Method and device for constructing high-speed airflow shearing liquid film flow slip boundary condition, equipment and medium

Abstract

The application discloses a method and device for constructing a high-speed airflow shearing liquid membrane flow slip boundary condition, equipment and medium, and relates to the technical field of fluid mechanics, which comprises the following steps: constructing a liquid membrane flow N-S equation, a liquid membrane interface kinematics boundary equation and an interface stress balance equation of a target high-speed aircraft under high-speed airflow, and simplifying the equations by using a lubrication approximation method and temperature variation of the target high-speed aircraft under high-speed airflow to obtain target simplified equations; performing numerical simulation on airflow shearing force driven liquid membrane movement of the target high-speed aircraft under high-speed airflow based on the target simplified equations to obtain liquid membrane displacement data of the target high-speed aircraft under high-speed airflow; and fitting the liquid membrane displacement data with airflow shearing force of the target high-speed aircraft under high-speed airflow to obtain target slip boundary conditions corresponding to liquid membrane flow of the high-speed airflow when shearing the liquid membrane. In this way, the aircraft development efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluid mechanics, in particular to a method and device for constructing a slip boundary condition of a high-speed airflow shearing liquid film flow, equipment and a medium. BACKGROUND

[0002] High-speed aircrafts face severe thermal protection challenges in extreme aerodynamic heating environments. With the development of aircrafts towards high Mach, long endurance and reusability, traditional passive ablative materials have been difficult to withstand harsh working conditions such as ultra-high temperature, strong oxidation and large temperature gradient, especially in the local high heat flux area, the existing heat protection materials are almost invalid. Active transpiration cooling as a new type of thermal protection method emerges as the times require, which injects cooling water into the wall surface to form a liquid film under the action of high-speed airflow, and absorbs aerodynamic heat by means of liquid film evaporation phase change, thereby effectively reducing the wall surface temperature. However, the existence of the liquid film will interfere with the structure of the external flow field and affect the aerodynamic performance of the aircraft, so it is urgent to develop a corresponding numerical simulation method. Although the water-vapor two-phase flow model based on VOF (Volume of Fluid, a numerical method for tracking fluid interfaces) can simulate the process in detail, the calculation cost is too high to meet the engineering design requirements.

[0003] In view of the fact that the actual liquid film is thin and the interface is smooth, some studies have proposed to simplify the liquid film interface as a boundary condition considering evaporation and slip, thereby significantly reducing the calculation complexity. Therefore, how to determine the slip boundary condition of the high-speed airflow shearing liquid film flow to quickly evaluate the influence of the liquid film flow on the flow field and aerodynamic performance of the aircraft is a problem to be solved. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a method and device for constructing a slip boundary condition of a high-speed airflow shearing liquid film flow, which can quickly evaluate the influence of the liquid film flow on the flow field and aerodynamic performance of the aircraft. The specific scheme is as follows:

[0005] In a first aspect, the present application discloses a method for constructing a slip boundary condition of a high-speed airflow shearing liquid film flow, comprising:

[0006] constructing a liquid film flow N-S equation, a liquid film interface kinematics boundary equation and an interface stress balance equation of a target high-speed aircraft under a high-speed airflow; the high-speed airflow is an airflow whose airflow velocity satisfies a preset high-speed judgment condition;

[0007] dimensionally simplifying the liquid film flow N-S equation, the liquid film interface kinematics boundary equation and the interface stress balance equation by using a lubrication approximation method and a target feature, to obtain a target simplified equation; the target feature is a parameter feature of the target high-speed aircraft whose temperature variation is less than a preset temperature variation threshold in the airflow direction of the high-speed airflow.

[0008] numerical simulation of the target high-speed aircraft under high-speed airflow based on the target simplified equation to obtain liquid film displacement data of the target high-speed aircraft under high-speed airflow;

[0009] fitting the liquid film displacement data with the airflow shear force of the target high-speed aircraft under high-speed airflow to obtain target slip boundary conditions corresponding to liquid film flow when high-speed airflow shears the liquid film.

[0010] Optionally, the constructing the liquid film flow N-S equation, the liquid film interface kinematic boundary equation and the interface stress balance equation of the target high-speed aircraft under high-speed airflow comprises:

[0011] constructing the liquid film flow N-S equation and the liquid film interface kinematic boundary equation of the target high-speed aircraft under high-speed airflow based on a high-speed airflow shear plane two-dimensional liquid film flow physical model; the high-speed airflow shear plane two-dimensional liquid film flow physical model is a physical model constructed based on the contact state of the liquid film of the target high-speed aircraft with a solid wall and the flow change form of the liquid film under high-speed airflow;

[0012] constructing a normal stress balance equation based on the pressure, viscous force, surface tension and intermolecular van der Waals force of the liquid film of the target high-speed aircraft under high-speed airflow; and constructing a tangential stress balance equation based on the balance of viscosity, thermal stress and gas shear of the liquid film.

