A method for analyzing dynamics interference of high-speed multi-particle aerodynamic coupling impact

Abstract

The application provides a kind of dynamics interference analysis method for high-speed multi-particle aerodynamic coupling impact, belongs to the field of gas-solid coupling analysis, including establishing the non-uniform multi-particle flow field model based on equivalent particle cloud flow field interference body;Discrete particle swarm dynamics evolution model is constructed by fusing aerodynamic interference coefficient matrix, the motion of each particle is solved and calculated, and the force feedback between the particle and the flow field is calculated into the flow field;The particle-material coupling penetration model considering dynamic damage field and strength degradation is established to describe the damage of the aircraft;Three-dimensional unsteady background flow field containing the influence of equivalent flow field interference body is obtained, the damage of the aircraft surface in each place is calculated to obtain the damage field, and the whole flight process is iteratively calculated according to time step, and finally the surface damage and damage distribution of the aircraft can be calculated.The application can realize the description and solution of high-speed multi-particle impact interference process.

Description

Technical Field

[0001] This invention belongs to the field of gas-solid coupling analysis, specifically relating to a dynamic disturbance analysis method for high-speed multi-particle aerodynamic coupling impact. Background Technology

[0002] High-speed aircraft (civilian airliners, high-speed civilian drones, etc.) may traverse dense, discrete particle environments such as dust storms, volcanic ash clouds, and ice crystal clouds during flight. In such environments, a large number of high-speed solid or liquid particles interact violently with the aircraft surface, triggering a series of complex coupled interference effects. First, the overall high-speed particle swarm forms a pre-established shock wave system and flow field interference zone in front of the aircraft, altering the incoming flow conditions for subsequent particles. Second, non-contact aerodynamic interactions occur between particles through their respective induced flow field disturbances, affecting the spatial distribution and trajectory of the particles. Finally, surface damage caused by the sequential impact of particles alters the local aerodynamic shape and material properties, which in turn affects subsequent impacts and the flow field.

[0003] Existing techniques typically simplify multi-particle impacts as a linear superposition of independent events, or only consider average aerodynamic and thermal effects and erosion, neglecting the complex disturbance processes mentioned above. Furthermore, calculating large-scale particle impact problems using high-fidelity fully coupled numerical methods is computationally intensive and difficult to meet engineering design requirements. Therefore, a dynamic disturbance analysis method that can fully describe the physical mechanism of high-speed multi-particle impacts and is computationally efficient is needed. Summary of the Invention

[0004] The purpose of this invention is to provide a dynamic disturbance analysis method for high-speed multi-particle aerodynamic coupling impacts, used to more accurately simulate the complex multiphysics coupling problems in the process.

[0005] The technical solution for achieving the objective of this invention is: a dynamic disturbance analysis method for high-speed multi-particle aerodynamic coupling impact, comprising:

[0006] Step S1: Establish a non-uniform multi-particle flow field model based on an equivalent particle cloud flow field disturbance body;

[0007] Step S2: Construct a discrete particle swarm dynamics evolution model that integrates the aerodynamic disturbance coefficient matrix, solve for the motion of each particle, and calculate the interaction force between the particle and the flow field and feed it back into the flow field.

[0008] Step S3: Establish a particle-material coupled penetration model that considers dynamic damage field and strength degradation to describe the damage of the aircraft;

[0009] Step S4: Solve the problem using an explicit-implicit dynamic partitioning coupling solution method based on the effective interference intensity to obtain a three-dimensional unsteady background flow field containing the influence of the equivalent flow field interference body. Calculate the damage field at various points on the aircraft surface and iteratively calculate the entire flight process according to the time step to finally calculate the surface damage and damage distribution of the aircraft.

[0010] The significant advantages of this invention compared to existing technologies are:

[0011] (1) This invention establishes a complete “flow field-particle-structural damage” chain disturbance analysis framework, which characterizes the full-link nonlinear coupling mechanism of multi-particle impact under high-speed conditions.

