Air curtain salt prevention three-dimensional numerical simulation method, device and storage medium

Abstract

The application discloses a kind of gas curtain anti-salt three-dimensional numerical simulation method and device and storage medium, it is related to seawater intrusion prevention technical field;The three-dimensional numerical simulation method utilizes the influence of gas curtain system on salinity transfer coefficient in the process of saltwater intrusion, based on the basic equation of mass and energy conservation, multiphase flow seepage field, physicochemical property and driving parameter coupling mathematical equation, establishes ship lock gas phase-fresh water-salt water three-phase numerical model, and through the targeted adjustment of numerical model boundary condition, initial condition and basic parameter, make numerical model can accurately simulate the movement process of saltwater intrusion under the condition of gas curtain in ship lock, to provide theoretical basis for the design and effect verification of ship lock gas curtain anti-salt system.

Description

Technical Field

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

[0002] In rivers with abundant freshwater, saltwater intrusion has minimal impact. However, for rivers in northern China with low runoff, the impact is more pronounced. With the rapid development of industry and agriculture, water demand in these rivers has increased dramatically upstream. Dams have been built on tributaries to intercept the incoming water, resulting in decreasing runoff each year. Saltwater is increasingly flowing upstream, leading to a gradual salinization of the riverbed. This salty freshwater not only causes soil salinization, resulting in the deterioration of water quality in numerous wells and a significant decline in agricultural output, but also worsens groundwater quality in coastal plains. Building new water sources or adding pipelines increases production costs. Furthermore, increased chloride ion content and total hardness in the water increase water treatment costs, reduce product quality, and severely corrode production equipment and pipelines. To prevent saltwater intrusion and contamination of freshwater, ship locks have been installed at the mouths of certain navigable rivers. These ship locks act as a saltwater prevention measure, blocking seawater intrusion into freshwater rivers and protecting freshwater resources and the ecological environment.

[0003] When the end of a ship lock is located in a tidal zone, it is affected by factors such as seawater tides, resulting in many differences from ship locks in inland waterways. The most notable point is its use in bidirectional head conditions, which requires consideration of reducing saltwater intrusion. The basic principle of saltwater intrusion through ship locks: without any special anti-salinity measures, due to the difference in density between saltwater and freshwater, saltwater will flow in from the bottom of the ship lock, while freshwater will flow out from the top of the ship lock, forming a heterogeneous flow and causing a replacement of saltwater and freshwater, thereby filling the ship lock space. Then, when a ship passes through the lock, saltwater will intrude from the ship lock into the inland freshwater channel, causing the freshwater 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 ship lock anti-salinization measures and technologies, and summarized several ship lock anti-salinization measures: (1) Air curtain facilities: by setting a perforated pipe under the ship lock sill, compressed air is used to release bubbles to form an upwelling, reducing or delaying the exchange of fresh and salt water, thus achieving a partial anti-salinization effect; (2) Facilities for directly discharging invading salt water: a salt collection pit is set under the sill of the lock on the freshwater channel side, and 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 corridor; anti-salt 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 for ships entering and exiting the saltwater side). In order to prevent the bottom of the ship from hitting the bottom plate of the lock chamber during the water replacement process, fresh water must be poured in while discharging the salt water (and vice versa), so it is also called simultaneous replacement method. During the replacement process, the inflow or outflow of seawater is carried out through the corridor set at the bottom of the lock chamber and the holes in the lock bottom plate, while the inflow or outflow of fresh water is carried out 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 in the lock chamber is flush with the salt water side, the salt water side gate 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 various 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 demonstrated the principle of air curtains for preventing salinity in estuaries through theoretical analysis and physical experiments. In 1964, Abraham et al. demonstrated the mechanism of air curtains for preventing salinity in ship locks through theoretical analysis combined with field experiments. In 1967, the United States conducted air curtain experiments for preventing salinity in the New York Harbor waterway, demonstrating their effectiveness. In the 1990s, Japan also conducted a series of field and laboratory experiments to analyze the factors influencing air curtains for preventing salinity. In China, Li Yongzhen tested the effectiveness of air curtains for preventing salinity in 1982 through experiments at the New York Harbor ship locks. A series of experimental studies have shown that the effectiveness of air curtains for preventing salinity is related to the intensity of the bubble plume, the density difference between fresh and salt water, and runoff volume (if any).

