Forward design method for aero-engine casing structure

Abstract

The invention discloses a forward design method for an aero-engine casing structure, which comprises the following steps of: dispersing a casing model of a known two-dimensional structure diagram into independent'surface elements'; recombining the'surface elements' according to positions to form a complete one-sided body; applying constraint conditions of strength and rigidity, and then calculating the thickness of each'surface element 'in the surface body by using finite elements; constructing a preliminary three-dimensional model of the casing according to a thickness calculation result; and checking and finely adjusting the initial three-dimensional model of the cartridge receiver to obtain a final three-dimensional model of the cartridge receiver. According to the design method, three-dimensional design of the aero-engine thin-wall casing can be rapidly completed, the completion degree and the design efficiency of the aero-engine casing in preliminary design are greatly improved, strength and rigidity analysis can be completed in the design process, subversive repetition caused by checking after empirical design in traditional design is avoided, and the design efficiency is improved. The time cost and the labor cost are effectively saved, and the design efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft engine structure design, and in particular to a forward design method for an aircraft engine casing structure. Background Art

[0002] At present, the structural design of aircraft engines is changing from test-based design to independent positive development. The traditional structural design of aircraft engine casings usually adopts the following methods: Figure 1 The design process shown in the figure. In this process, the preliminary structural design usually relies on the experience of testing and simulation, and the design quality varies due to the experience and preferences of the designers. Usually, if the preliminary structural design meets the requirements of strength, vibration, and life, the stage structural design is completed, and there is usually room for optimization of the stage structural design; if it does not meet the requirements, it will usually enter multiple rounds of iterations, accompanied by collaborative design changes, which generally takes a long time, and sometimes even subversive repetitions; an engine has many parts, and the design completion and iteration cycle of each part will also vary greatly due to different designers, which sometimes seriously affects the progress of engine development. This design method obviously can no longer meet the requirements of autonomous forward design. Summary of the invention

[0003] The present invention provides a forward design method for an aircraft engine casing structure, so as to solve the technical problems existing in the traditional test-and-simulation design, that is, the traditional test-and-simulation design takes a long time, sometimes even leads to subversive repetitions, and seriously affects the progress of engine development.

[0004] The technical solution adopted by the present invention is as follows: A forward design method for an aircraft engine casing structure comprises the following steps: discretizing a casing model of a known two-dimensional structure diagram into independent "surface elements"; recombining each "surface element" according to position to form a complete flake body; calculating the thickness of each "surface element" in the flake body by using finite element method after applying strength and stiffness constraints; constructing a preliminary three-dimensional casing model according to the thickness calculation result; and checking and fine-tuning the preliminary three-dimensional casing model to obtain a final three-dimensional casing model.

[0005] Furthermore, the step of "discretizing the casing model of the known two-dimensional structure diagram into separate "surface elements"" specifically includes the following steps: dividing the casing model of the known two-dimensional structure diagram into several blocks according to design elements; simplifying each block to form a separate "surface element".

[0006] Furthermore, in the step of "dividing the casing model of the known two-dimensional structure diagram into several blocks according to design elements", the design elements include one or more of function, position, and shape.

[0007] Furthermore, in the step of “simplifying each block into a separate “surface element””, the “surface element” is the surface of the separated block, or the middle surface within any thickness range of the block.

[0008] Furthermore, in the step of "recombining each "surface element" according to the position to form a complete flake-hedron", the flake-hedron is compared and analyzed with the mature receiver part structure to preliminarily judge the rationality of the flake-hedron structure design and make timely adjustments.

[0009] Furthermore, when performing the step of "calculating the thickness of each "surface element" in the faceted body using finite element method after applying strength and stiffness constraints", the thickness of the "surface element" is used as a design variable, the optimal quality is set as the design goal, and the thickness of each "surface element" is solved after inputting boundary conditions and constraints.

[0010] Furthermore, the step of "using finite element method to calculate the thickness of each "surface element" in the faceted body after applying strength and stiffness constraints" specifically includes the following steps: defining each "surface element"; setting the initial value and variation range of each "surface element"; applying load; setting constraints and optimization goals; and calculating and solving.