[0012] (2) This invention proposes an explicit-implicit adaptive partitioning solution strategy based on effective interference intensity, which greatly improves computational efficiency while ensuring the accuracy of key regions.

[0013] (3) This invention describes the non-contact synergistic effect between particles through an aerodynamic interference coefficient matrix, and through... A quantitative description of the cumulative effect of structural damage has been achieved. Attached Figure Description

[0014] Figure 1 This is a flowchart of the dynamic disturbance analysis method for aerodynamic coupling impact.

[0015] Figure 2 This is a schematic diagram of mesh generation for simulation using Fluent. Detailed Implementation

[0016] This embodiment presents a dynamic disturbance analysis method for high-speed multi-particle aerodynamic coupling impact, the specific process of which is as follows: Figure 1 As shown. This applies to applications using air as a medium, with particle size... for Particle concentration, i.e., particle volume fraction < Particle flow velocity for Taking a particle flow as an example, where the Mach number Ma represents the ratio of the particle flow velocity to the local speed of sound, the steps are as follows: Figure 1 As shown, it mainly includes:

[0017] Step S1: Establish a non-uniform multi-particle flow field model based on an equivalent particle cloud flow field disturbance body;

[0018] 1.1 Parameterized Definition of Equivalent Flow Field Disturbance Body

[0019] A certain control volume containing the aircraft The particle swarm within is equivalent to an equivalent flow field disturbance body with an ellipsoidal shape. The flow field disturbance body is an equivalent replacement of the actual huge particle flow field with an imaginary ellipsoid. Its geometric parameters are determined by the spatial distribution of the particles, and it is used as the actual flow field region for calculation.

[0020] Geometric parameters:

[0021] The semi-major axis of the ellipsoid middle half shaft short half-shaft ,in , , These are the shape factors for the major, middle, and minor semi-axis, respectively. This represents the length between the two farthest points on the aircraft. Equivalent density. ,in To control the average volume fraction of particles in the body. , These are the densities of the particle material and air, respectively.

[0022] in:

[0023]

[0024]

[0025] 1.2 Establishing a compressible Navier-Stokes equation system containing source terms

[0026] In finite element method (FEM) calculations, the first step is to mesh the flow field domain within the computational model. This involves dividing the flow field into numerous small meshes, and then solving the equations within each mesh. Figure 2 This is a schematic diagram of mesh generation using Fluent software.

[0027] Within the grid cells occupied by the equivalent flow field disturbance, the disturbance of the flow field by equivalent particles is simulated by adding source terms to the governing equations. The governing equations are as follows:

[0028] Continuity equation:

[0029] (1)

[0030] Momentum equation:

[0031] (2)

[0032] Energy equation:

[0033] (3)

[0034] in, , , , These are fluid density, fluid velocity vector, fluid pressure, and total fluid energy, respectively. For fluid viscous stress tensor; It is a heat flux vector; and These are the momentum source term and the energy source term, respectively, where time t is defined as t=0 at the start of the calculation. The gradient is a mathematical symbol used to describe the direction of the fastest change of a variable at a point and its rate of change.

[0035] 1.3 Establishing the source term model

[0036] Momentum source term The impediment effect of equivalent flow field disturbances on flow can be simulated using a porous medium model or a resistance model:

[0037] (4)

[0038] in, The dynamic viscosity of the fluid. The permeability of the equivalent flow field disturbance body. is the inertial drag coefficient of the equivalent flow field disturbance body. Porosity of the equivalent flow field disturbance body.

[0039] Energy source item Determined by the energy exchange between the particle phase and the fluid phase, it can be written as:

[0040] (5)

[0041] in The convective heat transfer coefficient is... The particle temperature can be assumed to be close to the fluid temperature for simplification. The fluid temperature.

