Air curtain salty-resistant three-dimensional numerical simulation method and device and storage medium

Abstract

The invention discloses an air curtain salt-proof three-dimensional numerical simulation method and device and a storage medium, and relates to the technical field of seawater intrusion prevention and control. According to the three-dimensional numerical simulation method, a ship lock gas phase-fresh water-salt water three-phase numerical model is established based on a mass and energy conservation basic equation, a multiphase flow seepage field, physicochemical properties and a driving parameter coupling mathematical equation by utilizing the influence of an air curtain system on a salinity transfer coefficient in a salt water invasion process; and through targeted adjustment of boundary conditions, initial conditions and basic parameters of the numerical model, the numerical model can accurately simulate the motion process of saline invasion in the ship lock under the air curtain condition, so that a theoretical basis is provided for design and effect verification of a ship lock air curtain salt prevention system.

Description

Technical Field

[0001] The invention relates to the technical field of seawater intrusion prevention and control, in particular to an air curtain anti-salinity technology, and in particular to an air curtain anti-salinity three-dimensional numerical simulation method and device and a storage medium. Background Art

[0002] In rivers with abundant fresh water, seawater intrusion has little impact on the river channel. For rivers with small runoff in the north, the impact of seawater intrusion on the river channel is more obvious. With the rapid development of industry and agriculture, the water consumption in the upper reaches of these rivers has increased sharply. The tributaries have successively built dams to intercept the incoming water, resulting in less runoff in the river channel year by year, and the salt water has been upstream year by year, and the river channel has gradually become salinized. The saltiness of fresh water will not only cause soil salinization, a large number of wells will be scrapped due to water quality deterioration, and agricultural output will drop sharply, but also lead to the deterioration of groundwater quality in the coastal plain. Building another water source or adding water pipelines will increase production costs; at the same time, the chloride ion content in the water increases, and the total hardness increases, which not only increases the cost of water treatment, but also reduces product quality, and causes serious corrosion of production equipment and water pipelines. In order to prevent seawater from entering the river and polluting freshwater, ship locks are set up at the mouths of some navigable rivers, so as to use the anti-salinity measures of ship locks to block the invasion of seawater into freshwater rivers, so as to achieve the purpose of protecting freshwater resources and ecological environment.

[0003] When the end of the lock is located in the tidal zone, it is affected by factors such as seawater tides, which leads to many differences from the locks in inland waterways. Among them, the most notable point is that it is used under the condition of bidirectional head, so it is necessary to consider reducing the problem of salt water intrusion. The basic principle of salt water intrusion through the lock: without taking any special anti-salinity measures, salt water and fresh water have different densities. Salt water will flow in from the bottom of the lock, and fresh water will flow out from the top of the lock, forming a heterogeneous flow, and produce a replacement of salt and fresh water, thereby completing the lock space; then when the ship passes through the lock, salt water will invade the inland freshwater channel from the lock, causing the fresh water to become salty.

[0004] In order to reduce the salinization of freshwater caused by the intrusion of seawater through ship locks, people have comprehensively analyzed the existing anti-salinity measures and technologies for ship locks and summarized several anti-salinity measures for ship locks: (1) Air curtain facilities: By setting a perforated pipe under the sill of the ship lock, compressed air is used to release bubbles to form an upwelling flow, reduce or delay the exchange of fresh and salt water, and achieve a partial anti-salinity effect; (2) Facilities for directly discharging invading salt water: A salt collection pit is set under the sill of the gate on the freshwater channel side, which is connected to the salt water side through a salt drainage corridor. When the water level on the freshwater side of the canal is higher than that on the tidal river side, the salt water is discharged into the tidal river side through the salt collection pit and the corridor; anti-salinity facilities for replacing the water in the lock chamber: when the ship enters the lock chamber, all the water in the lock chamber will be replaced to ensure that when the gate on the freshwater canal side is opened, the water quality in the lock chamber is the same as that of the canal (and vice versa). In order to prevent the bottom of the ship from hitting the bottom plate of the lock chamber during the replacement of the water in the lock chamber, fresh water must be poured in while discharging the salt water (and vice versa), so it is also called simultaneous replacement method. During the displacement process, the injection or discharge of seawater is carried out through the corridor set at the bottom of the lock chamber and flows through the holes in the lock bottom plate. The injection or discharge of fresh water flows through the lock chamber through the porous culvert set on the side of the lock chamber; Pumping facilities: The anti-salinity measure of the pumping method is to set up a pump room at the bow of the lock on the fresh water side. When the water level on the salt water side is higher than the fresh water side, after the ship enters the lock chamber from the fresh water side, the pump will pump water from the fresh water side to the lock chamber. After the water level in the lock chamber is flush with the salt water side, the gate on the salt water side will be opened to pass the ship. This method can only partially reduce the intrusion of salt water. During the gate opening process, salt water will still be replaced with fresh water in the form of heterogeneous flow.

