Pre-cooler matching simulation analysis method, system and application of air inlet channel

Abstract

This invention belongs to the interdisciplinary field of aerospace engineering and computational fluid dynamics (CFD). It discloses a simulation analysis method, system, and application for matching a precooler and an inlet. The method uses porous media theory to perform equivalent modeling of the precooler, applying an equivalent flow resistance source term within the computational domain to simulate the pressure loss of air flowing through the precooler. Based on the periodic symmetry of the precooler structure, the computational domain is truncated, and representative elements are selected for simulation analysis. An engineering-based rapid estimation method is employed, iteratively calculating the heat exchange between the cooling medium within the precooler and the air in the inlet, providing an energy source term for the porous media model to simulate the change in flow resistance caused by air temperature variations. Based on equivalent modeling, computational domain truncation, and heat exchange estimation, aerodynamic-thermal coupling analysis of the precooler and inlet matching is achieved. This invention significantly reduces computational resource requirements and improves simulation efficiency while maintaining computational accuracy, providing theoretical support for engineering design and optimization.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of aerospace engineering and computational fluid dynamics (CFD), and in particular relates to a simulation analysis method, system and application for matching precoolers and air inlets, which can be used for the optimization of advanced aerospace equipment such as hypersonic vehicles, ramjet engines or combined cycle engines. Background Technology

[0002] With the rapid development of aerospace technology, the performance requirements of high-speed aircraft are increasing. However, when aircraft fly at high Mach numbers, the high stagnation temperature at the engine inlet can adversely affect the engine. Installing a pre-cooling heat exchange device in the engine inlet can, on the one hand, reduce the airflow temperature at the engine inlet, improving the working environment of various engine components and alleviating the problem of high-temperature protection of the engine body; on the other hand, it can increase the intake air density, thereby increasing thrust and widening the engine's operating range. Pre-cooling technology can effectively reduce the temperature of the high-temperature airflow in the inlet, improving the engine's efficiency and stability.

[0003] However, the introduction of the precooler makes the flow and heat transfer processes inside the air intake more complex. Its complex structure and multi-physics coupling characteristics (such as aerodynamics, heat transfer, and chemical reactions of the cooling medium) lead to problems such as large computational load, difficulty in convergence, and low efficiency in traditional numerical simulation methods. Currently, there is still a lack of efficient and high-precision simulation methods for the integrated design of the precooler and air intake, which seriously restricts the optimization and performance improvement of high-speed aircraft propulsion systems and results in long development cycles and high costs.

[0004] Based on the above analysis, the problems and shortcomings of the existing technology are as follows:

[0005] (1) If experimental measurement methods are used to study the flow and heat transfer process in the intake duct with precooler, the development cost of the experimental platform is high, and it is difficult to carry out full physical field measurement under high Mach number intake conditions.

[0006] (2) If CFD calculation is used to numerically simulate the actual precooler structure and physical process, the traditional numerical simulation method faces problems such as large computational scale, low efficiency and difficulty in convergence due to the complex structure of the precooler and the strong multi-physics coupling characteristics of the internal flow heat transfer.

[0007] (3) At present, there is a lack of solutions that can significantly improve simulation efficiency while ensuring engineering accuracy. This seriously restricts the optimization design of high-speed aircraft power systems, resulting in long R&D cycles and high costs. Summary of the Invention

[0008] To overcome the problems of complex structure of precoolers in the air intake of high-speed aircraft engines, large computational scale, low efficiency, and difficulty in convergence in traditional numerical simulations, this invention discloses a simulation analysis method, system, and application for matching precoolers and air intakes. The technical solution is as follows:

[0009] This invention is achieved by using a simulation analysis method for matching the precooler and the inlet duct. This method constructs a three-in-one collaborative simulation framework integrating porous media equivalent, periodic domain interception, and heat transfer iterative coupling, resulting in a significant improvement in the analysis accuracy and efficiency of bidirectional flow-thermal coupling between the precooler and the inlet duct. Specifically, it includes the following steps:

[0010] S1. Equivalent Modeling: The precooler is modeled equivalently based on porous media theory. By applying an equivalent flow resistance source term in the computational domain, the pressure loss of air flowing through the precooler is simulated.

[0011] S2. Computational Domain Extraction: Based on the periodic symmetry of the precooler structure, the computational domain of the precooler structure is extracted, and representative elements are selected for simulation analysis to reduce the computational scale.

