Unit body division method and aero-engine unit body overall design method

Abstract

The invention provides a unit body dividing method and an aero-engine unit body overall design method. The unit body dividing method comprises the steps that 1.1, a unit body set is determined; 1.2, according to each basic unit body in the unit body set, the basic unit body is downwards split into secondary unit body modules; 1.3, the basic unit body is used as an object, and the fault rate standard deviation of a subordinate secondary unit body of the basic unit body is calculated; 1.4, comparing the fault rate standard deviation of the second-level unit body with a set threshold value, and deciding whether the basic unit body needs to be subdivided into the second-level unit body or not; 1.5, repeating the step 1.2 to the step 1.4, and constructing an initial division scheme of the unit body set; and 1.6, constructing a unit maintenance cost mathematical model for the initial division scheme of the unit set. According to the method, the purpose of effectively supporting the derived development design requirements of the engine unit body facing multiple use scenes can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engines, and in particular to a unit division method and an overall design method for aero-engine units. Background Art

[0002] The quality of unit design is directly related to the maintainability and modular reuse capability of aircraft engines. However, the unit design process involved in the existing aircraft engine unit design standards and other related literature has the following shortcomings:

[0003] 1) It is mainly based on single scenario design, and the differences and compatibilities of different scenarios are not fully considered during process design, resulting in a lack of integrity of process elements. For example, there is a lack of consideration of the determination of the basic unit for derived development, the design of assembly procedures and packaging and transportation for different scenarios, the design of assembly processes and test procedures for different scenarios, and other process designs. It is difficult to effectively support the design needs of derived development of engine units for multiple usage scenarios.

[0004] 2) The specific process design is relatively simple and rough, and there are no clear and detailed process constraints and specifications for the core pain points of unit design, such as how to quantitatively divide the unit based on mathematical models. It is difficult to effectively support the development trend of modular replacement and rapid reuse design of engine units. Summary of the invention

[0005] In view of this, the present invention provides a unit division method and an overall design method for aircraft engine units, so as to effectively support the derived development design needs of engine units for multiple usage scenarios.

[0006] The present invention provides the following technical solution: a unit body division method, comprising:

[0007] 1.1. Determine the unit set;

[0008] 1.2. According to each basic unit in the unit set, it is split down into secondary unit modules;

[0009] 1.3. Taking the basic unit as the object, calculate the standard deviation of the failure rate of the secondary units under the basic unit;

[0010] 1.4. Compare the standard deviation of the secondary unit failure rate with the set threshold to decide whether the basic unit needs to be subdivided into secondary units;

[0011] 1.5. Repeat steps 1.2 to 1.4 to construct an initial partitioning scheme for the unit set;

[0012] 1.6. Construct a mathematical model of unit maintenance cost based on the initial division scheme of the unit set.

[0013] Furthermore, step 1.6 specifically includes:

[0014] Calculate the coupling degree caused by the number of unit body interfaces

[0015] Calculate the coupling degree S2 caused by the difficulty of interface coordination = x z u z ;

[0016] Among them, q i is the number of parts involved in the replacement of the i-th unit, b ij is the number of interfaces of part j in the i-th unit, x z is the weight factor of interface Z, u z is the decomposition difficulty of interface Z.

[0017] Furthermore, step 1.6 also includes:

[0018] Get the maximum coupling degree caused by the number of unit body interfaces

[0019] Get the minimum coupling degree caused by the number of unit body interfaces

[0020] Furthermore, step 1.6 also includes:

[0021] Get the maximum coupling value S caused by the difficulty of unit interface matching 2max =x z u z ;

[0022] Get the minimum value S of the coupling degree caused by the difficulty of unit interface matching 2min =0.

[0023] Furthermore, step 1.6 also includes:

[0024] The maximum and minimum values ​​of the coupling degree caused by the number of unit body interfaces are normalized to obtain the normalized value of the coupling degree of the number of unit body interfaces.