[0005] According to the working principles, applicable scope and effects of the aforementioned anti-salinity facilities for ship locks, it can be seen that air curtain anti-salinity is more suitable for large-scale application in anti-salinity design of ship locks because of its adaptability to different anti-salinity requirements and its advantages of simple setting and low cost.

[0006] In 1960, Laren revealed the principle of air curtain anti-salinity at estuaries through theoretical analysis and physical experiments. In 1964, Abraham et al. explained the anti-salinity mechanism of air curtain at sea locks through theoretical analysis and field experiments. In 1967, the United States conducted an air curtain anti-salinity test in the New York Harbor waterway, and the results showed that the air curtain had a good anti-salinity effect. In the 1990s, Japan also conducted a series of field and indoor experiments to analyze the influencing factors of air curtain anti-salinity. In China, Li Yongzhen tested the anti-salinity effect of air curtain through the Xingang ship lock test in 1982. A series of experimental studies have shown that the anti-salinity effect of air curtain is related to the intensity of bubble plume, the density difference between salt and fresh water, and runoff flow (if there is runoff flow).

[0007] However, there are few studies on numerical simulation methods for air curtain anti-salinity, and the only ones are based on the solute transport model constructed by gas-liquid two phases. When used for air curtain anti-salinity simulation of saltwater intrusion in ship locks, there are problems of poor precision and inaccurate simulation effect, which is not conducive to guiding the design and construction of ship lock anti-salinity projects. Summary of the invention

[0008] The purpose of the present invention is to address the problems of poor precision and inaccurate simulation effect of the existing numerical model of air curtain anti-salinity, and to propose a three-dimensional numerical simulation method, device and storage medium for air curtain anti-salinity.

[0009] In order to achieve the above-mentioned object of the invention, the present invention provides a three-dimensional numerical simulation method for air curtain anti-salinity, comprising the following steps:

[0010] S1. Obtain the three-dimensional model parameters of the air curtain anti-salt ship lock and construct a three-dimensional model of the air curtain anti-salt ship lock; establish the control equation of the air-fresh water-salt water three-phase air curtain anti-salt system based on the basic equations of mass and energy conservation, multiphase flow seepage field, physical and chemical properties and driving parameter coupling mathematical equations;

[0011] S2. Mesh the three-dimensional model of the air curtain anti-salt water ship lock to ensure that the numerical model is fine enough to capture the key processes; based on the control equations and the meshed three-dimensional model, use Fluent software to establish a numerical simulation model of the air-fresh water-salt water three-phase air curtain anti-salt water system of the ship lock;

[0012] S3, setting basic parameters and initial conditions of the numerical simulation model;

[0013] S4, select the wall no-slip condition as the boundary condition of the numerical simulation;

[0014] S5, solving the control equations to obtain the numerical solution of the numerical model;

[0015] S6. Validate and calibrate the numerical model;

[0016] S7. Perform numerical simulation using the verified and calibrated numerical model to obtain numerical simulation results.

[0017] The invention discloses a three-dimensional numerical simulation method for preventing salt water from entering a ship lock by using an air curtain. The method utilizes the influence of an air curtain system on the salinity transfer coefficient in the process of salt water intrusion, and based on the basic equations of conservation of mass and energy, the multiphase flow seepage field, the physical and chemical properties and the coupled mathematical equations of the driving parameters, establishes a gas phase-fresh water-salt water three-phase numerical model for the ship lock, and through the targeted adjustment of the boundary conditions, initial conditions and basic parameters of the numerical model, enables the numerical model to accurately simulate the movement process of salt water intrusion under the air curtain condition in the ship lock, thereby providing a theoretical basis for the design of the air curtain system for preventing salt water from entering the ship lock and the verification of its effect.

[0018] Preferably, in step S1, the three-dimensional model parameters include: chamber model dimensions and air curtain device parameters.

[0019] Preferably, the size of the lock chamber model includes the lock chamber model width, the lock chamber model depth and the lock chamber model length; the lock chamber model width, the lock chamber model depth and the lock chamber model length are obtained by scaling the actual lock chamber size in proportion; the scaling ratio is confirmed according to actual conditions, and can be 1:50, 1:100, 1:200, 1:500, 1:1000, etc.

[0020] Preferably, the air curtain device parameters include the installation position, width and length of the air curtain in the lock chamber model.

[0021] Preferably, the control equation of the air-fresh water-salt water three-phase gas curtain anti-salt water system includes a basic control equation and an auxiliary equation.

[0022] Among them, the basic control equation is:

[0023]

[0024] In the formula, S u , S v , S w are the force source terms in the x, y, and z directions respectively, u is the velocity component of the velocity vector in the x-axis direction, v is the velocity component of the velocity vector in the y-axis direction, w is the velocity component of the velocity vector in the z-axis direction, P is the fluid pressure, ρ is the density of the mixed fluid, and μ is the viscosity coefficient of water molecules.

