Ship lock anti-salty air curtain structure and design method

Abstract

The invention discloses an anti-salty air curtain structure of a ship lock and a design method, and relates to the technical field of air curtain salty prevention. The design method comprises the following steps that S1, the length of an air curtain exhaust pipe and the length of a main air supply pipe are determined; s2, based on a ship lock salinity transfer coefficient design value, calculating to obtain an air curtain Froude number; s3, based on the air curtain Froude number, the unit width air supply amount of the air curtain exhaust pipe is obtained through calculation; s4, determining the air flow speed of the air curtain based on the flow speed of the salt water wedge head; s5, calculating the hole diameter and hole distance of exhaust holes of the air curtain exhaust pipe, the air curtain input pressure and the inner diameter of an air curtain pipeline; s6, performing simulation verification and correction on related parameters of the air curtain structure to obtain an air curtain structure design result; according to the design method, the ship lock anti-salty air curtain structure meeting the anti-salty design requirement can be designed more quickly and more accurately with fewer errors, positive guidance is provided for construction of the ship lock anti-salty air curtain structure, and large-scale application and popularization of the ship lock anti-salty air curtain structure are facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of seawater intrusion prevention and control, in particular to a salty air curtain prevention technology, and in particular to a ship lock salty air curtain prevention structure and a design method. Background Art

[0002] my country has a long coastline and is a country with many estuaries. There are different degrees of seawater intrusion in rivers such as the Huangpu River, Yangtze River, Pearl River, Yellow River, Haihe River, and Qiantang River. 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, causing the river runoff to decrease 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 cause the groundwater quality of the coastal plain to deteriorate day by day. 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. It can be seen that the saltiness of fresh water has caused great harm to water security, food security, ecological security and the lives and health of the people in my country's coastal areas. In order to prevent seawater from entering rivers and polluting freshwater, locks are set up at the mouths of certain navigable rivers. The anti-salinity measures of the locks are used to block seawater from invading freshwater rivers, thereby achieving the purpose of protecting freshwater resources and the 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 corridor; (3) Anti-salinity facilities for replacing the water in the lock chamber: When a ship enters the lock chamber, all the water in the lock chamber is 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 in 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 at the same time as the salt water is discharged (and vice versa), so it is also called simultaneous replacement method. During the displacement process, the inflow or outflow of seawater is through the corridor set at the bottom of the lock chamber and the holes in the lock bottom plate. The inflow or outflow of fresh water is through the porous culvert set at the side of the lock chamber. (4) Pumping facilities: The pumping method is to set up a pump room at the bow of the freshwater side of the ship lock. When the water level on the saltwater side is higher than the freshwater side, after the ship enters the lock chamber from the freshwater side, the pump will pump water from the freshwater side to the lock chamber. When the water level in the lock chamber is flush with the saltwater side, the gate on the saltwater side will be opened to pass the ship. This method can only partially reduce the intrusion of saltwater. During the gate opening process, saltwater will still be displaced with freshwater 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 the air curtain anti-salinity is suitable for the anti-salinity requirements of most coastal ship locks because of its applicability to different anti-salinity requirements and its advantages of simple setting and low cost.

