CN111501658A - Hydrodynamic lifting device based on vertical shaft plug flow and performance test method thereof - Google Patents

Hydrodynamic lifting device based on vertical shaft plug flow and performance test method thereof Download PDF

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CN111501658A
CN111501658A CN202010310349.0A CN202010310349A CN111501658A CN 111501658 A CN111501658 A CN 111501658A CN 202010310349 A CN202010310349 A CN 202010310349A CN 111501658 A CN111501658 A CN 111501658A
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hydrodynamic
flow
lifting device
hydrodynamic lifting
weak area
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CN111501658B (en
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陈求稳
林育青
朱立俊
范红霞
陈诚
王建中
冯然然
王智源
莫康乐
刘贝贝
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Nanjing Hydraulic Research Institute of National Energy Administration Ministry of Transport Ministry of Water Resources
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Nanjing Hydraulic Research Institute of National Energy Administration Ministry of Transport Ministry of Water Resources
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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B1/00—Equipment or apparatus for, or methods of, general hydraulic engineering, e.g. protection of constructions against ice-strains
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B1/00—Equipment or apparatus for, or methods of, general hydraulic engineering, e.g. protection of constructions against ice-strains
    • E02B1/02—Hydraulic models
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/28—Design optimisation, verification or simulation using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/10—Numerical modelling
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/08—Fluids

Abstract

The invention discloses a hydrodynamic lifting device based on vertical shaft plug flow, which comprises a support, a motor, a plug flow plate and a vertical shaft, wherein the motor is fixed on the support, the motor is connected with one end of the vertical shaft, the other end of the vertical shaft is fixed with the plug flow plate together, the plug flow plate is rectangular, and the length of the plug flow plate is 1/15-1/3 of the maximum radius of a hydrodynamic weak area. The invention also discloses two performance test methods of the hydrodynamic lifting device, one method is to adopt a physical reduction model, and the other method is to adopt mathematical modeling to carry out numerical simulation. The hydrodynamic lifting device provided by the invention realizes hydrodynamic lifting in a certain area, and the adopted test method accurately quantifies the improvement effect of the hydrodynamic weak area after the device is operated, thereby providing a decision basis for scientifically and economically operating the hydrodynamic device and improving the hydrodynamic condition of the river channel.

Description

Hydrodynamic lifting device based on vertical shaft plug flow and performance test method thereof
Technical Field
The invention relates to a water conservancy technology, in particular to a hydrodynamic lifting device based on vertical shaft plug flow and a performance test method thereof.
Background
Does not decay in running water and is a moth-proof house. In recent years, the natural hydrological conditions of a plurality of rivers are artificially changed, so that the dynamic conditions of the river water flow are remarkably changed; especially, the construction of excessive gate dams is favorable for improving the utilization efficiency of water resources, but easily causes the hydrodynamic conditions of local areas of the river channel to be greatly weakened, has poor water exchange capacity, and is not favorable for the migration and diffusion of pollutants flowing into the river channel, thereby aggravating the pollution of the water and influencing the production and life of people. In order to meet the requirements of people on living environment, the hydrodynamic force condition of the riverway is improved, the flow velocity of the riverway can be increased, the flowing effect of water flow is created, the reoxygenation capacity of the water body can be improved, the degradation of pollutants is accelerated, and therefore the purpose of improving the water quality is achieved.
In the prior art, most of the methods adopt a water adjusting and drainage mode to control and improve the hydrodynamic condition of the riverway, and an independent or series submersible pump is occasionally used for improving the hydrodynamic condition, but the effect is limited.
In addition, aiming at a local weak power area, because the operation effect of the hydrodynamic lifting device is often restricted by various factors such as power, river level and operation cost, how to determine proper power and how to realize economical and efficient operation, how to quantitatively evaluate the improvement effect of the hydrodynamic weak area after the device operates, and the method is a difficult point to be solved urgently in the technical application field of the existing hydrodynamic lifting device.
Disclosure of Invention
The purpose of the invention is as follows: the invention provides a hydrodynamic lifting device based on vertical axis plug flow and a performance testing method thereof, aiming at the problems in the prior art.
The technical scheme is as follows: the hydrodynamic lifting device based on the vertical shaft plug flow comprises a support, a motor, a plug flow plate and a vertical shaft, wherein the motor is fixed on the support, the motor is connected with one end of the vertical shaft, the other end of the vertical shaft is fixed with the plug flow plate, the plug flow plate is rectangular, and the length of the plug flow plate is 1/15-1/3 of the maximum radius of a hydrodynamic weak area, preferably 1/10-1/5.