[0011] Furthermore, in the step of "applying load", the load includes the aerodynamic load of the flow channel surface, the axial force load and torque load of the front mounting edge and the rear mounting edge, and the force load on the auxiliary mounting node on the front mounting edge.

[0012] Furthermore, in the step of "setting constraints and optimization objectives", the optimization objective is minimization of mass, or other design elements.

[0013] Furthermore, the step of "checking and fine-tuning the preliminary three-dimensional model of the casing to obtain the final three-dimensional model of the casing" specifically includes the following steps: calculating and checking the strength, vibration and life of the preliminary three-dimensional model of the casing; if the strength, vibration and life all meet the design requirements, the verification is completed; if one of the strength, vibration and life does not meet the design requirements, the size of the preliminary three-dimensional model of the casing is fine-tuned, and then the above two steps are repeated in sequence until the strength, vibration and life all meet the design requirements, and the verification is completed.

[0014] The present invention has the following beneficial effects: In the traditional design method, when the design variables need to be adjusted, the points, lines, and surfaces can be changed, so that the selection of design variables is very arbitrary and the design results are also very uncertain. In the forward design method of the present invention, step "S10: discretize the casing model of the known two-dimensional structure diagram into separate independent "surface elements"", that is, in the design method of the present invention, the surface elements in the two-dimensional diagram are set as design variables, and the selection of design variables is more specific, so that the design results are more certain, reducing the workload of subsequent adjustment operations, thereby improving the design efficiency; in step "S30: after applying strength and stiffness constraints, use finite elements to calculate the thickness of each "surface element" in the faceted body", the optimal thickness of the quality that meets the constraints can be obtained, and this thickness combination is a design benchmark in the three-dimensional design of casing parts. With this design "benchmark", there is a biggest difference from the traditional design method, because the traditional design The selection of design variables in the method is arbitrary and lacks necessary benchmark constraints. The design results have great uncertainty. Sometimes the local strength and stiffness do not meet the requirements and need to be re-designed. Sometimes the design margin is too large and the weight and other factors exceed the standard, and it is also necessary to re-optimize the weight reduction design later. All of these require multiple rounds of iterations, which will cost a lot of manpower and material resources, and have certain requirements on the designer's experience, and sometimes may affect the development progress. However, in the method of the present invention, after having this design "benchmark", there is a reference when carrying out the three-dimensional design of the casing parts, and the "benchmark" value is close to the optimal value of the casing parts under the verification conditions. As long as the design value is not lower than the "benchmark value" and is near the "benchmark value", a basic three-dimensional model with high design quality that preliminarily meets the design requirements can be obtained. Therefore, compared with the traditional design method, the completion degree of a single part in the preliminary design can reach a higher level.

[0015] Therefore, through the design method of the present invention, the three-dimensional design of the thin-walled casing of an aircraft engine can be quickly completed, and the completion degree of the aircraft engine casing in the preliminary design can be greatly improved. Compared with the traditional iterative design method, the design efficiency is greatly improved; and the strength and stiffness analysis can be completed in the design process, avoiding the subversive repetition caused by the traditional design after the design is completed according to experience and then verified, effectively saving time and labor costs, greatly improving the design efficiency, shortening the design cycle by 80%, and providing an effective design tool for the transformation of aircraft engine structural design from simulation to autonomous forward design. The newly designed aircraft engine casing has passed the strength verification test and has been officially installed and used.

