CN111324934A - Method and device for determining total amount of suspended sand in pump station approach channel and forebay - Google Patents
Method and device for determining total amount of suspended sand in pump station approach channel and forebay Download PDFInfo
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Abstract
The embodiment of the invention provides a method and a device for determining the total amount of suspended sand in a pump station approach channel and a front pool, wherein the method comprises the following steps: acquiring the flow velocity, the flow period, the sediment particle size and the ratio of the sediment to the water density of an outer boundary layer of a pump station approach channel and a front pool water body; obtaining the maximum Sierpillar number and the friction factor of the sand-containing movable bed surface based on the maximum value of the flow velocity of the outer boundary layer, the flow period, the grain size of the sediment and the ratio of the sediment to the water density; and obtaining the total amount of suspended sand on the sand-containing moving bed surface and the proportion of the total amount of the suspended sand in the total amount of the sediment above the initial bed surface according to the mass conservation law. The invention considers the conservation of mass, carries out design calculation through the determined related phase difference parameters, can reflect the time response required by the suspended sand total amount relative to water flow in the reciprocating flow process, reflects the phase residue of the suspended sand total amount and the phase drift of the relative flow velocity after the flow velocity is reduced, and avoids underestimation of the average value of the suspended sand total amount.
Description
Technical Field
The embodiment of the invention relates to the technical field of hydraulic engineering, in particular to a method and a device for determining the total amount of suspended sand in a pump station approach channel and a front pool.
Background
When the pump station runs, the total amount of suspended sand which is considered for mass conservation and contains the phase difference effect on the sand-containing movable bed surfaces of the approach channel and the forebay is determined, which is beneficial to selecting a proper sand-containing water taking place and is also the main basis for judging the sand and the water pump abrasion entering the pump and taking protective measures for the pump device.
In the engineering, the determination of the total suspended sand content of the sand-containing movable bed surface is mainly based on a constant flow theory, the mass conservation is not considered, and the phase difference effect, namely the time response required by the movement of the sand relative to the water flow, is not included. This results in that it: the phase drift time of the sediment movement relative to the flow velocity and the phase residue of the moving sediment total after the flow velocity is reduced cannot be reflected, and the average value of the suspended sediment total of the asymmetric flow can be underestimated.
So far, how to give the total amount of suspended sand of a water body under a reciprocating flow condition has no reference result or method.
Therefore, a method and a device for determining the total amount of suspended sand in a pump station approach channel and a forebay are needed.
Disclosure of Invention
In order to solve the above problems, embodiments of the present invention provide a method and an apparatus for determining the total amount of suspended sand in a pump station approach channel and a front pool.
In a first aspect, an embodiment of the present invention provides a method for determining a total amount of suspended sand in a lead channel and a front pool of a pump station, including:
acquiring the flow velocity, the flow period, the sediment particle size, the ratio of sediment to water density and the motion viscosity coefficient of water of an outer boundary layer of a pump station approach channel and a front pool water body;
obtaining the maximum Sherz number and the friction factor of the sand-containing movable bed surface based on the maximum value of the flow velocity of the outer boundary layer, the flow period, the particle size of the sediment, the ratio of the sediment to the water density, the motion viscosity coefficient of the water and the gravity acceleration;
and obtaining the total amount of suspended sand on the sand-containing moving bed surface and the proportion of the total amount of the suspended sand in the total amount of the sand above the initial bed surface according to the law of conservation of mass, the flow velocity of the outer boundary layer, the flow period, the particle size of the sand, the ratio of the sand to the water density, the maximum Sierpitz number and the friction factor of the sand-containing moving bed surface.
In a second aspect, an embodiment of the present invention provides a device for determining a total amount of suspended sand in a pump station approach channel and a front pool, including:
the first module is used for acquiring the flow velocity, the flow period, the sediment particle size, the ratio of sediment to water density and the motion viscosity coefficient of water of an outer boundary layer of a pump station approach and a front pool water body;
the second module is used for obtaining the maximum Sherz number and the friction factor of the sand-containing moving bed surface based on the maximum value of the flow velocity of the outer boundary layer, the flow period, the grain size of the silt, the ratio of the silt to the density of water, the motion viscosity coefficient of the water and the gravity acceleration;
and the third module is used for acquiring the total amount of suspended sand on the sand-containing movable bed surface and the proportion of the total amount of the suspended sand in the total amount of the sand above the initial bed surface according to the law of conservation of mass, the flow velocity of the outer boundary layer, the flow period, the particle size of the sand, the ratio of the sand to the water density, the maximum Sierpitz number and the friction factor of the sand-containing movable bed surface.