[0025] Normalize the maximum and minimum values ​​of the coupling degree caused by the difficulty of unit body interface matching to obtain the normalized value of the coupling degree of the unit body interface matching difficulty.

[0026] Furthermore, step 1.6 also includes:

[0027] Get the unit body interface coupling coefficient

[0028] Calculate the coupling coefficients of all unit cell interfaces and obtain the minimum value μ of the unit cell interface coupling coefficients min ;

[0029] Determine the cost of replacing the i-th unit in, is the weight value, C μmin is the minimum interface coupling coefficient μ min The replacement cost of the unit body, μ i is the interface coupling coefficient of the i-th unit cell.

[0030] Furthermore, step 1.6 also includes:

[0031] By formula Calculate the replacement cost of each unit in the initial division scheme during the entire life cycle, where C mmi is the cost of replacing the i-th unit, C 脱发 For engine hair loss costs, D 寿命期 is the total working time of the engine from the beginning of use to the end of life replacement, i is the failure rate of the i-th unit during the overhaul period.

[0032] Furthermore, step 1.6 also includes:

[0033] Get the return turnover efficiency coefficient

[0034] When H≤1, determine the number of spare parts N of the i-th unit bii =2;

[0035] When H>1, determine the number of spare parts for the i-th unit

[0036]

[0037] Calculate the total cost of spare parts

[0038] Among them, N bi is the number of spare parts of the i-th unit, C bi is the spare parts purchase cost of the i-th unit, H is the return turnover efficiency coefficient, D 寿命期 The total working time of the engine from the beginning of use to the end of life replacement; T 周转时间 is the time it takes for the unit to return to the factory and then to the base, λ i is the failure rate of the i-th unit during the overhaul period, T 平均单日飞行时间 The average daily flight time.

[0039] Furthermore, step 1.6 also includes:

[0040] Get the correction factor In the formula, c ij is the association degree of unit body subordinate part j to unit body i; c ijl is the association degree of unit body part j to unit body part l; β ij is the importance of unit body's subordinate part j to unit body i.

[0041] Furthermore, step 1.6 also includes:

[0042] Calculate the maximum value of the correction factor

[0043] Calculate the minimum value of the correction factor ω min =c ij β ij ;

[0044] Normalize the maximum and minimum values ​​of the correction coefficient to obtain the normalized value of the correction coefficient

[0045]

[0046] Furthermore, step 1.6 also includes:

[0047] Calculate the cost of returning each unit to the factory for repair during the entire life cycle

[0048] Among them, C fbi is the average replacement cost of the i-th unit, C w is the average cost of equipment and labor involved in the maintenance process, i * is the correction coefficient of the ith unit, D 寿命期 is the total working time of the engine from the beginning of use to the end of life replacement, i is the failure rate of the i-th unit during the overhaul period.

[0049] Furthermore, step 1.6 constructs a unit maintenance cost mathematical model for the unit initial division scheme, specifically including:

[0050] By the formula C = C mf +C b +C f Calculate the unit maintenance cost during the life cycle, where C is the total maintenance cost of the unit, C mf is the unit replacement cost, C b is the total purchase cost of the spare unit, C f For factory repair costs.

[0051] The present invention also provides an overall design method for an aircraft engine unit, including the above-mentioned unit division method. The overall design method for an aircraft engine unit includes:

[0052] Perform unit body division design according to the unit body division method;

[0053] Conduct unit performance and structural design;

[0054] Carry out unit assembly and packaging transportation design;

[0055] Carry out unit replacement process and commissioning program design;

[0056] Verify and evaluate the overall design of the unit.

[0057] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted by the present invention include at least:

[0058] 1) The process covers a wide range of stages and forms a complete system: Based on the concept of the V-shaped flowchart of system engineering, a full-process and full-element design process system is built in the form of main process + sub-process, covering stages such as unit division and demonstration, unit design, supporting process design, and integrated verification design. It also fully considers the differences and compatibility of unit designs in different scenarios, such as supplementing and improving the sub-process design of basic unit determination considering derivative development, assembly procedures and packaging and transportation design for different scenarios, and assembly process and test run procedure design for different scenarios, thereby effectively supporting the derivative development design needs of engine units for multiple usage scenarios.