[0013] Optionally, the dimension reduction simplification of the liquid film flow N-S equation, the liquid film interface kinematic boundary equation and the interface stress balance equation using the lubrication approximation method and the target characteristics to obtain the target simplified equation comprises:

[0014] dimension reduction simplification of the liquid film flow N-S equation, the liquid film interface kinematic boundary equation and the interface stress balance equation using the lubrication approximation method to obtain a one-dimensional lubrication equation;

[0015] ignoring the influence of temperature change in the direction of high-speed airflow on the target high-speed aircraft, simplifying the one-dimensional lubrication equation to obtain the target simplified equation.

[0016] Optionally, the numerical simulation of the target high-speed aircraft under high-speed airflow based on the target simplified equation comprises:

[0017] numerical solution of the target simplified equation based on a preset pseudospectral method and an implicit Euler method, and using a Newton iteration method to numerically simulate the movement of the liquid film driven by the airflow shear force of the target high-speed aircraft under high-speed airflow.

[0018] Optionally, before the numerical simulation of the moving of the liquid film driven by the shear force of the high-speed airflow of the target high-speed aircraft based on the target simplified equation, the method further comprises:

[0019] setting the initial shape of the liquid film of the target high-speed aircraft as an inclined liquid film, and setting the liquid film based on preset liquid film setting conditions to realize the moving of the liquid film driven by the shear force of the airflow; the preset liquid film setting conditions comprise: setting the size of the shear force of the airflow, using the precursor film method at the contact line position of the liquid film and the solid wall, setting the left side boundary liquid film height to be fixed, and setting the right side boundary condition to be a symmetric boundary condition.

[0020] Optionally, the numerical simulation of the moving of the liquid film driven by the shear force of the high-speed airflow of the target high-speed aircraft based on the target simplified equation to obtain the liquid film displacement data of the target high-speed aircraft under the high-speed airflow comprises:

[0021] determining the displacement data of the contact point of the liquid film and the solid wall of the target high-speed aircraft under the high-speed airflow based on the target simplified equation, and determining the liquid film interface slip velocity of the moving of the liquid film driven by the shear force of the airflow of the target high-speed aircraft under the high-speed airflow based on the displacement data.

[0022] Optionally, the fitting of the liquid film displacement data and the shear force of the high-speed airflow of the target high-speed aircraft under the high-speed airflow to obtain the target slip boundary condition corresponding to the liquid film flow when the high-speed airflow shears the liquid film comprises:

[0023] changing the shear force of the high-speed airflow of the target high-speed aircraft under the high-speed airflow to obtain the current liquid film interface slip velocity corresponding to the target high-speed aircraft under each shear force of the airflow;

[0024] fitting each shear force of the airflow and the corresponding liquid film interface slip velocity to obtain the functional relationship between the liquid film interface slip velocity and the shear force of the airflow, and determining the target slip boundary condition based on the functional relationship.

[0025] In a second aspect, the application discloses a device for constructing a slip boundary condition of a high-speed airflow shearing liquid film flow, comprising:

[0026] an equation construction module, configured to construct a liquid film flow N-S equation, a liquid film interface kinematic boundary equation and an interface stress balance equation of a target high-speed aircraft under a high-speed airflow; the high-speed airflow is an airflow with an airflow velocity satisfying a preset high-speed judgment condition;

[0027] An equation simplification module is configured to simplify the liquid film flow N-S equation, the liquid film interface kinematics boundary equation and the interface stress balance equation by using a lubrication approximation method and a target feature to obtain a target simplified equation, wherein the target feature is a flight parameter feature of the target high-speed aircraft in a high-speed airflow, and a temperature variation of the target high-speed aircraft in the high-speed airflow is less than a preset temperature variation threshold.

[0028] A numerical simulation module is configured to perform numerical simulation on the target high-speed aircraft in the high-speed airflow based on the target simplified equation to obtain liquid film displacement data of the target high-speed aircraft in the high-speed airflow.

[0029] A boundary condition determination module is configured to fit the liquid film displacement data and the airflow shear force of the target high-speed aircraft in the high-speed airflow to obtain a target slip boundary condition corresponding to the liquid film flow when the high-speed airflow shears the liquid film.

[0030] In a third aspect, the present application discloses an electronic device, comprising:

[0031] A memory is configured to save a computer program.

[0032] A processor is configured to execute the computer program to implement the construction method of the high-speed airflow shear liquid film flow slip boundary condition.

[0033] In a fourth aspect, the present application discloses a computer readable storage medium configured to save a computer program, and the computer program is executed by a processor to implement the construction method of the high-speed airflow shear liquid film flow slip boundary condition.