[0012] S3. Heat exchange estimation: An engineering rapid estimation method is adopted to iteratively calculate the heat exchange between the cooling medium in the precooler and the air in the intake duct, and to provide an energy source term for the porous medium model to simulate the change in flow resistance caused by changes in air temperature.

[0013] S4. Precooler and Inlet Matching Simulation Analysis: Based on the equivalent modeling, computational domain truncation and heat transfer estimation, the aerodynamic-thermal coupling analysis of the precooler and intake matching is realized.

[0014] In step S1, the actual complex structure of the precooler is simplified to a porous medium, which includes a multi-layer structure, each layer having a different viscous drag coefficient and inertial drag coefficient.

[0015] Furthermore, the multilayer structure includes an outermost layer, a middle layer, and an innermost layer, each layer having different drag coefficients in the axial and radial flow directions, the drag coefficients being determined through experiments or high-precision simulations.

[0016] Furthermore, the drag coefficient includes a viscous drag coefficient and an inertial drag coefficient, the values ​​of which are calibrated based on the actual structural parameters of the precooler and used for the calculation of the momentum loss source term of the porous medium model.

[0017] The drag coefficient is configured as follows:

[0018] The viscous drag coefficient of the outermost layer in the axial direction is 78176.6964 m. -2 The inertial drag coefficient is 0.7877m. -1The radial viscous drag coefficient is 316487.6804 m. -2 The inertial drag coefficient is 8.5612m. -1 ;

[0019] The viscous drag coefficient of the intermediate layer in the axial direction is 102586.1226m. -2 The inertial drag coefficient is 0.8644m. -1 The radial viscous drag coefficient is 724586.5614 m. -2 The inertial drag coefficient is 10.1091m. -1 ;

[0020] The axial viscous drag coefficient of the innermost layer is 277624.8770 m. -2 The inertial drag coefficient is 2.2306m. -1 The radial viscous drag coefficient is 704620.5663m. -2 The inertial drag coefficient is 16.5140m. -1 .

[0021] Furthermore, in the computational domain interception step, the flow field inside and outside the precooler pipe and the coupled heat transfer calculation adopt a spiral interception method to ensure that the intercepted model has periodicity, and set periodic boundary conditions so that the flow variables follow a rotational relationship on the paired boundaries.

[0022] Furthermore, in the heat exchange estimation step, the rapid engineering estimation method includes:

[0023] The flow rate of air entering the precooling section and the total inlet temperature are used as known conditions for the air-side heat transfer calculation, and the flow rate of cooling medium entering the precooler and the inlet temperature are used as known conditions for the cooling medium-side heat transfer inside the pipe.

[0024] Estimate the heat exchange capacity, calculate the outlet temperatures of the air and cooling medium, and calculate the qualitative temperatures during the heat exchange process of the air and cooling medium respectively;

[0025] The relationship between heat exchange and outlet temperature is as follows:

[0026]

[0027] In the formula, For the estimated heat exchange between the precooler and the air, Air mass flow rate, The specific heat capacity of air, and These are the temperatures of the air at the inlet and outlet of the precooling section, respectively.

[0028] The qualitative temperature is:

[0029]

[0030] In the formula, The average temperature of the air is used as the qualitative temperature;

[0031] Based on qualitative temperature, the physical properties of air and cooling medium are obtained. Based on empirical relationships between external tube bundle convective heat transfer and internal tube convective heat transfer, the average convective heat transfer coefficient between air and the outer surface of the precooler, the average convective heat transfer coefficient between the cooling medium and the inner surface of the precooler, and the overall heat transfer coefficient are calculated.

[0032] The empirical relationship for convective heat transfer in externally swept tube bundles is:

[0033]

[0034] In the formula, These are the Reynolds number, Prandtl number, and Nusselt number for air, respectively.

[0035] The average convective heat transfer coefficient between the air and the outer surface of the precooler is:

[0036]

[0037] In the formula, The thermal conductivity of air. The outer diameter of the precooler pipe. The average convective heat transfer coefficient between the air and the outer surface of the precooler;

[0038] The empirical relationship for convective heat transfer inside a pipe is:

[0039]

[0040] In the formula, These are the Reynolds number, Prandtl number, and Nusselt number of LAM, respectively.