[0042]

[0043] The particle Reynolds number , thermal conductivity For the reference thermal conductivity of air =0.0241, Reference Temperature =273K, Sutherland constant S=194.

[0044] 1.4 Solution Output

[0045] By discretizing equations (1)-(3) into each grid cell, and then iteratively solving the above set of nonlinear partial differential control equations (1)-(5) containing source terms at each time step, the three-dimensional unsteady background flow field containing the influence of the equivalent flow field disturbance body is obtained. Among them, field variables This refers to the non-uniform multi-particle flow field model established based on the equivalent particle cloud flow field disturbance body. , , , These represent the pressure, temperature, velocity, and Mach number of the fluid at point r in space at time t, respectively. Point r in space is a global inertial coordinate system established with the initial center of mass of the spacecraft as the origin. This flow field will serve as the time-varying mechanical environment for the subsequent discrete particle motion.

[0046] Step S2: Construct a discrete particle swarm dynamics evolution model that integrates the aerodynamic disturbance coefficient matrix, and establish a force model for particles in the flow field;

[0047] 2.1 Establishing a non-contact aerodynamic interference force model between particles

[0048] The presence of particle j will disturb the surrounding flow field, and this disturbance will in turn affect the force on particle i. Define the aerodynamic disturbance coefficient matrix. To quantify this effect, particle i is subjected to a non-contact disturbance force from particle j. The expression is:

[0049]

[0050] in The local velocity perturbation induced by the motion of particle j. Let the windward area of ​​particle j be denoted by potential flow theory, which can be used as an approximation:

[0051]

[0052] Let j be the velocity of particle j. This is a dimensionless interference coefficient matrix, typically related to the distance vector between particles i and j. It is related to relative velocity and can be expressed empirically:

[0053]

[0054] in The reference drag coefficient is typically taken as 0.44. , Let be the constant to be fitted. Here is a correction factor based on local flow conditions, where , In fixed and The following experiment measures the known non-contact interference force. In the case of passing

[0055]

[0056] Inverse solution obtained Then, by changing the distance between particles, the obtained data is fitted to obtain... , And then by changing and Based on the obtained data, we can obtain... .

[0057] Spatial decay function:

[0058]

[0059] The interference characteristic length is used to characterize the effective range of non-contact aerodynamic interference between particles. It can be taken as 2 to 10 times the average particle spacing, depending on the state of the fluid.

[0060] 2.2 Establishing the control equations for particle motion

[0061] Construct a discrete particle swarm dynamics evolution model that integrates the aerodynamic disturbance coefficient matrix, in the background flow field. In this context, the motion of each discrete particle i is described by Newton's second law:

[0062]

[0063] in Let i be the mass of particle i. Let be the velocity of particle i, and g be the acceleration due to gravity.

[0064] Particle drag ,in Let i be the windward area of ​​particle i, and let i be the particle drag coefficient. The following is an empirical formula related to the particle Reynolds number, using the Clift-Gauvin relationship for spherical particles with high Reynolds numbers:

[0065]

[0066] Pressure gradient force ,in Let i be the volume of particle i.

[0067] Virtual mass force The virtual mass force coefficient The value is usually 0.5.

[0068] Shear lift ,in It represents fluid vorticity.

[0069] Therefore, based on the background flow field Based on the established formula of Newton's second law of particle motion, the motion of each particle can be calculated. At the same time, the interaction force between the particle and the flow field and the reaction force of the particle on the flow field can be calculated, which will be fed back into the governing equation of the flow field as the source term in step one.

[0070] Step S3: Establish a particle material coupled penetration model that considers dynamic damage field and strength degradation to describe the damage of the aircraft;

[0071] 3.1 Defining the dynamic damage state field of the structure

[0072] In the structural finite element model, a scalar field is defined. Characterizing points on the surface of an aircraft At any moment The cumulative degree of damage. The damage evolution equation can be written as:

[0073]

[0074] Where x represents the position of a point on the surface of the aircraft in an inertial coordinate system established with the aircraft's center of mass as the origin. The damage generation rate caused by particle impact represents the amount of damage added to a point in the material per unit time due to particle impact.