[0034] It can be seen that in the present application, the N-S equation of the liquid film flow of the target high-speed vehicle under high-speed airflow, the kinematic boundary equation of the liquid film interface, and the interface stress balance equation are constructed; the high-speed airflow is an airflow whose airflow speed meets a preset high-speed judgment condition; the liquid film flow N-S equation, the liquid film interface kinematic boundary equation, and the interface stress balance equation are simplified by using lubrication approximation method and target characteristics to obtain target simplified equations; the target characteristics are vehicle parameter characteristics of the target high-speed vehicle under high-speed airflow, which are in the airflow direction of the high-speed airflow and have a temperature change less than a preset temperature change threshold; numerical simulation is performed on the liquid film movement driven by the airflow shear force of the target high-speed vehicle under high-speed airflow based on the target simplified equations to obtain liquid film displacement data of the target high-speed vehicle under high-speed airflow; and the liquid film displacement data is fitted with the airflow shear force of the target high-speed vehicle under high-speed airflow to obtain target slip boundary conditions corresponding to the liquid film flow when the high-speed airflow shears the liquid film. In this way, by changing the liquid film flow condition of the vehicle wall surface into a liquid film slip boundary condition, the numerical calculation work can be performed without solving the liquid flow and without processing the water vapor interface capture problem, so that the influence of the liquid film flow on the vehicle surface on the vehicle flow field and the aerodynamic performance can be evaluated more quickly, thereby saving the calculation and evaluation time for vehicle development and design. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on the provided drawings.

[0036] Figure 1 A flow chart of a method for constructing a high-speed airflow shear liquid film flow slip boundary condition disclosed in the present application;

[0037] Figure 2 A schematic diagram of a physical model of a high-speed airflow shear planar two-dimensional liquid film flow disclosed in the present application;

[0038] Figure 3 A schematic diagram of a numerical simulation result of airflow shear force driven liquid film movement disclosed in the present application;

[0039] Figure 4 A schematic diagram of a slip velocity and shear stress size ratio disclosed in the present application;

[0040] Figure 5 A flow chart of a method for constructing a specific high-speed airflow shear liquid film flow slip boundary condition disclosed in the present application;

[0041] Figure 6 A high-speed airflow shearing liquid film flow slip boundary condition construction device structure diagram disclosed by the application is shown in the figure;

[0042] Figure 7 An electronic device structure diagram disclosed by the application is shown in the figure. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the application.

[0044] Currently, active transpiration cooling is used as a new type of thermal protection method for hypersonic aircraft, and the cooling water is in the form of phase change evaporation to absorb the aerodynamic heating of the high-speed aircraft. The cooling water is injected into the outer wall of the aircraft, and a liquid film is formed under the shearing action of high-speed airflow. The liquid film evaporates and changes phase under the shearing action of high-speed and high-temperature airflow, absorbs the heat brought by high-speed airflow, and reduces the temperature of the aircraft wall, thereby protecting the high-speed aircraft. Liquid film cooling changes the distribution of aircraft flow field parameters, and thus affects the aerodynamic characteristics of the aircraft. Therefore, the application will specifically introduce a method for determining the flow slip boundary condition of the liquid film sheared by high-speed airflow, which is extremely crucial in the field of aircraft design.

[0045] Referring to Figure 1 The embodiment of the application discloses a method for constructing a flow slip boundary condition of a liquid film sheared by high-speed airflow, which comprises the following steps:

[0046] Step S11: constructing a liquid film flow N-S equation, a liquid film interface kinematics boundary equation and an interface stress balance equation of a target high-speed aircraft under high-speed airflow; the high-speed airflow is airflow with airflow velocity satisfying a preset high-speed judgment condition.

[0047] In this embodiment, the liquid film flow N-S equation, the liquid film interface kinematic boundary equation and the interface stress balance equation of the target high-speed vehicle under high-speed airflow are constructed, including: constructing the liquid film flow N-S equation and the liquid film interface kinematic boundary equation of the target high-speed vehicle under high-speed airflow based on a high-speed airflow shear plane two-dimensional liquid film flow physical model; the high-speed airflow shear plane two-dimensional liquid film flow physical model is a physical model constructed based on the contact state of the liquid film of the target high-speed vehicle with a solid wall and the flow change form of the liquid film under high-speed airflow; constructing the normal stress balance equation based on the pressure, viscous force, surface tension and intermolecular van der Waals force of the liquid film of the target high-speed vehicle under high-speed airflow; and constructing the tangential stress balance equation based on the balance of viscosity, thermal stress and gas shear of the liquid film. That is, based on the high-speed airflow shear plane two-dimensional liquid film flow physical model, the liquid film flow N-S equation is constructed, and according to the gas-liquid two-phase flow theory, the liquid film interface kinematic boundary condition and the interface stress balance condition (including the normal stress balance equation and the tangential stress balance equation) are considered, wherein the normal stress balance is mainly determined by the pressure, viscous force, surface tension and intermolecular van der Waals force, and the tangential stress balance is mainly dominated by viscosity, thermal stress and gas shear. It should be noted that, as shown in Figure 2 , the high-speed airflow shear plane two-dimensional liquid film flow physical model is a physical model constructed based on the contact state of the liquid film of the target high-speed vehicle with a solid wall and the flow change form of the liquid film under high-speed airflow. Wherein, the two-dimensional plane liquid film flow N-S equation is as follows:

[0048] ;

[0049] Wherein, x and y respectively represent the liquid film flow direction coordinate and the thickness direction coordinate, u and v respectively represent the flow velocity and the normal velocity of the liquid film, t is the time, p, , T respectively represent the pressure, density and temperature in the liquid film, k, , respectively represent the thermal conductivity, specific heat capacity and dynamic viscosity of the fluid in the liquid film. The interface kinematic boundary equation is:

[0050] ;