[0059] 2) The process is highly targeted and the key steps are clear. In view of the difficulties in the current unit design, that is, the quantitative division of unit levels and quantities based on mathematical models, the process is further decomposed in detail, and the technical routes and key control factors are sorted out. It has a strong guiding significance and can effectively support the development trend of modular replacement and rapid reuse design of engine units. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0061] Figure 1 It is a flow chart of the unit body partitioning method;

[0062] Figure 2 It is a flow chart of the overall design method of aero-engine unit;

[0063] Figure 3 It is a flow chart of unit body performance and structural design method;

[0064] Figure 4It is a flow chart of the design method of unit assembly and packaging transportation;

[0065] Figure 5 It is a flow chart of the design method of the unit replacement process and the commissioning procedure;

[0066] Figure 6 It is a flow chart of the verification and evaluation method of the overall design scheme of the unit. DETAILED DESCRIPTION

[0067] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0068] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0069] like Figure 1 As shown, an embodiment of the present invention provides a unit body division method, comprising the following steps:

[0070] 1.1. Determine the basic unit. Drawing on the demand analysis method, we first start with the common engine types that can be derived from the general core engine, and carry out the logical and physical main architecture design. At the same time, we refer to the design experience of similar engines at home and abroad to further decompose them into basic unit modules. Similar modules are combined to form a basic unit module solution.

[0071] The basic unit body is usually a component with independent functions, such as the air intake casing, fan, intermediate casing, high-pressure compressor, main combustion chamber, high-pressure turbine, low-pressure turbine, rear load-bearing casing, nozzle, outer casing, external pipelines, central transmission, engine accessory casing, aircraft accessory casing, etc.

[0072] 1.2. Based on the basic unit body scheme formed above, refer to the existing cases and further split it into secondary unit body modules according to the principle of structural independence, such as the fan can be divided into fan rotor, fan stator, etc.; upward according to functional aggregation into main unit body modules, such as compressor, main combustion, and high-pressure turbine combination as the core engine main unit body. As shown in Table 1, a splitting and combination scheme is formed with a certain type of engine as the analysis object (other types of engines are similar).

[0073] Table 1 Schematic diagram of basic unit body splitting and combination

[0074]

[0075] 1.3. Taking the basic unit as the object, calculate the standard deviation of the failure rate of the subordinate secondary units σ 故障率 , the formula is as follows:

[0076]

[0077] where x i is the preset failure rate of the i-th secondary unit, is the average failure rate. n is the number of secondary units under the basic unit.

[0078] 1.4. According to the principle that the basic unit body needs to be subdivided when the failure rate of the basic unit body is greater than 1 / 3 of the maximum failure rate of the subordinate secondary unit body, decide whether the basic unit body needs to be subdivided into secondary units.

[0079] 1.5. The initial division of units is formed according to the pure secondary unit, pure basic unit, pure main unit, and three types of mixed arrangements and combinations. At the same time, the unit restrictions in different scenarios are considered, such as the maximum weight limit of the unit M max , Maximum volume limit V max Etc., eliminate some over-constrained solutions, and then converge to form alternative unit division solutions for subsequent maintenance cost estimation (the sample size is not less than 10).

[0080] 1.6 Construct a mathematical model for unit maintenance costs. The benefits of replacing engine units are that they can reduce the number of returns to the overhaul plant and maintenance costs, and reduce the number of spare engines in the field. In order to facilitate the establishment of a mathematical model for unit maintenance costs, the target quantity is unified as the total unit maintenance cost.

