Dynamic regulation and control method for bearing / radiating integrated structure of lightweight engine

Abstract

The invention discloses a dynamic regulation and control method for a bearing / radiating integrated structure of a lightweight engine, which comprises the following steps of: adopting hollow grating type reinforcing ribs for a thin-wall structure of the engine, and introducing a coolant into the ribs to serve as an active cooling structure to absorb heat; constructing an optimization model by taking coolant inlet flow velocity and coolant outlet pressure in the reinforced thin-wall structure as design variables and taking minimum flexibility and pressure drop of the reinforced thin-wall structure as objective functions; physical fields of the coolant and the reinforced thin-wall structure are calculated, and an objective function and a constraint function are obtained through calculation; performing multi-objective optimization by adopting a multi-objective optimization algorithm to obtain a Pareto optimization solution set; and selecting an optimal Pareto solution to obtain an optimal solution and a design variable corresponding to the optimal solution as an optimal regulation and control parameter. The method is applied to the field of engine design, and the bearing maximization and lightweight design of the engine can be achieved on the premise that the reinforced thin-wall structure meets the complex working requirement under the wide Mach number.

Description

Technical Field

[0001] The invention relates to the technical field of engine design, and in particular to a dynamic control method for a lightweight engine load-bearing / heat-dissipating integrated structure. Background Art

[0002] With the development demand for high Mach numbers and long flight times, the conformal problem of thin-walled structures under high heat flux density has become the key issue restricting the normal operation and structural stability of scramjet engine systems.

[0003] In order to improve the shape-keeping ability of thin-walled structures, reinforced thin-walled structures are often used in the main load-bearing components of aerospace structures. By utilizing their characteristics such as high specific stiffness and high specific strength, on the one hand, the bending stiffness of the plate and shell structure is increased to improve the bearing capacity, and on the other hand, the reliability of the structure is improved by increasing its equivalent thickness to reduce the sensitivity to initial defects.

[0004] By arranging fluid channels inside structures that are subjected to high heat flux density, part of the heat carried by the structure can be removed by the circulation of cooling medium in the flow channel. The structure can be cooled to a lower temperature range while keeping the external heat flux density unchanged. This is a common method to reduce thermal deformation of thin-walled structures and ensure the normal operation of the system in a high temperature environment.

[0005] The existing reinforced structure and active cooling structure are located on the surface and inside of the thin-walled structure respectively, and the design methods of the reinforced structure and the active cooling structure separately are difficult to fully consider the coupling effect, which will also complicate the design. Therefore, it is urgent to propose a load-bearing / heat-dissipating integrated configuration and design a set of structures that meet multiple functions, that is, to ensure the lightweight requirements of the structure and reduce the design complexity, and to establish a dynamic control mechanism based on the integrated structure, so that the reinforced thin-walled structure can meet the complex working requirements under a wide Mach number, and further realize the maximum load-bearing and lightweight design of the scramjet engine. Summary of the invention

[0006] In view of the deficiencies in the above-mentioned prior art, the present invention provides a method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure, which can enable the reinforced thin-walled structure to achieve maximum load-bearing and lightweight design of the engine while meeting complex working requirements under a wide Mach number.

[0007] To achieve the above object, the present invention provides a method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure, comprising the following steps: Step 1: A hollow grid-type reinforcement is used for the thin-walled structure of the engine, and a coolant is introduced into the ribs to absorb heat as an active cooling structure, while the reinforcement configuration and the internal pressure of the channel jointly provide bearing capacity; Step 2, taking the coolant inlet flow rate and coolant outlet pressure in the stiffened thin-walled structure as design variables, and minimizing the flexibility of the stiffened thin-walled structure and the coolant inlet and outlet pressure drop as the objective function, constructing an optimization model that meets the constraints; Step 3, establishing a geometric model of the reinforced thin-walled structure, and randomly obtaining initial values ​​of the design variables; Step 4, under the current design variables, solving the control equations to obtain the physical fields of the coolant and the reinforced thin-walled structure; Step 5, based on the solved physical field, the objective function and constraint function are calculated respectively, including the flexibility of the reinforced thin-walled structure, the coolant inlet and outlet pressure drop, and the maximum temperature of the reinforced thin-walled structure; Step 6, using a multi-objective optimization algorithm to optimize the objective function, obtain the flexibility of the optimized reinforced thin-walled structure and the coolant inlet and outlet pressure drop, and determine whether the convergence condition is met: If so, obtain the Pareto optimal solution set; Otherwise, return to step 4; Step 7: determine the optimal Pareto solution based on the Pareto optimization solution set, and use the design variables corresponding to the optimal Pareto solution as the optimal control parameters under the current working conditions.

