A method for predicting and optimizing aerodynamic-thermal coupling performance of a parachute fabric

Abstract

This invention provides a method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics, comprising: acquiring fabric information of the parachute fabric and calculating the yarn diameter based on the fabric information; performing pore simulation on the parachute fabric based on the yarn diameter and fabric information to obtain the cross-sectional area and perimeter of a single pore, calculating the equivalent pore diameter based on the cross-sectional area and perimeter of the single pore, and calculating the porosity based on the fabric information; calculating the permeability and inertial drag coefficient based on the equivalent pore diameter and porosity, and constructing a porous medium model based on the permeability and inertial drag coefficient; performing transient flow field simulation on the porous medium model based on a fluid dynamics solver to obtain the drag coefficient and heat flux density; and optimizing the fabric parameters based on preset target constraints, drag coefficient, and heat flux density to obtain optimized fabric parameters.

Description

Technical Field

[0001] This invention relates to the fields of aerospace and fluid mechanics, and in particular to a method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics. Background Technology

[0002] In the fields of aerospace deceleration device design and high-performance textile materials, the aerodynamic-thermal coupling performance of parachute fabrics is crucial in determining the system's deceleration efficiency and thermal safety. Modern deep space exploration missions impose extreme operating conditions on parachutes, requiring their fabrics to effectively resist high heat loads generated by aerodynamic friction while ensuring high deceleration drag. This necessitates the dual attributes of "strong deceleration and high heat resistance" and the deep coupling of "structure, flow, and heat transfer." Accurate prediction of the quantitative correlation between fabric microstructure parameters and macroscopic aerodynamic and thermal properties has become a primary prerequisite for achieving lightweight and highly reliable parachute design.

[0003] However, existing methods for analyzing the performance of parachute fabrics still have significant technical limitations when facing complex aerodynamic-thermal coupling environments. First, traditional design methods often rely on wind tunnel tests or empirical formulas to evaluate fabric permeability, lacking a systematic modeling process from yarn geometry to macroscopic flow characteristics. This makes it difficult to reflect the true impact of fabric pore structure on flow field resistance and energy dissipation, resulting in low design efficiency and high experimental costs. Second, existing research typically focuses only on aerodynamic drag or permeability indices, lacking a unified predictive model for heat flux density caused by fluid viscous dissipation. This makes it impossible to comprehensively evaluate the aerodynamic-thermal coupling performance of fabrics in high-speed airflow environments, thus limiting the reliability of fabric materials in high-heat-load scenarios. Furthermore, while some numerical simulation methods can calculate flow field distribution, they often lack a direct correlation with fabric microstructure parameters, failing to achieve reversible design and optimization from fabric parameters to performance indicators. This means parachute fabric design still relies on empirical adjustments, making efficient parametric optimization design difficult. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics. This method has the advantages of being driven by physical parameters, using porous media for efficient equivalence, and automatically optimizing. It solves the problems of large drag prediction deviations, blurred thermal safety boundaries, low R&D efficiency, and insufficient reliability assessment caused by the lack of high-precision microscopic mapping, kinetic energy dissipation mechanism modeling, and multi-index trade-off optimization capabilities in aerospace recovery scenarios with high-speed parachute opening, high heat load, and multiple parameter variations.

[0005] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics, comprising the following steps: Obtain the fabric information of the parachute fabric and calculate the yarn diameter based on the fabric information, wherein the fabric information includes mass per unit area, thickness, yarn linear density, weaving structure type and fiber density; Based on the yarn diameter and the fabric information, the pore size of the parachute fabric is simulated to obtain the cross-sectional area and circumference of a single hole. Based on the cross-sectional area and circumference of the single hole, the equivalent pore diameter is calculated, and the porosity is calculated based on the fabric information. Based on the equivalent pore size and porosity, the permeability and inertial drag coefficient are calculated, and a porous medium model is constructed based on the permeability and inertial drag coefficient. Transient flow field simulation was performed on the porous medium model to obtain the drag coefficient and heat flux density; Based on preset target constraints, the fabric information is optimized according to the drag coefficient and heat flux density to obtain optimized fabric parameters.

[0006] According to a preferred embodiment of the present invention, calculating the yarn diameter based on the fabric information includes: The yarn linear density and fiber density are extracted from the fabric information; The yarn diameter is calculated based on the yarn linear density and fiber density.

[0007] According to another preferred embodiment of the present invention, the step of simulating the pore size of the parachute fabric based on the yarn diameter and the fabric information to obtain the cross-sectional area of ​​a single pore and the pore perimeter includes: A fabric geometric unit model of the parachute fabric is constructed based on the yarn diameter, the weaving structure type and thickness in the fabric information. Based on the unit area mass, yarn linear density and yarn diameter in the fabric information, the warp and weft fabric density is calculated, and the fabric geometric unit model is updated according to the warp and weft fabric density to obtain the fabric scale unit model. The fluid passage regions are identified from the fabric scale unit model, and a geometric difference operation is performed on the fluid passage regions to obtain the single-hole geometric region; The cross-sectional area of ​​the single-hole geometric region is calculated in two dimensions to obtain the cross-sectional area of ​​the single hole. The perimeter of the closed boundary of the single-hole geometric region is calculated to obtain the perimeter of the hole.