[0051] Wherein, h represents the thickness of the liquid film, since the thickness changes under the action of gas shear and temperature field, it is a variable evolving with space and time , J represents the mass flow of liquid evaporation / condensation. The normal stress balance equation is:

[0052] ;

[0053] Wherein, represents the intermolecular van der Waals force between the molecules of the gas and liquid, and represents the intermolecular attractive force between the molecules of the gas and liquid at the gas-liquid interface. The surface tension varies with temperature, and can be assumed to be linear:

[0054]

[0055] wherein, is the surface tension coefficient of the interface at a temperature of The tangential stress balance equation is:

[0056]

[0057] wherein, represents the surface tension coefficient of the liquid film, and S is the high-speed gas shear force. Since there is heat exchange at the interface, according to the heat flux balance (i.e., the balance between the heat input and output of the liquid film surface):

[0058]

[0059] wherein, represents the convective heat transfer coefficient. Finally, for the solid wall, the no-slip, no-penetration, and constant steady boundary conditions are selected:

[0060]

[0061] Step S12: using the lubrication approximation method and the target feature to reduce the dimensionality of the liquid film flow N-S equation, the liquid film interface kinematics boundary equation, and the interface stress balance equation to obtain a target simplified equation.

[0062] ​​​​In the embodiment, the dimension reduction simplification of the liquid film flow N-S equation, the liquid film interface kinematics boundary equation and the interface stress balance equation by using the lubrication approximation method and the target feature to obtain the target simplified equation comprises: dimension reduction simplification of the liquid film flow N-S equation, the liquid film interface kinematics boundary equation and the interface stress balance equation by using the lubrication approximation method to obtain a one-dimensional lubrication equation; ignoring the influence of temperature change of the high-speed airflow flow direction on the target high-speed aircraft, the one-dimensional lubrication equation is simplified to obtain the target simplified equation. That is, using the lubrication (long wave) approximation (the core idea of the lubrication approximation is that the physical quantity along the X direction is much larger than the physical quantity along the Y direction), the dimension reduction simplification of the above liquid film flow N-S equation and the interface equation is performed, and finally a one-dimensional lubrication equation is obtained, which contains the influence of complex physical factors such as surface tension, van der Waals force, flow shear and temperature field; ignoring the temperature change of the high-speed airflow flow direction in the X direction, that is, ignoring the influence of the temperature gradient in the X direction, the one-dimensional lubrication equation is further simplified. Specifically, using the lubrication (long wave) approximation (the core idea of the lubrication approximation is that the physical quantity along the X direction is much larger than the physical quantity along the Y direction), the dimension reduction simplification of the above liquid film flow N-S equation and the interface equation is performed, and dimension analysis is performed first:

[0063] ;

[0064] ;

[0065] Here, is the ratio of the characteristic length scales of the system Y, X direction, which is a small quantity. The above scale is brought into the N-S equation and the interface equation, all high-order terms about are eliminated and simplified, and finally a one-dimensional lubrication equation is obtained:

[0066] ;

[0067] The one-dimensional lubrication equation contains the influence of complex physical factors such as surface tension, intermolecular van der Waals force, flow shear and temperature field. Further, ignoring the temperature change of the high-speed airflow flow direction in the X direction, that is, ignoring the influence of the temperature gradient in the X direction, the one-dimensional lubrication equation is further simplified to obtain the equation .

[0068] Step S13: numerical simulation of the liquid film movement driven by the airflow shear force of the target high-speed aircraft under the high-speed airflow based on the target simplified equation to obtain the liquid film displacement data of the target high-speed aircraft under the high-speed airflow.

[0069] In this embodiment, the numerical simulation of the moving liquid film of the target high-speed aircraft driven by the airflow shear force under high-speed airflow based on the target simplified equation comprises: based on the preset pseudospectral method and the implicit Euler method, and by using the Newton iteration method to numerically solve the target simplified equation, the numerical simulation of the moving liquid film of the target high-speed aircraft driven by the airflow shear force under high-speed airflow is performed. That is, the numerical solution of the simplified equation is performed, the spatial discretization adopts the Fornberg format of any order, the time advancement adopts the implicit Euler method, and the Newton iteration is combined to perform the numerical simulation of the moving liquid film of the target high-speed aircraft driven by the airflow shear force under high-speed airflow. Wherein, the numerical simulation result is shown in Figure 3 , the dimensionless time , is the initial liquid film thickness, and the dimensionless shear stress . The numerical results show that the gas shear action on the interface can drive the liquid film to flow, and a protruding structure is formed in front of the liquid film contact line, and the protrusion will slowly increase with the movement of the liquid film.