[0006] A large number of experimental studies have shown that the factors affecting the anti-salinity effect of the air curtain mainly include the following: (1) The amount of air added to the air curtain: The amount of air added to the air curtain is an important factor affecting its anti-salinity effect; the greater the amount of air added, the stronger the upwelling generated by the air curtain, and the more effectively it can bring the bottom salt water to the surface, reducing the high-salinity body from entering the upstream, thereby achieving the purpose of anti-salinity; however, there is an optimal amount of air added, and after exceeding this amount, the effect of the increased amount of air added on the performance of the air curtain becomes negligible; (2) Water depth: Water depth has a significant effect on the effect of the air curtain; within a certain range, the greater the water depth, the anti-salinity effect of the air curtain may be subject to certain restrictions, because the mixing effect of the water body may weaken the local mixing effect of the air curtain; (3) Salinity: The salinity level of the estuary will also affect the anti-salinity effect of the air curtain; the higher the salinity, the greater the density of the salt water, and the easier it is to form a salt water wedge, which may increase the density difference that the air curtain needs to overcome, thereby affecting the effect of the air curtain. ;(4) Tidal velocity: The magnitude of tidal velocity will affect the effect of the air curtain. The greater the tidal velocity, the stronger the air curtain needs to generate upwelling to offset the mixing effect brought by the tide, thereby inhibiting the upward movement of the salt tide;(5) Seawater density: The increase in seawater density will increase the salinity intrusion force, resulting in a clockwise rotating flow upstream of the air curtain, which intensifies the salinity intrusion upstream of the air curtain and reduces the efficiency of the air curtain;(6) The design of the air curtain device: Including the size of the air curtain orifice, the orifice spacing and the pipeline layout, etc., will affect the surface velocity and thickness of the horizontal flow generated by the air curtain, and thus affect the anti-salinity effect of the air curtain;(7) Water jet and other auxiliary measures: The use of air curtain alone or in combination with water jet, as well as auxiliary measures such as assembled thresholds used to reduce the effective depth, can significantly improve the anti-salinity effect of the air curtain; Therefore, by adjusting the above factors, the design and operation of the air curtain system can be optimized to achieve a better anti-salinity effect. It can be seen from this that targeted design of the air curtain structure is obviously beneficial to improving the anti-salinity effect of the air curtain. However, in the prior art, no clear air curtain structure design method and rules are given to guide the design and construction of the air curtain structure, which is obviously not conducive to the large-scale promotion and application of the anti-salty air curtain structure. Summary of the invention

[0007] The purpose of the invention is to provide a ship lock anti-salinity air curtain structure and a design method for guiding the design and construction of the air curtain structure.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides a design method for a ship lock anti-salty air curtain structure, comprising the following steps:

[0009] S1. Determine the length of the air curtain exhaust pipe and the length of the main air supply pipe based on the design parameters of the ship lock; the design parameters include the ship lock water depth, the ship lock length, the ship lock width and the design value of the ship lock salinity transfer coefficient;

[0010] S2. Based on the design value of the salinity transfer coefficient of the ship lock, the air curtain Froude number is calculated;

[0011] S3. Based on the Froude number of the air curtain, the air supply per unit width of the air curtain exhaust pipe is calculated;

[0012] S4. Determine the air curtain air velocity based on the flow velocity of the brine wedge head;

[0013] S5. Based on the air supply per unit width of the air curtain exhaust pipe and the air flow rate of the air curtain, the aperture and hole spacing of the exhaust holes of the air curtain exhaust pipe, the air curtain input pressure, and the inner diameter of the air curtain pipe are calculated;

[0014] S6. Use the numerical model to simulate the effect, simulate and verify and correct the relevant parameters of the air curtain structure, and obtain the design results of the air curtain structure.

[0015] The design method of a ship lock anti-salty air curtain structure of the present invention not only utilizes the air system pipeline design principle of flow velocity to design the pipeline parameters of the anti-salty air curtain structure, but also utilizes a numerical model for verification, so that the ship lock anti-salty air curtain structure that meets the anti-salty design requirements can be designed faster, more accurately and with less errors, and provides active guidance for the construction of the ship lock anti-salty air curtain structure, which is conducive to the large-scale promotion and application of the ship lock anti-salty air curtain structure.

[0016] Among them, in step S1, the length of the air curtain exhaust pipe is equal to the width of the ship lock; the length of the main air supply pipe is determined based on the length of the ship lock and the setting position of the air supply chamber.

[0017] Among them, in step S2, the design value of the salinity transfer coefficient of the ship lock is the salt-proof target value to be achieved when designing the air curtain salt-proof structure.

[0018] Preferably, the air curtain Froude number is given by the formula and θ=0.4Fr air Calculated;

[0019] Where η is the salinity transfer coefficient, θ is the dimensionless air curtain plume intensity, and Fr air is the air curtain Froude number.

[0020] Among them, in step S3, preferably, the air supply per unit width is calculated by the formula Calculated; 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 of the lock.

