A dynamic control method for a lightweight engine load-bearing / heat-dissipating integrated structure

Abstract

The present invention discloses a method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure, comprising: employing hollow grid-like reinforcements on the thin-walled structure of the engine, and introducing coolant into the ribs to serve as an active cooling structure to absorb heat; constructing an optimization model using the coolant inlet flow rate and coolant outlet pressure in the reinforced thin-walled structure as design variables, and minimizing the flexibility and pressure drop of the reinforced thin-walled structure as the objective function; calculating the physical fields of the coolant and the reinforced thin-walled structure, and calculating the objective function and constraint function; performing multi-objective optimization using a multi-objective optimization algorithm to obtain a Pareto optimization solution set; and selecting the optimal Pareto solution to obtain the optimal solution and its corresponding design variables as the optimal control parameters. The present invention is applicable to the field of engine design, and can enable the reinforced thin-walled structure to achieve maximum load-bearing capacity and lightweight design of the engine while meeting complex operating requirements under a wide Mach number.

Description

Technical Field

[0001] The present 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 bearing capacity is improved by increasing the bending stiffness of the plate and shell structure, 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 subjected to high heat flux density, the circulation of cooling fluid in the channels removes part of the heat carried by the structure. This allows the structure to be cooled to a lower temperature range while maintaining the external heat flux density. This is a common method for reducing thermal deformation of thin-walled structures and ensuring the normal operation of the system in high-temperature environments.

[0005] The existing reinforced structure and active cooling structure are located on the surface and inside of the thin-walled structure respectively. In addition, the design methods of the reinforced structure and the active cooling structure separately make it difficult to fully consider the coupling effect, which will also complicate the design. Therefore, it is urgent to propose an integrated load-bearing / heat-dissipating configuration and design a set of structures that meet multiple functions, that is, to ensure the lightweight structure requirements and reduce the design complexity. Based on the integrated structure, a dynamic control mechanism should be established to enable the reinforced thin-walled structure to 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 response to the above-mentioned deficiencies in the prior art, the present invention provides a method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure, which enables the reinforced thin-walled structure to maximize the engine's load-bearing capacity and achieve lightweight design while meeting complex working requirements under a wide Mach number.

[0007] To achieve the above objectives, the present invention provides a method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure, comprising the following steps:

[0008] Step 1: Use hollow grid-like reinforcements on the thin-walled structure of the engine, and pass coolant through the ribs to act as an active cooling structure to absorb heat. At the same time, the reinforcement configuration and the internal pressure of the channel jointly provide bearing capacity;

[0009] Step 2: Using 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, a constrained optimization model is constructed;

[0010] Step 3: establishing a geometric model of the reinforced thin-walled structure and randomly obtaining initial values ​​of the design variables;

[0011] Step 4, obtaining the physical fields of the coolant and the reinforced thin-walled structure based on the control equations under the current design variables;

[0012] Step 5: Calculate the objective function and constraint functions based on the solved physical field, 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;

[0013] Step 6: Optimize the objective function using a multi-objective optimization algorithm to 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:

[0014] If so, obtain the Pareto optimal solution set;

[0015] Otherwise, return to step 4;

[0016] 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.

[0017] In one embodiment, in step 2, the optimization model is specifically:

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024] 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 reinforced 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.

[0025] 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.

[0026] In one embodiment, the calculation process of the physical field is specifically as follows:

[0027] The temperature field, velocity field, and pressure field distribution of the fluid domain are calculated based on the mass, momentum, and energy equations:

[0028]

[0029]

[0030]

[0031] in, Represents 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;

[0032] The temperature field in the solid domain is calculated by the heat conduction differential equation without the heat source term, which is:

[0033]

[0034] in, is the solid thermal conductivity, is the temperature field in the solid domain.

[0035] The fluid-solid interface follows the following relationship:

[0036]

[0037]

[0038] The displacement field of the solid domain is calculated using the governing equations of the thermoelastic structure, which is:

[0039]

[0040]

[0041]

[0042] 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 .

[0043] In one embodiment, in step 4, the maximum temperature of the reinforced thin-walled structure is calculated according to the aggregation function, which is:

[0044]

[0045] in, For reinforced thin-walled structures Node temperature, is the number of nodes, is the aggregation coefficient.

[0046] In one embodiment, in step 6, the convergence condition is:

[0047] The objective function value changes less than 1e-4 in the last three iterations; or

[0048] The number of iterations exceeds 200.

[0049] In one embodiment, in step 6, the objective function is optimized using the NSGA-II optimization algorithm.

[0050] In one embodiment, in step 7, the optimal Pareto solution is determined using a minimum distance method.

[0051] Compared with the prior art, the present invention has the following beneficial technical effects:

[0052] 1. This invention reduces the mass of the reinforced thin-walled structure through a hollow reinforced configuration, thereby achieving a lightweight engine design. Simultaneously, the introduction of a cooling medium reduces the adverse effects of high heat flux on the conformal ability of the reinforced thin-walled structure and compensates for the loss of load-bearing capacity caused by reduced material, thereby achieving maximum load-bearing capacity and lightweight design for the engine.