[0041] The average convective heat transfer coefficient between the cooling medium and the inner surface of the precooler is:

[0042]

[0043] In the formula, The thermal conductivity of air. This refers to the inner diameter of the precooler pipe. The average convective heat transfer coefficient between the LAM and the inner surface of the precooler;

[0044] The formula for calculating the overall heat transfer coefficient is:

[0045]

[0046] The heat transfer is calculated by the average logarithmic temperature difference inside and outside the precooler, the overall heat transfer coefficient and the heat transfer area of ​​the precooler, and iteratively compared with the estimated heat transfer until the heat balance relationship is satisfied.

[0047] The logarithmic mean temperature difference is:

[0048]

[0049] In the formula, These are the temperatures of LAM at the inlet and outlet of the precooler, respectively.

[0050] The heat exchange is:

[0051]

[0052] In the formula, To calculate the heat exchange, This refers to the heat exchange area.

[0053] Furthermore, in the iterative calculation, the calculated heat exchange... As a new estimate Perform iterations, when When the convergence rate is less than the preset convergence threshold of 0.1%, it is determined that the thermal balance relationship is satisfied, thereby determining the final heat exchange between the precooler and the intake duct.

[0054] Another objective of this invention is to provide an application of the aforementioned simulation analysis method for matching the precooler and the air intake in the design of the air intake of a high-speed aircraft engine, wherein the design of the high-speed aircraft engine air intake includes hypersonic aircraft, ramjet engines, or combined cycle engines.

[0055] Another object of the present invention is to provide a precooler and inlet matching simulation analysis system for implementing the aforementioned precooler and inlet matching simulation analysis method, comprising:

[0056] The equivalent modeling module is used to model the precooler based on porous media theory. It simulates the pressure loss of air flowing through the precooler by applying an equivalent flow resistance source term in the computational domain.

[0057] The computational domain extraction module is used to extract the computational domain of the precooler structure based on the periodic symmetry of the precooler structure, select representative elements for simulation analysis, and reduce the computational scale.

[0058] The heat exchange estimation module is used to calculate the heat exchange between the cooling medium in the precooler and the air in the intake duct by iteratively using a rapid engineering estimation method, and to simulate the change in flow resistance caused by changes in air temperature.

[0059] The coupling analysis module is used to perform aerodynamic-thermal coupling analysis of the precooler and the intake duct based on the equivalent modeling, computational domain truncation and heat transfer estimation.

[0060] The equivalent modeling module, the computational domain interception module, the heat exchange estimation module, and the coupling analysis module are implemented by the processor executing computer program instructions stored in the memory.

[0061] Furthermore, the system is integrated into the digital design platform of high-speed aircraft engines, and is used to quickly evaluate and optimize the selection of air intake schemes that include precoolers.

[0062] Combining all the above technical solutions, the beneficial effects of this invention are as follows:

[0063] First, this invention establishes a highly efficient simulation analysis method system for matching precoolers and air intakes. This system significantly reduces computational resource requirements and improves simulation efficiency while ensuring computational accuracy, providing reliable theoretical support for engineering design and optimization. This method system mainly includes the following three key technologies:

[0064] (1) An equivalent modeling method for precoolers based on porous media theory simplifies the actual complex structure of the precooler into a porous medium. By applying an equivalent resistance source term to the precooler region in the inlet duct, the pressure loss of air flowing through the precooler is simulated. This method can significantly reduce the mesh size (from 10). 8 The magnitude was reduced to 10 6 (Scale), suitable for large-scale numerical simulation calculations of different structures and multiple operating conditions.

[0065] (2) The computational domain truncation and simplification method based on periodic symmetry utilizes the periodic characteristics of the precooler structure to select a single representative element for refined simulation analysis. This reduces the computational scale while ensuring computational accuracy, and can save computational resources for three-dimensional numerical simulation based on the actual structure of the precooler to a certain extent (mesh size from 10). 8 The magnitude was reduced to 10 7 (At the order of magnitude), the calculation results can provide a basis for model verification and accuracy checking for other simplified calculation methods and engineering estimation results.

[0066] (3) A rapid estimation method for heat exchange in precoolers: a theoretical model of heat exchange between the cooling medium in the precooler and the air in the inlet is established. Through iterative calculation, the flow heat exchange effect and heat exchange of the given model under different inlet flow conditions and different precooler operating parameters are estimated. The heat exchange results can provide an energy source term for the calculation of porous media modeling method applicable to precoolers, and then simulate the change in flow resistance caused by air temperature change when matching precooler-inlet.