[0025] Preferably, the density of the mixed fluid

[0026] Where ρ1 and ρ2 are the densities of fresh water and salt water, respectively; v1 and v2 are the volumes of fresh water and salt water, respectively.

[0027] Preferably,

[0028]

[0029] In the formula, s x ,s y ,s z are the viscous force sources in the x, y, and z directions respectively. When the fluid is incompressible, s x =s y =s z =0; F x 、F y and F z is the volume force on the microelement in the x, y, and z directions. If the volume force is only gravity, then F x =Fy =0,F z =-ρg, ρ is the density of the mixed fluid, g is the gravitational acceleration; λ is the volume viscosity coefficient; divu is the divergence of the velocity field, that is,

[0030] The auxiliary equations include the transport equations of turbulent kinetic energy k and turbulent kinetic energy ￡ in the standard k-￡ model.

[0031] The transport equation of turbulent kinetic energy k in the standard k-￡ model is:

[0032]

[0033] The transport equation of the turbulent kinetic energy ￡ is:

[0034]

[0035] In the formula, x i 、x j are the spatial coordinates in the i and j directions respectively, μ t is the turbulent viscosity coefficient, ρ is the density of the mixed fluid, k is the turbulent kinetic energy, μ is the viscosity coefficient of water molecules, T is the temperature, u i is the velocity component of the fluid in the i direction, ε is the turbulent kinetic energy dissipation rate, M t is the turbulent Mach number, σ k is the Prandtl number corresponding to the turbulent kinetic energy k, σ ε is the Prandtl number corresponding to the turbulent kinetic energy ε, p rt is the turbulent Prandtl number, β is the thermal expansion coefficient, g i The component of gravitational acceleration in the i direction, C 1ε , C 2ε and C 3ε is the empirical constant, S u and S ε Custom source term for turbulent kinetic energy.

[0036] Preferably, the turbulent viscosity

[0037] Where μ is the viscosity coefficient of water molecules and η is the salinity transfer coefficient.

[0038] Preferably, the salinity transfer coefficient

[0039] Where θ is the dimensionless air curtain plume intensity, θ = 0.4Fr air ; Fr air is the air curtain Froude number.

[0040] Preferably,

[0041] In the formula, Q a is the air supply per unit width; ρ is the fresh water density; Δρ is the density difference between salt and fresh water; g is the gravitational acceleration; h is the water depth.

[0042] In step S2, the three-dimensional model is divided into regular hexahedral structural grids, and the grid side length is 2 mm.

[0043] Wherein, in step S3, preferably, the basic parameters include fluid properties of salt water phase, fresh water phase and gas phase; the fluid properties include density, viscosity, specific heat capacity, thermal conductivity and depth.

[0044] Preferably, the initial conditions include an initial velocity field, an initial pressure field, an initial turbulent kinetic energy and a dissipation rate field.

[0045] In step S4, preferably, the no-slip wall boundary is confirmed by using the wall function method; the specific method includes: using the dimensionless wall normal distance y + and the dimensionless wall-parallel velocity u + Semi-empirical formulas directly relate the no-flow region in the wall to the unknown quantities in the turbulent core region;

[0046] in,

[0047] Where u is the velocity component of the fluid in the direction parallel to the wall, U T is the wall friction velocity, y is the normal distance from the wall; when y + When <5, the fluid is in the viscous bottom layer; when 60 <y + When <300, the flow is in the logarithmic layer; v is the kinematic viscosity of the fluid.

[0048] Wherein, in step S5, preferably, a pressure-velocity coupling algorithm is used to solve the control equation of the numerical model to obtain a numerical solution of the numerical model.

[0049] Preferably, the specific steps of solving the numerical model control method using the pressure-velocity coupling algorithm include:

[0050] (1) Setting the initial velocity field and pressure field, and setting the convergence criteria and number of iterations of the numerical model control equations;

[0051] (2) Using the finite volume method to discretize the control equations of the numerical model to obtain discrete equations;

[0052] (3) Based on the current pressure field, substitute it into the discrete equation to obtain a predicted velocity field;

[0053] (4) Solving the pressure correction equation: Substitute the predicted velocity field into the discrete equation and use the diagonal decomposition technique to derive the pressure Poisson equation; Solve the pressure Poisson equation to obtain a new pressure field;

[0054] (5) Update velocity and pressure: Update the velocity field and pressure field using the new pressure field correction;

[0055] (6) Iteration: Repeat steps 3-5 above until the discrete equation converges and the numerical solution of the control equation of the numerical model is obtained.

[0056] Wherein, in step S6, preferably, experimental data or field observation data are used to verify and calibrate the numerical model to ensure the accuracy of the simulation results.

[0057] Furthermore, the present invention also proposes a three-dimensional numerical simulation device for air curtain anti-salinity, comprising at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the above-mentioned three-dimensional numerical simulation method for air curtain anti-salinity.