[0016] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a flow chart of the design of the casing structure of a traditional aircraft engine; Figure 2 It is the preliminary design of the traditional receiver Figure 1 ; Figure 3 It is the preliminary design of the traditional receiver Figure 2 ; Figure 4 It is a schematic diagram of dividing the casing model with a known two-dimensional structure diagram into blocks according to design elements; Figure 5 It is to simplify each block into a separate "surface element" schematic diagram; Figure 6 It is a schematic diagram of recombining each "surface element" according to its position to form a complete flake-hedron; Figure 7 It is a schematic diagram that defines each "surface element"; Figure 8 It is a schematic diagram of the thickness of each surface element calculated by finite element analysis; Fig. 9 It is a schematic diagram of the preliminary three-dimensional model of the optimized casing; Fig.10 This is a schematic diagram of the preliminary 3D model verification of the casing Figure 1 ; Fig.11 This is a schematic diagram of the preliminary 3D model verification of the casing Figure 2 . DETAILED DESCRIPTION

[0018] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0019] Reference Figure 1 The preferred embodiment of the present invention provides a forward design method for an aircraft engine casing structure, comprising the following steps: S10: discretize the casing model with a known two-dimensional structure diagram into independent “surface elements”; S20: Recombining each "surface element" according to position to form a complete flake face; S30: After applying the constraints of strength and stiffness, the thickness of each "surface element" in the faceted body is calculated using finite element method; S40: constructing a preliminary three-dimensional model of the casing according to the thickness calculation result; S50: Check and fine-tune the preliminary three-dimensional model of the receiver to obtain the final three-dimensional model of the receiver.

[0020] like Figure 1-3 As shown, according to the traditional design method, the preliminary structural design usually relies on the designer's experience. If the preliminary structural design meets the strength, vibration and life requirements, the stage structural design is completed, and there is usually room for optimization after the stage structural design; according to the development time limit, after the strength, vibration and life of the verification model meet the requirements, if time is tight, the design will be directly completed and transferred to the next stage; if time is sufficient, it will enter a long cycle of adjusting the structure-verification-adjusting the structure-re-verification, and in this process, it may also be accompanied by the situation that other parts are changed due to the adjustment of the part structure, so that the cycle of improving the model will be longer. Therefore, in view of the problems existing in the traditional design method, the present invention proposes a forward design method of the casing structure of an aircraft engine based on simulation calculation. In the forward design method, the casing model of the known two-dimensional structure diagram is first discretized into independent "surface elements", and then each "surface element" is recombined according to the position to form a complete flake body, and then the thickness of each "surface element" in the flake body is calculated by finite element after applying the constraints of strength and stiffness, and finally the preliminary three-dimensional model of the casing can be quickly constructed according to the thickness calculation result.

[0021] In the traditional design method, when the design variables need to be adjusted, the points, lines, and surfaces can be changed, so that the selection of design variables is very arbitrary and the design results are also very uncertain. In the forward design method of the present invention, step "S10: discretize the casing model of the known two-dimensional structure diagram into separate independent "surface elements"", that is, in the design method of the present invention, the surface elements in the two-dimensional diagram are set as design variables, and the selection of design variables is more specific, so that the design results are more certain, reducing the workload of subsequent adjustment operations, thereby improving the design efficiency; in step "S30: after applying strength and stiffness constraints, use finite elements to calculate the thickness of each "surface element" in the faceted body", the optimal thickness of the quality that meets the constraints can be obtained, and this thickness combination is a design benchmark in the three-dimensional design of casing parts. With this design "benchmark", there is a biggest difference from the traditional design method, because the traditional design The selection of design variables in the method is arbitrary and lacks necessary benchmark constraints. The design results have great uncertainty. Sometimes the local strength and stiffness do not meet the requirements and need to be re-designed. Sometimes the design margin is too large and the weight and other factors exceed the standard, and it is also necessary to re-optimize the weight reduction design later. All of these require multiple rounds of iterations, which will cost a lot of manpower and material resources, and have certain requirements on the designer's experience, and sometimes may affect the development progress. However, in the method of the present invention, after having this design "benchmark", there is a reference when carrying out the three-dimensional design of the casing parts, and the "benchmark" value is close to the optimal value of the casing parts under the verification conditions. As long as the design value is not lower than the "benchmark value" and is near the "benchmark value", a basic three-dimensional model with high design quality that preliminarily meets the design requirements can be obtained. Therefore, compared with the traditional design method, the completion degree of a single part in the preliminary design can reach a higher level.