[0081] Step 1.6 is as follows:

[0082] (1) Considering that the unit maintenance cost during the life cycle is composed of direct replacement costs, spare unit purchase costs, and return to the factory for repair costs, the formula is as follows:

[0083] C=C mf +C b +C f ;

[0084] Where C is the total maintenance cost of the unit, C mf is the unit replacement cost, C b is the total purchase cost of the spare unit, C f For factory repair costs.

[0085] (2) Assuming that the engine is divided into n basic-level replaceable units, the replacement cost of each unit in each scheme during the entire life cycle is calculated based on the engine life, the failure rate of each unit and the replacement cost. The formula is as follows:

[0086]

[0087] Among them, C mmi is the cost of replacing the i-th unit, C 脱发 For engine hair loss costs, D 寿命期 is the total working time of the engine from the beginning of use to the end of life replacement, i is the failure rate of the i-th unit during the overhaul period.

[0088] (1.1) The cost C for replacing the i-th unit mmi The further analysis is as follows. Assuming that the replacement cost of a certain unit is known, based on the similarity of disassembly and assembly work, the concept of unit interface coupling coefficient μ can be introduced to calculate the replacement cost of the remaining units. That is, the more unit interfaces there are, the greater the replacement and disassembly workload, and the higher the replacement cost. Specifically, the coupling degree S1 caused by the number of unit interfaces and the coupling degree S2 caused by the difficulty of interface matching are jointly evaluated. For the nth unit, the details are as follows.

[0089] Calculate the coupling degree caused by the number of unit body interfaces

[0090] Calculate the coupling degree S2 caused by the difficulty of interface coordination = x z u z ;

[0091] Among them, q i is the number of parts involved in the replacement of the i-th unit, b iijj is the number of interfaces of part j in the i-th unit, x z is the weight factor of interface Z, u z is the decomposition difficulty of interface Z.

[0092] (1.2) The more parts a unit has, the larger the values ​​of S1 and S2 are, and vice versa. Therefore, the following operation is adopted:

[0093] Get the maximum coupling degree caused by the number of unit body interfaces

[0094] Get the minimum coupling degree caused by the number of unit body interfaces

[0095] (1.3) For ease of comparison, the two coefficients are normalized.

[0096] Get the maximum coupling value S caused by the difficulty of unit interface matching 2max =x z u z ;

[0097] Get the minimum value S of the coupling degree caused by the difficulty of unit interface matching 2min =0.

[0098] (1.4) The weights of the two are (can be determined by the hierarchical analysis method), then the formula for the coupling coefficient μ of a unit interface is:

[0099] (1.5) Calculate the coupling coefficients of all unit cell interfaces and obtain the minimum value μ of the coupling coefficients of the unit cell interfaces min , so the cost of replacing the i-th unit Where C μmin is the minimum interface coupling coefficient μ min The replacement cost of the unit body, μ i is the interface coupling coefficient of the i-th unit cell.

[0100] (2) Considering the return turnover efficiency coefficient and the number of spare parts under different coefficients, the total purchase cost of spare parts (for delivery) is calculated as follows:

[0101] Get the return turnover efficiency coefficient

[0102] When H≤1, determine the number of spare parts N of the i-th unit bii =2;

[0103] When H>1, determine the number of spare parts for the i-th unit

[0104]

[0105] Then calculate the total purchase cost of spare parts

[0106] Among them, N bi is the number of spare parts of the i-th unit, C bi is the spare parts purchase cost of the i-th unit, H is the return turnover efficiency coefficient, D 寿命期 The total working time of the engine from the beginning of use to the end of life replacement; T 周转时间 is the time it takes for the unit to return to the factory and then to the base, λ i is the failure rate of the i-th unit during the overhaul period, T 平均单日飞行时间 The average daily flight time.

[0107] (3) Calculate the return-to-factory repair costs of each solution unit during the entire life cycle. The calculation formula is as follows:

[0108] Among them, C fbi is the average replacement cost of the i-th unit, C w is the average cost of equipment and labor involved in the maintenance process, i * is the correction coefficient of the ith unit, D 寿命期 is the total working time of the engine from the beginning of use to the end of life replacement, i is the failure rate of the i-th unit during the overhaul period.