[0008] According to another preferred embodiment of the present invention, the step of calculating the equivalent pore diameter based on the single-pore cross-sectional area and pore perimeter, and calculating the porosity based on the fabric information, includes: The equivalent orifice diameter is calculated using the hydraulic diameter formula based on the cross-sectional area of ​​the single orifice and the orifice circumference. Extract the mass per unit area, thickness, and fiber density from the fabric information; Based on the law of conservation of mass, the porosity is calculated according to the mass per unit area, thickness, and fiber density.

[0009] According to another preferred embodiment of the present invention, the calculation of permeability and inertial drag coefficient based on the equivalent pore size and porosity includes: Obtain the viscosity constant and inertia constant corresponding to the fabric scale unit model; The permeability is calculated based on the viscosity constant, equivalent pore size, and porosity. The inertial drag coefficient is calculated based on the inertial constant, equivalent pore size, and porosity.

[0010] According to another preferred embodiment of the present invention, constructing a porous medium model based on the permeability and the inertial drag coefficient includes: Based on Darcy's law, the pressure gradient equation of the parachute fabric is constructed according to the permeability and inertial drag coefficient. The pressure gradient equation is subjected to momentum conversion to obtain the momentum source term; Initialize the fluid dynamics solver and configure the porous medium model in the fluid dynamics solver according to the momentum source term.

[0011] According to another preferred embodiment of the present invention, the step of performing transient flow field simulation on the porous medium model to obtain the drag coefficient and heat flux density includes: Configure transient boundary conditions for the porous medium model; Configure simulation parameters for the porous medium model and initialize the simulation flow field for the porous medium model; The porous medium model is subjected to transient numerical solution using the simulated flow field to obtain flow field data. The flow field data is monitored for stability to obtain stable flow field data, and the drag coefficient and heat flux density are extracted from the stable flow field data.

[0012] According to another preferred embodiment of the present invention, extracting the drag coefficient and heat flux density from the steady flow field data includes: Pressure field data is extracted from the stable flow field data, and the average pressure is integrated on the upstream and downstream sections corresponding to the pressure field data to obtain the pressure difference; The drag coefficient is calculated based on the pressure difference. Kinetic energy dissipation field data is extracted from the stable flow field data, and heat flux density is calculated based on the kinetic energy dissipation field data and the preset material heat conversion coefficient.

[0013] According to another preferred embodiment of the present invention, the step of optimizing the fabric information based on the drag coefficient and heat flux density according to a preset target constraint to obtain optimized fabric parameters includes: Extract the drag coefficient constraint range and the heat flux density constraint range from the preset target constraints, and extract the fabric parameter range corresponding to the fabric information. Initialize the target fabric parameters within the fabric parameter range, and construct the target porous medium model based on the target fabric parameters; Transient flow field simulation was performed on the target porous medium model to obtain the target drag coefficient and target heat flux density. The target fabric parameters are iteratively updated based on the difference between the target drag coefficient and the boundary of the drag coefficient constraint interval, and the difference between the target heat flux density and the boundary of the heat flux density constraint interval, to obtain optimized fabric parameters.

[0014] To achieve at least one of the above-mentioned objectives, the present invention further provides a system for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics. The system includes an information acquisition module, a pore simulation module, a model building module, a fluid simulation module, and a parameter optimization module, wherein: The information acquisition module acquires the fabric information of the parachute fabric and calculates the yarn diameter based on the fabric information. The fabric information includes the mass per unit area, thickness, yarn linear density, weaving structure type, and fiber density. The pore simulation module performs pore simulation on the parachute fabric based on the yarn diameter and the fabric information to obtain the cross-sectional area and circumference of a single pore. Based on the cross-sectional area and circumference of the single pore, it calculates the equivalent pore diameter and the porosity based on the fabric information. The model building module calculates the permeability and inertial drag coefficient based on the equivalent pore size and porosity, and builds a porous medium model based on the permeability and inertial drag coefficient. The fluid simulation module performs transient flow field simulation on the porous medium model to obtain the drag coefficient and heat flux density. The parameter optimization module optimizes the fabric information based on preset target constraints, according to the drag coefficient and heat flux density, to obtain optimized fabric parameters.

[0015] (III) Beneficial Effects Compared with the prior art, the present invention provides a method and system for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics, which has the following beneficial effects: The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics obtains the basic physical parameters of the parachute fabrics and calculates the equivalent yarn diameter based on the volume conservation relationship between yarn linear density and fiber density. This achieves a theoretical mapping from measurable material parameters to microscopic geometric features, avoiding direct reliance on microscopic measurements or experimental back-calibration, and improving the efficiency and consistency of parameter acquisition. It provides key fundamental variables for subsequent porosity calculations and porous media permeability modeling. By constructing the core geometric parameter of yarn diameter, the correlation between pore structure and aerodynamic drag and thermal effects can be further established, thereby supporting the establishment of the entire aerodynamic-thermal coupling prediction model and improving fabric selection and optimization. The design demonstrates scientific rigor and engineering reliability. By constructing a fabric geometric unit model and performing geometric difference operations, the computable extraction of single-pore geometric features was achieved, ensuring that pore structure parameters originate from a traceable structural geometric modeling process rather than empirical estimation. By calculating the cross-sectional area and perimeter of a single pore, the equivalent pore diameter was obtained using the hydraulic diameter formula, providing key input parameters for subsequent calculations of permeability and inertial drag coefficient. Porosity was calculated using the mass conservation relationship, establishing a quantitative connection between the fabric's macroscopic mass parameters and microscopic pore structure. This enabled a systematic mapping from material physical parameters to porous medium characteristic parameters, improving the physical consistency and engineering reliability of the aerodynamic-thermal coupling prediction model.