[0075] 3.2 Calculation of effective strength

[0076] Effective strength of material under current damage state Compared with the original strength The relationship is achieved through the reduction factor. Related:

[0077]

[0078] Among them, the reduction factor Should meet , It can be expressed in an exponential decay form:

[0079]

[0080] Damage sensitivity coefficient Damage evolution index The parameters are determined by fitting the relationship between loss and material strength through experimental measurement.

[0081] 3.3 Erosion and Interface Update

[0082] When particle i impacts the material, the volume of material removed during the k-th impact is calculated using a semi-empirical penetration model based on the impact point intensity and impact parameters. The Finnie erosion model was adopted:

[0083]

[0084] in The impact angle, The erosion factor is a function of the impact angle. (Volume removal) This leads to changes in surface geometry, which are then fed back to the CFD mesh as boundary conditions. The flow field computational domain is updated through dynamic meshing or mesh reconstruction techniques.

[0085] when hour

[0086]

[0087] when hour

[0088]

[0089] The critical impact angle is usually taken as 18.43°.

[0090] For material point x, the material damage in the k-th impact of a discrete particle impact event is:

[0091]

[0092] in The critical failure volume of the material element is obtained by measuring the failure volume of the aircraft material through strength experiments. The total damage is the sum of the contributions from all impact events; the damage field used to characterize the target damage is obtained by calculating the total damage at each point on the aircraft surface. The corresponding specific numerical value.

[0093] Step S4: Construct an explicit and implicit dynamic partitioning coupling solution method based on effective interference intensity.

[0094] 4.1 Define the effective interference intensity index

[0095] Define a scalar index for each fluid mesh element This is used to quantify the complexity and coupling strength of the physical processes within the unit:

[0096]

[0097] Where: cell represents a fluid mesh element, the first term on the right side of the equation is the kinetic energy ratio, the second term is the concentration term, the third term is the disturbance term, and the last term is the damage term. , This represents the average density and average velocity vector of particles within the fluid grid cell; The average pressure of the flow field within the fluid grid cell; This represents the number of particles within a fluid mesh cell. The reference particle number can be taken as the average number of particles contained in all fluid mesh cells; This is the sum of the aerodynamic interference coefficients between all particle pairs within a fluid grid cell. For example, particle i and particle j constitute a particle pair, and the number of particle pairs... ( 1); Points on the surface of the aircraft in the fluid grid cell exist The accumulated damage value over time;

[0098] , , For the weighting coefficients, satisfying =0.5. Different weighting coefficients can be considered for different problems. For example, in the scenario of a high-speed sandstorm impacting a composite material wing, the effect of particle concentration and the damage to the aircraft are the main concerns. Aerodynamic interference between particles affects the trajectory, but at high speeds, the shock wave dominates, and the interference is relatively secondary. Therefore, a weighting of 0.5 can be used. , 1. 2.

[0099] 4.2 Dynamic Partitioning Rules

[0100] Set high threshold and low threshold , there are 0 < < At each coupling time step, based on the calculated... The units are labeled as three types of regions:

[0101] Explicit fine area: The physical processes in this region are complex, requiring a high-precision, small-step-size method for solving.

[0102] Implicit statistics area: If the physical processes in this region are relatively simple, then the solution can be reduced to a lower order.

[0103] Dynamic buffer: This region is a transition zone, which enables the transfer of particle motion parameters between the explicit and implicit regions and the conversion of algorithms between the two regions.

[0104] 4.3 Partition Solution Method

[0105] Explicit fine-grained region: using a small time step In the formula The smallest grid size for the explicit area. Let be the local maximum fluid velocity and c be the local speed of sound. The complete equations of motion, including collision and disturbance forces, are solved for each particle within the region. Transient finite element analysis is performed on the structure, achieving tight coupling between the fluid, solid, and particles. The bidirectional coupling between the flow field and particles iterates until convergence within each small step.