[0109] (3.1) For the correction coefficient ω i The further analysis is as follows: based on the similarity of equipment and manual work involved in the maintenance process, the C of different units is modified considering the complexity of the internal structure of the unit. w That is, the more complicated the internal structure of the unit is, the greater the maintenance workload will be. w The higher. For the nth unit cell, the formula is as follows.

[0110]

[0111] In the formula, c ij is the association degree of unit body subordinate part j to unit body i; c ijl is the association degree of unit body part j to unit body part l; β ij is the importance of unit body's subordinate part j to unit body i.

[0112] (3.2) The more parts a unit has, the larger the ω value is, and vice versa. Therefore:

[0113] Calculate the maximum value of the correction factor

[0114] Calculate the minimum value of the correction factor ω min =c ij β ij ;

[0115] (3.3) To facilitate comparison, the maximum and minimum values ​​of the correction coefficient are normalized to obtain the normalized value of the correction coefficient:

[0116] 1.7 Calculate the total maintenance cost C of each unit division scheme, sort them from low to high according to the cost, and comprehensively determine the optimal scheme among the first three schemes. The decision-making process for other types of engine units is similar.

[0117] like Figure 2 As shown, the present invention also provides an overall design method for an aircraft engine unit body, including the above-mentioned unit body division method. The overall design method for an aircraft engine unit body specifically includes the following steps:

[0118] The unit division design is carried out according to the unit division method. First, the basic unit is determined. The basic unit can be considered as the smallest unit. The present invention adopts a bottom-up approach. The first step of the process is to determine the set of basic units decomposed based on different types of engine architectures. After the basic unit is determined, the downward structure is split into secondary units, and the upward functions are aggregated into the main unit. On this basis, based on rules and scenario constraints, alternative unit division schemes are formed, and a mathematical model based on unit maintenance costs is established. All alternative schemes are substituted in turn for calculation, thereby forming a preferred unit division scheme. So as to further carry out targeted detailed design based on this.

[0119] Unit performance and structural design. For a unit division scheme formed above, the performance consistency, structural interchangeability, and general quality characteristics are designed to determine its detailed design scheme. The overall design process of different types of engine units is basically the same. This process is the core of the entire unit design process, which determines whether the performance and structure decoupling can be truly achieved between units, so as to create basic conditions for modular derivative development.

[0120] Unit assembly and packaging and transportation design. After the detailed unit plan is determined, it is necessary to pass the assembly procedure and process control requirements, independent packaging and transportation and protection requirements design. The original intention of this process design is to ensure the quality of the unit trial production, assembly, delivery and transportation.

[0121] Unit replacement process and test run program design. Based on the above-determined assembly procedures, the unit replacement process and test run program design is carried out considering multiple usage scenarios. The original intention of this process design is to ensure that the assembly quality and functional performance in multiple scenarios meet the requirements.

[0122] Unit design verification and evaluation. The original intention of this process design is to check and confirm the compliance of the above unit-related design work. If it fails, it is necessary to return to the corresponding process for iterative design. Compared with the above process, the main contents of this sub-process involve functional performance verification, maintainability verification and packaging and transportation verification.

[0123] Reference Figure 3 As shown, the unit performance and structural design method are as follows:

[0124] In this example, this sub-process is further decomposed into three sub-processes: unit performance consistency design, unit structure interchangeability design, unit six-property design, and finally the main unit performance and structure plan are output.

[0125] Taking a certain unit body design as an example, for performance consistency design, firstly, the performance design of components should be as efficient and wide as possible, and secondly, the sensitive structural characteristic factors affecting the performance inside the unit body should be comprehensively identified and controlled through the combination of multi-level performance simulation calculation analysis and special tests; for structural interchangeability design, firstly, the structural dimension tolerance and interface matching accuracy should be appropriately improved, and secondly, the combined measurement and adjustment work should be eliminated as much as possible by adopting measures such as segmented coaxial measurement and step-by-step high-precision rotor balancing; for performance design, the design can be implemented according to the top-level requirements of the specific engine.