Furthermore, the support includes a plurality of branch and supports fixed mesa through branch, branch height is greater than the distance of thrust plate bottom to the mesa of support. The vertical shaft is fixed on the central line of the thrust plate.
The invention relates to a performance test method of a hydrodynamic lifting device based on vertical shaft plug flow, which comprises the following steps:
s1, acquiring a hydrodynamic weak area and the size of the corresponding hydrodynamic lifting device;
s2, establishing a physical model of the hydrodynamic weak area and the hydrodynamic lifting device after reduction, wherein the reduction scale is a preset plane scale lambdaL；
S3, placing the physical model of the hydrodynamic lifting device in the center of the physical model of the hydrodynamic weak area, and setting m flow rate monitoring devices at radial intervals by taking the center point of a flow pushing plate of the physical model of the hydrodynamic lifting device as a starting point;
s4, setting n working conditionsThe rotating speed of the motor of the hydrodynamic lifting device is w1、w2、…、wnAnd according to the rotation speed scale lambdawConverting the set rotating speed to obtain the rotating speed w of the motor in the physical model of the hydrodynamic lifting device1’、w2’、…、wn', wherein,
Figure BDA0002457536120000021
s5, according to the rotating speed w1’、w2’、…、wnStarting a motor to drive a flow pushing plate to rotate, and obtaining a flow velocity set V ' ═ V ' monitored by a flow velocity monitoring device at all rotating speeds 'ij1, …, n, j 1, …, m, v'ijDenotes a rotational speed w'iThe flow rate monitored by the flow rate monitoring device j;
s6, all the flow rates in the flow rate set V' are measured according to the flow rate scale lambdavConverting to obtain a flow velocity set V ═ V in the natural state of the hydrodynamic weak region ij1, …, n, j 1, …, m }, wherein vij＝λvv'ij，
Figure BDA0002457536120000022
And S7, obtaining the performance of the hydrodynamic lifting device according to the flow velocity set V, wherein the larger the flow velocity is, the better the hydrodynamic lifting performance is.
The invention relates to another performance test method of a hydrodynamic lifting device based on vertical shaft plug flow, which comprises the following steps:
s1, establishing a hydrodynamic mathematical model of the hydrodynamic weak area, which specifically comprises the following steps:
(1) mass continuity equation:
Figure BDA0002457536120000023
wherein u, v, w are the velocity components in three directions of a Cartesian coordinate system x, y and z, Ax,Ay,AzFlowable in the x, y, z directions respectivelyArea fraction, ρ is the fluid density, RSORIs a density source item;
(2) the momentum equation:
Figure BDA0002457536120000024
Figure BDA0002457536120000025
Figure BDA0002457536120000026
in the formula, Gx,Gy,GzThe gravity acceleration in the x direction, the y direction and the z direction respectively; f. ofx,fy,fzThe viscous force acceleration in the x direction, the y direction and the z direction respectively; item Uw＝(uw，vw，ww) Representing the velocity of the source assembly in three directions; item Us＝(us，vs，ws) Representing the velocity of the fluid at the source surface in three directions relative to the source itself; vFThe fluid volume fraction with a free surface, R is a coordinate coefficient, when a Cartesian coordinate system is selected, the value is1, a coefficient is represented, when 0 is taken, the pressure boundary condition is a stagnation type, and when 1 is taken, the pressure boundary condition is a static pressure type;
(3) a turbulence model:
Figure BDA0002457536120000031
Figure BDA0002457536120000034
in the formula, kTIs kinetic energy of turbulence, PTFor the turbulence-generating term, GTFor buoyancy-generating terms, DiffkTIn order to be a diffusion term, the diffusion term,Tfor turbulence energy dissipation ratio, RMTKE, CDIS1 and CNU are user-defined parameters with default values of 1.39, 1.42 and 0.085, respectively, CDIS2 is defined by kTAnd PTComputingTo obtain vTIs a kinematic turbulent viscosity;
(4) fluid distribution:
the fluid distribution is defined in terms of a fluid volume function F (x, y, z, t) that represents the volume of fluid #1 per unit volume and satisfies the following equation:
Figure BDA0002457536120000032
Figure BDA0002457536120000033
in the formula: f is an abbreviation for the function F (x, y, z, t), ζ is the coordinate coefficient whose value is 0, ν when a Cartesian coordinate system is usedFAs diffusion coefficient, FSORIs the density source term, is the volume fraction time rate of change of fluid #1 associated with the mass source;