[0070] In this embodiment, before the numerical simulation of the moving liquid film of the target high-speed aircraft driven by the airflow shear force under high-speed airflow based on the target simplified equation, the initial shape of the liquid film of the target high-speed aircraft is set to be an inclined liquid film, and the liquid film is set based on the preset liquid film setting condition to realize the moving liquid film driven by the airflow shear force; the preset liquid film setting condition comprises: setting the size of the airflow shear force, using the precursor film method at the contact line position of the liquid film and the solid wall, setting the left side boundary liquid film height to be fixed, and setting the right side boundary condition to be a symmetric boundary condition. That is, in order to realize the moving liquid film driven by the gas shear force, the initial shape is an inclined liquid film, the contact line position uses the precursor film method, the left side boundary liquid film height is fixed, and the right side boundary condition is set to a symmetric boundary condition, which can realize the moving liquid film driven by the gas shear force. It should be noted that the precursor film method is used to solve the contradiction between the moving contact line and the macro flow (no slip boundary condition), especially the singularity of the shear stress near the contact line, that is, in the lubrication equation, the separation pressure term is set, and when h is very small, the gradient becomes very large to balance and offset the stress singularity near the contact line, so that the equation obtains a finite solution. That is, the precursor film method is a method for eliminating the stress singularity near the contact line position, that is, the stress singularity balance of the contact line position of the liquid film and the solid wall is performed by using the precursor film model.

[0071] In the embodiment, the numerical simulation of the liquid film movement driven by the airflow shear force of the target high-speed aircraft under the high-speed airflow based on the target simplified equation comprises: determining the displacement data of the contact point between the liquid film and the solid wall of the target high-speed aircraft under the high-speed airflow based on the target simplified equation, and determining the interface slip velocity of the liquid film movement driven by the airflow shear force of the target high-speed aircraft under the high-speed airflow based on the displacement data. That is, the interface slip velocity of the liquid film movement driven by the airflow shear force of the target high-speed aircraft under the high-speed airflow is obtained by calculating Figure 2 The displacement of the contact point can be used to evaluate the interface movement velocity, and then the interface slip velocity of the liquid film is obtained.

[0072] Step S14: fitting the liquid film displacement data with the airflow shear force of the target high-speed aircraft under the high-speed airflow to obtain the target slip boundary condition corresponding to the liquid film flow when the high-speed airflow shears the liquid film.

[0073] In the embodiment, the fitting of the liquid film displacement data with the airflow shear force of the target high-speed aircraft under the high-speed airflow to obtain the target slip boundary condition corresponding to the liquid film flow when the high-speed airflow shears the liquid film comprises: changing the airflow shear force of the target high-speed aircraft under the high-speed airflow to obtain the current liquid film interface slip velocity corresponding to the target high-speed aircraft under each airflow shear force; fitting each airflow shear force with the corresponding liquid film interface slip velocity to obtain the functional relationship between the liquid film interface slip velocity and the airflow shear force, and determining the target slip boundary condition based on the functional relationship. Specifically, the size of the airflow shear force is changed, and the movement velocity of the liquid film interface under different shear forces is calculated, as shown in FIG. 4. Figure 4 As shown in FIG. 4, it can be found that the slip velocity and the size of the shear stress are basically in a linear relationship, so the expression of the liquid film interface slip velocity and the airflow shear force can be fitted This allows for the determination of the slip boundary conditions for high-speed airflow shear liquid film flow. The sharp leading edges of aircraft wings, control surfaces, and nose cones experience the most extreme aerodynamic and thermal loads during high-speed flight. By determining the slip boundary conditions, this application can accurately simulate the formation and evaporation of the liquid film during sweating cooling in these locally high-heat-flux regions, evaluate its effectiveness in reducing wall temperature and preventing structural ablation, and design and adjust the liquid film cooling scheme for the sharp leading edges of the aircraft wings, control surfaces, and nose cones based on the evaluation results. Furthermore, control surfaces generate complex local flow fields and shock waves during deflection, exacerbating aerodynamic heating. Determining the slip boundary conditions for high-speed airflow shear liquid film flow allows for the analysis of the stability of the coolant film under strong pressure gradients and airflow shear, optimizing coolant injection strategies, and ensuring the maneuverability and structural integrity of control surfaces at high temperatures. Additionally, the inlet lip of a hypersonic vehicle is another high-heat-flux region, and the coolant film may interfere with the intake airflow field. Determining the slip boundary conditions for high-speed airflow shear liquid film flow can help assess the impact of liquid film cooling on inlet start-up characteristics and compression efficiency, and provide feasibility for providing stable inlet flow to the engine.

[0074] As can be seen, in this embodiment, as Figure 5 As shown, based on the physical model of two-dimensional liquid film flow in a high-speed airflow shear plane, the NS equation for liquid film flow is constructed. According to the gas-liquid two-phase flow theory, considering the kinematic boundary conditions and interface stress equilibrium conditions of the liquid film interface, the above-mentioned NS equation and interface equation for liquid film flow are simplified by dimension reduction. Finally, the NS equation and interface equation for liquid film flow can be obtained, which include the influence of complex physical factors such as surface tension, van der Waals force, flow shear, and temperature field. The temperature change of the high-speed airflow in the X direction is ignored, that is, the influence of the temperature gradient in the X direction is ignored, and the one-dimensional lubrication equation is further simplified. The simplified equation is numerically solved. In order to realize the gas shear force driving the liquid film movement, the initial shape is an inclined liquid film, the contact line position uses the precursor film method, the liquid film height on the left boundary is fixed, and the boundary conditions on the right are set as symmetrical boundary conditions, which can realize the gas shear force driving the liquid film movement. Then, numerical solutions are performed. Spatial discretization uses an arbitrary-order Fornberg scheme, and time progression uses an implicit Euler method combined with Newton iteration. The interface movement velocity is evaluated by calculating the displacement of the contact point, and the slip velocity of the gas-liquid interface is obtained. Analysis shows that the slip velocity and shear stress are basically linearly related, thus fitting an expression for the slip velocity of the liquid film interface and the airflow shear force. In this way, by transforming the liquid film flow conditions on the aircraft wall into liquid film slip boundary conditions, the numerical calculation can avoid solving the liquid flow and dealing with the water vapor interface capture problem. This allows for a faster evaluation of the impact of liquid film flow on the aircraft surface on the aircraft flow field and aerodynamic performance, saving computational evaluation time for aircraft development and design.