[0126] Reference Figure 4 As shown in the figure, the design method of unit assembly and packaging transportation is as follows:

[0127] In this embodiment, this sub-process is further decomposed: first, the requirements for unit assembly, packaging and transportation in different scenarios are sorted out as input, and based on the structural composition of the subordinate modules of the unit and combined with existing design cases, the main unit assembly procedure and process control requirements, independent packaging and transportation and protection requirements are determined, and finally, the unit assembly and packaging and transportation solutions for different scenarios are output.

[0128] Assembly procedures and process control usually involve the design of assembly conditions and routes, key position rotor-stator shaft, radial clearance control, in-place dimension control, coaxiality measurement, rotor balancing, and sealing inspection; independent packaging and transportation protection usually involves centering and limiting the unit during transportation, packaging protection of fragile and easily contaminated structures such as graphite bearings, and three-accessory design (random tools, random spare parts, and random data).

[0129] Reference Figure 5 As shown in the figure, the unit replacement process and commissioning program design method are as follows:

[0130] In this embodiment, this sub-process is further decomposed: first, the unit replacement and maintenance requirements in different scenarios are sorted out as input, and based on the unit composition and existing design cases, the unit replacement process and tooling design and the whole machine test program design after the unit replacement are carried out. Finally, the unit replacement and test plan under different scenarios is output.

[0131] Taking into account various common engine maintenance scenarios, the replacement process and tooling design are subdivided into conventional vertical assembly process and tooling design content; the whole machine test run procedure design after replacement is subdivided into on-board / on-wing test run procedure design, as well as the test run procedure design content of indoor whole machine test bench and outdoor mobile test bench.

[0132] Reference Figure 6 As shown in the figure, the unit design verification and evaluation method is as follows:

[0133] In this embodiment, this sub-process is further decomposed: first, the verification requirements of the above-mentioned unit division and design are sorted out as input, and the unit verification technical requirements design and corresponding verification are carried out in combination with the existing unit design specifications and cases. Finally, the main unit verification summary report is output.

[0134] Verification projects, verification requirements design and corresponding tests can be carried out from the aspects of whole machine function and performance verification after unit replacement (verification of unit performance consistency and structural interchangeability design and assembly process design), unit disassembly and maintainability verification in the whole machine environment (verification of unit division and structural design), and unit independent transportation verification (verification of unit transportation bracket and packaging box design).

[0135] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A unit body division method, characterized in that: include: 1.

1. Determine the unit set; 1.

2. According to each basic unit in the unit set, it is split down into secondary unit modules; 1.

3. Taking the basic unit as the object, calculate the standard deviation of the failure rate of the secondary units under the basic unit; 1.

4. Compare the standard deviation of the secondary unit failure rate with the set threshold to decide whether the basic unit needs to be subdivided into secondary units; 1.

5. Repeat steps 1.2 to 1.4 to construct an initial partitioning scheme for the unit set; 1.

6. Construct a mathematical model of unit maintenance cost based on the initial division scheme of the unit set.

2. The unit cell division method according to claim 1, characterized in that: Step 1.6 specifically includes: Calculate the coupling degree caused by the number of unit body interfaces Calculate the coupling degree S2 caused by the difficulty of interface coordination = x z u z ; Among them, q i is the number of parts involved in the replacement of the i-th unit, b ij is the number of interfaces of part j in the i-th unit, x z is the weight factor of interface Z, u z is the decomposition difficulty of interface Z.

3. The unit cell division method according to claim 2, characterized in that: Step 1.6 also includes: Get the maximum coupling degree caused by the number of unit body interfaces Get the minimum coupling degree caused by the number of unit body interfaces 4. The unit cell division method according to claim 3, characterized in that: Step 1.6 also includes: Get the maximum coupling value S caused by the difficulty of unit interface matching 2max =x z u z ; Get the minimum value S of the coupling degree caused by the difficulty of unit interface matching 2min =0.