[0022] Therefore, through the design method of the present invention, the three-dimensional design of the thin-walled casing of an aircraft engine can be quickly completed, and the completion degree of the aircraft engine casing in the preliminary design can be greatly improved. Compared with the traditional iterative design method, the design efficiency is greatly improved; and the strength and stiffness analysis can be completed in the design process, avoiding the subversive repetition caused by the traditional design after the design is completed according to experience and then verified, effectively saving time and labor costs, greatly improving the design efficiency, shortening the design cycle by 80%, and providing an effective design tool for the transformation of aircraft engine structural design from simulation to autonomous forward design. The newly designed aircraft engine casing has passed the strength verification test and has been officially installed and used.

[0023] Alternatively, if Figure 4-5 As shown, step “S10: discretizing the casing model of the known two-dimensional structure diagram into independent “surface elements”” specifically includes the following steps: S101: Divide a casing model of a known two-dimensional structure diagram into a plurality of blocks according to design elements; S102: Simplify each block to form a separate “surface element”.

[0024] In this optional solution, compared with the traditional optimization method, when decomposing and discretizing the two-dimensional casing structure, it is not necessary to stick to a specific method. It can be divided into different surface elements according to factors such as function, position, shape, etc., which does not affect the effectiveness of the calculation, and can be flexible and changeable with stronger applicability. It can also be applicable to particularly complex engine casings. In traditional design, when the design variables need to be adjusted, the points, lines, and surfaces can be changed. The selection of design variables is very arbitrary, and the design results are also very uncertain. In the method of the present invention, the surface elements in the two-dimensional diagram are set as design variables, and the selection of design variables is more specific. At the same time, when the surface elements are divided, it can be flexible and changeable, and has strong applicability and practicality.

[0025] In this option, if Figure 4 As shown, in step "S101: dividing the casing model of the known two-dimensional structure diagram into several blocks according to design elements", the design elements include one or more of function, position, and shape. In a specific embodiment of this optional solution, the casing model is divided into several blocks according to functional elements.

[0026] In this option, if Figure 5 As shown, in step "S102: simplifying each block to form a separate "surface element", the "surface element" is the surface of the separated block, or the middle surface within any thickness range of the block. In the specific embodiment of this optional solution, Figure 5 As shown, the surface element is the surface of the block, so when the thickness of the subsequent surface element is designed, the thickness only increases in one direction, making the subsequent operation simple; when the surface element is the middle surface within any thickness range of the separated block, when the thickness of the subsequent surface element is designed, the thickness can increase from the middle surface to both sides, so that the thickness design is flexible and can adapt to mechanical parts with more complex structures.

[0027] Alternatively, if Figure 6As shown, in step "S20: Recombining each "surface element" according to position to form a complete flake-faced body", the flake-faced body is compared and analyzed with the mature receiver part structure to preliminarily judge the rationality of the flake-faced body structure design and make timely adjustments. In actual operation, when the discrete "surface elements" are recombined according to position to form a preliminary complete flake-faced body, the flake-faced body is a continuous spatial sheet composed of multiple faces, which has preliminarily possessed the three-dimensional appearance of the receiver part. At this time, although the three-dimensional design of the receiver part has not been fully completed, a comparative analysis can be conducted based on the preliminary three-dimensional appearance of the receiver part and the structure of the mature receiver part, so that a preliminary judgment can be made on the rationality of the structural design, and timely adjustments can be made, thereby effectively avoiding the repetitiveness that sometimes occurs in traditional design, where all design work is completed and then has to be started over again due to unreasonable structural layout, thereby improving design efficiency and reducing the intensity of design work.