[0021] Among them, in step S4, preferably, the flow velocity (υ0) at the head of the brine wedge refers to the flow velocity of the brine being "sucked away" by the downstream fresh water in the front part of the brine wedge, that is, the area where the brine and fresh water meet, which can be obtained through actual measurement or physical model prediction; the air curtain air flow rate (υ) is the speed of the air when it is ejected through the exhaust hole of the air curtain.

[0022] Preferably, the air flow rate (υ) of the air curtain is greater than the flow rate of the brine wedge head (υ0) and less than 2.4 times the flow rate of the brine wedge head, that is, v0<v<2.4v0.

[0023] Wherein, in step S5, preferably, the aperture of the exhaust hole of the air curtain exhaust pipe is calculated by the formula Calculated; where q a is the air supply per unit width, υ is the air velocity of the air curtain, and d is the exhaust hole diameter.

[0024] Preferably, the hole spacing of the exhaust holes of the air curtain exhaust pipe is determined according to the principles of fluid mechanics. If the spacing between the exhaust holes is too small, the exhausted airflows may interfere with each other. If the spacing between the exhaust holes is too large, it may cause uneven air supply and reduce the air curtain effect.

[0025] Preferably, the inner diameter of the air curtain pipeline (including the main air supply pipe and the air curtain exhaust pipe) is In the formula, Q a is the gas flow rate of the air curtain pipe, υ is the air velocity of the air curtain, d1 is the inner diameter of the air curtain pipe, and Π is the pi.

[0026] Preferably, the gas flow rate of the air curtain exhaust pipe is expressed by the formula Q a =q a ·l is calculated; where Q a is the gas flow rate of the air curtain exhaust pipe, q a is the air supply per unit width, and l is the exhaust pipe length.

[0027] Preferably, the air curtain input pressure is calculated by the formula P=P0+ΔP, where P is the air curtain input pressure, P0 is the air curtain exhaust hole pressure, and ΔP is the pressure loss; wherein, the pressure loss Where, υ is the air velocity in the duct, d1 is the inner diameter of the air curtain duct, l is the length of the duct, μ is the friction coefficient, and ρ is the air density.

[0028] Preferably, the air pressure of the air curtain exhaust hole is calculated by the formula P0=0.5ρv 2 It is calculated that, where υ is the air velocity of the air curtain and ρ is the air density.

[0029] Preferably, in step S6, using a numerical model to simulate the effect includes: using a computational fluid dynamics (CFD) model to simulate the flow characteristics of the gas in the air curtain pipe and using an air curtain anti-salinity three-dimensional numerical model to simulate the anti-salinity effect of the air curtain structure on saltwater intrusion into the lock; through the simulation of the above two models, the anti-salinity effect of the designed air curtain structure can be evaluated, thereby ensuring that the air curtain structure can meet the design requirements.

[0030] Preferably, the method of simulating the anti-salinity effect of the air curtain structure on the saltwater intrusion of the ship lock by using the air curtain anti-salinity three-dimensional numerical model includes:

[0031] 1. Based on the design parameters of the ship lock and the design parameters of the air curtain structure, a three-dimensional model of the air curtain anti-salinity ship lock is constructed by proportional reduction; 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-salinity system are established;

[0032] 2. Mesh the three-dimensional model of the air curtain anti-salt water ship lock; based on the control equation 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;

[0033] 3. Set the basic parameters and initial conditions of the numerical simulation model;

[0034] 4. Select the wall no-slip condition as the boundary condition for numerical simulation;

[0035] 5. Solve the control equation and obtain the numerical solution of the numerical model, which is the simulation result.

[0036] Preferably, in step 1, the scaling ratio is confirmed according to actual conditions, and may be 1:50, 1:100, 1:200, 1:500, 1:1000, etc.

[0037] 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.

[0038] Among them, the basic control equation is:

[0039]

[0040] 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.

[0041] Preferably, the density of the mixed fluid

[0042] 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.

[0043] Preferably,

[0044]

[0045] 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,

[0046] The auxiliary equations include the transport equations of turbulent kinetic energy k and turbulent kinetic energy ￡ in the standard k-￡ model.