s2, obtaining the boundary of the hydrodynamic weak area, dividing the boundary into a plurality of grids by adopting a hexahedral structured grid, adding 2 layers of nested grids near the plug flow plate, adopting non-displacement Wall boundaries at the periphery and the bottom of the hydrodynamic weak area, setting the top of the hydrodynamic weak area as a pressure boundary, setting the atmospheric pressure to be 1.01 × 105Pa, and setting the fluid fraction to be 0, wherein the hydrodynamic weak area is completely air;
s3, establishing a mathematical model of the hydrodynamic lifting device, and placing the mathematical model in the center of a hydrodynamic weak area;
s4, setting n working conditions, specifically setting the rotating speed of the flow pushing plate of the hydrodynamic lifting device to w1、w2、…、wn；
S5, the hydrodynamic lifting device respectively rotates at a rotating speed w1、w2、…、wnStarting, tracking free surface flow through an established hydrodynamic mathematical model, determining the position of a free liquid level, and performing discrete solution and GMRES implicit solver calculation on the model based on a finite difference method to obtain the velocity distribution of each region under all working conditions;
and S6, obtaining the performance of the hydrodynamic lifting device according to the speed distribution of each region under each working condition, wherein the larger the flow speed is, the better the hydrodynamic lifting performance is.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: the invention provides a hydrodynamic weak area vertical axis flow pushing device and a performance testing method thereof, the overall and local effects of the hydrodynamic lifting device are quantitatively analyzed and predicted through a physical model and a mathematical model, and the final result also shows that the hydrodynamic device improves the hydrodynamic conditions of the weak power area, enhances the water flow exchange capacity of the area, and provides decision basis for scientifically and economically operating the hydrodynamic device, optimizing the hydrodynamic lifting scheme and improving the hydrodynamic conditions of a river channel.
Drawings
FIG. 1 is a schematic diagram of a vertical axis thrust based hydrodynamic lift device according to the present invention;
FIG. 2 is a schematic view of a Meishan water course and a Wanren beach weak dynamic area research range;
FIG. 3 is a schematic diagram of a vertical axis plug flow plate configuration;
FIG. 4 is a schematic diagram of a physical model of a ten-thousand-person beach;
FIG. 5 is a diagram of a physical model of a hydrodynamic lifting device;
FIG. 6 is a graph of average velocity of vertical lines of water outside the hydrokinetic lifting device versus distance;
FIG. 7 is a numerical simulation calculation region and a local enlargement region;
FIG. 8 is a schematic view of a position of the hydrodynamic lift device;
FIG. 9 is a flow velocity profile near (partially enlarged area) a hydrodynamic lift device;
fig. 10 is a diagram of the whole flow velocity distribution of the ten-thousand-person beach.
Detailed Description
The embodiment provides a hydrodynamic lifting device based on vertical shaft pushing flow, as shown in fig. 1, the hydrodynamic lifting device includes a bracket 1, a motor 2, a pushing flow plate 3 and a vertical shaft 4, the motor 2 is fixed on the bracket 1, the motor 2 is connected to one end of the vertical shaft 4, the other end of the vertical shaft 4 is fixed with the pushing flow plate 3, specifically, fixed on a center line of the pushing flow plate 3, the pushing flow plate 3 is rectangular, and has a length of 1/15-1/3, and most preferably 1/10-1/5, where the maximum radius of the hydrodynamic weak area is an infinite radius, so that the maximum radius of the area where hydrodynamic lifting effect is desired is used as a measurement standard, and the maximum radius represents a value obtained by dividing the maximum diameter of the area by 2. The support 1 comprises a plurality of supporting rods and a table board which is supported and fixed through the supporting rods, and the height of each supporting rod is larger than the distance from the bottom of the flow pushing plate to the table board of the support, so that the flow pushing plate can normally rotate.
The embodiment also provides a performance test method of the hydrodynamic lifting device based on the vertical axis thrust flow, and specifically provides two test methods, wherein one test method is performed through a reduced physical model, and the other test method is performed through a mathematical model. The method for testing by adopting the reduced physical model specifically comprises the following steps:
and S1, acquiring the hydrodynamic weak area and the size of the corresponding hydrodynamic lifting device.