[0028] Optionally, when performing step "S30: using finite element method to calculate the thickness of each "surface element" in the faceted body after applying strength and stiffness constraints", the thickness of the "surface element" is used as a design variable, the optimal quality is set as the design goal, and the thickness of each "surface element" is solved after inputting boundary conditions and constraints. During the specific operation, the thickness of each "surface element" in the one-sided body formed in step S20 is used as a design variable, and an interval value is assigned to each "surface element" as a design interval. At the same time, boundary load conditions are applied to the one-sided body, and constraints are imposed according to criteria such as strength and stiffness. The optimal quality is taken as the design goal, and finite element calculation is carried out to obtain the optimal thickness of each surface with the optimal quality that meets the constraints. This thickness combination is a design benchmark in the three-dimensional design of the casing parts. With this design "benchmark", there is the biggest difference from the traditional design method. Because the selection of design variables in the traditional design method is arbitrary and lacks the necessary benchmark constraints, the design result has a large uncertainty. Sometimes the local strength and stiffness do not meet the requirements and need to be re-designed. Sometimes the design margin is too large, and the weight and other factors exceed the standard, and it is also necessary to re-optimize the weight reduction design later. All of these require multiple rounds of iterations, which will cost a lot of manpower and material resources, and have certain requirements on the designer's experience, and sometimes may affect the development progress. However, with this design "benchmark", there is a reference when carrying out the three-dimensional design of the receiver parts, and the "benchmark" value is close to the optimal value of the receiver parts under the verification conditions. As long as the design value is not lower than the "benchmark value" and is close to the "benchmark value", a basic three-dimensional model with high design quality that initially meets the design requirements can be obtained. Therefore, compared with traditional design methods, the completion degree of a single part in the preliminary design can reach a higher level.

[0029] In this option, if Figure 7-8As shown, step "S30: applying strength and stiffness constraints and using finite element method to calculate the thickness of each "surface element" in the faceted body" specifically includes the following steps: S301: define each "surface element"; in this optional solution, if Figure 7 As shown, six surfaces, T-1, T-2, T-3, T-4, T-5, and jin, are used to define the design variables of six surface elements.

[0030] S302: Set the initial value and variation range of each "surface element". The initial value is specifically designed as follows: Design variables Initial value (mm) Variation range (mm) Jin 4 1-8 T-1 4 1-8 T-2 4 1-8 T-3 4 1-8 T-4 4 1-8 T-5 4 1-8 S303: Apply load; in this optional solution, the load includes the aerodynamic load of the flow channel surface, the axial force load and torque load of the front mounting edge and the rear mounting edge, and the force load on the auxiliary mounting node on the front mounting edge.

[0031] S304: Setting constraints and optimization goals; in this optional solution, the constraints are to constrain the maximum stress and the maximum displacement; the optimization goal is to minimize the mass, and can also be other design elements.

[0032] S305: Calculate and solve, the final thickness optimization result is as follows Figure 8 The calculation results are as follows: Design variables Initial value (mm) Design value (mm) Rate of change Jin 4 2 -50% T-1 4 3.9 -2.5% T-2 4 5 +25% T-3 4 2.7 -32.5% T-4 4 5 +25% T-5 4 2.8 -30% Alternatively, if Fig. 9 As shown, in step S40, based on the three-dimensional design dimension benchmark of the casing obtained in step S30, the preliminary three-dimensional design of the casing is completed, and the three-dimensional structural dimensions of the casing are fine-tuned according to the interface design requirements and other general design requirements. It should be noted that the adjusted dimensions should not be lower than the design benchmark value as much as possible to avoid the occurrence of local strength or life design that does not meet the requirements, and the casing part model is verified and calculated, and it is decided whether to fine-tune the dimensions based on the calculation results, and the final three-dimensional design model of the casing parts is obtained. In the scheme design stage, each part is designed synchronously. If the design method of the present invention is adopted, compared with the isolated design of each part in the traditional design method, not only the quality of the design process is controllable, but also the final single part design quality is higher, the design coordination of the entire engine is better, the completion degree in the preliminary design is also higher, and the overall design quality can also reach a higher level.