According to the method and the device for determining the total amount of suspended sand in the pump station approach channel and the forebay, provided by the embodiment of the invention, the mass conservation is considered, the design calculation is carried out through the determined related phase difference parameters, the time response required by the total amount of suspended sand relative to water flow in the reciprocating flow process can be reflected, the phase residue of the total amount of suspended sand after the flow speed is reduced and the phase drift time of the relative flow speed are reflected, and the underestimation of the average value of the total amount of suspended sand is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic diagram illustrating the definition of a sand-containing movable bed surface and the total amount of suspended sand according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method for determining the total amount of suspended sand in a pump station approach channel and a front pool according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the reciprocation rate and the position of the movable bed surface used in the operation of one embodiment of the present invention;
FIG. 4 is a schematic representation of the total amount of suspended sand on a moving bed containing sand in an embodiment of the present invention;
FIG. 5 is a schematic illustration of the ratio of the total suspended sand to the total silt above the initial bed level in an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a device for determining the total amount of suspended sand in a pump station approach channel and a front pool in the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
During the reciprocating flow of the pumping station approach channel and the front pool sand-containing bed surface, the total amount of suspended sand on the bed surface per unit area is changed.
Fig. 1 is a schematic diagram illustrating the definition of the sand-containing movable bed surface and the total amount of suspended sand in the embodiment of the invention, as shown in fig. 1, the abscissa represents the volume concentration S of the sand, and changes with the flow velocity U of the outer boundary layer and the vertical coordinate y; wherein the position where y is 0 is an initial bed surface; t is time; delta is the depth of the sand-containing layer eroded by water flow, namely the distance from the surface of the saturated sand-containing layer to the initial bed surface; the subscript m represents the maximum value; smThe maximum volume concentration of the silt is generally 0.6; d is the sand grain size. In engineering, the 2D above the initial bed surface is generally taken as a boundary, y>2D silt was considered a suspensoid.
Fig. 1 shows the total amount of suspended sand on the bed surface per unit area in terms of the volume of sediment.
In the engineering, the determination of the total suspended sand content of the sand-containing movable bed surface is mainly based on a constant flow theory, the mass conservation is not considered, and the phase difference effect, namely the time response required by the movement of the sand relative to the water flow, is not included.
This results in that it: the phase drift time of the sediment movement relative to the flow velocity and the phase residue of the moving sediment total after the flow velocity is reduced cannot be reflected, and the average value of the suspended sediment total of the asymmetric flow can be underestimated. The determination of the total amount of suspended sand of the sand-containing moving bed surface containing the phase difference is beneficial to selecting a proper sand-containing water taking place and is also a main basis for judging the sand and sand entering the pump, the abrasion of the water pump and taking protective measures for the pump device.
However, so far, there is no achievement or method for reference on how to give the total amount of suspended sand of a sand-containing movable bed surface under the reciprocating flow condition.
In view of the above problem, fig. 2 is a flowchart of a method for determining the total amount of suspended sand in a pump station approach channel and a front pool in an embodiment of the present invention, as shown in fig. 2, the method includes:
s1, acquiring the flow velocity, the flow period, the sediment particle size, the ratio of sediment to water density and the motion viscosity coefficient of water of the outer boundary layer of the water body of the pump station approach channel and the forebay;
s2, obtaining the maximum Sherz number and the friction factor of the sand-containing moving bed surface based on the maximum value of the flow velocity of the outer boundary layer, the flow period, the grain size of the silt, the ratio of the silt to the density of water, the motion viscosity coefficient of the water and the gravity acceleration;
and S3, obtaining the total amount of suspended sand on the sand-containing moving bed surface and the proportion of the total amount of the suspended sand in the total amount of the sand above the initial bed surface according to the law of conservation of mass, the flow velocity of the outer boundary layer, the flow period, the particle size of the sand, the ratio of the sand to the water density, the maximum Sierpitz number and the friction factor of the sand-containing moving bed surface.