The hydrodynamic weak area of the embodiment is a beach with thousands of people in the meishan watercourse, as shown in fig. 2, the meishan watercourse is located on the west and north sides of the meishan island in the north-enden area of ningbo, the length of the watercourse in the south and north directions is 11.5km, the width is 500-800 m, and the average water depth is 5-10 m. The plum mountain water channel is originally a tide channel, the average tidal range is 3.0m, the average flow velocity of the rising tide and the falling tide is about 0.3-0.5 m/s, the construction of the south and north dykes at the two ends of the water channel is implemented in 2012-2016, the hydrodynamic force in the water channel is greatly weakened after the south and north dykes are closed, and more than ten inland rivers are arranged around the water channel, so that the problem of the water environment in the water channel is increasingly prominent. The location of the ten-thousand sand beach is at the north side of the south dike of the Meishan watercourse, near the red bridge of the northern Meishan mountain, the south to south dike, the sand beach is totally arc-shaped, the total length of the sand beach is about 1.88 kilometers, the plane of the ten-thousand sand beach is totally arc-shaped, and the arc radius of the sand blocking dike is about 340 m. The hydrodynamic force of local areas of the beach is weak, which easily causes the disaster problems of pollutant accumulation, poor water quality, easy red tide outbreak and the like.
In an optimal scale, if the arc radius of the sand levee is about 340m, the length of the impeller plate of the hydrodynamic lifting device should be 1/5 of 340m, but in order to study the effect of various scales, the impeller plate is reduced in size, specifically, the height of the impeller plate is set to be 2.5m, the width of the impeller plate is set to be 10m (i.e., the radius is 10m), and the rotating direction is clockwise, as shown in fig. 3.
S2, establishing a physical model of the hydrodynamic weak area and the hydrodynamic lifting device after reduction, wherein the reduction scale is a preset plane scale lambdaL。
In this embodiment, the plane scale λLAnd (4) establishing a physical model after the hydrodynamic weak area is reduced by adopting a normal model, which is specifically shown in fig. 4. According to the plane scale, the hydrodynamic lifting device is converted into a physical model: the height 250/64 of the plug-flow plate is 3.9cm, the diameter 2000/64 of the plug-flow plate is 31.25cm, and the flow model is shown in fig. 5.
The method is characterized in that a flow pushing effect test of a flow pushing plate with different rotating speeds on a beach part is carried out in a beach model, the model test follows hydrodynamic force similarity and also follows flow pushing plate motion similarity, therefore, according to a theoretical mechanics related theory, a related scale is calculated as follows: if the angular velocity of the rigid body of the thrust plate is ω (rad/s) and the rotation speed is w (r/min), then: angular velocity
Figure BDA0002457536120000051
From the angular velocity, linear velocity is estimated
Figure BDA0002457536120000052
Following the similarity of water flow gravity, the linear velocity or flow rate scale can be known:
Figure BDA0002457536120000053
so that the rotating speed is proportional
Figure BDA0002457536120000054
The scales are shown in table 1.
TABLE 1 summary of model scales
Figure BDA0002457536120000055
Figure BDA0002457536120000061
And S3, placing the physical model of the hydrodynamic lifting device in the center of the physical model of the hydrodynamic weak area, and setting m flow velocity monitoring devices at radial intervals by taking the central point of a flow pushing plate of the physical model of the hydrodynamic lifting device as a starting point.
In this embodiment, 18 flow rate monitoring devices are provided at intervals, and the set distances and the corresponding distances in the actual natural state are shown in table 2.
TABLE 2 distance of flow rate monitoring device from axial line of flow pushing plate
Figure BDA0002457536120000062
S4, setting n working conditions, specifically setting the rotating speed of a motor of the hydrodynamic lifting device to be w respectively1、w2、…、wnAnd according to the rotation speed scale lambdawConverting the set rotating speed to obtain the rotating speed w of the motor in the physical model of the hydrodynamic lifting device1’、w2’、…、wn', wherein,
Figure BDA0002457536120000063
TABLE 3 different rotation speed working condition settings
Figure BDA0002457536120000064
Figure BDA0002457536120000071
In the present embodiment, n is set to 4 conditions, the rotation speed is 3.75, 5.0, 6.25, and 7.5r/min in the natural state, and the converted plug flow plate model rotation speed is 30, 40, 50, and 60r/min, respectively, according to the rotation speed scale. As shown in table 3.
S5, according to the rotating speed w1’、w2’、…、wnStarting a motor to drive a flow pushing plate to rotate, and obtaining a flow velocity set V ' ═ V ' monitored by a flow velocity monitoring device at all rotating speeds 'ij1, …, n, j 1, …, m, v'ijDenotes a rotational speed w'iThe flow rate monitored by the flow rate monitoring device j.