[0047] The transport equation of turbulent kinetic energy k in the standard k-￡ model is:

[0048]

[0049] The transport equation of the turbulent kinetic energy ￡ is:

[0050]

[0051] 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.

[0052] Preferably, the turbulent viscosity

[0053] Where μ is the viscosity coefficient of water molecules and η is the design value of salinity transfer coefficient.

[0054] Among them, in step 2, the three-dimensional model is divided into regular hexahedral structural grids with a grid side length of 2 mm.

[0055] Wherein, in step 3, 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.

[0056] Preferably, the initial conditions include an initial velocity field, an initial pressure field, an initial turbulent kinetic energy and a dissipation rate field.

[0057] Among them, in step 4, 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;

[0058] in,

[0059] 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.

[0060] Wherein, in step 5, 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.

[0061] Preferably, the specific steps of solving the numerical model control method using the pressure-velocity coupling algorithm include:

[0062] (a) Setting the initial velocity field and pressure field, and setting the convergence criteria and iteration times of the numerical model control equations;

[0063] (b) using the finite volume method to discretize the control equations of the numerical model to obtain discrete equations;

[0064] (c) Based on the current pressure field, substitute it into the discrete equation to obtain a predicted velocity field;

[0065] (d) 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;

[0066] (e) Update velocity and pressure: Update the velocity field and pressure field using the new pressure field correction;

[0067] (f) Iteration: Repeat the above steps ce until the discretized equations converge and the numerical solutions of the control equations of the numerical model are obtained.

[0068] In order to achieve the above-mentioned purpose of the invention, the present invention also provides a ship lock anti-salt gas curtain structure, which includes a gas generating device, a control device, a main gas supply pipe and an air curtain exhaust pipe; the gas generating device is used to generate high-pressure gas, such as an air pump; the control device is arranged on the main gas supply pipe and / or the air curtain exhaust pipe, and is used for the pressure of the gas in the pipeline, such as an air pressure valve, a gas flow meter; the main gas supply pipe serves as a gas flow channel, is connected to the gas generating device, and is used to transmit gas; the air curtain exhaust pipe is used to discharge the gas to form an air curtain; wherein, the size and input gas pressure of the main gas supply pipe and the air curtain exhaust pipe are designed by the above-mentioned design method.

[0069] Preferably, the anti-salty air curtain structure of the ship lock includes at least one air curtain exhaust pipe; the air curtain exhaust pipe is provided with exhaust holes, and the size and spacing of the exhaust holes are designed by the above-mentioned design method.

[0070] Compared with the prior art, the present invention has the following beneficial effects:

[0071] The design method of the ship lock anti-salty air curtain structure of the present invention not only utilizes the air system pipeline design principle of flow velocity to design the pipeline parameters of the anti-salty air curtain structure, but also utilizes the numerical model for verification, so that the ship lock anti-salty air curtain structure that meets the anti-salty design requirements can be designed faster, more accurately and with less error, which provides positive guidance for the construction of the ship lock anti-salty air curtain structure and is conducive to the large-scale promotion and application of the ship lock anti-salty air curtain structure. DETAILED DESCRIPTION

[0072] The present invention is further described in detail below in conjunction with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being 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.

[0073] 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 based on the expression of the orientation or position relationship, or are 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, and do not indicate or imply 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 of the present invention.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] Embodiment 1:

[0079] A design method for a ship lock anti-salty air curtain structure is used to design an anti-salty air curtain structure in a ship lock at an estuary (referring to the existing air curtain project, the air curtain is arranged 7m away from the upper lock head, and the air curtain consists of 3 rows of exhaust pipes with air holes, each exhaust pipe is evenly arranged with an exhaust hole, and the exhaust pipes are spaced 100mm apart), including the following steps:

[0080] S1. Based on the design parameters of the ship lock, determine the length of the air curtain exhaust pipe (the length of the air curtain exhaust pipe is equal to the width of the ship lock, which is 34m) and the length of the main air supply pipe (determined based on the length of the ship lock and the setting position of the air supply chamber, which is 150m); the design parameters include the ship lock water depth (the water depth at the air curtain position may be 8.4m (upstream water level 8.7m) and 7.7m (upstream water level 8m)), ship lock length (300m), ship lock width (34m) and the design value of the ship lock salinity transfer coefficient;