[0067] Ultimately, based on the above three methods and their interrelationships, this invention forms a complete methodological system. This system can significantly improve the aerodynamic-thermal coupling analysis efficiency of the precooler and inlet matching study while meeting engineering accuracy requirements. It lays the theoretical and methodological foundation for efficiently evaluating the inlet flow resistance performance considering the precooler under certain accuracy conditions, and provides important technical support for the optimized design of high-speed aircraft power systems.

[0068] Secondly, the simulation analysis method system for matching the precooler and the air inlet established in this invention significantly improves the computational efficiency of complex flow-heat transfer coupling problems through methods such as equivalent modeling of porous media, geometric model simplification, and engineering estimation, while ensuring the reliability of simulation results. This invention formulates strategies to improve the computational efficiency of matching the precooler and the air inlet, which not only provides theoretical support for the integrated design of the precooler and the air inlet, but also shortens the development cycle of the engine intake system and reduces testing costs. This has significant engineering value for promoting the development of advanced aerospace equipment such as hypersonic vehicles, ramjet engines, and combined cycle engines.

[0069] Third, the technical solution of this invention, by establishing an efficient simulation analysis method system for matching precoolers and air inlets, can significantly shorten the development cycle of high-speed aircraft air intake systems and reduce testing costs, thus bringing advantages to the rapid design and optimization of related equipment. Addressing the current lack of efficient and high-precision simulation methods in the integrated design of precoolers and air inlets, this invention proposes a complete system of simplified and equivalent analysis methods. Through the comprehensive application of key technologies such as porous media equivalent modeling, periodic symmetry simplification, and rapid engineering estimation, this invention successfully solves the long-standing technical problem of traditional numerical simulation methods being computationally intensive, inefficient, and difficult to converge in the complex flow and heat transfer coupling analysis of precoolers and air inlets. This invention overcomes the prejudice that detailed three-dimensional models are necessary to accurately simulate the complex flow and heat transfer of precoolers, proving that through scientific simplification and equivalent methods, simulation efficiency can be improved by orders of magnitude while ensuring engineering accuracy. Attached Figure Description

[0070] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure;

[0071] Figure 1 This is a flowchart of the simulation analysis method for matching the precooler and the intake duct provided in an embodiment of the present invention;

[0072] Figure 2 This is a schematic diagram of the simulation analysis method for matching the precooler and the intake duct provided in this embodiment of the invention.

[0073] Figure 3 This is a structural diagram of a porous media model provided in an embodiment of the present invention;

[0074] Figure 4 This is a schematic diagram of the actual spiral structure of the intake precooling section provided in an embodiment of the present invention;

[0075] Figure 5 This is the main calculation flowchart of the rapid estimation method for heat exchange between the precooler and the intake duct provided in the embodiments of the present invention. Detailed Implementation

[0076] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0077] The innovation of the simulation analysis method and system for matching the precooler and the intake duct provided in this invention is as follows:

[0078] (1) Integration of the method system: A complete simulation analysis method system for matching precoolers and air intakes is proposed, which organically combines three key technologies: equivalent modeling of porous media, simplified truncation of computational domain, and rapid estimation of heat exchange engineering, thus solving the problems of large computational load and low efficiency in traditional numerical simulation.

[0079] (2) Porous media equivalent modeling: The complex structure of the precooler is simplified into a porous medium. Pressure loss is simulated by applying an equivalent resistance source term, which greatly reduces the mesh size and is suitable for batch calculation under multiple working conditions.

[0080] (3) Periodic symmetry computational domain selection: By utilizing the periodicity of the precooler structure, representative units are selected for simulation, reducing computational resource requirements while ensuring accuracy.

[0081] (4) Rapid estimation of heat exchange engineering: The heat exchange theoretical model is established through iterative calculation, the heat exchange is rapidly estimated, the energy source term is provided for the porous medium model, and the flow resistance change caused by temperature change is simulated.

[0082] (5) Balance between efficiency and accuracy: Under the premise of meeting the engineering accuracy requirements, significantly improve the efficiency of aerodynamic-thermal-coupled analysis, and provide technical support for the optimized design of engine intake system.

[0083] Example 1, such as Figure 1 and Figure 2 As shown, the simulation analysis method for matching the precooler and the intake duct provided in this embodiment of the invention includes the following steps:

[0084] S1. Equivalent Modeling: The precooler is modeled equivalently based on porous media theory. By applying an equivalent flow resistance source term in the computational domain, the pressure loss of air flowing through the precooler is simulated.