S6, all the flow rates in the flow rate set V' are measured according to the flow rate scale lambdavConverting to obtain a flow velocity set V ═ V in the natural state of the hydrodynamic weak region ij1, …, n, j 1, …, m }, wherein vij＝λvv'ij。
In this example, the flow rates in the natural state obtained are shown in Table 4 and FIG. 6.
TABLE 4 average flow velocity test result table for vertical line of outside water area of flow pushing plate (flow velocity: m/s)
Figure BDA0002457536120000072
And S7, obtaining the performance of the hydrodynamic lifting device according to the flow velocity set V, wherein the larger the flow velocity is, the better the hydrodynamic lifting performance is.
From the obtained flow rates:
(1) the average flow velocity of the water flow perpendicular line of the water area outside the thrust plate is inversely proportional to the distance from the axial line of the thrust plate, and the area with larger influence on the flow velocity of the water flow by the thrust plate is concentrated in the range (100m) of 10 times of the length radius (10m) of the thrust plate; when the rotating speed is 3.75 r/min, 5.0 r/min, 6.25 r/min and 7.5r/min, the average flow velocity of the vertical line at the position 100m outside the axial line of the flow pushing plate is 0.07 m/s, 0.09 m/s, 0.13 m/s and 0.15m/s respectively;
(2) the change of the flow velocity of the water flow beyond 100m outside the flow pushing plate and the distance from the flow pushing plate to the axis of the flow pushing plate becomes gentle, namely the influence is gradually smaller, the flow velocity at the position 340m away from the axis of the flow pushing plate, namely the flow velocity near the sand blocking dam, is respectively 0.005, 0.01, 0.015 and 0.02m/s when the rotating speed is 3.75, 5.0, 6.25 and 7.5r/min, and therefore, the flow pushing plate has a certain pulling effect on the water flow at the position of the sandy beach;
(3) the flow velocity of water flow in the radius range of the thrust plate is large, for example, at the rotating speed of 3.75, 5.0, 6.25 and 7.5r/min according to the rotating speed of the plate, the speed of the edge of the thrust plate reaches 3.93, 5.23, 6.54 and 7.85m/s respectively, and the flow velocity is transmitted to the surface of the seabed, so that the scouring of the seabed is inevitably caused, and therefore, if the flow is increased in such a way, the seabed around the thrust plate must be protected.
The tests show that the flow pushing plate plays a role in pulling water flow within a certain range, when the length of the flow pushing plate is 20 meters, a certain water flow pulling role is played in an area which is about 300 meters away from the center of the flow pushing plate, the flow pushing plate cannot be arranged too large without limitation, and therefore 1/3 which does not exceed the radius of the area to the maximum extent is the best, and the arrangement proportion of the flow pushing plate is proved to be 1/15-1/3. In addition, the area with larger water flow pulling action is about 100 meters in radius, and the flow velocity can still reach 0.03-0.06 cm/s in the range of about 200 meters in radius, so the optimal length proportion of the flow pushing plate is 1/10-1/5. Finally, the flow increasing speed of the sand beach near the sand blocking dam is 0.5-2.0 cm/s, plane rotating flow is formed in a certain range outside the flow pushing plate, the flow speed value is large in the rotating range of the flow pushing plate, strong disturbance can be generated on the bottom of the seabed, scouring can be generated, and if the flow increasing mode is adopted, the seabed in a certain range near the flow pushing plate needs to be protected against scouring.