[0016] The method for predicting and optimizing the aerodynamic-thermal coupling performance of the parachute fabric calculates permeability and inertial drag coefficient based on equivalent pore size and porosity, and constructs a Darcy-Forchheimer porous medium model. This model can transform the complex yarn interweaving structure into a continuous porous medium region, avoiding detailed modeling of individual yarns and significantly reducing computational load and mesh size. By separating the viscous and inertial terms, the method can accurately describe the air permeability behavior of the fabric in different Reynolds number ranges, achieving unified modeling of low-speed permeation and high-speed impact stages. This improves the accuracy of aerodynamic response prediction during parachute opening and allows the fabric's geometric parameters to directly participate in the overall parachute fluid-structure interaction simulation, enhancing the engineering feasibility and parameter optimizability of the solution.

[0017] The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics constructs a transient flow field simulation model of porous media to numerically solve the flow behavior of parachute fabrics under airflow. By extracting stable flow field data through stability monitoring, the drag coefficient and heat flux density of the fabric can be calculated. Compared with traditional empirical formula estimation methods, this invention can accurately predict aerodynamic drag and aerodynamic-thermal effects based on the actual pore structure parameters and flow state of the fabric, improving the accuracy of aerodynamic performance analysis of parachute fabrics and providing reliable simulation data support for subsequent parachute structure design and material optimization. Attached Figure Description

[0018] Figure 1The diagram shows a flowchart of a method for predicting and optimizing the aerodynamic thermal coupling performance of a parachute fabric according to the present invention.

[0019] Figure 2 The diagram shown is a schematic representation of the fabric pore structure of a parachute fabric according to the present invention.

[0020] Figure 3 The diagram shows the implementation interface of the hydrodynamic solver for a parachute fabric according to the present invention.

[0021] Figure 4 This image shows a visualization of the velocity field data under high porosity conditions of a parachute fabric according to the present invention.

[0022] Figure 5 This image shows a visualization of the velocity field data at medium porosity for a parachute fabric according to the present invention.

[0023] Figure 6 This image shows a visualization of the velocity field data under low porosity conditions of a parachute fabric according to the present invention. Detailed Implementation

[0024] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0025] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0026] Example 1: Please combine Figure 1 This invention discloses a method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics, the method comprising the following steps: Obtain the fabric information of the parachute fabric and calculate the yarn diameter based on the fabric information, wherein the fabric information includes the mass per unit area, thickness, yarn linear density, weaving structure type and fiber density.

[0027] Among them, parachute fabric is a textile material used to manufacture parachute canopies. It is characterized by being porous, high-strength, and lightweight, allowing air to pass through the pores in a controllable manner, generating air resistance during descent and deceleration. In high-speed parachute opening scenarios, parachute fabric also needs to consider the thermal effects generated by aerodynamic friction to prevent heat accumulation on the canopy and damage to it. Therefore, it is necessary to predict and analyze the aerodynamic-thermal coupling performance of parachute fabric.

[0028] In detail, information about the parachute fabric can be obtained by searching data sheets provided by the manufacturer, querying experimental test information from national standards for textile materials or American Society for Testing and Materials (ASTM) standards, or by performing microstructure analysis.

[0029] Specifically, calculating the yarn diameter based on the fabric information includes: The yarn linear density and fiber density are extracted from the fabric information; The yarn diameter is calculated based on the yarn linear density and fiber density.

[0030] The yarn diameter can be calculated using the following formula: in, The diameter of the yarn. The yarn linear density, Pi Fiber density; mass per unit area This refers to the mass of parachute fabric per unit area, measured in units of... Thickness T refers to the thickness of the parachute fabric under specified pressure, and the unit is 1. Yarn linear density This refers to the mass of 1000 meters of yarn at a standard moisture regain, measured in units of... Weave structure type refers to the organizational form of parachute fabric, including plain weave, twill weave, satin weave, mesh structure, and warp knitting structure. Different weave structure types can affect the pore morphology, anisotropy, permeation directionality, and local eddy formation of parachute fabric; fiber density. This refers to the bulk density of the fibrous material itself, and the unit is... Yarn diameter This refers to the equivalent transverse dimension of a yarn in the direction perpendicular to its axial direction, used to characterize the thickness of the yarn, and is measured in units of... .