According to the method for determining the total amount of suspended sand in the pump station approach channel and the forebay, provided by the embodiment of the invention, the mass conservation is considered, the design calculation is carried out through the determined related phase difference parameters, the time response required by the total amount of suspended sand relative to water flow in the reciprocating flow process can be reflected, the phase residue of the total amount of suspended sand after the flow speed is reduced and the phase drift of the relative flow speed are reflected, and the underestimation of the average value of the total amount of suspended sand is avoided.
On the basis of the above embodiment, the method includes the steps of obtaining the total amount of suspended sand on the sand-containing movable bed surface and the proportion of the total amount of suspended sand in the total amount of sand above the initial bed surface according to the law of conservation of mass, the flow velocity of the outer boundary layer, the flow period, the particle size of the sand, the ratio of the sand to the water density, the maximum siertz number and the friction factor of the sand-containing movable bed surface, and specifically includes:
obtaining the ratio of the settling time of the silt in the sand conveying layer to the flow period and the settling velocity of the silt according to the particle size of the silt, the maximum Sherz number, the flow period, the maximum value of the flow velocity of the outer boundary layer, the ratio of the silt to the density of water, the gravitational acceleration and the motion viscosity coefficient of water;
obtaining the phase drift time of the erosion depth to the flow velocity and the residue of the sediment phase according to the ratio of the sedimentation time and the flow period of the sediment in the sediment transport layer and the flow period;
and obtaining the total amount of suspended sand on the sand-containing moving bed surface and the proportion of the total amount of the suspended sand to the total amount of the sediment above the initial bed surface according to the mass conservation law and all the parameters.
In order to embody the phase difference effect, the technical scheme of the embodiment of the invention adopts three parameters psi, psi and α:
α＝exp(-0.2/Ψ)， (3)
where Ψ is the ratio of settling time of silt in the sediment transport layer to the flow period, Ψ represents the phase drift time of erosion depth versus flow velocity, and α represents the residual silt phase, i.e., the ratio of the amount of silt still in motion at the flow diversion time to the maximum amount of sand entrainment.
The relevant parameters satisfy the following conditions:
wherein Θ is the Sherz number; thetamIs the maximum Sherz number; f is the friction factor of the sand bed surface; u shapemIs the outer boundary layer maximum flow velocity; s is the ratio of silt to water density; g is the acceleration of gravity; t is the flow period; w is the silt settling velocity; ν is the kinetic viscosity coefficient of water.
In order to meet the mass conservation, the technical scheme of the invention adopts the erosion depth of reciprocating flow:
wherein, thetacrThe critical Sherz number is generally 0.05, and the total volume of silt above the surface of the saturated sand-containing layer which meets the mass conservation, namely the y is more than or equal to-delta, is SmΔ; the total volume of silt above the initial bed surface is SmΔe-1。
Finally, the total amount C of suspended sand on the sand-containing moving bed surface which flows back and forth is as follows:
the formula (8) is the amount of sand in volume per unit area, and the unit is m3/m2＝m。
The proportion P of the total suspended sand amount in the total sediment amount above the initial bed surface is as follows:
after the values of the parameters are calculated by the formulas (1) to (6) according to U, T, D, s, g and v, the delta of the formula (7) can be determined.
After the delta delay time psi is substituted into formula (8), the total amount of the instant suspended sand is obtained, and the total amount of the suspended sand of the invention is obtained by substituting formula (9).
Specifically, the maximum siertz number and the friction factor of the sand-containing movable bed surface are obtained based on the maximum value of the flow velocity of the outer boundary layer, the flow period, the particle size of the sediment, the ratio of the sediment to the water density, and the gravitational acceleration, and specifically:
wherein, thetamRepresenting the maximum Sherz number, f representing the friction factor of the sand-containing moving bed surface, UmAnd the maximum value of the flow velocity of the outer boundary layer is represented, D represents the particle size of the silt, s represents the ratio of the silt to the density of water, g represents the gravitational acceleration, and T represents the flow period.