[0058] Furthermore, the present invention also proposes a computer-readable storage medium, characterized in that instructions executable by a processor are stored thereon, and when the instructions are executed by the processor, the processor executes the above-mentioned three-dimensional numerical simulation method for air curtain anti-salinity.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] The three-dimensional numerical simulation method of air curtain anti-salinity of the present invention utilizes the influence of the air curtain system on the salinity transfer coefficient in the process of salt water intrusion, and based on the basic equations of conservation of mass and energy, the multiphase flow seepage field, the physical and chemical properties and the driving parameter coupling mathematical equations, a gas phase-fresh water-salt water three-phase numerical model of the ship lock is established, and through the targeted adjustment of the boundary conditions, initial conditions and basic parameters of the numerical model, the numerical model can accurately simulate the movement process of salt water intrusion under air curtain conditions in the ship lock, thereby providing a theoretical basis for the design of the air curtain anti-salinity system of the ship lock and the verification of its effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a curve diagram of relative concentration variation on the fresh water side in numerical simulation and tank experiment in Example 1 of the present invention;

[0062] Figure 2 This is a process diagram of numerically simulating saltwater intrusion in a lock chamber in Example 1 of the present invention;

[0063] Figure 3The process diagram of the numerical simulation of salt water intrusion in the lock chamber in Example 2 of the present invention (the air intake volume of the air curtain anti-salt system in a is 0.01m 3 / s; b The air intake volume of the air curtain anti-salinity system is 0.03m 3 / s);

[0064] Figure 4 This is a curve diagram of relative concentration change on the fresh water side in the numerical simulation and the water tank experiment in Example 2 of the present invention. DETAILED DESCRIPTION

[0065] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0066] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all expressions based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, rather than indicating or implying that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0067] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0068] In addition, the expressions “first”, “second”, “third”, etc. that appear in the terms are merely descriptions used to distinguish the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0069] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0070] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0071] Embodiment 1:

[0072] A three-dimensional numerical simulation of air curtain anti-salinity is used to simulate the process of saltwater intrusion in the test arrangement of the Dutch Deltares Institute. The specific steps are as follows:

[0073] S1. Obtain the three-dimensional model parameters of the air curtain anti-salt ship lock, and construct a three-dimensional model of the air curtain anti-salt ship lock (length 2.4m×width 0.5m×height 0.7m, air groove width 2mm, located 1m upstream of the salt water side);

[0074] Based on the basic equations of mass and energy conservation, the multiphase flow field, the physical and chemical properties and the coupled mathematical equations of driving parameters, the control equations of the three-phase air curtain system of air-fresh water-salt water are established;

[0075] Among them, the control equations of the three-phase air curtain anti-salinity system of air-fresh water-salt water include basic control equations and auxiliary equations;

[0076] Among them, the basic control equation is:

[0077]

[0078] In the formula, S u , S v , S w are the force source terms in the x, y, and z directions respectively, u is the velocity component of the velocity vector in the x-axis direction, v is the velocity component of the velocity vector in the y-axis direction, w is the velocity component of the velocity vector in the z-axis direction, P is the fluid pressure, ρ is the density of the mixed fluid, and μ is the viscosity coefficient of water molecules;

[0079] The density of the mixed fluid is In the formula, ρ1, ρ2 are the densities of fresh water and salt water, respectively, v1, v2 are the volumes of fresh water and salt water, respectively;

[0080] Among them, the force source term

[0081] In the formula, s x ,s y ,s z are the viscous force sources in the x, y, and z directions respectively. When the fluid is incompressible, s x =s y =s z =0; F x 、F y and F z is the volume force on the microelement in the x, y, and z directions. If the volume force is only gravity, then F x =F y =0,F z =-ρg, ρ is the density of the mixed fluid, g is the gravitational acceleration; λ is the volume viscosity coefficient; divu is the divergence of the velocity field, that is,

[0082] Among them, the auxiliary equations include the transport equations of turbulent kinetic energy k and turbulent kinetic energy ￡ in the standard k-￡ model;

[0083] Among them, the transport equation of turbulent kinetic energy k in the standard k-￡ model is:

[0084]

[0085] Among them, the transport equation of turbulent kinetic energy £ is:

[0086]

[0087] In the formula, x i 、x j are the spatial coordinates in the i and j directions respectively, μ t is the turbulent viscosity coefficient, ρ is the density of the mixed fluid, k is the turbulent kinetic energy, μ is the viscosity coefficient of water molecules, T is the temperature, u i is the velocity component of the fluid in the i direction, ε is the turbulent kinetic energy dissipation rate, M t is the turbulent Mach number, σ k is the Prandtl number corresponding to the turbulent kinetic energy k, σ ε is the Prandtl number corresponding to the turbulent kinetic energy ε, p rt is the turbulent Prandtl number, β is the thermal expansion coefficient, g i The component of gravitational acceleration in the i direction, C 1ε , C 2ε and C 3ε is the empirical constant, S u and S ε Custom source terms for turbulent kinetic energy;

[0088] Among them, turbulent viscosity

[0089] Where μ is the viscosity coefficient of water molecules and η is the salinity transfer coefficient.