[0008] In one embodiment, in step 2, the optimization model is specifically:

[0009]

[0010]

[0011]

[0012]

[0013]

[0014] in, is the design variable, is the coolant inlet flow rate, is the coolant outlet pressure, is the coolant inlet pressure, is the pressure drop of the coolant inlet and outlet cross sections, is the flexibility of the reinforced thin-walled structure, is the equivalent nodal load acting on the stiffened thin-walled structure, is the structural displacement, is the maximum temperature of the reinforced thin-walled structure, is the upper temperature limit of the reinforced thin-walled structure, , are the minimum and maximum coolant inlet flow rates, , are the minimum and maximum coolant outlet pressures.

[0015] In one embodiment, in step 4, the physical field includes the temperature field, velocity field and pressure field of the fluid domain corresponding to the coolant, and the temperature field and displacement field of the solid domain corresponding to the reinforced thin-walled structure.

[0016] In one embodiment, the calculation process of the physical field is specifically as follows: Based on the mass, momentum and energy equations, the temperature field, velocity field and pressure field distribution of the fluid domain are calculated as follows:

[0017]

[0018]

[0019] in, Represents the X, Y, and Z directions respectively. , is the coolant fluid velocity component, is the temperature field of the fluid domain; is the pressure difference force field, are the density, dynamic viscosity, specific heat capacity and thermal conductivity of the fluid respectively; The temperature field in the solid domain is calculated by the heat conduction differential equation without the heat source term, which is:

[0020] in, is the solid thermal conductivity, is the temperature field in the solid domain.

[0021] The fluid-solid interface follows the following relationship:

[0022]

[0023] The displacement field of the solid domain is calculated using the governing equations of the thermoelastic structure, which is:

[0024]

[0025]

[0026] in, represents the stress coefficient due to thermal expansion, is the material linear expansion coefficient; U is the structural displacement; are body force, body strain, stress, and shear strain respectively, G is the shear elastic modulus, is the Lame coefficient, is the Kronecker symbol, which is defined as .

[0027] In one embodiment, in step 4, the maximum temperature of the reinforced thin-walled structure is calculated according to the aggregation function as follows:

[0028] in, For the reinforced thin-walled structure The node temperature, is the number of nodes, is the aggregation coefficient.

[0029] In one embodiment, in step 6, the convergence condition is: The objective function value changes less than 1e-4 in the last three iterations; or The number of iterations exceeds 200.

[0030] In one embodiment, in step 6, the objective function is optimized using the NSGA-II optimization algorithm.

[0031] In one embodiment, in step 7, the optimal Pareto solution is determined using a minimum distance method.

[0032] Compared with the prior art, the present invention has the following beneficial technical effects: 1. The present invention reduces the mass of the reinforced thin-walled structure through the hollow reinforced configuration, thereby realizing the lightweight design of the engine. At the same time, the adverse effect of high heat flux density on the shape-keeping ability of the reinforced thin-walled structure is reduced by introducing a cooling medium, and the loss of bearing capacity caused by the reduction of materials is compensated, thereby realizing the maximum load-bearing capacity and lightweight design of the engine; 2. The present invention optimizes the optimal flow parameters of the cooling medium in the reinforced thin-walled structure so that the reinforced thin-walled structure can meet the working requirements under multiple working conditions and effectively improve the adaptability of the reinforced thin-walled structure under a wide Mach number. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0034] Figure 1An example diagram of a reinforced thin-walled structure according to an embodiment of the present invention; Figure 2 Flow chart of a method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure in an embodiment of the present invention.

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] This embodiment discloses a method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure, which reduces the mass of the reinforced thin-walled structure through a hollow reinforced configuration, thereby achieving a lightweight design of the engine. At the same time, the introduction of a cooling medium reduces the adverse effect of high heat flux density on the conformal ability of the reinforced thin-walled structure, and compensates for the loss of load-bearing capacity caused by material reduction, thereby achieving maximum load-bearing and lightweight design of the engine. Figure 1 What is shown is a reinforced thin-walled structure corresponding to a plane rectangular domain in the engine isolation section. The four sides of the bottom are fixedly constrained by hollow ribs, the middle part is grid-type reinforcement, the grid angle is 90°, the ribs are interconnected, and the two ends are the coolant inlet and coolant outlet respectively.