Another performance testing method for a hydrodynamic lifting device based on vertical axis thrust flow, provided by this embodiment, is implemented through mathematical modeling, and specifically includes the following steps:
s1, establishing a hydrodynamic mathematical model of the hydrodynamic weak area, which specifically comprises the following steps:
(1) mass continuity equation:
Figure BDA0002457536120000081
wherein u, v, w are the velocity components in three directions of a Cartesian coordinate system x, y and z, Ax,Ay,AzIs the fractional area of the flow in the x, y, z directions, respectively, ρ is the fluid density, RSORA density source term that can be used to simulate mass injection, for example, through the surface of a porous barrier;
(2) the momentum equation:
Figure BDA0002457536120000091
Figure BDA0002457536120000092
Figure BDA0002457536120000093
in the formula, Gx,Gy,GzThe gravity acceleration in the x direction, the y direction and the z direction respectively; f. ofx,fy,fzThe viscous force acceleration in the x direction, the y direction and the z direction respectively; item Uw＝(uw，vw，ww) Representing the velocity of the source assembly in three directions; item Us＝(us，vs，ws) Representing the velocity of the fluid at the source surface in three directions relative to the source itself; vFThe fluid volume fraction with a free surface, R is a coordinate coefficient, when a Cartesian coordinate system is selected, the value is1, a coefficient is represented, when 0 is taken, the pressure boundary condition is a stagnation type, and when 1 is taken, the pressure boundary condition is a static pressure type;
(3) a turbulence model:
Figure BDA0002457536120000094
Figure BDA0002457536120000095
in the formula, kTIs kinetic energy of turbulence, PTFor the turbulence-generating term, GTFor buoyancy-generating terms, DiffkTIn order to be a diffusion term, the diffusion term,Tfor turbulence energy dissipation ratio, RMTKE, CDIS1 and CNU are user-defined parameters with default values of 1.39, 1.42 and 0.085, respectively, CDIS2 is defined by kTAnd PTIs calculated to obtain vTIs a kinematic turbulent viscosity; μ is the molecular dynamic viscosity; ρ is the fluid density; p is pressure; CHRO is another turbulence parameter with a default value of 0.0, but for thermally buoyant flow, should be chosen to be about 2.5; upsilon iskIs kTAnd is calculated based on local values of the turbulence viscosity. The user-defined parameter RMTKE is the viscosity coefficient (with a default value of RMTKE) used to calculate the turbulent diffusion coefficient1.0)。
(4) Fluid distribution:
the fluid distribution is defined in terms of a fluid volume function F (x, y, z, t) that represents the volume of fluid #1 per unit volume and satisfies the following equation:
Figure BDA0002457536120000101
Figure BDA0002457536120000102
in the formula: f is an abbreviation for the function F (x, y, z, t), ζ is the coordinate coefficient whose value is 0, ν when a Cartesian coordinate system is usedFAs diffusion coefficient, FSORIs the density source term, which is the volume fraction time rate of change of fluid #1 associated with the mass source. The interpretation of item F depends on the type of problem to be solved, the incompressible problem must involve a single fluid or two fluids with free surfaces and no free surfaces. For a single fluid, the term F represents the volume fraction occupied by the fluid. Thus, there is a fluid, where the term F is1, and the void region corresponds to the location of F0. "voids" are areas of no fluid mass that have a uniform pressure assigned to them. Physically, they represent areas filled with vapor or gas, the density of which is negligible with respect to the density of the fluid.
S2, obtaining the boundary of the hydrodynamic weak area, dividing the boundary into a plurality of grids by adopting a hexahedral structured grid, adding 2 layers of nested grids near the flow pushing plate, adopting non-displacement Wall boundaries at the periphery and the bottom of the hydrodynamic weak area, setting the top of the hydrodynamic weak area as a pressure boundary, setting the atmospheric pressure to be 1.01 × 105Pa, and setting the fluid fraction to be 0, wherein the hydrodynamic weak area is completely air.
In this example, the hydrodynamic weak area studied was the same as the area tested in the previous test method, as shown in fig. 7. The total grid cell number after division is 262617, and the active grid cell number is 215875.
And S3, establishing a mathematical model of the hydrodynamic lifting device, and placing the mathematical model in the center of the hydrodynamic weak area.
In this embodiment, the length of the thrust plate of the hydrodynamic lifting device is 10m, the height thereof is 2.5m, and the position thereof is shown in fig. 8.
S4, setting n working conditions, specifically setting the rotating speed of the flow pushing plate of the hydrodynamic lifting device to w1、w2、…、wn。
S5, the hydrodynamic lifting device respectively rotates at a rotating speed w1、w2、…、wnStarting, tracking free surface flow through the established hydrodynamic mathematical model, determining the position of the free liquid level, and performing discrete solution and GMRES implicit solver calculation on the model based on a finite difference method to obtain the velocity distribution of each region under all working conditions.
The finite difference method comprises the following solving steps:
(1) an explicit approximation is made by the momentum equation for calculating the initial conditions for all advection, pressure and other accelerations, or the first guess of a new time-level velocity from a previous time-level value.
(2) To satisfy the mass continuity equation, when the implicit option is used, the pressure is iteratively adjusted in each cell and the velocity change caused by each pressure change is added to the velocity calculated in step (1). Iterations are required because the pressure changes required in one cell will upset the balance in six adjacent cells. In explicit calculations, iterations can still be performed within each cell to satisfy the state equations of the compressible problem.