[0085] To address the complex flow structure inside the precooler, a porous media model is used for simplification. An equivalent flow resistance source term is applied within the computational domain to simulate the pressure loss of air flowing through the precooler. This method significantly reduces the number of meshes, is suitable for large-scale numerical simulations of precoolers with different configurations, and significantly improves computational efficiency. Three layers of porous media are used to replace the different heat exchange layers of the precooler being analyzed, such as... Figure 3 As shown.

[0086] Fluids satisfy the momentum equation during flow:

[0087]

[0088] In the formula, For speed For pressure, For viscous shear stress, This is a source term for resistance in porous media.

[0089] By analyzing the pressure drop and velocity relationship of the fluid flowing through the precooler, a descriptive equation can be established for the momentum loss source term of the porous medium:

[0090]

[0091] In the formula, The coefficient of viscosity resistance. The inertial drag coefficient, For fluid density, subscript Indicates the direction of flow.

[0092] The drag coefficients corresponding to each layer of porous media are shown in Table 1.

[0093] Table 1. Resistance coefficient of porous media in the precooler

[0094]

[0095] S2. Computational Domain Extraction: Based on the periodic symmetry of the precooler structure, the computational domain of the precooler structure is extracted, and representative elements are selected for simulation analysis to reduce the computational scale.

[0096] Because the entire inlet precooling section structure requires an excessively large mesh count for simulation, a partial truncation of the structure is performed based on the periodic symmetry of the precooler structure to reduce the computational scale. During the truncation process, the structural integrity and representativeness of each simplified part are considered. A spiral truncation is used for the flow field and coupled heat transfer calculations inside and outside the precooler pipes to ensure the integrity of the spiral tube as much as possible so that the fluid inside the pipe can pass smoothly, thereby ensuring the representativeness of the truncated model. The entire inlet precooling section after the spiral truncation is as follows: Figure 4 As shown.

[0097] The model ensures periodicity during the truncation process; that is, the truncation portion of the structure, after periodic and complex expansion, remains the original complete model, and the fluid flow within the truncation model should be completely consistent with the complete model. The boundary conditions used to ensure consistency are set as periodic boundaries. The core idea is to map the flow state on one boundary to another paired boundary, thereby simulating infinitely repeating or cyclical structures with a minimal computational domain. The flow is completely repeatable when crossing periodic boundaries. This means that all flow variables (velocity, pressure, temperature, turbulent flow rate, etc.) follow a rotational relationship at their corresponding points on the paired boundaries for this model.

[0098] S3. Heat exchange estimation: An engineering rapid estimation method is adopted to iteratively calculate the heat exchange between the cooling medium in the precooler and the air in the intake duct, and to provide an energy source term for the porous medium model to simulate the change in flow resistance caused by changes in air temperature.

[0099] S4. Precooler and Inlet Matching Simulation Analysis: Based on the equivalent modeling, computational domain truncation and heat transfer estimation, the aerodynamic-thermal coupling analysis of the precooler and intake matching is realized.

[0100] The three-dimensional calculation of the precooler-inlet matching based on the actual structure is extremely time-consuming. To avoid a large number of complex calculations, a rapid analysis theory and method for the flow heat transfer effect between the cooling medium in the precooler and the air in the inlet is established. Through iterative calculation, the flow heat transfer effect and heat transfer of a given model under different inlet flow conditions and different precooler parameters are estimated. The obtained heat transfer results can provide an energy source term for the porous medium model, thereby simulating the change in flow resistance caused by changes in air temperature during the precooler-inlet matching calculation. The main calculation flow of the rapid estimation method for heat transfer between the precooler and the inlet established in this invention is as follows: Figure 5 As shown.