[0081] S2, based on the design value of the salinity transfer coefficient of the ship lock, the air curtain Froude number (minimum 0.69, maximum 0.9) is calculated;

[0082] The Froude number of the air curtain is given by the formula and θ=0.4Fr air Calculated; where η is the salinity transfer coefficient, θ is the dimensionless air curtain plume intensity, Fr air is the air curtain Froude number;

[0083] S3. Based on the air curtain Froude number, the air supply per unit width of the air curtain exhaust pipe is calculated (see Table 1); the air supply per unit width is calculated by the formula Calculated; 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 acceleration of gravity; h is the water depth of the lock;

[0084] Table 1 Air supply per unit width at different depths and saltiness prevention rates

[0085]

[0086] S4. Based on the flow rate of the saline wedge head, confirm the air curtain air flow rate; the air curtain air flow rate (υ) is greater than the flow rate of the saline wedge head (υ0) and less than 2.4 times the flow rate of the saline wedge head, that is, v0<v<2.4v0;

[0087] The physical model predicts that the flow velocity of the salt water wedge head in the ship lock (υ0) is 15m / s, and the air curtain air velocity (υ) is 20.5m / s;

[0088] S5. Based on the air supply per unit width of the air curtain exhaust pipe and the air flow rate of the air curtain, the aperture and hole spacing of the exhaust holes of the air curtain exhaust pipe (see Table 2), the air curtain input pressure (0.25MPa), and the inner diameter of the air curtain pipe (see Table 2) are calculated;

[0089] Table 2 Design parameters of air curtain structure pipeline

[0090]

[0091] The diameter of the exhaust hole of the air curtain exhaust pipe is calculated by the formula Calculated; where q a is the air supply per unit width, υ is the air velocity of the air curtain, and d is the exhaust hole diameter;

[0092] The hole spacing of the exhaust holes of the air curtain exhaust pipe is determined according to the principles of fluid mechanics;

[0093] Inner diameter of air curtain pipe (including main air supply pipe and air curtain exhaust pipe) In the formula, Q a is the gas flow rate of the air curtain pipe, υ is the air velocity of the air curtain, d1 is the inner diameter of the air curtain pipe, and Π is the pi;

[0094] The gas flow rate of the air curtain exhaust pipe is calculated by the formula Q a =q a ·l is calculated; where Q a is the gas flow rate of the air curtain exhaust pipe, q a is the air supply per unit width, and l is the exhaust pipe length.

[0095] The air curtain input pressure is calculated by the formula P = P0 + ΔP, where P is the air curtain input pressure, P0 is the air curtain exhaust hole pressure, and ΔP is the pressure loss. Where, υ is the air velocity in the duct, d1 is the inner diameter of the air curtain duct, l is the length of the duct, μ is the friction coefficient, and ρ is the air density.

[0096] The air pressure at the air curtain exhaust hole is calculated by the formula P0 = 0.5ρv 2 Calculated, where υ is the air velocity of the air curtain and ρ is the air density;

[0097] S6. Use the numerical model to simulate the effect, simulate and verify and calibrate the relevant parameters of the air curtain structure, and obtain the design result of the air curtain structure;

[0098] Computational fluid dynamics (CFD) model is used to simulate the flow characteristics of gas in the air curtain duct, which meets the design requirements;

[0099] The three-dimensional numerical model of air curtain anti-salinity is used to simulate the anti-salinity effect of air curtain structure on saltwater intrusion into ship locks to meet the anti-salinity requirements;

[0100] Among them, the method of using the air curtain anti-salinity three-dimensional numerical model to simulate the anti-salinity effect of the air curtain structure on the saltwater intrusion of the ship lock includes:

[0101] 1. Based on the design parameters of the ship lock and the design parameters of the air curtain structure, a three-dimensional model of the air curtain anti-salinity ship lock is constructed by proportional reduction; 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-salinity system are established;

[0102] 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;

[0103] Among them, the basic control equation is:

[0104]

[0105] 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;

[0106] 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;

[0107] Among them, the force source term

[0108] 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,

[0109] Among them, the auxiliary equations include the transport equations of turbulent kinetic energy k and turbulent kinetic energy ￡ in the standard k-￡ model;

[0110] Among them, the transport equation of turbulent kinetic energy k in the standard k-￡ model is:

[0111]

[0112] Among them, the transport equation of turbulent kinetic energy £ is:

[0113]

[0114] 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;

[0115] Among them, turbulent viscosity

[0116] Where μ is the viscosity coefficient of water molecules and η is the salinity transfer coefficient.