Solid line U/UmIs a dimensionless flow rate; dotted line Δ/ΔmIs a dimensionless depth of attack; the abscissa T/T is dimensionless time.
On the basis of the foregoing embodiment, preferably, the obtaining of the ratio of the settling time of the sediment in the sediment transport layer to the flow period and the sediment settling velocity of the sediment according to the sediment particle size, the maximum siertz number, the flow period, the maximum value of the flow velocity of the outer boundary layer, the ratio of the sediment to the water density, the gravitational acceleration, and the kinetic viscosity coefficient of water specifically includes:
where Ψ represents the ratio of the settling time of silt in the sediment transport layer to the flow period, w represents the settling velocity of the silt, and v represents the kinetic viscosity coefficient of the water.
On the basis of the foregoing embodiment, preferably, the obtaining of the phase drift time of the erosion depth to the flow velocity and the residue of the sediment phase according to the ratio of the settling time of the sediment in the sediment transport layer to the flow period and the flow period specifically includes:
α＝exp(-0.2/Ψ)，
where ψ represents the phase drift time of the erosion depth against the flow velocity, and α represents the residue of the silt phase.
On the basis of the above embodiment, preferably, the obtaining, according to the law of conservation of mass and the above parameters, the total amount of suspended sand on the sand-containing moving bed surface and the proportion of the total amount of suspended sand to the total amount of sediment above the initial bed surface specifically includes:
wherein U represents the outer boundary layer flow velocity, ΘcrDenotes the critical Sherz number, SmDelta represents the total volume of the sand above the surface of the saturated sand-containing layer satisfying the conservation of mass, SmIs the maximum sediment volume concentration, and delta represents the depth of erosion of the sand-bearing layer by the water flow, i.e. the surface of the saturated sand-bearing layer to the beginningThe distance from the bed surface, C, is the total amount of suspended sand on the surface of the sand-containing moving bed in unit area, and P represents the proportion of the total amount of suspended sand to the total amount of sand above the initial bed surface.
In the embodiment of the invention, the method is verified.
One known standard atmospheric pressure, water temperature of 20 deg.c and UmFig. 3 is a schematic diagram of the reciprocating flow velocity and the moving bed surface position adopted in the working process of an embodiment of the present invention, as shown in fig. 3, and the change of the 2-step Stokes reciprocating flow time is shown in fig. 3, and is as follows:
U(t)＝0.8cos[2π(t/T-0.214)]+0.2cos[4π(t/T-0.214)]， (10)
(II) calculating theta by using the formulas (4) to (5) provided in the embodiment of the inventionm、f，。
(1) First, let's assume thetam<1, from formula (5), yield f 7.0 × 10-3(ii) a Substituting formula (4) to obtain thetam＝2.16>1. If the situation is not true, the step (2) is required;
(2) according to the formula thetam>1, substituting formula (4) for formula (5) to obtain
From formula (9) to f 9.3 × 10-3Substituting formula (4) to obtain thetam＝2.87。
And (III) calculating w and psi, and adopting the formula (1) and the formula (6) provided by the invention.
W is 8.4 × 10 from formula (6)-3m/s, substituted by formula (1) to obtain psi ═ 6.3 × 10-1。
And fourthly, calculating psi and α, and adopting the formulas (2) to (3) provided by the invention.
Obtaining ψ of 5.0 × 10 from formula (2)-1s, α from formula (3) is 0.73.
And (V) calculating the ratio of the total suspended sand amount to the total suspended sand amount of the bed surface in unit area by using the sediment volume concentration meter, and adopting the formulas (7) to (9) provided by the invention.