[0101] In the calculation, the air flow rate and total inlet temperature entering the precooling section are used as known conditions for the air-side heat transfer calculation, while the cooling medium flow rate and inlet temperature entering the precooler are used as known conditions for the cooling medium-side heat transfer within the pipes. Since the heat transfer between air and the cooling medium is an unknown quantity to be determined, a heat transfer rate is first estimated. The corresponding air and cooling medium outlet temperatures were obtained, and the qualitative temperatures during the heat exchange process of air and cooling medium were calculated respectively. After obtaining the physical properties of air and cooling medium based on the qualitative temperatures, the average convective heat transfer coefficients between air and the outer surface of the precooler, and between the cooling medium and the inner surface of the precooler, were calculated based on empirical heat transfer relationships for external tube bundle convective heat transfer and internal tube convective heat transfer, respectively. The overall heat transfer coefficient of the heat transfer process was then obtained. The heat transfer capacity was calculated based on the average logarithmic temperature difference between the inside and outside of the precooler, the overall heat transfer coefficient, and the heat exchange area of ​​the precooler. Using the calculated heat exchange For the previously estimated heat exchange Make corrections, and use the corrected heat exchange rate as a new estimate in the next step of the calculation until... and When they are approximately equal, it can be assumed that the heat exchange parameters satisfy a thermal equilibrium relationship. Through the above iterative process, the heat exchange between the precooler and the intake duct is finally estimated.

[0102] (1) Estimate the heat exchange, calculate the outlet temperatures of the air and cooling medium, and calculate the qualitative temperatures during the heat exchange process of the air and cooling medium respectively:

[0103] The relationship between heat exchange and outlet temperature is as follows:

[0104]

[0105] In the formula, For the estimated heat exchange between the precooler and the air, Air mass flow rate, The specific heat capacity of air, and These are the temperatures of the air at the inlet and outlet of the precooling section, respectively.

[0106] The qualitative temperature is:

[0107]

[0108] In the formula, The average temperature of the air is used as the qualitative temperature;

[0109] (2) Obtain the physical properties of air and cooling medium based on qualitative temperature, and calculate the average convective heat transfer coefficient between air and the outer surface of the precooler, the average convective heat transfer coefficient between the cooling medium and the inner surface of the precooler, and the total heat transfer coefficient based on the empirical relationship between the external tube bundle convective heat transfer and the internal tube convective heat transfer.

[0110] Empirical relationship for convective heat transfer in external tube bundles:

[0111]

[0112] In the formula, These are the Reynolds number, Prandtl number, and Nusselt number for air, respectively.

[0113] The average convective heat transfer coefficient between the air and the outer surface of the precooler is:

[0114]

[0115] In the formula, The thermal conductivity of air. The outer diameter of the precooler pipe. The average convective heat transfer coefficient between the air and the outer surface of the precooler;

[0116] The empirical relationship for convective heat transfer inside a pipe is:

[0117]

[0118] In the formula, These are the Reynolds number, Prandtl number, and Nusselt number of LAM, respectively.

[0119] The average convective heat transfer coefficient between the cooling medium and the inner surface of the precooler is:

[0120]

[0121] In the formula, The thermal conductivity of air. This refers to the inner diameter of the precooler pipe. The average convective heat transfer coefficient between the LAM and the inner surface of the precooler;

[0122] The formula for calculating the overall heat transfer coefficient is:

[0123]

[0124] (3) Calculate the heat transfer by the average logarithmic temperature difference inside and outside the precooler, the total heat transfer coefficient and the heat transfer area of ​​the precooler, and compare it iteratively with the estimated heat transfer until the heat balance relationship is satisfied.

[0125] The logarithmic mean temperature difference is:

[0126]

[0127] In the formula, These are the temperatures of LAM at the inlet and outlet of the precooler, respectively.

[0128] The heat exchange is:

[0129]

[0130] In the formula, To calculate the heat exchange, This refers to the heat exchange area.

[0131] Furthermore, in the iterative calculation, the calculated heat exchange... As a new estimate Perform iterations, when When the convergence rate is less than the preset convergence threshold of 0.1%, it is determined that the thermal balance relationship is satisfied, thereby determining the final heat exchange between the precooler and the intake duct.

[0132] Example 2: This embodiment of the invention also provides an application of the precooler and inlet matching simulation analysis method in the design of high-speed aircraft engine inlets, wherein the high-speed aircraft engine inlet design includes hypersonic aircraft, ramjet engines or combined cycle engines.

[0133] Example 3: This embodiment of the invention also provides a precooler and inlet matching simulation analysis system for implementing the aforementioned precooler and inlet matching simulation analysis method, comprising:

[0134] The equivalent modeling module is used to model the precooler based on porous media theory. It simulates the pressure loss of air flowing through the precooler by applying an equivalent flow resistance source term in the computational domain.