[0053] 2. The present invention optimizes the flow parameters of the cooling medium in the reinforced thin-walled structure to enable the reinforced thin-walled structure to 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

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0055] Figure 1 This is an example diagram of a reinforced thin-walled structure according to an embodiment of the present invention;

[0056] Figure 2 Flowchart of a method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure in an embodiment of the present invention.

[0057] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0058] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0059] 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 this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0060] This embodiment discloses a method for dynamically controlling a lightweight engine load-bearing / heat-dissipating integrated structure. By reducing the mass of the reinforced thin-walled structure through a hollow reinforced configuration, the lightweight design of the engine is achieved. At the same time, the introduction of a cooling medium reduces the adverse effects of high heat flux 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 1The figure shows a reinforced thin-walled structure corresponding to a planar rectangular domain in the engine isolation section. The four sides of the bottom are fixedly constrained by hollow ribs. The middle part is reinforced with a grid-like structure with a 90° grid angle. The ribs are interconnected, and the two ends are the coolant inlet and coolant outlet, respectively.

[0061] 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:

[0062] Step 1: Use hollow grid-like reinforcements on the thin-walled structure of the engine, and pass coolant through the ribs to act as an active cooling structure to absorb heat. At the same time, the reinforcement configuration and the internal pressure of the channel jointly provide bearing capacity;

[0063] Step 2: Using 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, a constrained optimization model is constructed;

[0064] Step 3: Establish a geometric model of the reinforced thin-walled structure and randomly obtain the initial values ​​of the design variables;

[0065] Step 4: Under the current design variables, the physical fields of the coolant and the reinforced thin-walled structure are obtained based on the control equations.

[0066] Step 5: Calculate the objective function and constraint functions based on the solved physical field, 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;

[0067] 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:

[0068] If so, obtain the Pareto optimal solution set;

[0069] Otherwise, return to step 4;

[0070] 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.

[0071] In the specific implementation process of step 2, the optimization model is specifically as follows:

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078] 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 reinforced 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 lower than the allowable temperature), 、 are the minimum and maximum coolant inlet flow rates, 、 are the minimum and maximum coolant outlet pressures.

[0079] 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:

[0080] First, the temperature field, velocity field, and pressure field distribution of the fluid domain are calculated based on the mass, momentum, and energy equations, which are:

[0081]

[0082]

[0083]

[0084] in, Represents 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;

[0085] The temperature field in the solid domain is then calculated using the heat conduction differential equation without the heat source term, as:

[0086]

[0087] in, is the solid thermal conductivity, is the temperature field in the solid domain.

[0088] The fluid-solid interface follows the following relationship:

[0089]

[0090]

[0091] The displacement field of the solid domain is calculated using the governing equations of the thermoelastic structure, which is:

[0092]

[0093]

[0094]

[0095] 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 .

[0096] After obtaining the pressure field of the fluid domain, the pressure drop of the coolant inlet and outlet sections in the objective function can be obtained. At the same time, the flexibility of the reinforced thin-walled structure in the objective function can be obtained based on 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 based on the temperature field of the solid domain. This embodiment calculates the maximum temperature of the reinforced thin-walled structure based on the aggregation function, specifically:

[0097]

[0098] in is the maximum temperature of the reinforced thin-walled structure, For reinforced thin-walled structures Node temperature, is the number of nodes, is the aggregation coefficient;

[0099] In the specific implementation of step 6, the NSGA-II optimization algorithm is used to optimize the objective function. The convergence condition is that the change in 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 the specific application process is not limited to the NSGA-II optimization algorithm. Other optimization algorithms, such as the moving asymptote method, can also be used.

[0100] 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.

[0101] 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 transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application 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: Use hollow grid-like reinforcements on the thin-walled structure of the engine, and pass coolant through the ribs to act as an active cooling structure to absorb heat. At the same time, the reinforcement configuration and the internal pressure of the channel jointly provide bearing capacity; Step 2: Using 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, a constrained optimization model is constructed; Step 3: establishing a geometric model of the reinforced thin-walled structure and randomly obtaining initial values ​​of the design variables; Step 4, obtaining the physical fields of the coolant and the reinforced thin-walled structure based on the control equations under the current design variables; Step 5: Calculate the objective function and constraint functions based on the solved physical field, 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: Optimize the objective function using a multi-objective optimization algorithm to 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.

2. The dynamic control method of the 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 reinforced 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 fields 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.

4. The dynamic control method of the 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: The temperature field, velocity field, and pressure field distribution of the fluid domain are calculated based on the mass, momentum, and energy equations: in, Represents 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 solid thermal conductivity, is the temperature field of 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 dynamic control method of the 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 based on the aggregation function, which is: in, For reinforced thin-walled structures Node temperature, is the number of nodes, is the aggregation coefficient.

6. 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 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 dynamic control method of the 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 dynamic control method of the 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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