5. The unit cell division method according to claim 4, characterized in that: Step 1.6 also includes: The maximum and minimum values ​​of the coupling degree caused by the number of unit body interfaces are normalized to obtain the normalized value of the coupling degree of the number of unit body interfaces. Normalize the maximum and minimum values ​​of the coupling degree caused by the difficulty of unit body interface matching to obtain the normalized value of the coupling degree of the unit body interface matching difficulty.

6. The unit cell division method according to claim 5, characterized in that: Step 1.6 also includes: Get the unit body interface coupling coefficient Calculate the coupling coefficients of all unit cell interfaces and obtain the minimum value μ of the unit cell interface coupling coefficients min ; Determine the cost of replacing the i-th unit in, is the weight value, C μmin is the minimum interface coupling coefficient μ min The replacement cost of the unit body, μ i is the interface coupling coefficient of the i-th unit cell.

7. The unit cell division method according to claim 6, characterized in that: Step 1.6 also includes: By formula Calculate the replacement cost of each unit in the initial division scheme during the entire life cycle, where C mmi is the cost of replacing the i-th unit, C 脱发 For engine hair loss costs, D 寿命期 is the total working time of the engine from the beginning of use to the end of life replacement, i is the failure rate of the i-th unit during the overhaul period.

8. The unit cell division method according to claim 7, characterized in that: Step 1.6 also includes: Get the return turnover efficiency coefficient When H≤1, determine the number of spare parts N of the i-th unit bii =2; When H>1, determine the number of spare parts of the i-th unit Calculate the total cost of spare parts Among them, N bi is the number of spare parts of the i-th unit, C bi is the spare parts purchase cost of the i-th unit, H is the return turnover efficiency coefficient, D 寿命期 The total working time of the engine from the beginning of use to the end of life replacement; T 周转时间 is the time it takes for the unit to return to the factory and then to the base, λ i is the failure rate of the i-th unit during the overhaul period, T 平均单日飞行时间 The average daily flight time.

9. The unit cell division method according to claim 8, characterized in that: Step 1.6 also includes: Get the correction factor In the formula, c ij is the association degree of unit body subordinate part j to unit body i; c ijl is the association degree of unit body part j to unit body part l; β ij is the importance of unit body's subordinate part j to unit body i.

10. The unit cell division method according to claim 9, characterized in that: Step 1.6 also includes: Calculate the maximum value of the correction factor Calculate the minimum value of the correction factor ω min =c ij β ij ; Normalize the maximum and minimum values ​​of the correction coefficient to obtain the normalized value of the correction coefficient 11. The unit cell division method according to claim 10, characterized in that: Step 1.6 also includes: Calculate the cost of returning each unit to the factory for repair during the entire life cycle Among them, C fbi is the average replacement cost of the i-th unit, C w is the average cost of equipment and labor involved in the maintenance process, i * is the correction coefficient of the ith unit, D 寿命期 is the total working time of the engine from the beginning of use to the end of life replacement, i is the failure rate of the i-th unit during the overhaul period.

12. The unit cell division method according to claim 11, characterized in that: Step 1.6: Constructing a mathematical model of unit maintenance cost for the initial unit division scheme specifically includes: By the formula C = C mf +C b +C f Calculate the unit maintenance cost during the life cycle, where C is the total maintenance cost of the unit, C mf is the unit replacement cost, C b is the total purchase cost of the spare unit, C f For factory repair costs.

13. An overall design method for an aircraft engine unit, comprising the unit division method according to any one of claims 1 to 12, characterized in that: The overall design method of aero-engine unit includes: Perform unit body division design according to the unit body division method; Conduct unit performance and structural design; Carry out unit assembly and packaging transportation design; Carry out unit replacement process and test run program design; Verify and evaluate the overall design of the unit.

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