[0039] refer to Figure 2 The dynamic control method of the lightweight engine load-bearing / heat-dissipating integrated structure in this embodiment specifically includes the following steps: Step 1: A hollow grid-type reinforcement is used for the thin-walled structure of the engine, and a coolant is introduced into the ribs to absorb heat as an active cooling structure, while the reinforcement configuration and the internal pressure of the channel jointly provide bearing capacity; Step 2, taking the coolant inlet flow rate and coolant outlet pressure in the stiffened thin-walled structure as design variables, and minimizing the flexibility of the stiffened thin-walled structure and the coolant inlet and outlet pressure drop as the objective function, constructing an optimization model that meets the constraints; Step 3, establishing a geometric model of the reinforced thin-walled structure and randomly obtaining initial values ​​of the design variables; Step 4, under the current design variables, obtain the physical fields of the coolant and the reinforced thin-walled structure based on the control equations; Step 5, based on the solved physical field, the objective function and constraint function are calculated respectively, including the flexibility of the reinforced thin-walled structure, the coolant inlet and outlet pressure drop, and the maximum temperature of the reinforced thin-walled structure; Step 6: Use a multi-objective optimization algorithm to optimize the objective function, obtain the flexibility of the optimized reinforced thin-walled structure and the coolant inlet and outlet pressure drop, and determine whether the convergence conditions are met: If so, obtain the Pareto optimal solution set; Otherwise, return to step 4; Step 7: determine the optimal Pareto solution based on the Pareto optimization solution set, and use the design variables corresponding to the optimal Pareto solution as the optimal control parameters under the current working conditions.

[0040] In the specific implementation process of step 2, the optimization model is specifically:

[0041]

[0042]

[0043]

[0044]

[0045]

[0046] in, is the design variable, is the coolant inlet flow rate, is the coolant outlet pressure, is the transpose of the matrix, which is, is the flexibility of the reinforced thin-walled structure, is the equivalent nodal load acting on the stiffened thin-walled structure, is the displacement of the reinforced thin-walled structure, is the maximum temperature of the reinforced thin-walled structure, is the upper temperature limit of the stiffened thin-walled structure (i.e. the allowable temperature of the material of the stiffened thin-walled structure or a predefined value less than the allowable temperature), , are the minimum and maximum coolant inlet flow rates, , are the minimum and maximum coolant outlet pressures.

[0047] In this embodiment, the physical fields of the coolant and the reinforced thin-walled structure include the temperature field, velocity field and pressure field of the fluid domain corresponding to the coolant, and the temperature field and displacement field of the solid domain corresponding to the reinforced thin-walled structure. The calculation process is as follows: First, the temperature field, velocity field, and pressure field distribution of the fluid domain are calculated based on the mass, momentum, and energy equations:

[0048]

[0049]

[0050] in, Represents the X, Y, and Z directions respectively. , is the coolant fluid velocity component, is the temperature field of the fluid domain; is the pressure difference force field, are the density, dynamic viscosity, specific heat capacity and thermal conductivity of the fluid respectively; Then, the temperature field in the solid domain is calculated by the heat conduction differential equation without the heat source term, which is:

[0051] in, is the solid thermal conductivity, is the temperature field in the solid domain.

[0052] The fluid-solid interface follows the following relationship:

[0053]

[0054] The displacement field of the solid domain is calculated using the governing equations of the thermoelastic structure, which is:

[0055]

[0056]

[0057] in, represents the stress coefficient due to thermal expansion, is the material linear expansion coefficient; U is the structural displacement; are body force, body strain, stress, and shear strain respectively, G is the shear elastic modulus, is the Lame coefficient, is the Kronecker symbol, which is defined as .

[0058] After obtaining the pressure field of the fluid domain, the pressure drop of the coolant inlet and outlet cross section in the objective function can be obtained. , and the flexibility of the reinforced thin-walled structure in the objective function can be obtained according to the displacement field of the solid domain. In addition, the maximum temperature of the reinforced thin-walled structure in the constraint function can be obtained according to the temperature field of the solid domain. This embodiment calculates the maximum temperature of the reinforced thin-walled structure according to the aggregation function, specifically:

[0059] in is the maximum temperature of the reinforced thin-walled structure, For the reinforced thin-walled structure The node temperature, is the number of nodes, is the aggregation coefficient; In the specific implementation process of step 6, the NSGA-II optimization algorithm is used to optimize the objective function, and its convergence condition is that the change of the objective function value in the last three iterations is less than 1e-4 or the number of iterations exceeds 200. It is worth noting that in the specific application process, it is not limited to the use of the NSGA-II optimization algorithm, and other optimization algorithms, such as the moving asymptote method, can also be used.

[0060] In the specific implementation process of step 7, the minimum distance method is used to determine the optimal Pareto solution, that is, ,in, is the minimum distance.