[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-phase. When used to simulate air curtain anti-salinity for saltwater intrusion in ship locks, there are problems of poor precision and inaccurate simulation effects, 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 effects of existing numerical models 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; based on the quality

[0011] The control equations of the three-phase air curtain system for preventing saltwater from entering the air-fresh water-salt water are established by coupling the mathematical equations of energy conservation, multiphase flow seepage field, physical and chemical properties and driving parameters;

[0012] S2. Mesh the 3D model of the air curtain anti-salinity ship lock to ensure that the numerical model is sufficiently refined to capture key processes. Based on the governing equations and the meshed 3D model, use Fluent software to establish a numerical simulation model of the lock's three-phase air curtain anti-salinity system, which involves air, fresh water, and salt water.

[0013] S3. Setting the basic parameters and initial conditions of the numerical simulation model;

[0014] S4. Select the wall no-slip condition as the boundary condition for numerical simulation;

[0015] S5. Solve the control equations to obtain the numerical solution of the numerical model;

[0016] S6. Validate and calibrate the numerical model;

[0017] S7. Perform numerical simulation using the verified and calibrated numerical model to obtain numerical simulation results.

[0018] The present invention provides a three-dimensional numerical simulation method for air curtain anti-salinity, which utilizes the influence of the air curtain system on the salinity transfer coefficient during saltwater intrusion, establishes a gas phase-fresh water-saltwater three-phase numerical model of the ship lock 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 driving parameters, and through 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 saltwater intrusion under air curtain conditions in the ship lock, thereby providing a theoretical basis for the design and effect verification of the ship lock air curtain anti-salinity system.

[0019] Wherein, preferably, in step S1, the three-dimensional model parameters include: lock chamber model size and air curtain device parameters.

[0020] Preferably, the lock chamber model dimensions include lock chamber model width, lock chamber model depth and lock chamber model length; the lock chamber model width, lock chamber model depth and lock chamber model length are obtained by scaling the actual lock chamber dimensions in equal proportion; the scaling ratio is confirmed according to actual conditions and can be 1:50, 1:100, 1:200, 1:500, 1:1000, etc.

[0021] Preferably, the air curtain device parameters include the installation position, width and length of the air curtain in the lock chamber model.

[0022] 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.

[0023] Among them, the basic control equation is:

[0024]

[0025] Where 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.

[0026] Preferably, the density of the mixed fluid

[0027] 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.

[0028] Preferably,

[0029] Where 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 in the x, y, and z directions of the microelement. If the volume force is only gravity, then Fx =F y =0,F z =-ρg, ρ is the density of the mixed fluid, g is the acceleration of gravity; 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] Where 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 £, 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 coefficient is as follows

[0037]

[0038] Where μ is the viscosity coefficient of water molecules and η is the salinity transfer coefficient.

[0039] Preferably, the salinity transfer coefficient

[0040] Where θ is the dimensionless air curtain plume intensity, θ = 0.4Fr air ; Fr air is the air curtain Froude number.

[0041] Preferably,

[0042] Where Q a is the air supply per unit width; is the fresh water density; Δρ is the density difference between salt and fresh water; g is the acceleration due to gravity; and h is the water depth.

[0043] In step S2, the three-dimensional model is divided into regular hexahedral structural grids with a grid side length of 2 mm.

[0044] Wherein, in step S3, preferably, the basic parameters include fluid properties of the salt water phase, the fresh water phase and the gas phase; the fluid properties include density, viscosity, specific heat capacity, thermal conductivity and depth.

[0045] Preferably, the initial conditions include an initial velocity field, an initial pressure field, an initial turbulent kinetic energy and a dissipation rate field.

[0046] 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;

[0047] in,

[0048] 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.