[0106] Implicit statistical region: using a large time step The magnification factor M is typically taken as 5~20, which aggregates the particles in this region into several statistical particle clusters. Each particle cluster is represented by its average position. Average speed Average mass and quantity Description. The motion of the particle cluster is governed by the average form of the equation of motion:

[0107]

[0108] Among them, particle cluster drag It is calculated from the average velocity of the flow field at the location of the particle cluster. This represents the sum of the pressure gradient force, virtual mass force, shear lift, non-contact aerodynamic disturbance force, and gravity acting on the particle cluster. The interaction between the particle cluster and the flow field is achieved through the average source term.

[0109] Dynamic buffer: The core function of this area is to realize the transfer of particle motion parameters between the explicit area and the implicit area, as well as the conversion of algorithms between the two areas.

[0110] Specifically, it includes:

[0111] De-aggregation process: When a cluster of hidden particles moves from the hidden region to the buffer region, assuming the cluster moves at the current average velocity... sports And its calculations yielded Based on the change value calculated each time, the rate of change is obtained, and the rate of change is used to predict whether it will exceed [a certain value] in the next time step. When this happens, it needs to be decomposed into multiple explicit particles. That is, a set of discrete particles is generated based on the particle motion parameters of the particle cluster according to a normal distribution.

[0112] Aggregation process: When multiple explicit particles move from the explicit region to the buffer zone, and the unit they belong to... Reduce to When this happens, these particles can be aggregated into a cluster. That is, the mean and variance of the positions and velocities of these particles are statistically analyzed and used as attributes of the cluster, which then participates in subsequent calculations in the form of a cluster.

[0113] Therefore, the entire flow domain and the aircraft are first meshed. Then, an explicit-implicit dynamic partitioning coupling solution method based on effective disturbance intensity is used to solve the compressible Navier-Stokes equations containing source terms in the established equivalent particle cloud flow field disturbance body to obtain the three-dimensional unsteady background flow field containing the influence of the equivalent flow field disturbance body. For the velocity cloud map of the flow field of a regular civil aircraft flying under low-concentration particulate flow, the forces and motions of particles in the flow field are calculated based on the background flow field information. The damage field is then calculated based on the particle motion and material strength to determine the damage experienced at various points on the aircraft surface. Then, the entire flight process is continuously calculated iteratively based on time steps. Ultimately, the surface damage and damage distribution of the aircraft can be calculated. Based on this damage distribution, protective designs can be implemented for different parts of the aircraft, taking into account the pressure and velocity distribution of the fluid in the flow field during flight, as well as the aircraft's lift coefficient. The analysis is conducted to evaluate the aircraft's performance in a particle stream, among other things. The characteristic area of ​​the aircraft, and the lift force acting on the aircraft.

[0114]

[0115] Indicates the surface area of ​​the aircraft. The fluid pressure on the aircraft surface is determined by the pressure distribution in the flow field calculated above. get, Let be the normal vector of the aircraft surface.

Claims

1. A dynamic disturbance analysis method for high-speed multi-particle aerodynamic coupling impact, characterized in that, include: Step S1: Establish a non-uniform multi-particle flow field model based on an equivalent particle cloud flow field disturbance body; Step S2: Construct a discrete particle swarm dynamics evolution model that integrates the aerodynamic disturbance coefficient matrix, solve for the motion of each particle, and calculate the interaction force between the particle and the flow field and feed it back into the flow field. Step S3: Establish a particle-material coupled penetration model that considers dynamic damage field and strength degradation to describe the damage of the aircraft; Step S4: Solve the problem using an explicit-implicit dynamic partitioning coupling solution method based on the effective interference intensity to obtain a three-dimensional unsteady background flow field containing the influence of the equivalent flow field interference body. Calculate the damage field at various points on the aircraft surface and iteratively calculate the entire flight process according to the time step to finally calculate the surface damage and damage distribution of the aircraft.