[0031] By acquiring the basic physical parameters of parachute fabrics and calculating the equivalent yarn diameter based on the volume conservation relationship between yarn linear density and fiber density, a theoretical mapping from measurable material parameters to microscopic geometric features was achieved. This avoids direct reliance on microscopic measurements or experimental back-calibration, improving the efficiency and consistency of parameter acquisition and providing key basic variables for subsequent porosity calculations and porous media permeability modeling. By constructing the core geometric parameter of yarn diameter, the correlation between pore structure and aerodynamic drag and thermal effects can be further established, thereby supporting the establishment of the entire aerodynamic-thermal coupling prediction model and improving the scientific and engineering reliability of fabric selection and optimization design.

[0032] Based on the yarn diameter and the fabric information, the pore size of the parachute fabric is simulated to obtain the cross-sectional area and circumference of a single pore. The equivalent pore diameter is calculated based on the cross-sectional area and circumference of the single pore, and the porosity is calculated based on the fabric information.

[0033] Among them, the single-pore cross-sectional area refers to the two-dimensional projected area of ​​a single fluid passing through the pore in the direction perpendicular to the fabric thickness within a fabric-scale unit, affecting the air permeability and permeability of the parachute fabric; the pore perimeter refers to the total length of the boundary curve of the single-pore cross-section, affecting the intensity of the boundary layer interaction between air and the parachute; the equivalent pore diameter refers to the equivalent diameter of a non-circular fabric pore equivalent to a circular flow channel with the same flow characteristics, used to reflect the influence of pore size and shape on fluid passage; porosity is the proportion of the total volume occupied by the pore portion in the entire fabric, used to reflect the looseness and density of the material.

[0034] In detail, the step of simulating the pore size of the parachute fabric based on the yarn diameter and the fabric information to obtain the cross-sectional area and perimeter of a single pore includes: A fabric geometric unit model of the parachute fabric is constructed based on the yarn diameter, the weaving structure type and thickness in the fabric information. Based on the unit area mass, yarn linear density and yarn diameter in the fabric information, the warp and weft fabric density is calculated, and the fabric geometric unit model is updated according to the warp and weft fabric density to obtain the fabric scale unit model. The fluid passage regions are identified from the fabric scale unit model, and a geometric difference operation is performed on the fluid passage regions to obtain the single-hole geometric region; The cross-sectional area of ​​the single-hole geometric region is calculated in two dimensions to obtain the cross-sectional area of ​​the single hole. The perimeter of the closed boundary of the single-hole geometric region is calculated to obtain the perimeter of the hole.

[0035] In this regard, please combine Figure 2 Fabrics have complex and flexible structures, and their pore sizes and distributions are not uniform. For ease of pore simulation, we assume that the fabric is... Figure 2 c is a rectangular hole structure with length a and width b or Figure 2 The structure d is a square hole with side length a, assuming the yarn has a uniform thickness along its entire length; the yarns in the fabric are regularly and uniformly arranged; the yarns are not flattened or deformed under pressure; the fabric geometric unit is a representative modeling unit of the periodic microstructure of the parachute fabric. Constructing the fabric geometric unit model refers to determining the arrangement of the warp and weft yarns of the parachute fabric according to the weaving structure type, constructing a cylindrical yarn cross-section according to the yarn diameter, and determining the yarn overlap position and undulation height according to the thickness, thus obtaining a fabric geometric unit model composed of warp and weft yarns; the warp and weft fabric density refers to the number of warp and weft yarns per unit length. The calculation of warp and weft fabric density refers to calculating the total length of yarns per unit area based on the mass per unit area and the yarn linear density (assuming the number of warp and weft yarns is the same), and then deriving the distance parameters between the warp and weft yarns to obtain the warp and weft fabric density; the updating of the fabric geometric unit model refers to sparsening or densifying the fabric geometric unit model based on the warp and weft fabric density to obtain the fabric scale unit model; the identification of fluid passage areas refers to calculating the yarn overlapping areas in the fabric scale unit model, then extracting the unoccupied spaces between the yarns, and determining the single-hole closed boundary of each unoccupied space to obtain the fluid passage area. The table above shows the structural parameters of three different types of fabrics.

[0036] Specifically, the step of calculating the equivalent pore diameter based on the single-pore cross-sectional area and pore perimeter, and calculating the porosity based on the fabric information, includes: The equivalent orifice diameter is calculated using the hydraulic diameter formula based on the cross-sectional area of ​​the single orifice and the orifice circumference. Extract the mass per unit area, thickness, and fiber density from the fabric information; Based on the law of conservation of mass, the porosity is calculated according to the mass per unit area, thickness, and fiber density.

[0037] The mathematical formula for calculating the equivalent aperture is as follows: in, It is the equivalent aperture. It is the cross-sectional area of ​​a single hole. Given the circumference of the pore, the corresponding mathematical formula for calculating the porosity is as follows: in, Porosity For thickness, Mass per unit area.

[0038] By constructing a fabric geometric unit model and performing geometric difference operations, the computable extraction of single-pore geometric features was achieved, allowing pore structure parameters to originate from a traceable structural geometric modeling process rather than empirical estimation. By calculating the cross-sectional area and perimeter of a single pore, the equivalent pore diameter was obtained using the hydraulic diameter formula, providing key input parameters for subsequent calculations of permeability and inertial drag coefficient. Porosity was calculated using the mass conservation relationship, establishing a quantitative connection between the macroscopic mass parameters of the fabric and the microscopic pore structure. This achieved a systematic mapping from material physical parameters to porous medium characteristic parameters, improving the physical consistency and engineering reliability of the aerodynamic-thermal coupling prediction model.