[0049] 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.

[0050] Preferably, the specific steps of solving the numerical model control method using the pressure-velocity coupling algorithm include:

[0051] (1) Set the initial velocity field and pressure field, and set the convergence criteria and number of iterations of the numerical model control equations;

[0052] (2) Using the finite volume method to discretize the numerical model control equation to obtain the discrete equation;

[0053] (3) Based on the current pressure field, a predicted velocity field is obtained by substituting it into the discrete equation;

[0054] (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;

[0055] (5) Update velocity and pressure: Update the velocity field and pressure field using the new pressure field correction;

[0056] (6) Iteration: Repeat steps 3-5 above until the discrete equations converge and the numerical solution of the control equations of the numerical model is obtained.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] The three-dimensional numerical simulation method of air curtain anti-salinity in the present invention utilizes the influence of the air curtain system on the salinity transfer coefficient during saltwater 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 driving parameters, establishes a gas phase-fresh water-salt water three-phase numerical model of the ship lock. By 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 saltwater intrusion under air curtain conditions in the ship lock, thereby providing a theoretical basis for the design and effect verification of the air curtain anti-salinity system of the ship lock. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 Graph showing relative concentration changes on the fresh water side in the numerical simulation and the flume experiment in Example 1 of the present invention;

[0063] Figure 2 This is a process diagram of numerical simulation of saltwater intrusion in a lock chamber in Example 1 of the present invention;

[0064] 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);

[0065] Figure 4 This is a curve diagram of the relative concentration change on the fresh water side in the numerical simulation and the flume experiment in Example 2 of the present invention. DETAILED DESCRIPTION

[0066] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments, as all technologies implemented based on the present invention fall within the scope of the present invention.

[0067] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating orientation or positional relationships such as "upper," "lower," "left," "right," "center," "inside," and "outside" are based on the orientation or positional relationships shown in the accompanying drawings, or are the orientation or positional relationships in which the inventive product / device / apparatus is typically placed when in use. These terms indicating orientation or positional relationships are merely for the purpose of facilitating the description of the present invention or simplifying the description of the specific embodiments to facilitate a quick understanding of the solutions by technicians. They do not indicate or imply that a particular device / component / element must have a specific orientation or be constructed and operated in a specific positional relationship, and therefore should not be construed as limiting the present invention.

[0068] 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 simply understood that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", and "parallel", 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 solution of the present invention.

[0069] 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.

[0070] In addition, in the description of the embodiments of the present invention, "several," "plurality," and "a number" represent at least two. It can also be any number such as two, three, four, five, six, seven, eight, nine, or even more than nine.

[0071] Furthermore, in the description of the technical solution of the present invention, unless otherwise expressly specified, defined, or limited, the terms "disposed," "installed," "connected," "connected," "provided with," "laid," and "arranged" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections. They may be welded, riveted, bolted, threaded, or other commonly used connection methods in the art. Such connections may be mechanical, electrical, or communicative; they may be direct, indirect via an intermediate medium, or internally connected between two components.

[0072] Example 1:

[0073] A three-dimensional numerical simulation of air curtain anti-salinity was used to simulate the saltwater intrusion process in the test arrangement of the Dutch Deltares Institute. The specific steps are as follows:

[0074] 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);

[0075] 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 anti-salinity system of air-fresh water-salt water are established;

[0076] 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;

[0077] Among them, the basic control equation is:

[0078]

[0079] Where 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;

[0080] The density of the mixed fluid is 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;

[0081] wherein the force source term

[0082] wherein s x , s y , and s z are the viscous force source terms in 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 are the body force in x, y, and z directions respectively, if the body force is only gravity, F x = F y = 0, F z = -pg, p is the density of the mixture, g is the acceleration of gravity; λ is the volume viscosity coefficient; div u is the divergence of the velocity field, i.e.