[0033] Alternatively, if Figure 10-11 As shown, step “S50: verifying and fine-tuning the preliminary three-dimensional model of the casing to obtain the final three-dimensional model of the casing” specifically includes the following steps: S501: Calculate and verify the strength, vibration and life of the preliminary three-dimensional model of the casing; S502: If strength, vibration and life all meet the design requirements, the verification is completed; S503: If any one of the strength, vibration and life does not meet the design requirements, fine-tune the size of the preliminary three-dimensional model of the casing, and then repeat the above two steps in sequence until the strength, vibration and life all meet the design requirements, and then the verification is completed. In actual operation, due to the above-mentioned S10-S40 operations, the model stress level is within a reasonable range, and the model completion degree is high. Even if adjustments are required in step S50, only fine-tuning is required. Compared with the traditional casing structure design method, the design cycle is shortened by 80%. The preliminary design of the parts is highly complete, which avoids subversive repetitions and greatly shortens the part design cycle.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A forward design method for an aircraft engine casing structure, characterized in that: The following steps are involved: Discretize the casing model with a known two-dimensional structure diagram into independent "surface elements"; Recombine each "face element" according to its position to form a complete flake-hedron; After applying the constraints of strength and stiffness, the thickness of each "surface element" in the flake body is calculated by finite element method. During the operation, the thickness of the "surface element" is taken as the design variable, the optimal quality is taken as the design goal, and the thickness of each "surface element" is solved after the boundary conditions and constraints are input. During the specific operation, the thickness of each "surface element" in the flake body formed in the step "recombining each "surface element" according to the position to form a complete flake body" is taken as the design variable, and an interval value is assigned to each "surface element" as the design interval. At the same time, boundary load conditions are applied to the flake body, and constraints are applied according to the strength, stiffness and other criteria. The optimal quality is taken as the design goal, and the finite element calculation is carried out to obtain the optimal thickness of each surface with the optimal quality under the constraints. The specific operation steps are as follows: Define each "surface element"; Set the initial value and variation range of each "surface element"; Apply loads; the loads include aerodynamic loads on the flow channel surface, axial force loads and torque loads on the front and rear mounting edges, and force loads on the auxiliary mounting joint on the front mounting edge; Set constraints and optimization goals; constraints are to constrain maximum stress and maximum displacement; optimization goals are to minimize mass or other design elements; Calculate and solve; A preliminary three-dimensional model of the receiver is constructed based on the thickness calculation results; The preliminary three-dimensional model of the receiver is checked and fine-tuned to obtain the final three-dimensional model of the receiver.

2. The forward design method for aircraft engine casing structure according to claim 1, characterized in that: The step of "discretizing the casing model of the known two-dimensional structure diagram into independent "surface elements"" specifically includes the following steps: The casing model with a known two-dimensional structure diagram is divided into several blocks according to design elements; Simplify each block into individual "surface elements".

3. The forward design method for aircraft engine casing structure according to claim 2, characterized in that: In the step of "dividing the casing model of the known two-dimensional structure diagram into several blocks according to design elements", the design elements include one or more of function, position, and shape.

4. The forward design method for aircraft engine casing structure according to claim 2, characterized in that: In the step of "simplifying each block into a separate "surface element", the "surface element" is the surface of the separated block, or the middle surface within any thickness range of the block.

5. The forward design method for aircraft engine casing structure according to claim 1, characterized in that: In the step "recombining each "surface element" according to the position to form a complete one-sided body", the one-sided body is compared and analyzed with the mature receiver part structure to preliminarily judge the rationality of the one-sided body structure design and make timely adjustments.

6. The forward design method for aircraft engine casing structure according to claim 1, characterized in that: The step of "checking and fine-tuning the preliminary three-dimensional model of the casing to obtain the final three-dimensional model of the casing" specifically includes the following steps: Calculate and verify the strength, vibration and life of the preliminary three-dimensional model of the casing; If strength, vibration and life all meet the design requirements, the verification is completed; If one of the strength, vibration and life does not meet the design requirements, the size of the preliminary three-dimensional model of the casing is fine-tuned, and then the above two steps are repeated in sequence until the strength, vibration and life all meet the design requirements, and the verification is completed.

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