(3) Finally, when a free surface or fluid interface is present, it is updated with the formula for the fluid distribution to provide a new fluid distribution. For compressibility problems, the density and energy must be updated to reflect advection, diffusion and source processes.
(4) And repeating the steps to gradually approach to the precise solution within the calculation time. Of course, in each step, appropriate boundary conditions must be applied across all meshes, obstacles and free boundary surfaces.
In the research, a finite difference method is adopted to solve a calculation region after dispersion, and grids are uniformly set to be cubes, so that the calculation precision and efficiency are improved.
In addition to the GMRES solver, F L OW3D also provides a new alternative algorithm, the Generalized Conjugate Gradient (GCG) algorithm, for solving the sticky term in the new GMRES solver.
And S6, obtaining the performance of the hydrodynamic lifting device according to the speed distribution of each region under each working condition, wherein the larger the flow speed is, the better the hydrodynamic lifting performance is.
As a result of the logarithmic simulation, a flow velocity distribution diagram at a cross section of 1m below the horizontal plane (a plane where Z is 0m, that is, Z is-1 m) was extracted, and the flow velocity distribution in the vicinity of the vertical-axis thrust plate and the flow velocity distribution in the vicinity of the sand bank were analyzed. Fig. 9 shows the flow velocity distribution near the vertical axis thrust plate, and fig. 10 shows the overall flow velocity distribution of the ten-thousand-person beach. Fig. 9 and 10 are the results of the rotational speed of the impeller being 3.75 rpm. As can be seen from FIG. 9, the region of maximum flow velocity occurs at the top of the vertical thrust plate, and the maximum flow velocity can reach 0.4 m/s. The flow velocity is between 0.05m/s and 0.4m/s within an influence radius of about 2 times the length of the vertical axis thrust plate; beyond the influence radius of about 2 times the length of the vertical axis thrust plate, the flow velocity is reduced to below 0.05 m/s. As can be seen from FIG. 10, the flow velocity near the sand bank is substantially between 0m/s and 0.05m/s, the vertical axis thrust plate hardly affects the sand bank, and the improvement effect of the hydrodynamic weak area is limited.

Claims (6)

1. The utility model provides a hydrodynamic lifting device based on vertical axis plug flow which characterized in that: including support, motor, thrust plate and vertical axis, the motor is fixed on the support, the motor is connected the one end of vertical axis, the other end of vertical axis with the thrust plate is together fixed, the thrust plate is the rectangle, and length is 1/15 ~ 1/3 of hydrodynamic force weak area maximum radius.
2. The vertical axis thrust based hydrodynamic lift device of claim 1, wherein: the support comprises a plurality of supporting rods and a table board which is supported and fixed through the supporting rods, and the height of each supporting rod is larger than the distance from the bottom of the flow pushing plate to the table board of the support.
3. The vertical axis thrust based hydrodynamic lift device of claim 1, wherein: the vertical shaft is fixed on the central line of the thrust plate.
4. The vertical axis thrust based hydrodynamic lift device of claim 1, wherein: the length of the thrust plate is 1/10-1/5 of the maximum radius of the hydrodynamic weak area.
5. A method for testing the performance of a hydrodynamic lifting device based on vertical axis thrust flow according to claim 1, comprising the steps of:
s1, acquiring a hydrodynamic weak area and the size of the corresponding hydrodynamic lifting device;
s2, establishing a physical model of the hydrodynamic weak area and the hydrodynamic lifting device after reduction, wherein the reduction scale is a preset plane scale lambdaL；
S3, placing the physical model of the hydrodynamic lifting device in the center of the physical model of the hydrodynamic weak area, and setting m flow rate monitoring devices at radial intervals by taking the center point of a flow pushing plate of the physical model of the hydrodynamic lifting device as a starting point;
s4, setting n working conditions, specifically setting the rotating speed of a motor of the hydrodynamic lifting device to be w respectively1、w2、…、wnAnd according to the rotation speed scale lambdawConverting the set rotating speed to obtain the rotating speed w of the motor in the physical model of the hydrodynamic lifting device1’、w2’、…、wn', wherein,
Figure FDA0002457536110000011
s5, according to the rotating speed w1’、w2’、…、wnStarting a motor to drive a flow pushing plate to rotate, and obtaining a flow velocity set V ' ═ V ' monitored by a flow velocity monitoring device at all rotating speeds 'ij1, …, n, j 1, …, m, v'ijDenotes a rotational speed w'iThe flow rate monitored by the flow rate monitoring device j;
s6, all the flow rates in the flow rate set V' are measured according to the flow rate scale lambdavConverting to obtain a flow velocity set V ═ V in the natural state of the hydrodynamic weak regionij1, …, n, j 1, …, m }, wherein vij＝λvv’ij，
Figure FDA0002457536110000012
And S7, obtaining the performance of the hydrodynamic lifting device according to the flow velocity set V, wherein the larger the flow velocity of the weak power area is, the better the hydrodynamic lifting performance is.