[0090] Among them, the salinity transfer coefficient

[0091] Where θ is the dimensionless air curtain plume intensity, θ = 0.4Fr air ; Fr air is the air curtain Froude number.

[0092] Among them, the air curtain Froude number

[0093] In the formula, Q a is the air supply per unit width; ρ is the fresh water density; Δρ is the density difference between salt and fresh water; g is the gravitational acceleration; h is the water depth;

[0094] S2. The three-dimensional model of the air curtain anti-salt ship lock is divided into regular hexahedral structural grids with a grid side length of 2 mm (the minimum grid volume is 2.08×10 -7 m 3 , maximum volume 10×10 -7 m 3 ) to ensure that the numerical model is fine enough to capture the key processes; based on the control equations and the three-dimensional model after meshing, the Fluent software is used to establish a numerical simulation model of the ship lock's air-fresh water-salt water three-phase air curtain anti-salt water system;

[0095] S3, setting basic parameters and initial conditions of the numerical simulation model; the basic parameters include fluid properties of salt water phase, fresh water phase and gas phase; the fluid properties include density, viscosity, specific heat capacity, thermal conductivity, depth; the initial conditions include initial velocity field, initial pressure field, initial turbulent kinetic energy and dissipation rate field;

[0096] Specifically: the water depth is 0.4m, the salinity of the salt water is 20‰, and the corresponding density is 1019kg / m 3 The aeration pipe is replaced by a single slit with a width of 2 mm, an inlet pressure of 39 pa, an average inlet volume of 34 L / min, and a temperature of 17.5 °C.

[0097] S4, select the wall no-slip condition as the boundary condition of the numerical simulation;

[0098] The no-slip wall boundary is confirmed by the wall function method; the specific method includes: using the dimensionless wall normal distance y + and the dimensionless wall-parallel velocity u +Semi-empirical formulas directly relate the no-flow region in the wall to the unknown quantities in the turbulent core region;

[0099] in,

[0100] Where u is the velocity component of the fluid in the direction parallel to the wall, U T is the wall friction velocity, y is the normal distance from the wall; when y + When <5, the fluid is in the viscous bottom layer; when 60 <y + When <300, the flow is in the logarithmic layer; v is the kinematic viscosity of the fluid;

[0101] S5. Using a pressure-velocity coupling algorithm to solve the control equation of the numerical model, and obtaining a numerical solution of the numerical model; the specific steps include:

[0102] (1) Setting the initial velocity field and pressure field, and setting the convergence criteria and number of iterations of the numerical model control equations;

[0103] (2) Using the finite volume method to discretize the control equations of the numerical model to obtain discrete equations;

[0104] (3) Based on the current pressure field, substitute it into the discrete equation to obtain a predicted velocity field;

[0105] (4) Solving the pressure correction equation: Substitute the predicted velocity field into the discrete equation and use the diagonal decomposition technique to derive the pressure Poisson equation; Solve the pressure Poisson equation to obtain a new pressure field;

[0106] (5) Update velocity and pressure: Update the velocity field and pressure field using the new pressure field correction;

[0107] (6) Iteration: Repeat steps 3-5 above until the discrete equation converges and the numerical solution of the control equation of the numerical model is obtained.

[0108] S6. Use experimental data (obtained from literature) to verify and calibrate the numerical model to ensure the accuracy of the simulation results;

[0109] S7. Perform numerical simulation using the verified and calibrated numerical model to obtain numerical simulation results.

[0110] The simulation results are as follows Figure 2 As shown, the blue color is the gas phase, the yellow color is the fresh water phase, and the red color is the salt water phase. The color changes with the fluid density.

[0111] Analysis of results: Under the intake conditions of a pressure of 39 pa and an average air intake of 34 L / min, the bubble curtain formed by the gas in the water body is very sparse, which cannot hinder the movement of salt water with a salinity of up to 20‰, and cannot interfere with the formation of salt wedges, ultimately causing the salt water mold to disperse the air curtain and invade the fresh water side.

[0112] Figure 1 The graph is a graph of the experimental results and simulation results of the relative concentration of salt water on the fresh water side from 0 to 10 seconds after the salt water is invaded by the air curtain; the results show that under the air intake conditions, the simulation results are slightly larger than the measured data, but the change trend is relatively consistent. The simulation results are basically consistent with the experimental results in the literature. The simulation method used in Example 1 can more accurately reflect the physical process of air curtain anti-salinity.