[0039] Based on the equivalent pore size and porosity, the permeability and inertial drag coefficient are calculated, and a porous medium model is constructed based on the permeability and inertial drag coefficient.

[0040] Among them, permeability is a physical quantity used to describe the ability of porous media to allow fluid to pass through, reflecting the air permeability of fabrics; the inertial drag coefficient is a parameter used to describe the intensity of additional drag caused by the inertial effect of airflow at high flow rates.

[0041] Specifically, the calculation of permeability and inertial drag coefficient based on the equivalent pore size and porosity includes: Obtain the viscosity constant and inertia constant corresponding to the fabric scale unit model; The permeability is calculated based on the viscosity constant, equivalent pore size, and porosity. The inertial drag coefficient is calculated based on the inertial constant, equivalent pore size, and porosity.

[0042] The viscosity and inertial constants can be obtained through a calibration scheme for resistance simulation. Resistance simulation refers to simulating the magnitude of resistance experienced by the fabric under aerodynamic influence. Resistance simulation includes multi-velocity staged simulations in low-velocity and medium-to-high-velocity regions. The viscosity and inertial constants are separated by quadratic fitting of pressure gradient and velocity. The low-velocity region is used to extract the viscosity constant from the Darcy term, while the medium-to-high-velocity region is used to extract the inertial constant from the Forchheimer term. The viscosity constant, corresponding to the Darcy term, is determined by the viscous friction force exerted on the yarn surface by the airflow. Based on the Ergun theoretical model and calibration results at typical Reynolds numbers for parachute fabrics, the viscosity constant is determined to be 150. The inertial constant, corresponding to the Forchheimer term, reflects the splitting, impact, and leeward eddy dissipation generated when air impacts the yarn. Based on experimental data of fiber fabrics, it is corrected to 3.5. For example, the permeability and inertial drag coefficient can be calculated using the Ergun equation in fluid mechanics. The permeability is calculated... The mathematical formula is as follows: Calculate the inertial drag coefficient The mathematical formula is as follows: Where 150 is the viscosity constant, The inertial constant is determined based on wind tunnel experiments and numerical fitting results within the typical porosity range of parachute fabrics. Given that parachute fabrics are highly porous media with regularly interwoven fibers, their flow channel tortuosity is significantly lower than that of particle packing structures. Based on numerical simulations and experimental data fitting within the typical Reynolds number range, the porosity exponent in the Ergun inertial term is corrected. To improve the prediction accuracy of the high-porosity region, the porosity index is corrected, and the porosity index in the inertial drag coefficient is set to 1.5.

[0043] Specifically, constructing the porous medium model based on the permeability and inertial drag coefficient includes: Based on Darcy's law, the pressure gradient equation of the parachute fabric is constructed according to the permeability and inertial drag coefficient. The pressure gradient equation is subjected to momentum conversion to obtain the momentum source term; Initialize the fluid dynamics solver and configure the porous medium model in the fluid dynamics solver according to the momentum source term.

[0044] Darcy's law refers to the Darcy-Forchheimer equation, and the mathematical formula for the corresponding pressure gradient equation is as follows: in, It's pressure difference. It is the equivalent thickness of the fabric. This is the dynamic viscosity of the gas; the dynamic viscosity of air is approximately... And it will increase as the temperature rises. For the incoming flow velocity, Let be the fluid density; the mathematical formula for the momentum conversion is as follows: in, This is the momentum source term, which is the resistance of the porous medium to a unit volume of fluid; the fluid dynamics (CFD) solver can be the LS-DYNA ICFD solver; the initialization of the fluid dynamics solver refers to defining the properties of the porous medium component and the permeability constraints; Please refer to Figure 3This is the implementation interface diagram in the LS-DYNA ICFD solver. The configuration of continuous porous medium refers to establishing a three-dimensional flow field model containing a porous medium region in the LS-DYNA ICFD solver and loading the momentum source term as an internal property of the three-dimensional flow field model.

[0045] By calculating permeability and inertial drag coefficient based on equivalent pore size and porosity, and constructing a Darcy-Forchheimer porous medium model, complex yarn interlacing structures can be equivalently represented as continuous porous medium regions, avoiding detailed modeling of individual yarns and significantly reducing computational load and mesh size. By separating viscous and inertial terms, the air permeability behavior of fabrics can be accurately described in different Reynolds number ranges, achieving unified modeling of low-speed permeation and high-speed impact stages, improving the accuracy of aerodynamic response prediction during parachute opening, and enabling fabric geometric parameters to directly participate in the whole-parachute fluid-structure interaction simulation, thereby improving the engineering feasibility and parameter optimizability of the scheme.

[0046] Transient flow field simulation was performed on the porous medium model to obtain the drag coefficient and heat flux density.