[0083] wherein the auxiliary equations include the transport equation of the turbulent kinetic energy k and the transport equation of the turbulent kinetic energy dissipation rate ε in the standard k-ε model;

[0084] wherein the transport equation of the turbulent kinetic energy k in the standard k-ε model is:

[0085]

[0086] wherein the transport equation of the turbulent kinetic energy dissipation rate ε is:

[0087]

[0088] wherein x i , x j are the spatial coordinates in i and j directions respectively, μ t is the turbulent viscosity coefficient, p is the density of the mixture, 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 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 dissipation rate ε, p rt is the turbulent Prandtl number, β is the thermal expansion coefficient, g i is the component of the acceleration of gravity in i direction, C 1ε , C 2ε , and C 3ε are empirical constants, S u , and S ε are the self-defined source terms of the turbulent kinetic energy.

[0089] where the turbulent viscosity coefficient is given by

[0090]

[0091] where μ is the viscosity coefficient of water and η is the salinity transfer coefficient.

[0092] where the salinity transfer coefficient is given by

[0093] where θ is the dimensionless gas curtain jet intensity, θ = 0.4Fr air ; Fr air is the gas curtain Froude number.

[0094] where the gas curtain Froude number is given by

[0095] where Q a is the air supply per unit width; ρf 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;

[0096] S2, the three-dimensional model of the gas curtain salt prevention ship lock is divided into a regular hexahedral structural grid, the grid length is 2mm (the smallest volume of the grid is 2.08x10 -7 m 3 , the maximum volume is 10x10 -7 m 3 ), to ensure that the numerical model is fine enough to capture the key processes; based on the control equation and the three-dimensional model after grid division, a numerical simulation model of the gas-fresh salt water three-phase gas curtain salt prevention system of the ship lock is established by using the Fluent software;

[0097] S3, the basic parameters and initial conditions of the numerical simulation model are set; the basic parameters include the fluid properties of the salt water phase, the fresh water phase and the gas phase; the fluid properties include density, viscosity, specific heat capacity, thermal conductivity, depth; the initial conditions include the initial velocity field, the initial pressure field, the initial turbulent flow energy and the dissipation rate field;

[0098] Specifically, the water depth is 0.4m, the salinity of the salt water is 20‰, the corresponding density is 1019kg / m 3 , the aeration pipe is replaced by a single slit, the single slit width is 2mm, the air inlet pressure is 39pa, the time-averaged air inlet quantity is 34L / min; the temperature is 17.5℃;

[0099] S4, the wall surface no-slip condition is selected as the boundary condition of the numerical simulation;

[0100] where 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;

[0101] in,

[0102] 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;

[0103] S5. Solve the governing equations of the numerical model using a pressure-velocity coupling algorithm to obtain a numerical solution of the numerical model. The specific steps include:

[0104] (1) Set the initial velocity field and pressure field, and set the convergence criteria and number of iterations of the numerical model control equations;

[0105] (2) Using the finite volume method to discretize the numerical model control equation to obtain the discrete equation;

[0106] (3) Based on the current pressure field, a predicted velocity field is obtained by substituting it into the discrete equation;

[0107] (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;

[0108] (5) Update velocity and pressure: Update the velocity field and pressure field using the new pressure field correction;

[0109] (6) Iteration: Repeat steps 3-5 above until the discrete equations converge and the numerical solution of the control equations of the numerical model is obtained.

[0110] S6. Use experimental data (obtained from literature) to verify and calibrate the numerical model to ensure the accuracy of the simulation results;

[0111] S7. Perform numerical simulation using the verified and calibrated numerical model to obtain numerical simulation results.

[0112] 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.

[0113] Result analysis: under the conditions of 39pa pressure and 34L / min average air intake, the bubble curtain formed by the gas in the water is very sparse, which cannot hinder the saltwater with salinity up to 20‰ from advancing, cannot interfere with the formation of salt wedge, and finally leads to the saltwater model dispersing the gas curtain and invading the fresh water side.

[0114] Figure 1 The test results of the relative concentration of saltwater after invading the gas curtain on the 0-10s fresh water side and the simulation results curve; the results show that under the air intake conditions, the simulation results are slightly larger than the measured data, but the change trend is consistent, the simulation results are basically consistent with the experimental results in the literature, and the simulation method used in example 1 can accurately reflect the physical process of gas curtain anti-salt.