[0113] Example 2

[0114] A three-dimensional numerical simulation of air curtain anti-salinity is used to simulate the process of saltwater intrusion in a coastal estuary hub lock. The specific steps are as follows:

[0115] S1. Obtain the three-dimensional model parameters of the air curtain anti-salt ship lock, and construct a three-dimensional model of the air curtain anti-salt ship lock (length 2m×width 0.5m×height 0.5m, air groove width 2mm, located 0.9m upstream of the salt water side);

[0116] Based on the basic equations of mass and energy conservation, the multiphase flow field, the physical and chemical properties and the coupled mathematical equations of driving parameters, the control equations of the three-phase air curtain system of air-fresh water-salt water are established;

[0117] Among them, the control equations of the three-phase air curtain anti-salinity system of air-fresh water-salt water include basic control equations and auxiliary equations;

[0118] Among them, the basic control equation is:

[0119]

[0120] In the formula, S u , S v , S w are the force source terms in the x, y, and z directions respectively, u is the velocity component of the velocity vector in the x-axis direction, v is the velocity component of the velocity vector in the y-axis direction, w is the velocity component of the velocity vector in the z-axis direction, P is the fluid pressure, ρ is the density of the mixed fluid, and μ is the viscosity coefficient of water molecules;

[0121] The density of the mixed fluid is In the formula, ρ1, ρ2 are the densities of fresh water and salt water, respectively, v1, v2 are the volumes of fresh water and salt water, respectively;

[0122] Among them, the force source term

[0123] In the formula, s x ,s y ,s z are the viscous force sources in the x, y, and z directions respectively. When the fluid is incompressible, s x =s y =s z =0; F x 、F y and F z is the volume force on the microelement in the x, y, and z directions. If the volume force is only gravity, then F x =F y =0,F z =-ρg, ρ is the density of the mixed fluid, g is the gravitational acceleration; λ is the volume viscosity coefficient; divu is the divergence of the velocity field, that is,

[0124] Among them, the auxiliary equations include the transport equations of turbulent kinetic energy k and turbulent kinetic energy ￡ in the standard k-￡ model;

[0125] Among them, the transport equation of turbulent kinetic energy k in the standard k-￡ model is:

[0126]

[0127] Among them, the transport equation of turbulent kinetic energy £ is:

[0128]

[0129] In the formula, x i 、x j are the spatial coordinates in the i and j directions respectively, μ t is the turbulent viscosity coefficient, ρ is the density of the mixed fluid, k is the turbulent kinetic energy, μ is the viscosity coefficient of water molecules, T is the temperature, u i is the velocity component of the fluid in the i direction, ε is the turbulent kinetic energy dissipation rate, M t is the turbulent Mach number, σ k is the Prandtl number corresponding to the turbulent kinetic energy k, σ ε is the Prandtl number corresponding to the turbulent kinetic energy ε, p rt is the turbulent Prandtl number, β is the thermal expansion coefficient, g i The component of gravitational acceleration in the i direction, C 1ε , C 2ε and C 3ε is the empirical constant, S u and S ε Custom source terms for turbulent kinetic energy;

[0130] Among them, turbulent viscosity

[0131] Where μ is the viscosity coefficient of water molecules and η is the salinity transfer coefficient.

[0132] Among them, the salinity transfer coefficient

[0133] Where θ is the dimensionless air curtain plume intensity, θ = 0.4Fr air ; Fr air is the air curtain Froude number.

[0134] Among them, the air curtain Froude number

[0135] In the formula, Q a is the air supply per unit width; ρ is the fresh water density; Δρ is the density difference between salt and fresh water; g is the gravitational acceleration; h is the water depth;

[0136] S2. The three-dimensional model of the air curtain anti-salt ship lock is divided into regular hexahedral structural grids with a grid side length of 2 mm (the minimum grid volume is 2.08×10 -7 m 3 , maximum volume 10×10 -7 m 3 ) to ensure that the numerical model is fine enough to capture the key processes; based on the control equations and the three-dimensional model after meshing, the Fluent software is used to establish a numerical simulation model of the ship lock's air-fresh water-salt water three-phase air curtain anti-salt water system;

[0137] S3, setting basic parameters and initial conditions of the numerical simulation model; the basic parameters include fluid properties of salt water phase, fresh water phase and gas phase; the fluid properties include density, viscosity, specific heat capacity, thermal conductivity, depth; the initial conditions include initial velocity field, initial pressure field, initial turbulent kinetic energy and dissipation rate field;

[0138] The test used salt water with a salinity of 2.5‰ and a density of 1001.92kg / m 3 , the water depth is 0.4m, the diameter of the hole is 2mm; the width of the single slit is 2mm, and the average air intake is 0.003m 3 / s and O.Ol m 3 / s; temperature is 17.5℃;

[0139] S4, select the wall no-slip condition as the boundary condition of the numerical simulation;

[0140] The no-slip wall boundary is confirmed by the wall function method; the specific method includes: using the dimensionless wall normal distance y + and the dimensionless wall-parallel velocity u + Semi-empirical formulas directly relate the no-flow region in the wall to the unknown quantities in the turbulent core region;