6. A method for testing the performance of a hydrodynamic lifting device based on vertical axis thrust flow according to claim 1, comprising the steps of:
s1, establishing a hydrodynamic mathematical model of the hydrodynamic weak area, which specifically comprises the following steps:
(1) mass continuity equation:
Figure FDA0002457536110000021
wherein u, v, w are the velocity components in three directions of a Cartesian coordinate system x, y and z, Ax,Ay,AzIs the fractional area of the flow in the x, y, z directions, respectively, ρ is the fluid density, RSORIs a density source item;
(2) the momentum equation:
Figure FDA0002457536110000022
Figure FDA0002457536110000023
Figure FDA0002457536110000024
in the formula, Gx,Gy,GzThe gravity acceleration in the x direction, the y direction and the z direction respectively; f. ofx,fy,fzThe viscous force acceleration in the x direction, the y direction and the z direction respectively; item Uw＝(uw，vw，ww) Representing the velocity of the source assembly in three directions; item Us＝(us，vs，ws) Representing the velocity of the fluid at the source surface in three directions relative to the source itself; vFThe fluid volume fraction with a free surface, R is a coordinate coefficient, when a Cartesian coordinate system is selected, the value is1, a coefficient is represented, when 0 is taken, the pressure boundary condition is a stagnation type, and when 1 is taken, the pressure boundary condition is a static pressure type;
(3) a turbulence model:
Figure FDA0002457536110000025
Figure FDA0002457536110000026
Figure FDA0002457536110000027
in the formula, kTIs kinetic energy of turbulence, PTFor the turbulence-generating term, GTIn order to generate the term for the buoyancy,
Figure FDA0002457536110000028
in order to be a diffusion term, the diffusion term,Tfor turbulence energy dissipation ratio, RMTKE, CDIS1 and CNU are user-defined parameters with default values of 1.39, 1.42 and 0.085, respectively, CDIS2 is defined by kTAnd PTIs calculated to obtain vTIs a kinematic turbulent viscosity;
(4) fluid distribution:
the fluid distribution is defined in terms of a fluid volume function F (x, y, z, t) that represents the volume of fluid #1 per unit volume and satisfies the following equation:
Figure FDA0002457536110000031
Figure FDA0002457536110000032
in the formula: f is an abbreviation for the function F (x, y, z, t), ζ is the coordinate coefficient whose value is 0, ν when a Cartesian coordinate system is usedFAs diffusion coefficient, FSORIs the density source term, is the volume fraction time rate of change of fluid #1 associated with the mass source;
s2, obtaining the boundary of the hydrodynamic weak area, dividing the boundary into a plurality of grids by adopting a hexahedral structured grid, adding 2 layers of nested grids near the plug flow plate, adopting non-displacement Wall boundaries at the periphery and the bottom of the hydrodynamic weak area, setting the top of the hydrodynamic weak area as a pressure boundary, setting the atmospheric pressure to be 1.01 × 105Pa, and setting the fluid fraction to be 0, wherein the hydrodynamic weak area is completely air;
s3, establishing a mathematical model of the hydrodynamic lifting device, and placing the mathematical model in the center of a hydrodynamic weak area;
s4, setting n working conditions, specifically setting the rotating speed of the flow pushing plate of the hydrodynamic lifting device to w1、w2、…、wn；
S5, the hydrodynamic lifting device respectively rotates at a rotating speed w1、w2、…、wnStarting, tracking free surface flow through an established hydrodynamic mathematical model, determining the position of a free liquid level, and performing discrete solution and GMRES implicit solver calculation on the model based on a finite difference method to obtain the velocity distribution of each region under all working conditions;
and S6, obtaining the performance of the hydrodynamic lifting device according to the speed distribution of each region under each working condition, wherein the larger the flow speed is, the better the hydrodynamic lifting performance is.
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