[0117] Among them, the salinity transfer coefficient

[0118] Where θ is the dimensionless air curtain plume intensity, θ = 0.4Fr air ; Fr air is the air curtain Froude number.

[0119] Among them, 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;

[0120] 2. Mesh the three-dimensional model of the air curtain anti-salt water ship lock; based on the control equation 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;

[0121] 3. Set the basic parameters and initial conditions of the numerical simulation model; the basic parameters include the fluid properties of the 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;

[0122] 4. Select the wall no-slip condition as the boundary condition for numerical simulation;

[0123] 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;

[0124] in,

[0125] 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;

[0126] 5. Use the pressure-velocity coupling algorithm to solve the control equation of the numerical model and obtain the numerical solution of the numerical model; the specific steps include:

[0127] (1) Setting the initial velocity field and pressure field, and setting the convergence criteria and number of iterations of the numerical model control equations;

[0128] (2) Using the finite volume method to discretize the control equations of the numerical model to obtain discrete equations;

[0129] (3) Based on the current pressure field, substitute it into the discrete equation to obtain a predicted velocity field;

[0130] (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;

[0131] (5) Update velocity and pressure: Update the velocity field and pressure field using the new pressure field correction;

[0132] (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.

[0133] S6. Use experimental data to verify and calibrate numerical models to ensure the accuracy of simulation results;

[0134] S7, performing numerical simulation using the verified and calibrated numerical model to obtain numerical simulation results;

[0135] The simulation results show that the design parameters of the air curtain structure meet the requirements of anti-salinity design, and the salinity transfer coefficient of the ship lock meets the design value;

[0136] Based on the above design method, the pipeline parameters of the anti-salty gas curtain structure of the ship lock are designed. The anti-salty gas curtain structure includes a gas generating device (the air compressor model BST-lOOSA is selected, and the overall dimensions are 1.95×1.32×1.57m in length, width and height; 5 air compressors are set, and generally 3 are working), a control device (air pressure valve and gas flow meter), a main air supply pipe (150m in length and 160mm in inner diameter) and an air curtain exhaust pipe (3 pipes, 34m in length and 107mm in inner diameter); the main air supply pipe is connected to the gas generating device as a gas flow channel for transmitting gas; the air curtain exhaust pipe is used to discharge the gas to form an air curtain; each air curtain exhaust pipe is provided with an exhaust hole (aperture 2mm) with a spacing of 12mm.

[0137] 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 design method for a ship lock anti-salty air curtain structure, characterized in that: The following steps are involved: S1. Determine the length of the air curtain exhaust pipe and the length of the main air supply pipe based on the design parameters of the ship lock; the design parameters include the ship lock water depth, the ship lock length, the ship lock width and the design value of the ship lock salinity transfer coefficient; S2. Based on the design value of the salinity transfer coefficient of the ship lock, the air curtain Froude number is calculated; S3. Based on the air curtain Froude number, the air supply per unit width of the air curtain exhaust pipe is calculated; S4. Determine the air curtain air velocity based on the flow velocity of the brine wedge head; S5. Based on the air supply per unit width of the air curtain exhaust pipe and the air flow rate of the air curtain, the aperture and hole spacing of the exhaust holes of the air curtain exhaust pipe, the air curtain input pressure, and the inner diameter of the air curtain pipe are calculated; S6. Use the numerical model to simulate the effect, simulate and verify and correct the relevant parameters of the air curtain structure, and obtain the design results of the air curtain structure.