[0115] Example 2

[0116] The process of saltwater intrusion in a certain coastal river estuary hub ship lock is simulated by using a kind of gas curtain anti-salt three-dimensional numerical simulation, the specific steps are as follows:

[0117] S1, obtain the three-dimensional model parameters of the gas curtain anti-salt ship lock, and build the three-dimensional model of the gas curtain anti-salt ship lock (length 2m x width 0.5m x height 0.5m, air slot width is 2mm, located at 0.9m upstream of the saltwater side);

[0118] 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 equation of gas-fresh water-salt water three-phase gas curtain anti-salt system is established;

[0119] Among them, the control equation of gas-fresh water-salt water three-phase gas curtain anti-salt system includes basic control equation and auxiliary equation;

[0120] Among them, the basic control equation is:

[0121]

[0122] In the formula, S u , S v , S w are the force source terms in x, y, z directions respectively, u is the velocity component of velocity vector in X axis direction, v is the velocity component of velocity vector in y axis direction, w is the velocity component of velocity vector in Z axis direction, P is the fluid pressure, p is the mixed fluid density, and μ is the water molecular viscosity coefficient;

[0123] Among them, the mixed fluid density In the formula, p1, p2 are the densities of fresh water and saltwater respectively, and v1, v2 are the volumes of fresh water and saltwater respectively;

[0124] Among them, the force source term

[0125] Where 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 in the x, y, and z directions of the microelement. 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 acceleration of gravity; λ is the volume viscosity coefficient; divu is the divergence of the velocity field, that is,

[0126] Among them, the auxiliary equations include the transport equations of turbulent kinetic energy k and turbulent kinetic energy ￡ in the standard k-￡ model;

[0127] Among them, the transport equation of turbulent kinetic energy k in the standard k-￡ model is:

[0128]

[0129] Among them, the transport equation of turbulent kinetic energy £ is:

[0130]

[0131] Where 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 £, 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;

[0132] Among them, the turbulent viscosity coefficient

[0133] where μ is the viscosity coefficient of water molecule, and η is the salinity transfer coefficient.

[0134] where the salinity transfer coefficient

[0135] where θ is the dimensionless gas curtain plume intensity, θ = 0.4Fr air ; Fr air is the gas curtain Froude number.

[0136] where the gas curtain Froude number

[0137] where 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;

[0138] S2, the three-dimensional model of the gas curtain salt prevention ship lock is divided into a regular hexahedral structural grid, the grid length is 2mm (the smallest volume of the grid is 2.08x10 -7 m 3 , the maximum volume is 10x10 -7 m 3 ), to ensure that the numerical model is fine enough to capture the key processes; based on the control equation and the three-dimensional model after grid division, a numerical simulation model of the gas-fresh salt water three-phase gas curtain salt prevention system of the ship lock is established by using the Fluent software;

[0139] S3, the basic parameters and initial conditions of the numerical simulation model are set; the basic parameters include the fluid properties of the salt water phase, the fresh water phase and the gas phase; the fluid properties include density, viscosity, specific heat capacity, thermal conductivity, depth; the initial conditions include the initial velocity field, the initial pressure field, the initial turbulent kinetic energy and the dissipation rate field;

[0140] wherein the test uses salt water with a salinity of 2.5‰, a density of 1001.92kg / m 3 , a water depth of 0.4m, and a hole pipe opening diameter of 2mm; the single slit width is 2mm, and the time-averaged air supply is 0.003m 3 / s and 0.01m 3 / s respectively; the temperature is 17.5℃;

[0141] S4, the wall surface no-slip condition is selected as the boundary condition of the numerical simulation;

[0142] wherein the no-slip wall surface 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 formula to directly link the no-flow of the wall surface area with the unknown quantity of the turbulent core area.