[0141] in,

[0142] Where u is the velocity component of the fluid in the direction parallel to the wall, U T is the wall friction velocity, y is the normal distance from the wall; when y + When <5, the fluid is in the viscous bottom layer; when 60 <y + When <300, the flow is in the logarithmic layer; v is the kinematic viscosity of the fluid;

[0143] S5. Using a pressure-velocity coupling algorithm to solve the control equation of the numerical model, and obtaining a numerical solution of the numerical model; the specific steps include:

[0144] (1) Setting the initial velocity field and pressure field, and setting the convergence criteria and number of iterations of the numerical model control equations;

[0145] (2) Using the finite volume method to discretize the control equations of the numerical model to obtain discrete equations;

[0146] (3) Based on the current pressure field, substitute it into the discrete equation to obtain a predicted velocity field;

[0147] (4) Solving the pressure correction equation: Substitute the predicted velocity field into the discrete equation and use the diagonal decomposition technique to derive the pressure Poisson equation; Solve the pressure Poisson equation to obtain a new pressure field;

[0148] (5) Update velocity and pressure: Update the velocity field and pressure field using the new pressure field correction;

[0149] (6) Iteration: Repeat steps 3-5 above until the discrete equation converges and the numerical solution of the control equation of the numerical model is obtained.

[0150] S6. Use experimental data to verify and calibrate numerical models to ensure the accuracy of simulation results;

[0151] S7. Perform numerical simulation using the verified and calibrated numerical model to obtain numerical simulation results.

[0152] The simulation results under two intake conditions are shown in Figure 2. Figure 3 As shown, Figure 3 The medium blue is the gas phase, the yellow is fresh water, and the red is salt water.

[0153] The results show that when the air intake conditions are very small, the barrier effect on salt water intrusion is very limited. After increasing, the salt-blocking effect is significantly improved. However, further increasing it intensifies the mixing effect of the water body, causing the bottom salt water to be transported to the surface by the flow field, and then pass through the air curtain that is sparser than the bottom to enter the fresh water side.

[0154] Comparison of measured and simulated data of relative concentration in freshwater water Figure 4 As shown, the solid line in the figure is the measured data of the water tank test under the condition of smaller air intake volume, which is in good agreement with the numerical simulation results under the corresponding conditions. The simulation method adopted in Example 2 of the present invention can more accurately reflect the physical process of air curtain anti-salinity.

[0155] Example 3

[0156] A three-dimensional numerical simulation device for preventing saltwater from entering an air curtain comprises a processor and a memory in communication with the processor; the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute a three-dimensional numerical simulation method for preventing saltwater from entering an air curtain in Example 1 or 2.

[0157] Example 4

[0158] A computer-readable storage medium stores instructions executable by a processor, wherein when the instructions are executed by the processor, the processor executes a three-dimensional numerical simulation method for air curtain anti-salinity in embodiment 1 or 2.

[0159] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-dimensional numerical simulation method for air curtain anti-salinity, characterized in that: The following steps are involved: S1. Obtain the three-dimensional model parameters of the air curtain anti-salt ship lock and construct a three-dimensional model of the air curtain anti-salt ship lock; establish the control equation of the air-fresh water-salt water three-phase air curtain anti-salt system based on the basic equations of mass and energy conservation, multiphase flow seepage field, physical and chemical properties and driving parameter coupling mathematical equations; The control equations of the air-fresh water-salt water three-phase air curtain anti-salt system include basic control equations and auxiliary equations; the auxiliary equations include the transport equations of turbulent kinetic energy k and turbulent kinetic energy ￡ in the standard k-￡ model; The basic governing equation is: S u , S v , S w are the force source terms in the x, y, and z directions respectively, u is the velocity component of the velocity vector in the x-axis direction, v is the velocity component of the velocity vector in the y-axis direction, w is the velocity component of the velocity vector in the z-axis direction, P is the fluid pressure, ρ is the density of the mixed fluid, and μ is the viscosity coefficient of water molecules; S2. Mesh the three-dimensional model of the air curtain anti-salt water ship lock to ensure that the numerical model is fine enough to capture the key processes; based on the control equations and the meshed three-dimensional model, use Fluent software to establish a numerical simulation model of the air-fresh water-salt water three-phase air curtain anti-salt water system of the ship lock; S3, setting basic parameters and initial conditions of the numerical simulation model; the basic parameters include fluid properties of the salt water phase, the fresh water phase and the gas phase; the initial conditions include initial velocity field, initial pressure field, initial turbulent kinetic energy and dissipation rate field; S4, select the wall no-slip condition as the boundary condition of the numerical simulation; S5. Solving the control equation of the numerical model using a pressure-velocity coupling algorithm to obtain a numerical solution of the numerical model; S6. Validate and calibrate the numerical model; S7. Perform numerical simulation using the verified and calibrated numerical model to obtain numerical simulation results.