[0047] Specifically, the transient flow field simulation of the porous medium model to obtain the drag coefficient and heat flux density includes: Configure transient boundary conditions for the porous medium model; Configure simulation parameters for the porous medium model and initialize the simulation flow field for the porous medium model; The porous medium model is subjected to transient numerical solution using the simulated flow field to obtain flow field data. The flow field data is monitored for stability to obtain stable flow field data, and the drag coefficient and heat flux density are extracted from the stable flow field data.

[0048] The transient boundary conditions include inlet boundary conditions, outlet boundary conditions, and wall boundary conditions. The inlet boundary condition refers to the velocity inlet, used to specify the incoming flow velocity. The outlet boundary condition refers to the pressure outlet. The solid wall boundary adopts a no-slip condition, and the far-field boundary of the computational domain adopts a symmetric or open boundary condition. The simulation parameters include the time step, total simulation time, turbulence model, and convergence criterion. The simulated flow field refers to the fluid field used for performance simulation, which can be set to a static state or uniform incoming flow conditions. The transient numerical solution refers to configuring the porous medium model in the simulated flow field and monitoring the corresponding flow field data in real time. The stability monitoring refers to monitoring the change curves of key physical quantities in the flow field data over time in real time. When the change curves tend to stabilize, and the residual fluctuations of multiple time steps are lower than a preset threshold or reach periodic stability, the corresponding flow field data is taken as stable flow field data.

[0049] The key physical quantities include volumetric flow rate, pressure difference across the fabric, and kinetic energy at the computational domain outlet; the stable flow field data includes velocity field data, pressure field data, and kinetic energy dissipation field data, etc. Velocity field data refers to the velocity vector distribution of the fluid at various spatial locations within the computational domain. Please refer to... Figure 4 , Figure 5 , Figure 6 The image shows a visualization of the velocity field data for three fabrics with different porosities. Figure 4 The velocity field data is for a porosity of 0.347. Figure 5 The velocity field data is for a porosity of 0.331. Figure 6 This is the velocity field data corresponding to a porosity of 0.232, which shows that from... Figures 4 to 6 The red high-velocity core region shortens, while the green and blue low-velocity regions expand; the pressure field data represents the pressure distribution of the fluid at various spatial locations within the computational domain; the kinetic energy dissipation field data represents the rate distribution of fluid kinetic energy converted into internal energy due to viscosity or turbulence.

[0050] Specifically, extracting the drag coefficient and heat flux density from the steady flow field data includes: Pressure field data is extracted from the stable flow field data, and the average pressure is integrated on the upstream and downstream sections corresponding to the pressure field data to obtain the pressure difference; The drag coefficient is calculated based on the pressure difference. Kinetic energy dissipation field data is extracted from the stable flow field data, and heat flux density is calculated based on the kinetic energy dissipation field data and the preset material heat conversion coefficient.

[0051] The upstream section refers to the section before the airflow enters the fabric, used to measure the inlet pressure; the downstream section refers to the section after the airflow passes through the fabric, used to measure the outlet pressure; the pressure difference refers to the pressure difference across the fabric, representing the resistance generated when the airflow passes through the fabric; the drag coefficient refers to the dimensionless resistance of the fabric to the airflow, and the drag coefficient is used to calculate the drag coefficient. The formula is as follows: Material thermal conversion coefficient It refers to the proportionality coefficient of kinetic energy dissipation into heat, heat flux density. Heat flux density refers to the amount of heat transferred per unit area per unit time. Since dissipated kinetic energy is mainly converted into thermal energy in practical use, it can be used to calculate heat flux density. The formula for calculating heat flux density is as follows: in, The kinetic energy dissipation rate of the flow field in the kinetic energy dissipation field data. This represents the gradient of the incoming flow velocity.

[0052] By constructing a transient flow field simulation model of porous media, the flow behavior of parachute fabric under airflow is numerically solved, and stable flow field data is extracted through stability monitoring to calculate the drag coefficient and heat flux density of the fabric. Compared with traditional empirical formula estimation methods, this invention can accurately predict aerodynamic drag and aerothermal effects based on the actual pore structure parameters and flow state of the fabric, improving the accuracy of aerodynamic performance analysis of parachute fabric and providing reliable simulation data support for subsequent parachute structure design and material optimization.

[0053] Based on preset target constraints, the fabric information is optimized according to the drag coefficient and heat flux density to obtain optimized fabric parameters.

[0054] The target constraints include a drag coefficient constraint range and a heat flux density constraint range. The drag coefficient constraint range refers to the range of drag coefficients set by the target, and the heat flux density constraint range is the range of heat flux densities set by the target. The drag coefficient and heat flux density can determine the aerodynamic thermal coupling performance of the parachute fabric.

[0055] Specifically, the step of optimizing the fabric parameters based on the preset target constraints, the drag coefficient, and the heat flux density to obtain optimized fabric parameters includes: Extract the drag coefficient constraint range and the heat flux density constraint range from the preset target constraints, and extract the fabric parameter range corresponding to the fabric information. Initialize the target fabric parameters within the fabric parameter range, and construct the target porous medium model based on the target fabric parameters; Transient flow field simulation was performed on the target porous medium model to obtain the target drag coefficient and target heat flux density. The target fabric parameters are iteratively updated based on the difference between the target drag coefficient and the boundary of the drag coefficient constraint interval, and the difference between the target heat flux density and the boundary of the heat flux density constraint interval, to obtain optimized fabric parameters.