[0135] The computational domain extraction module is used to extract the computational domain of the precooler structure based on the periodic symmetry of the precooler structure, select representative elements for simulation analysis, and reduce the computational scale.

[0136] The heat exchange estimation module is used to calculate the heat exchange between the cooling medium in the precooler and the air in the intake duct by iteratively using a rapid engineering estimation method, and to simulate the change in flow resistance caused by changes in air temperature.

[0137] The coupling analysis module is used to perform aerodynamic-thermal coupling analysis of the precooler and the intake duct based on the equivalent modeling, computational domain truncation and heat transfer estimation.

[0138] The equivalent modeling module, the computational domain interception module, the heat exchange estimation module, and the coupling analysis module are implemented by the processor executing computer program instructions stored in the memory.

[0139] In one embodiment, the system is integrated into the digital design platform of a high-speed aircraft engine for rapid evaluation and optimization of inlet design schemes that include precoolers.

[0140] To further demonstrate the positive effects of the above embodiments, the present invention conducts the following experiments based on the above technical solutions.

[0141] Table 2 Effects of the Invention

[0142]

[0143] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A simulation analysis method for matching a precooler with an intake duct, characterized in that, This method achieves a significant improvement in the analytical accuracy and efficiency of bidirectional thermal coupling between the precooler and the inlet by constructing a three-in-one collaborative simulation framework of porous media equivalent-periodic domain interception-heat transfer iterative coupling. Specifically, it includes the following steps: S1. Equivalent Modeling: The precooler is modeled equivalently based on porous media theory. By applying an equivalent flow resistance source term in the computational domain, the pressure loss of air flowing through the precooler is simulated. S2. Computational Domain Extraction: Based on the periodic symmetry of the precooler structure, the computational domain of the precooler structure is extracted, and representative elements are selected for simulation analysis to reduce the computational scale. S3. Heat exchange estimation: An engineering rapid estimation method is adopted to iteratively calculate the heat exchange between the cooling medium in the precooler and the air in the intake duct, and to provide an energy source term for the porous medium model to simulate the change in flow resistance caused by changes in air temperature. S4. Precooler and Inlet Matching Simulation Analysis: Based on the equivalent modeling, computational domain truncation and heat transfer estimation, the aerodynamic-thermal coupling analysis of the precooler and intake matching is realized.

2. The simulation analysis method for matching the precooler and the intake duct according to claim 1, characterized in that, In step S1, the actual complex structure of the precooler is simplified to a porous medium, which includes a multi-layer structure, each layer having a different viscous drag coefficient and inertial drag coefficient.

3. The simulation analysis method for matching the precooler and the intake duct according to claim 2, characterized in that, The multi-layer structure includes an outermost layer, a middle layer, and an innermost layer. Each layer has a different drag coefficient in the axial and radial flow directions, and the drag coefficient is determined by experiments or high-precision simulation.

4. The simulation analysis method for matching the precooler and the intake duct according to claim 3, characterized in that, The drag coefficients include viscous drag coefficients and inertial drag coefficients, the values ​​of which are calibrated based on the actual structural parameters of the precooler and used for the calculation of the momentum loss source term of the porous medium model. The drag coefficient is configured as follows: The viscous drag coefficient of the outermost layer in the axial direction is 78176.6964 m. -2 The inertial drag coefficient is 0.7877m. -1 The radial viscous drag coefficient is 316487.6804 m. -2 The inertial drag coefficient is 8.5612m. -1 ; The viscous drag coefficient of the intermediate layer in the axial direction is 102586.1226m. -2 The inertial drag coefficient is 0.8644m. -1 The radial viscous drag coefficient is 724586.5614 m. -2 The inertial drag coefficient is 10.1091m. -1 ; The axial viscous drag coefficient of the innermost layer is 277624.8770 m. -2 The inertial drag coefficient is 2.2306m. -1 The radial viscous drag coefficient is 704620.5663m. -2 The inertial drag coefficient is 16.5140m. -1 .

5. The simulation analysis method for matching the precooler and the intake duct according to claim 1, characterized in that, In the computational domain interception step, the flow field inside and outside the precooler pipe and the coupled heat transfer calculation adopt a spiral interception method to ensure that the intercepted model has periodicity, and set periodic boundary conditions so that the flow variables follow a rotational relationship on the paired boundaries.