[0143] where,

[0144] where u is the velocity component of the fluid in the wall-parallel direction, U T is the wall friction velocity, y is the normal distance from the wall; when y + < 5, the fluid is in the viscous sublayer; when 60 < y + < 300, the flow is in the logarithmic layer; v is the kinematic viscosity of the fluid;

[0145] S5, solving the control equations of the numerical model using a pressure-velocity coupling algorithm to obtain the numerical solution of the numerical model; the specific steps include:

[0146] (1) setting the initial velocity field and pressure field, setting the convergence criteria and iteration number of the control equations of the numerical model;

[0147] (2) using the finite volume method to discretely process the control equations of the numerical model to obtain discrete equations;

[0148] (3) based on the current pressure field, substituting into the discrete equation to obtain a predicted velocity field;

[0149] (4) solving the pressure correction equation: substituting the predicted velocity field into the discrete equation, and using the diagonal decomposition technique to derive the pressure Poisson equation; solving the pressure Poisson equation to obtain a new pressure field;

[0150] (5) updating the velocity and pressure: updating the velocity field and pressure field using the new pressure field correction;

[0151] (6) iteration: repeating steps 3-5 above until the discrete equation converges to obtain the numerical solution of the control equations of the numerical model.

[0152] S6, using experimental data to verify and calibrate the numerical model to ensure the accuracy of the simulation results;

[0153] S7, using the verified and calibrated numerical model to perform numerical simulation to obtain the numerical simulation results.

[0154] The simulation results under the two air inlet conditions are shown in Figure 3 Figure 3 The blue is the gas phase, the yellow is fresh water, and the red is salt water.

[0155] The results show that when the air inlet condition is very small, the effect of hindering saltwater intrusion is very limited, and increasing it can significantly improve the saltwater blocking effect, but further increasing it will intensify the mixing action of the water body, causing the bottom saltwater to be transported to the surface layer by the flow field, and then entering the fresh water side through the gas curtain which is relatively sparse compared to the bottom.

[0156] ​Comparison of measured and simulated data of relative concentrations in freshwater water Figure 4 As shown in the figure, the solid line 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.

[0157] Example 3

[0158] A three-dimensional numerical simulation device for air curtain anti-salinity includes a processor and a memory communicatively connected to the processor; the memory stores instructions executable by the processor, and the instructions are executed by the processor to enable the processor to perform a three-dimensional numerical simulation method for air curtain anti-salinity in embodiment 1 or 2.

[0159] Example 4

[0160] 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.

[0161] 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 scope of protection 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 parameters of the three-dimensional model 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 equations of the air-fresh water-salt water three-phase air curtain anti-salt system based on the basic equations of mass and energy conservation, the multiphase flow seepage field, the physical and chemical properties and the coupled mathematical equations of the driving parameters; The control equations of the three-phase air curtain anti-salt water system of air, fresh water and salt water 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: Where 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 3D model of the air curtain anti-salinity ship lock to ensure that the numerical model is sufficiently refined to capture key processes. Based on the governing equations and the meshed 3D model, use Fluent software to establish a numerical simulation model of the lock's three-phase air curtain anti-salinity system, which involves air, fresh water, and salt water. 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 the initial velocity field, the initial pressure field, the initial turbulent kinetic energy, and the dissipation rate field; S4. Select the wall no-slip condition as the boundary condition for numerical simulation; S5. Solve the control equations 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, Where 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 in the x, y, and z directions of the microelement. 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 acceleration of gravity; 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: Where 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 £, 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 coefficient is as follows 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 Where Q a is the air supply per unit width; ρ1 is the fresh water density; Δρ is the density difference between salt and fresh water; g is the acceleration of gravity; and 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, characterized in that: In step S4, the no-slip wall boundary is confirmed 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; 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) Set the initial velocity field and pressure field, and set the convergence criteria and number of iterations of the numerical model control equations; (2) Using the finite volume method to discretize the numerical model control equation to obtain the discrete equation; (3) Based on the current pressure field, a predicted velocity field is obtained by substituting it into the discrete equation; (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 equations converge and the numerical solution of the control equations 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 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 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 according to any one of claims 1 to 10.

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