2. The dynamic disturbance analysis method according to claim 1, characterized in that, Step S1 specifically includes: equating the particle swarm containing the aircraft to an equivalent flow field disturbance body with an ellipsoidal shape; and numerically simulating the non-uniform multi-particle flow field model induced by the equivalent flow field disturbance body around the aircraft by solving the compressible Navier-Stokes equations with added momentum and energy source terms.

3. The dynamic disturbance analysis method according to claim 1, characterized in that, The discrete particle swarm dynamics evolution model constructed in step S2 is as follows: in Let i be the mass of particle i. Let t be the velocity of particle i, and t be the time. , , , Let $i$ be the drag force, pressure gradient force, virtual mass force, and shear lift force acting on particle $i$, respectively, and $g$ be the gravitational acceleration. For particle i, a non-contact disturbance force is exerted by particle j: in The local velocity perturbation induced by the motion of particle j. Let be the windward area of ​​particle j. For reference drag coefficient, For fluid density, The local velocity perturbation induced by the motion of particle j. For spatial decay function, This is the aerodynamic interference coefficient matrix.

4. The dynamic disturbance analysis method according to claim 3, characterized in that, The aerodynamic interference coefficient matrix is ​​as follows: in Particle size, Let i be the distance vector between particles i and j. , Let be the constant to be fitted. This is a correction factor based on local flow conditions; Spatial decay function for: in The length of the interference feature.

5. The dynamic disturbance analysis method according to claim 1, characterized in that, The particle-material coupling penetration model established in step S3 adopts the Finnie erosion model: The damage to the aircraft is obtained by summing the damage at various points on the aircraft surface. For material point x, the damage from the k-th particle impact is: in Let i be the mass of particle i. Let i be the velocity of particle i. The effective strength of the material under the current damage state. Regarding the impact angle Corrosive factors, This represents the critical failure volume of the material element.

6. The dynamic disturbance analysis method according to claim 1, characterized in that, Erosion factor for; when hour ； when hour 。 7. The dynamic disturbance analysis method according to claim 1, characterized in that, The solution process of the explicit-implicit dynamic partitioning coupling solution method in step S4 is as follows: Explicit fine-grained region: using time step In the formula The smallest grid size for the explicit area. The local maximum fluid velocity is given by denoted as c, and the local speed of sound is given by denoted as c. The bidirectional coupling between the flow field and particles iterates until convergence in each time step. Implicit statistical region: using time step M is the amplification factor; the motion of the particle cluster is controlled by the average form of the equation of motion, and the interaction between the particle cluster and the flow field is achieved through the average source term; Dynamic buffer: Enables the transfer of particle motion parameters between the explicit and implicit regions and the conversion between the two regions; The entire flow domain and the aircraft are meshed, and then the compressible Navier-Stokes equations containing source terms are solved in the established equivalent particle cloud flow field disturbance body to obtain the three-dimensional unsteady background flow field containing the influence of the equivalent flow field disturbance body.

8. The dynamic disturbance analysis method according to claim 7, characterized in that, The partitioning rule is: set a high threshold. and low threshold , there are 0 < < ; At each coupling time step, based on the calculated scalar index The units are labeled as three types of regions: Explicit fine area: Implicit statistics area: Dynamic buffer: ; Among them scalar indicators for: in: , This represents the average density and average velocity vector of particles within the fluid grid cell; The average pressure of the flow field within the fluid grid cell; This represents the number of particles within a fluid mesh cell. The reference particle number; It is the sum of the aerodynamic interference coefficients between all particle pairs within the fluid mesh cell. The number of particle pairs formed by particle i and particle j. Points on the surface of the aircraft in the fluid grid cell exist The accumulated damage value over time. , , These are the weighting coefficients.

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