[0056] The fabric parameter range refers to the range of parameters that the fabric can achieve within the existing process. The target fabric parameters can be initialized using random generation or heuristic algorithms. The method for constructing the target porous medium model involves calculating the yarn diameter based on the fabric information, simulating the pores of the parachute fabric based on the yarn diameter and fabric information to obtain the single-pore cross-sectional area and pore perimeter, calculating the equivalent pore diameter based on the single-pore cross-sectional area and pore perimeter, calculating the porosity based on the fabric information, and calculating the permeability and inertial drag coefficient based on the equivalent pore diameter and porosity. The method for constructing a porous medium model based on permeability and inertial drag coefficient is the same and will not be repeated here; the method for transient flow field simulation is the same as in the above steps and will not be repeated here; the iterative update refers to constructing a cost function based on the difference between the target drag coefficient and the boundary of the drag coefficient constraint interval, and the difference between the target heat flux density and the boundary of the heat flux density constraint interval, and updating the target fabric parameters based on the result of the cost function using linear correction or gradient correction methods. When the result of the total cost function is less than a preset threshold, or the objective function converges, or the preset number of updates is reached, the iterative target fabric parameters are used as the optimized fabric parameters.

[0057] By constructing drag coefficient and heat flux density constraint ranges, the aerodynamic drag performance and aerothermal protection performance of parachute fabrics are uniformly incorporated into the optimization objectives. Target fabric parameters are initialized within the fabric parameter range. The target drag coefficient and target heat flux density are obtained by constructing a target porous medium model and performing transient flow field simulation. The fabric parameters are then iteratively updated based on the deviation between these parameters and the target constraints, thereby achieving automatic optimization of fabric structural parameters. This approach effectively controls aerodynamic frictional heat load while meeting aerodynamic deceleration performance requirements, preventing heat accumulation or structural damage to the parachute canopy under high-speed opening conditions and improving the aerodynamic-thermal coupling adaptability of parachute fabrics. It also enables the aerodynamic-thermal simulation results to guide fabric structural design, transforming parachute fabric design from traditional experience-based design to simulation-driven parameter optimization design, thereby improving design efficiency and enhancing fabric performance reliability.

[0058] Example 2: This invention discloses a system for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics. The system includes an information acquisition module, a pore simulation module, a model building module, a fluid simulation module, and a parameter optimization module, wherein: The information acquisition module acquires the fabric information of the parachute fabric and calculates the yarn diameter based on the fabric information. The fabric information includes the mass per unit area, thickness, yarn linear density, weaving structure type, and fiber density. The pore simulation module performs pore simulation on the parachute fabric based on the yarn diameter and the fabric information to obtain the cross-sectional area and circumference of a single pore. Based on the cross-sectional area and circumference of the single pore, it calculates the equivalent pore diameter and the porosity based on the fabric information. The model building module calculates the permeability and inertial drag coefficient based on the equivalent pore size and porosity, and builds a porous medium model based on the permeability and inertial drag coefficient. The fluid simulation module performs transient flow field simulation on the porous medium model to obtain the drag coefficient and heat flux density. The parameter optimization module optimizes the fabric information based on preset target constraints, according to the drag coefficient and heat flux density, to obtain optimized fabric parameters.

[0059] The processes described above with reference to the flowcharts in the embodiments disclosed in this invention can be implemented as computer software programs. The embodiments disclosed in this invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication component, and / or installed from a removable medium. When the computer program is executed by a central processing unit (CPU), it performs the functions defined in the methods of this application. It should be noted that the computer-readable medium described above in this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wire segments, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in connection with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on a computer-readable medium may be transmitted using any suitable medium, including but not limited to: wireless segments, wire segments, optical fibers, RF, etc., or any suitable combination thereof.

[0060] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0061] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been shown and explained in the embodiments. Without departing from the stated principles, the implementation of the present invention may have any variations or modifications.

Claims

1. A method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics, characterized in that, The method includes: Obtain the fabric information of the parachute fabric and calculate the yarn diameter based on the fabric information, wherein the fabric information includes mass per unit area, thickness, yarn linear density, weaving structure type and fiber density; Based on the yarn diameter and the fabric information, the pore size of the parachute fabric is simulated to obtain the cross-sectional area and circumference of a single hole. Based on the cross-sectional area and circumference of the single hole, the equivalent pore diameter is calculated, and the porosity is calculated based on the fabric information. Based on the equivalent pore size and porosity, the permeability and inertial drag coefficient are calculated, and a porous medium model is constructed based on the permeability and inertial drag coefficient. Transient flow field simulation was performed on the porous medium model to obtain the drag coefficient and heat flux density; Based on preset target constraints, the fabric information is optimized according to the drag coefficient and heat flux density to obtain optimized fabric parameters.

2. The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabric according to claim 1, characterized in that, The calculation of yarn diameter based on the fabric information includes: The yarn linear density and fiber density are extracted from the fabric information; The yarn diameter is calculated based on the yarn linear density and fiber density.

