3 together to obtain the intermediate casing unit body.

[0067] The rotating body parts in step 1 include an outer casing 1, a diverter ring 2 and an inner casing 4.

[0068] Specifically, the structure of the intermediate casing of an aircraft engine varies depending on the engine type, but the overall structure consists of an annular casing with rotating body characteristics and a number of radial support plates. Turbofan engines and turbojet engines have different numbers of annular rotating body structures depending on the number of flow channels, but are all suitable for the method provided by the present invention.

[0069] The structural design method and manufacturing method of the aircraft engine intermediate casing provided by the present invention have the following beneficial effects:

[0070] 1. A structural design method for the intermediate casing support plate 3 was established, and the structural design was completed using topology optimization to ensure a support plate structure with a high safety factor and solve the design load calculation problem of the intermediate casing support plate 3.

[0071] 2. Simple-structured rotating parts are machined, and the support plate 3 with a complex structure is processed by additive manufacturing. Combining the advantages of high efficiency and low cost of traditional machining with the advantages of additive manufacturing for processing complex cavities, a manufacturing method for the intermediate casing is established, which improves the production efficiency of the intermediate casing and reduces the production cost of the intermediate casing.

[0072] Example 2:

[0073] 1. The intermediate casing structure of a certain type of engine is as follows Figure 1 and Figure 2 As shown, the intermediate casing includes an outer casing 1, a diverter ring 2, an inner casing 4 and six support plates 3, and the main bearing pins of the engine are designed in the outer casing 1.

[0074] 2. The whole machine load calculation engineer shall provide the external load of each installation side of the intermediate casing under unit overload. The load definition is as follows: Figure 6 The external bearing loads are shown in Table 1, the loads on each mounting edge are shown in Table 2 (all loads are normalized), and the engine overload factor provided by the aircraft is shown in Table 3.

[0075] Table 1 Bearing external load (unit: N)

[0076]

[0077] Table 2 Unit load of intermediate casing (unit: N or N·m)

[0078]

[0079]

[0080] Table 3 Intermediate casing overload coefficient

[0081]

[0082]

[0083]

[0084] 3. Use the general finite element calculation tool Workbench to establish the intermediate casing finite element model and apply the loads in Tables 1 and 2. Calculate the intermediate casing stress under six unit overloads, namely nx, ny, nz, Ωy, Ωz, and pneumatic, and output the intermediate casing stress component (Vector Principal Stress) under each unit overload. Multiply the output stress component by the overload coefficient shown in Table 3 to obtain the maximum equivalent stress of the intermediate casing under each overload coefficient, as shown in Figure 3. Figure 7 The loads on each mounting side of the intermediate casing under the most severe working conditions are shown in Table 4 (normalized). The first four working conditions with the maximum equivalent stress are determined as the assessment conditions for the intermediate casing.

[0085] Table 4 External load on the mounting side of the intermediate casing under the most severe working conditions (unit: N or N·m)

[0086]

[0087] 4. Use the general finite element calculation tool Workbench to calculate the stress of the intermediate casing under load in step 3 and obtain the displacement boundaries of the 6 support plates 3, as shown in Figure 8 The external load of each support plate 3 can also be output in the format shown in Table 5. The support plates 3 are numbered in the direction of heading, with support plate 3 No. 1 being directly above, and the numbers increase clockwise.

[0088] Table 5 Loads on each support plate of the intermediate casing under the most severe working conditions (unit: N or N·m)

[0089]

[0090]

[0091] 5. Use the topology optimization module TopologyOptimization in the general finite element calculation tool Workbench platform to perform topology optimization of the support plate 3. The outer surface of the support plate 3 is the non-optimized area, and the interior of the support plate 3 is the optimized area. The results are as follows: Figure 9 and Figure 10 shown.

[0092] 6. Repeat steps 4 and 5 to obtain the topological optimization structure of the intermediate casing support plate 3 under four test conditions, as shown in the following example: Figures 11 to 14 The main purpose of superimposing multiple working condition topological structures is to increase structural safety. The structure after superposition (structural intersection) is as follows: Figure 15 shown.

[0093] 7. The support plate 3 is produced by an additive manufacturing method, and the diverter ring 2, the outer casing 1 and the inner casing 4 are processed by a traditional machining method. Then, the support plate 3, the diverter ring 2, the inner casing 4 and the outer casing 1 are welded by a welding method to obtain an intermediate casing.