6. The simulation analysis method for matching the precooler and the intake duct according to claim 1, characterized in that, In the heat exchange estimation step, the rapid engineering estimation method includes: The flow rate of air entering the precooling section and the total inlet temperature are used as known conditions for the air-side heat transfer calculation, and the flow rate of cooling medium entering the precooler and the inlet temperature are used as known conditions for the cooling medium-side heat transfer inside the pipe. Estimate the heat exchange capacity, calculate the outlet temperatures of the air and cooling medium, and calculate the qualitative temperatures during the heat exchange process of the air and cooling medium respectively; The relationship between heat exchange and outlet temperature is as follows: ； In the formula, For the estimated heat exchange between the precooler and the air, Air mass flow rate, The specific heat capacity of air, and These are the temperatures of the air at the inlet and outlet of the precooling section, respectively. The qualitative temperature is: ； In the formula, The average temperature of the air is used as the qualitative temperature; Based on qualitative temperature, the physical properties of air and cooling medium are obtained. Based on empirical relationships between external tube bundle convective heat transfer and internal tube convective heat transfer, the average convective heat transfer coefficient between air and the outer surface of the precooler, the average convective heat transfer coefficient between the cooling medium and the inner surface of the precooler, and the overall heat transfer coefficient are calculated. The empirical relationship for convective heat transfer in externally swept tube bundles is: ； In the formula, These are the Reynolds number, Prandtl number, and Nusselt number for air, respectively. The average convective heat transfer coefficient between the air and the outer surface of the precooler is: ； In the formula, The average convective heat transfer coefficient between air and the outer surface of the precooler. The thermal conductivity of air. This refers to the outer diameter of the precooler pipe; The empirical relationship for convective heat transfer inside a pipe is: ； In the formula, These are the Reynolds number, Prandtl number, and Nusselt number of LAM, respectively. The average convective heat transfer coefficient between the cooling medium and the inner surface of the precooler is: ； In the formula, The thermal conductivity of air. This refers to the inner diameter of the precooler pipe. The average convective heat transfer coefficient between the LAM and the inner surface of the precooler; Overall heat transfer coefficient The calculation formula is: ； The heat transfer is calculated by the average logarithmic temperature difference inside and outside the precooler, the overall heat transfer coefficient and the heat transfer area of ​​the precooler, and iteratively compared with the estimated heat transfer until the heat balance relationship is satisfied. Logarithmic mean temperature difference for: ； In the formula, These are the temperatures of LAM at the inlet and outlet of the precooler, respectively. The heat exchange is: ； In the formula, To calculate the heat exchange, This refers to the heat exchange area.

7. The simulation analysis method for matching the precooler and the intake duct according to claim 6, characterized in that, In the iterative calculation, the calculated heat exchange... As a new estimate Perform iterations, when When the convergence rate is less than the preset convergence threshold of 0.1%, it is determined that the thermal balance relationship is satisfied, thereby determining the final heat exchange between the precooler and the intake duct.

8. The application of a simulation analysis method for matching precoolers and air inlets as described in any one of claims 1-7 in the design of air inlets for high-speed aircraft engines, characterized in that, The high-speed aircraft engine inlet design includes hypersonic aircraft, ramjet engines, or combined cycle engines.

9. A precooler and inlet matching simulation analysis system for implementing the precooler and inlet matching simulation analysis method as described in any one of claims 1-7, characterized in that, include: The equivalent modeling module is used to model the precooler based on porous media theory. It simulates the pressure loss of air flowing through the precooler by applying an equivalent flow resistance source term in the computational domain. The computational domain extraction module is used to extract the computational domain of the precooler structure based on the periodic symmetry of the precooler structure, select representative elements for simulation analysis, and reduce the computational scale. The heat exchange estimation module is used to calculate the heat exchange between the cooling medium in the precooler and the air in the intake duct by iteratively using a rapid engineering estimation method, and to simulate the change in flow resistance caused by changes in air temperature. The coupling analysis module is used to perform aerodynamic-thermal coupling analysis of the precooler and the intake duct based on the equivalent modeling, computational domain truncation and heat transfer estimation. The equivalent modeling module, the computational domain interception module, the heat exchange estimation module, and the coupling analysis module are implemented by the processor executing computer program instructions stored in the memory.

10. The simulation analysis system for matching the precooler and the intake duct according to claim 9, characterized in that, The system is integrated into the digital design platform of high-speed aircraft engines and is used to quickly evaluate and optimize inlet designs that include precoolers.

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