[0061] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure, characterized in that: The steps include: Step 1: A hollow grid-type reinforcement is used for the thin-walled structure of the engine, and a coolant is introduced into the ribs to absorb heat as an active cooling structure, while the reinforcement configuration and the internal pressure of the channel jointly provide bearing capacity; Step 2, taking the coolant inlet flow rate and coolant outlet pressure in the stiffened thin-walled structure as design variables, and minimizing the flexibility of the stiffened thin-walled structure and the coolant inlet and outlet pressure drop as the objective function, constructing an optimization model that meets the constraints; Step 3, establishing a geometric model of the reinforced thin-walled structure, and randomly obtaining initial values ​​of the design variables; Step 4, under the current design variables, solving the control equations to obtain the physical fields of the coolant and the reinforced thin-walled structure; Step 5, based on the solved physical field, the objective function and constraint function are calculated respectively, including the flexibility of the reinforced thin-walled structure, the coolant inlet and outlet pressure drop, and the maximum temperature of the reinforced thin-walled structure; Step 6, using a multi-objective optimization algorithm to optimize the objective function, obtain the flexibility of the optimized reinforced thin-walled structure and the coolant inlet and outlet pressure drop, and determine whether the convergence condition is met: If so, obtain the Pareto optimal solution set; Otherwise, return to step 4; Step 7: determine the optimal Pareto solution based on the Pareto optimization solution set, and use the design variables corresponding to the optimal Pareto solution as the optimal control parameters under the current working conditions.

2. The method for dynamic control of a lightweight engine load-bearing / heat-dissipating integrated structure according to claim 1, characterized in that: In step 2, the optimization model is specifically: in, is the design variable, is the coolant inlet flow rate, is the coolant outlet pressure, is the coolant inlet pressure, is the pressure drop of the coolant inlet and outlet cross sections, is the flexibility of the reinforced thin-walled structure, is the equivalent nodal load acting on the stiffened thin-walled structure, is the structural displacement, is the maximum temperature of the reinforced thin-walled structure, is the upper temperature limit of the reinforced thin-walled structure, , are the minimum and maximum coolant inlet flow rates, , are the minimum and maximum coolant outlet pressures.

3. The dynamic control method of the lightweight engine load-bearing / heat-dissipating integrated structure according to claim 1 or 2, characterized in that: In step 4, the physical field includes the temperature field, velocity field and pressure field of the fluid domain corresponding to the coolant, and the temperature field and displacement field of the solid domain corresponding to the reinforced thin-walled structure.

4. The method for dynamic control of a lightweight engine load-bearing / heat-dissipating integrated structure according to claim 3, characterized in that: The calculation process of the physical field is specifically as follows: Based on the mass, momentum and energy equations, the temperature field, velocity field and pressure field distribution of the fluid domain are calculated as follows: in, Represents the X, Y, and Z directions respectively. , is the coolant fluid velocity component, is the temperature field of the fluid domain; is the pressure difference force field, are the density, dynamic viscosity, specific heat capacity and thermal conductivity of the fluid respectively; The temperature field in the solid domain is calculated by the heat conduction differential equation without the heat source term, which is: in, is the thermal conductivity of the solid, is the temperature field in the solid domain. The fluid-solid interface follows the following relationship: The displacement field of the solid domain is calculated using the governing equations of the thermoelastic structure, which is: in, represents the stress coefficient due to thermal expansion, is the material linear expansion coefficient; U is the structural displacement; are body force, body strain, stress, and shear strain respectively, G is the shear elastic modulus, is the Lame coefficient, is the Kronecker symbol, which is defined as .

5. The method for dynamic control of a lightweight engine load-bearing / heat-dissipating integrated structure according to claim 4, characterized in that: In step 4, the maximum temperature of the reinforced thin-walled structure is calculated according to the aggregation function, which is: in, For reinforced thin-walled structures The node temperature, is the number of nodes, is the aggregation coefficient.

6. The method for dynamic control of a lightweight engine load-bearing / heat-dissipating integrated structure according to claim 1 or 2, characterized in that: In step 6, the convergence condition is: The objective function value changes less than 1e-4 in the last three iterations; or The number of iterations exceeds 200.

7. The method for dynamic control of a lightweight engine load-bearing / heat-dissipating integrated structure according to claim 1 or 2, characterized in that: In step 6, the objective function is optimized using the NSGA-II optimization algorithm.

8. The method for dynamic control of a lightweight engine load-bearing / heat-dissipating integrated structure according to claim 1 or 2, characterized in that: In step 7, the optimal Pareto solution is determined using the minimum distance method.

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