Claims

1. A structural design method for an intermediate casing of an aircraft engine, characterized by: The intermediate casing comprises an outer casing (1), a diverter ring (2), an inner casing (4) and a plurality of support plates (3); a main load-bearing pin hole (10) is provided radially on the outer casing (1); the diverter ring (2) is coaxially arranged in the outer casing (1); the inner casing (4) is coaxially arranged in the diverter ring (2); a plurality of support plates (3) connect the outer casing (1), the diverter ring (2) and the inner casing (4) into one body; the plurality of support plates (3) are evenly distributed, and the support plates (3) are arranged radially along the outer casing (1); The structural design method of the intermediate casing of the aircraft engine comprises the following steps: a. Establish a Cartesian three-dimensional rectangular coordinate system for the engine, with the engine axis forward as +X, the rightward direction along the course as +Y, and +Z determined by the right-hand rule, and the intersection of the center axis of the main bearing pin hole (10) and the center axis of the intermediate casing as the origin; b. Calculate the external loads on the intermediate casing under several unit overloads, where unit overload means the engine is subjected to a load in a single direction, and output the stress components of the intermediate casing under various unit overloads to obtain array 1. c. Array 2 is formed using the overload coefficients of the engine flight envelope. Array 2 is multiplied by array 1 to obtain the maximum equivalent stress of the intermediate casing under all overload coefficients within the flight envelope, thereby obtaining array 3. The most severe operating condition of the intermediate casing is then determined. d. Multiply the unit overload of the intermediate casing by the most severe working condition of the intermediate casing in step (c) to obtain the external load of the intermediate casing under the most severe working condition, and calculate the stress distribution; e. extracting the external loads of the n support plates (3) from the calculation results of step (d); f. Using the external load of the support plate (3) extracted in step (e) as input, perform radial topology optimization calculations on each of the n support plates (3); g. Based on the safety factor of the intermediate casing, repeat steps (d) to (f) to obtain the topologically optimized support plate (3) structure under several overload factors of array 3, and then superimpose the above several support plate (3) structure models to obtain a support plate (3) structure with a higher safety factor; In step (b), the external loads of the intermediate casing under six unit overloads, namely, nx, ny, nz, Ωy, Ωz, and aerodynamic load, are calculated respectively, where nx indicates that the engine is subjected to an inertial overload in the +X direction only, ny indicates that the engine is subjected to an inertial overload in the +Y direction only, nz indicates that the engine is subjected to an inertial overload in the +Z direction only, Ωy indicates that the engine is subjected to a gyroscopic torque generated by a rotor rotating at a constant speed of 1 rad / s in the +Y direction, and Ωz indicates that the engine is subjected to a gyroscopic torque generated by a rotor rotating at a constant speed of 1 rad / s in the +Z direction. The aerodynamic load indicates the aerodynamic axial force and torque borne by each component under the maximum aerodynamic operating condition of the engine.

2. The structural design method for an aircraft engine intermediate casing according to claim 1, wherein: In the step (b), a finite element model of the intermediate casing is first established in a finite element calculation tool, and then several unit overloads are applied to the finite element model of the intermediate casing, and the stress components of the intermediate casing under various unit overloads are calculated.

3. The structural design method for an aircraft engine intermediate casing according to claim 1, wherein: In step (c), the operating condition when the aerodynamic load is maximum is selected as the most severe operating condition of the intermediate casing, that is, (nx, ny, nz, Ωy, Ωz, aerodynamic) = (X1, X2, X3, X4, X5, maximum).

4. The structural design method for an aircraft engine intermediate casing according to claim 1, wherein: The extraction position of the external load of the support plate (3) in the step (e) is the intersection of the support plate (3) and the rotary body casing, including the interface between the support plate (3) and the outer casing (1), the interface between the support plate (3) and the diverter ring (2), and the interface between the support plate (3) and the inner casing (4); the external load of the support plate (3) extracted in the step (e) includes Fx, Fy, Fz, Mx, My, and Mz.

5. The structural design method for an aircraft engine intermediate casing according to claim 1, wherein: In step (e), the displacement boundary is extracted using the sub-model method provided by the finite element calculation tool. In step (f), the sub-model displacement boundary is used as input to perform radial topology optimization calculations on the n support plates (3).

6. The structural design method for an aircraft engine intermediate casing according to claim 1, wherein: The variable area of ​​topology optimization in step (f) is all areas inside the intermediate casing except the flow path surface outside the support plate and the pipes designed for ventilation, power transmission, air ventilation, lubricating oil flow, and signal transmission functions.

7. A method for manufacturing an aircraft engine intermediate casing based on the design method according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: machining the rotating parts in the intermediate casing; Step 2: Producing the support plate (3) using an additive manufacturing method; Step 3: Position and weld the rotating body parts and the support plate (3) together to obtain the intermediate casing unit body.

8. The method for manufacturing an aircraft engine intermediate casing according to claim 7, wherein: The rotating body parts in step one include an outer casing (1), a diverter ring (2) and an inner casing (4).

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