2. The design method of the ship lock anti-salty air curtain structure according to claim 1 is characterized in that: In step S1, the length of the air curtain exhaust pipe is equal to the width of the ship lock; the length of the main air supply pipe is determined based on the length of the ship lock and the setting position of the air supply chamber.

3. The design method of the ship lock anti-salty air curtain structure according to claim 1 is characterized in that: In step S2, the air curtain Froude number is calculated by the formula and θ=0.4Fr air Calculated; where η is the salinity transfer coefficient, θ is the dimensionless air curtain plume intensity, Fr air is the air curtain Froude number.

4. The design method of the ship lock anti-salty air curtain structure according to claim 1 is characterized in that: In step S3, the air supply per unit width is calculated by the formula Calculated; 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 of the lock.

5. The design method of the ship lock anti-salty air curtain structure according to claim 1 is characterized in that: In step S4, the air flow rate of the air curtain is greater than the flow rate of the salt water wedge head and less than 2.4 times the flow rate of the salt water wedge head.

6. The design method of the ship lock anti-salty air curtain structure according to claim 1 is characterized in that: In step S5, the diameter of the exhaust hole of the air curtain exhaust pipe is calculated by the formula Calculated; where q a is the air supply per unit width, υ is the air velocity of the air curtain, and d is the exhaust hole diameter.

7. The design method of the ship lock anti-salty air curtain structure according to claim 1 is characterized in that: In step S5, the inner diameter of the air curtain pipe In the formula, Q a is the gas flow rate of the air curtain pipe, υ is the air velocity of the air curtain, d1 is the inner diameter of the air curtain pipe, and Π is the pi; The gas flow rate of the air curtain exhaust pipe is calculated by the formula Q a =q a ·l is calculated; where Q a is the gas flow rate of the air curtain exhaust pipe, q a is the air supply per unit width, and l is the exhaust pipe length.

8. The design method of the ship lock anti-salty air curtain structure according to claim 1 is characterized in that: In step S5, the air curtain input pressure is calculated by the formula P=P0+ΔP, where P is the air curtain input pressure, P0 is the air curtain exhaust hole pressure, and ΔP is the pressure loss; wherein, the pressure loss In the formula, υ is the air velocity in the duct, d1 is the inner diameter of the air curtain duct, l is the length of the duct, μ is the friction coefficient, and ρ is the air density; The air pressure of the air curtain exhaust hole is calculated by the formula P0=0.5ρv 2 It is calculated that, where υ is the air velocity of the air curtain and ρ is the air density.

9. The design method of the ship lock anti-salty air curtain structure according to claim 1 is characterized in that: In step S6, using a numerical model to simulate the effect includes: using a computational fluid dynamics model to simulate the flow characteristics of the gas in the air curtain pipeline and using an air curtain anti-salinity three-dimensional numerical model to simulate the anti-salinity effect of the air curtain structure on saltwater intrusion into the lock.

10. The design method of the ship lock anti-salty air curtain structure according to claim 9, characterized in that: The method of using the air curtain anti-salinity three-dimensional numerical model to simulate the anti-salinity effect of the air curtain structure on the saltwater intrusion of the ship lock includes:

1. Based on the design parameters of the ship lock and the design parameters of the air curtain structure, a three-dimensional model of the air curtain anti-salinity ship lock is constructed by proportional reduction; 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-salinity system are established; 2. Mesh the three-dimensional model of the air curtain anti-salt water ship lock; based on the control equation 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; 3. Set the basic parameters and initial conditions of the numerical simulation model; 4. Select the wall no-slip condition as the boundary condition for numerical simulation; 5. Solve the control equation and obtain the numerical solution of the numerical model, which is the simulation result.

11. A ship lock anti-salt air curtain structure, comprising a gas generating device, a control device, a main air supply pipe and an air curtain exhaust pipe; characterized in that: The size and input air pressure of the main air supply pipe and the air curtain exhaust pipe are designed by the design method described in any one of claims 1-10.

12. The ship lock anti-salty air curtain structure according to claim 11, characterized in that: The anti-salty air curtain structure of the ship lock comprises at least one air curtain exhaust pipe; and the air curtain exhaust pipe is provided with exhaust holes.

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