[0075] Reference Figure 6 According to the description, the application further discloses a device for constructing a high-speed airflow shearing liquid film flow slip boundary condition, comprising:

[0076] An equation construction module 11 is configured to construct a liquid film flow N-S equation, a liquid film interface kinematics boundary equation and an interface stress balance equation of a target high-speed aircraft under high-speed airflow; the high-speed airflow is airflow with airflow velocity satisfying a preset high-speed judgment condition;

[0077] An equation simplification module 12 is configured to simplify the liquid film flow N-S equation, the liquid film interface kinematics boundary equation and the interface stress balance equation by using a lubrication approximation method and a target feature to obtain a target simplified equation; the target feature is an aircraft parameter feature of the target high-speed aircraft under high-speed airflow, which has a temperature variation less than a preset temperature variation threshold in the airflow direction of the high-speed airflow;

[0078] A numerical simulation module 13 is configured to perform numerical simulation on liquid film movement driven by airflow shearing force of the target high-speed aircraft under high-speed airflow based on the target simplified equation to obtain liquid film displacement data of the target high-speed aircraft under high-speed airflow;

[0079] A boundary condition determination module 14 is configured to fit the liquid film displacement data with airflow shearing force of the target high-speed aircraft under high-speed airflow to obtain a target slip boundary condition corresponding to liquid film flow when high-speed airflow shears liquid film.

[0080] In this embodiment, the liquid film flow condition of the aircraft wall surface is changed into a liquid film slip boundary condition, so that the numerical calculation work can be performed without solving liquid flow and without processing water vapor interface capture problems, thereby the influence of the liquid film flow on the aircraft surface on the aircraft flow field and aerodynamic performance can be evaluated more quickly, and the calculation and evaluation time for aircraft development and design is saved.

[0081] In some specific embodiments, the equation construction module 11 can specifically comprise:

[0082] A first equation construction unit is configured to construct a liquid film flow N-S equation and a liquid film interface kinematics boundary equation of a target high-speed aircraft under high-speed airflow based on a high-speed airflow shearing plane two-dimensional liquid film flow physical model; the high-speed airflow shearing plane two-dimensional liquid film flow physical model is a physical model constructed based on the contact state of the liquid film of the target high-speed aircraft with a solid wall and the flow change form of the liquid film under high-speed airflow;

[0083] A second equation construction unit is configured to construct a normal stress balance equation based on pressure, viscous force, surface tension, and intermolecular van der Waals force of the liquid film of the target high-speed aircraft under high-speed airflow, and construct a tangential stress balance equation based on balance of viscosity, thermal stress, and gas shear of the liquid film.

[0084] In some specific embodiments, the equation simplification module 12 can specifically include:

[0085] An equation dimension reduction unit is configured to reduce the dimension of the liquid film flow N-S equation, the liquid film interface kinematics boundary equation, and the interface stress balance equation by using a lubrication approximation method to obtain a one-dimensional lubrication equation.

[0086] An equation simplification unit is configured to ignore the influence of temperature change in the direction of high-speed airflow on the target high-speed aircraft, and simplify the one-dimensional lubrication equation to obtain a target simplified equation.

[0087] In some specific embodiments, the numerical simulation module 13 can be specifically configured to perform numerical solution of the target simplified equation based on a preset pseudospectral method and an implicit Euler method, and utilize a Newton iteration method to perform numerical simulation of the liquid film movement driven by the airflow shear force of the target high-speed aircraft under high-speed airflow.

[0088] In some specific embodiments, the construction device of the high-speed airflow shear liquid film flow slip boundary condition can further include:

[0089] A liquid film flow setting module is configured to set the initial form of the liquid film of the target high-speed aircraft as an inclined liquid film, and set the liquid film based on a preset liquid film setting condition to realize the liquid film movement driven by the airflow shear force; the preset liquid film setting condition includes setting the size of the airflow shear force, using a precursor film method at the contact line position of the liquid film and the solid wall, setting the left boundary liquid film height to be fixed, and setting the right boundary condition to be a symmetric boundary condition.

[0090] In some specific embodiments, the numerical simulation module 13 can specifically include:

[0091] A displacement data determination unit is configured to determine displacement data of a contact point of the liquid film and the solid wall of the target high-speed aircraft under high-speed airflow based on the target simplified equation, and determine a liquid film interface slip velocity of the liquid film movement driven by the airflow shear force of the target high-speed aircraft under high-speed airflow based on the displacement data.