3. The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabric according to claim 2, characterized in that, The step of simulating the pore size of the parachute fabric based on the yarn diameter and the fabric information to obtain the cross-sectional area and perimeter of a single pore includes: A fabric geometric unit model of the parachute fabric is constructed based on the yarn diameter, the weaving structure type and thickness in the fabric information. Based on the unit area mass, yarn linear density and yarn diameter in the fabric information, the warp and weft fabric density is calculated, and the fabric geometric unit model is updated according to the warp and weft fabric density to obtain the fabric scale unit model. The fluid passage regions are identified from the fabric scale unit model, and a geometric difference operation is performed on the fluid passage regions to obtain the single-hole geometric region; The cross-sectional area of ​​the single-hole geometric region is calculated in two dimensions to obtain the cross-sectional area of ​​the single hole. The perimeter of the closed boundary of the single-hole geometric region is calculated to obtain the perimeter of the hole.

4. The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabric according to claim 1, characterized in that, The calculation of the equivalent pore diameter based on the single-pore cross-sectional area and pore perimeter, and the calculation of porosity based on the fabric information, include: The equivalent orifice diameter is calculated using the hydraulic diameter formula based on the cross-sectional area of ​​the single orifice and the orifice circumference. Extract the mass per unit area, thickness, and fiber density from the fabric information; Based on the law of conservation of mass, the porosity is calculated according to the mass per unit area, thickness, and fiber density.

5. The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabric according to claim 3, characterized in that, The calculation of permeability and inertial drag coefficient based on the equivalent pore size and porosity includes: Obtain the viscosity constant and inertia constant corresponding to the fabric scale unit model; The permeability is calculated based on the viscosity constant, equivalent pore size, and porosity. The inertial drag coefficient is calculated based on the inertial constant, equivalent pore size, and porosity.

6. The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabric according to claim 1, characterized in that, The process of constructing a porous medium model based on the permeability and inertial drag coefficient includes: Based on Darcy's law, the pressure gradient equation of the parachute fabric is constructed according to the permeability and inertial drag coefficient. The pressure gradient equation is subjected to momentum conversion to obtain the momentum source term; Initialize the fluid dynamics solver and configure the porous medium model in the fluid dynamics solver according to the momentum source term.

7. The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabric according to claim 1, characterized in that, The transient flow field simulation of the porous medium model to obtain the drag coefficient and heat flux density includes: Configure transient boundary conditions for the porous medium model; Configure simulation parameters for the porous medium model and initialize the simulation flow field for the porous medium model; The porous medium model is subjected to transient numerical solution using the simulated flow field to obtain flow field data. The flow field data is monitored for stability to obtain stable flow field data, and the drag coefficient and heat flux density are extracted from the stable flow field data.

8. The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabric according to claim 7, characterized in that, The extraction of drag coefficient and heat flux density from the stable flow field data includes: Pressure field data is extracted from the stable flow field data, and the average pressure is integrated on the upstream and downstream sections corresponding to the pressure field data to obtain the pressure difference; The drag coefficient is calculated based on the pressure difference. Kinetic energy dissipation field data is extracted from the stable flow field data, and heat flux density is calculated based on the kinetic energy dissipation field data and the preset material heat conversion coefficient.

9. The method for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabric according to claim 8, characterized in that, The optimized fabric parameters are obtained by optimizing the fabric information based on the preset target constraints, the drag coefficient, and the heat flux density, to obtain optimized fabric parameters, including: Extract the drag coefficient constraint range and the heat flux density constraint range from the preset target constraints, and extract the fabric parameter range corresponding to the fabric information. Initialize the target fabric parameters within the fabric parameter range, and construct the target porous medium model based on the target fabric parameters; Transient flow field simulation was performed on the target porous medium model to obtain the target drag coefficient and target heat flux density. The target fabric parameters are iteratively updated based on the difference between the target drag coefficient and the boundary of the drag coefficient constraint interval, and the difference between the target heat flux density and the boundary of the heat flux density constraint interval, to obtain optimized fabric parameters.

10. A system for predicting and optimizing the aerodynamic-thermal coupling performance of parachute fabrics, characterized in that, The system includes an information acquisition module, a pore simulation module, a model building module, a fluid simulation module, and a parameter optimization module, wherein: The information acquisition module acquires the fabric information of the parachute fabric and calculates the yarn diameter based on the fabric information. The fabric information includes the mass per unit area, thickness, yarn linear density, weaving structure type, and fiber density. The pore simulation module performs pore simulation on the parachute fabric based on the yarn diameter and the fabric information to obtain the cross-sectional area and circumference of a single pore. Based on the cross-sectional area and circumference of the single pore, it calculates the equivalent pore diameter and the porosity based on the fabric information. The model building module calculates the permeability and inertial drag coefficient based on the equivalent pore size and porosity, and builds a porous medium model based on the permeability and inertial drag coefficient. The fluid simulation module performs transient flow field simulation on the porous medium model to obtain the drag coefficient and heat flux density. The parameter optimization module optimizes the fabric information based on preset target constraints, according to the drag coefficient and heat flux density, to obtain optimized fabric parameters.

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