2. The three-dimensional numerical simulation method for air curtain anti-salinity according to claim 1 is characterized in that: In step S1, the three-dimensional model parameters include: chamber model size and air curtain device parameters.

3. The three-dimensional numerical simulation method for air curtain anti-salinity according to claim 1 is characterized in that: In the basic control equation of step S1, In the formula, s x ,s y ,s z are the viscous force sources in the x, y, and z directions respectively. When the fluid is incompressible, s x =s y =s z =0; F x 、F y and F z is the volume force on the microelement in the x, y, and z directions. If the volume force is only gravity, then F x =F y =0,F z =-ρg, ρ is the density of the mixed fluid, g is the gravitational acceleration; λ is the volume viscosity coefficient; divu is the divergence of the velocity field, that is, 4. The three-dimensional numerical simulation method for air curtain anti-salinity according to claim 1 is characterized in that: In step S1, the transport equation of turbulent kinetic energy k in the standard k-￡ model is: The transport equation of the turbulent kinetic energy ￡ is: In the formula, x i 、x j are the spatial coordinates in the i and j directions respectively, μ t is the turbulent viscosity coefficient, ρ is the density of the mixed fluid, k is the turbulent kinetic energy, μ is the viscosity coefficient of water molecules, T is the temperature, u i is the velocity component of the fluid in the i direction, ε is the turbulent kinetic energy dissipation rate, M t is the turbulent Mach number, σ k is the Prandtl number corresponding to the turbulent kinetic energy k, σ ε is the Prandtl number corresponding to the turbulent kinetic energy ε, p rt is the turbulent Prandtl number, β is the thermal expansion coefficient, g i The component of gravitational acceleration in the i direction, C 1ε , C 2ε and C 3ε is the empirical constant, S u and S ε Custom source term for turbulent kinetic energy.

5. The three-dimensional numerical simulation method for air curtain anti-salinity according to claim 4 is characterized in that: The turbulent viscosity Where μ is the viscosity coefficient of water molecules and η is the salinity transfer coefficient.

6. The three-dimensional numerical simulation method for air curtain anti-salinity according to claim 5 is characterized in that: The salinity transfer coefficient Where θ is the dimensionless air curtain plume intensity, θ = 0.4Fr air ; Fr air is the air curtain Froude number.

7. The three-dimensional numerical simulation method for air curtain anti-salinity according to claim 6 is characterized in that: The air curtain Froude number In the formula, Q a is the air supply per unit width; ρ is the fresh water density; Δρ is the density difference between salt and fresh water; g is the gravitational acceleration; h is the water depth.

8. The three-dimensional numerical simulation method for air curtain anti-salinity according to claim 1 is characterized in that: In step S2, the three-dimensional model is divided into regular hexahedral structural grids with a grid side length of 2 mm.

9. The three-dimensional numerical simulation method for air curtain anti-salinity according to claim 1 is characterized in that: In step S4, the no-slip wall boundary is confirmed by using the wall function method; the specific method includes: using the dimensionless wall normal distance y + and the dimensionless wall-parallel velocity u + Semi-empirical formulas directly relate the no-flow region in the wall to the unknown quantities in the turbulent core region; in, Where u is the velocity component of the fluid in the direction parallel to the wall, U T is the wall friction velocity, y is the normal distance from the wall; when y + When <5, the fluid is in the viscous bottom layer; when 60 <y + When <300, the flow is in the logarithmic layer; v is the kinematic viscosity of the fluid.

10. The three-dimensional numerical simulation method for air curtain anti-salinity according to claim 1, characterized in that: In step S5, the specific steps of using the pressure-velocity coupling algorithm to solve the numerical model control method include: (1) Setting the initial velocity field and pressure field, and setting the convergence criteria and number of iterations of the numerical model control equations; (2) Using the finite volume method to discretize the control equations of the numerical model to obtain discrete equations; (3) Based on the current pressure field, substitute it into the discrete equation to obtain a predicted velocity field; (4) Solving the pressure correction equation: Substitute the predicted velocity field into the discrete equation and use the diagonal decomposition technique to derive the pressure Poisson equation; Solve the pressure Poisson equation to obtain a new pressure field; (5) Update velocity and pressure: Update the velocity field and pressure field using the new pressure field correction; (6) Iteration: Repeat the above steps (3), (4), and (5) until the discrete equation converges and the numerical solution of the control equation of the numerical model is obtained.

11. A three-dimensional numerical simulation device for air curtain anti-salinity, characterized in that: The invention comprises at least one processor and a memory which is communicatively connected to the at least one processor; the memory stores instructions which can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute a three-dimensional numerical simulation method for air curtain anti-salinity according to any one of claims 1 to 10.

12. A storage medium, characterized in that: Instructions executable by a processor are stored thereon, and when the instructions are executed by the processor, the processor executes a three-dimensional numerical simulation method for air curtain anti-salinity as described in any one of claims 1 to 10.

Images