[0092] In some specific embodiments, the boundary condition determination module 14 can specifically include:

[0093] a slip velocity determination unit configured to change the airflow shear force of the target high-speed vehicle under a high-speed airflow to obtain a current liquid film interface slip velocity corresponding to the target high-speed vehicle under each airflow shear force;

[0094] a boundary condition determination unit configured to fit each airflow shear force with the corresponding liquid film interface slip velocity to obtain a functional relationship between the liquid film interface slip velocity and the airflow shear force, and determine a target slip boundary condition based on the functional relationship.

[0095] Further, the embodiment of the present application further discloses an electronic device, Figure 7 is a structural diagram of an electronic device 20 according to an exemplary embodiment, and the contents in the figure cannot be considered as any limitation on the use range of the present application.

[0096] Figure 7 A structural diagram of an electronic device 20 is provided in the embodiment of the present application. The electronic device 20 can specifically include at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25 and a communication bus 26. The memory 22 is used to store a computer program, which is loaded and executed by the processor 21 to implement the related steps in the construction method of the high-speed airflow shear liquid film flow slip boundary condition disclosed in any of the preceding embodiments. In addition, the electronic device 20 in the embodiment can be an electronic computer.

[0097] In the embodiment, the power supply 23 is used to provide working voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and external devices, and the communication protocol followed by the communication interface 24 can be any communication protocol applicable to the technical solution of the present application, which is not limited here; the input / output interface 25 is used to obtain external input data or output data to the outside, and the specific interface type can be selected according to the specific application needs, which is not limited here.

[0098] In addition, the memory 22 as a carrier for resource storage can be a read-only memory, a random access memory, a magnetic disk or an optical disk, etc., and the resources stored thereon can include an operating system 221, a computer program 222, etc., and the storage mode can be temporary storage or permanent storage.

[0099] The operating system 221 is configured to manage and control the various hardware devices on the electronic device 20 and the computer program 222, which can be Windows Server, Netware, Unix, Linux, etc. In addition to the computer program for constructing the high-speed airflow shear liquid membrane flow slip boundary condition executed by the electronic device 20, the computer program 222 can further include computer programs for completing other specific work.

[0100] Further, the application also discloses a computer readable storage medium for storing a computer program; wherein the computer program is executed by a processor to implement the method for constructing the high-speed airflow shear liquid membrane flow slip boundary condition disclosed above. The specific steps of the method can refer to the corresponding content disclosed in the foregoing embodiments, which will not be repeated here.

[0101] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant part can refer to the method part.

[0102] The skilled person can further realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware, computer software or a combination of the two. In order to clearly show the interchangeability of hardware and software, the components and steps of each example have been described in the above description. Whether the functions are realized by hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the application.

[0103] The steps of the method or algorithm described in combination with the embodiments disclosed herein can be directly implemented by hardware, a software module executed by a processor, or a combination of the two. The software module can be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0104] Finally, it needs to be pointed out that in this document, relational terms such as first and second and the like can only be used to distinguish one entity or action from another entity or action, without necessarily requiring or implying that there is any such actual relationship or order between these entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof are intended to cover non-exclusive inclusions, so that a process, method, article, or apparatus that comprises a list of elements does not only include those elements, but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0105] The above detailed description of the technical solutions provided by the present application has been provided, and the principles and implementation modes of the present application have been described by applying specific examples. The above description of the examples is only for the purpose of helping to understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed, and the above description of the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method for constructing a high-speed gas flow shear liquid membrane flow slip boundary condition, characterized in that, The application relates to a method for obtaining a target slip boundary condition of a liquid film flow corresponding to high-speed airflow shearing of a target high-speed aircraft. The method comprises the following steps: constructing a liquid film flow N-S equation, a liquid film interface kinematic boundary equation and an interface stress balance equation of the target high-speed aircraft under high-speed airflow; the high-speed airflow is airflow with airflow velocity satisfying a preset high-speed judgment condition; simplifying the liquid film flow N-S equation, the liquid film interface kinematic boundary equation and the interface stress balance equation by using a lubrication approximation method and a target feature, so as to obtain a target simplified equation; the target feature is a parameter feature of the target high-speed aircraft under the high-speed airflow, and the parameter feature is a feature of the target high-speed aircraft under the high-speed airflow, and the temperature variation of the target high-speed aircraft under the high-speed airflow is less than a preset temperature variation threshold; numerically simulating the liquid film movement driven by the airflow shearing force of the target high-speed aircraft under the high-speed airflow based on the target simplified equation, so as to obtain liquid film displacement data of the target high-speed aircraft under the high-speed airflow; 2. The method according to claim 1, wherein, fitting the liquid film displacement data and the airflow shearing force of the target high-speed aircraft under the high-speed airflow, so as to obtain the target slip boundary condition of the liquid film flow corresponding to the high-speed airflow shearing of the target high-speed aircraft. The method for constructing the liquid film flow N-S equation, the liquid film interface kinematic boundary equation and the interface stress balance equation of the target high-speed aircraft under the high-speed airflow comprises the following steps: constructing the liquid film flow N-S equation and the liquid film interface kinematic boundary equation of the target high-speed aircraft under the high-speed airflow based on a high-speed airflow shearing plane two-dimensional liquid film flow physical model; the high-speed airflow shearing plane two-dimensional liquid film flow physical model is a physical model constructed based on the contact state of the liquid film of the target high-speed aircraft and a solid wall and the flow variation form of the liquid film under the high-speed airflow; 3. The method according to claim 1, wherein, constructing a normal stress balance equation based on the pressure, viscous force, surface tension and intermolecular van der Waals force of the liquid film of the target high-speed aircraft under the high-speed airflow, and constructing a tangential stress balance equation based on the balance of the liquid film, the viscosity, thermal stress and gas shearing. The method for simplifying the liquid film flow N-S equation, the liquid film interface kinematic boundary equation and the interface stress balance equation by using the lubrication approximation method and the target feature, so as to obtain the target simplified equation, comprises the following steps: simplifying the liquid film flow N-S equation, the liquid film interface kinematic boundary equation and the interface stress balance equation by using the lubrication approximation method, so as to obtain a one-dimensional lubrication equation; 4. The method according to claim 1, wherein, ignoring the influence of the temperature variation in the direction of the airflow on the target high-speed aircraft, and simplifying the one-dimensional lubrication equation, so as to obtain the target simplified equation. The method for numerically simulating the liquid film movement driven by the airflow shearing force of the target high-speed aircraft under the high-speed airflow based on the target simplified equation comprises the following steps:

5. The method according to any one of claims 1 to 4, wherein, numerically solving the target simplified equation by using a preset pseudospectral method and an implicit Euler method, and by using a Newton iteration method, so as to numerically simulate the liquid film movement driven by the airflow shearing force of the target high-speed aircraft under the high-speed airflow. Before the method for numerically simulating the liquid film movement driven by the airflow shearing force of the target high-speed aircraft under the high-speed airflow based on the target simplified equation, the method further comprises the following steps: The initial shape of the liquid film of the target high-speed vehicle is set as an inclined liquid film, and the liquid film is set based on preset liquid film setting conditions to realize airflow shear force driving liquid film movement; the preset liquid film setting conditions include: setting the size of the airflow shear force, using the precursor film method at the contact line position of the liquid film and the solid wall, setting the left side boundary liquid film height fixed, and setting the right side boundary condition as a symmetric boundary condition.

6. The method according to claim 5, wherein, The numerical simulation of the target high-speed vehicle under the airflow shear force driving liquid film movement under the high-speed airflow based on the target simplified equation includes: Determine the displacement data of the contact point of the liquid film and the solid wall of the target high-speed vehicle under the high-speed airflow based on the target simplified equation, and determine the liquid film interface slip velocity of the airflow shear force driving liquid film movement of the target high-speed vehicle under the high-speed airflow based on the displacement data.

7. The method according to claim 6, wherein, The liquid film displacement data and the airflow shear force of the target high-speed vehicle under the high-speed airflow are fitted to obtain the target slip boundary condition corresponding to the liquid film flow when the high-speed airflow shears the liquid film, including: Change the airflow shear force of the target high-speed vehicle under the high-speed airflow to obtain the current liquid film interface slip velocity corresponding to the target high-speed vehicle under each airflow shear force; Fit each airflow shear force and the corresponding liquid film interface slip velocity to obtain the functional relationship between the liquid film interface slip velocity and the airflow shear force, and determine the target slip boundary condition based on the functional relationship.

8. A device for constructing a high-speed airflow shearing liquid film flow slip boundary condition, characterized in that, Including: An equation construction module for constructing a liquid film flow N-S equation, a liquid film interface kinematic boundary equation and an interface stress balance equation of a target high-speed vehicle under a high-speed airflow; The high-speed airflow is an airflow whose airflow velocity meets a preset high-speed judgment condition; An equation simplification module for dimension reduction and simplification of the liquid film flow N-S equation, the liquid film interface kinematic boundary equation and the interface stress balance equation using lubrication approximation method and target characteristics to obtain a target simplified equation; the target characteristics are the aircraft parameter characteristics of the target high-speed vehicle under the airflow direction of the high-speed airflow, and the temperature change is less than a preset temperature change threshold; A numerical simulation module for numerical simulation of the target high-speed vehicle under the airflow shear force driving liquid film movement under the high-speed airflow based on the target simplified equation to obtain the liquid film displacement data of the target high-speed vehicle under the high-speed airflow; A boundary condition determination module for fitting the liquid film displacement data and the airflow shear force of the target high-speed vehicle under the high-speed airflow to obtain the target slip boundary condition corresponding to the liquid film flow when the high-speed airflow shears the liquid film.

9. An electronic device, comprising: Including: A memory for saving a computer program; A processor for executing the computer program to implement the construction method of the high-speed airflow shear liquid film flow slip boundary condition according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, Computer program product for saving a computer program which, when executed by a processor, implements a method for constructing a high-speed gas flow shear liquid membrane flow slip boundary condition as claimed in any one of claims 1 to 7.

Images