S, g,D、UmAnd obtaining all parameters theta from the step 2 to the step 4mF, ψ, α, and w are substituted for equation (7) to obtain the dotted line of fig. 3:
fig. 4 is a schematic diagram of the total amount of suspended sand in the embodiment of the present invention, and as shown in fig. 4, formula (12) is substituted for formula (8) to obtain the total amount of suspended sand in the present invention in fig. 4:
FIG. 5 is a schematic diagram of the ratio of the total suspended sand to the total sediment above the initial bed surface according to an embodiment of the present invention, as shown in FIG. 5, where the abscissa T/T is dimensionless time and the ordinate is the ratio P of the total suspended sand to the total sediment above the initial bed surface; the solid line represents the present invention and the dotted line represents the conventional method. Substituting the formula (9) to obtain the proportion of the total suspended sand in the total sediment above the initial bed surface, which is determined by the invention in the figure 5:
by adopting the technical scheme, the invention ensures that the determination of the total amount of the suspended sand and the proportion thereof meets the mass conservation, and has the following 3 advantages brought by the phase difference effect:
1. the phase drift of the total amount of suspended sand relative to the flow speed is reflected.
Fig. 4 and 5 the solid line of the present invention lags behind fig. 3 by the flow rate ψ/T being 0.1 cycle phase. U/U as in FIG. 3m0 is T/T0, 0.42 time, maximum value U/UmTime T/T is 0.21 as 1; due to phase drift, the minimum value of the total amount of suspended sand in the solid lines of fig. 4 and 5 occurs at times T/T0 +0.1 and T/T0.42 +0.1, and the maximum value occurs at times T/T0.21 + 0.1. While the dotted lines of fig. 4-5 represent the conventional method are in phase with the flow rate of fig. 3.
2. The phase residue of the total amount of the suspended sand after the flow speed is reduced is reflected.
In the reciprocating flow, even if U is reduced to 0, the phase residue makes the total amount of suspended sand and the ratio thereof not reduced to 0. FIG. 4 shows the minimum value of the solid line of the total amount of suspended sand of the present invention at 0.29mm, and FIG. 5 shows the solid line of the suspended sand content ratio of the present invention at a constant value. Whereas the dash-dot line representing the conventional method is near the flow direction (U/U)m0, T/T0, 0.42) decreases rapidly to 0.
3. The underestimation of the total amount of suspended sand and the ratio mean value thereof is avoided.
In the asymmetric reciprocating flow, the phase difference action enables suspended sand raised in a part of positive flow velocity stages (T/T is 0-0.42) to be retained in negative flow velocity stages (T/T is 0.42-1), so that the total amount and proportion of the suspended sand in the negative flow velocity stages are closer to those in the positive flow stages, as shown by solid lines in fig. 4 and fig. 5 of the invention. This avoids underestimation of the total amount of suspended sand and its proportion during the negative flow phase of the conventional method represented by the dash-dot line.
Fig. 6 is a schematic structural diagram of a device for determining the total amount of suspended sand in a pump station approach channel and a front pool in an embodiment of the present invention, as shown in fig. 6, the device includes: a first module 601, a second module 602, and a third module 603, wherein:
the first module 601 is used for acquiring the flow velocity, the flow period, the sediment particle size, the ratio of sediment to water density and the motion viscosity coefficient of water of the outer boundary layer of the water body of the pump station approach and the forebay;
the second module 602 is configured to obtain a maximum siertz number and a friction factor of a sand-containing moving bed surface based on the maximum value of the flow velocity of the outer boundary layer, the flow period, the particle size of the silt, the ratio of the silt to the density of water, the kinematic viscosity coefficient of water, and the gravitational acceleration;
the third module 603 is configured to obtain the total amount of suspended sand and the proportion of the total amount of suspended sand to the total amount of sediment above the initial bed surface according to the law of conservation of mass, the flow rate of the outer boundary layer, the flow period, the particle size of the sediment, the ratio of the sediment to the water density, the maximum siertes number, and the friction factor of the sand-containing movable bed surface.
The method comprises the steps that firstly, a first module 601 obtains the flow velocity, the flow period, the sediment particle size, the ratio of sediment to water density and the movement viscosity coefficient of water of an outer boundary layer of a pump station approach and a forebay water body, a second module 602 obtains the maximum Sierpillar number and the friction factor of a sediment-bearing movable bed surface through calculation according to relevant parameters obtained by the first module, and a third module 603 obtains the total amount of suspended sediment and the proportion of the total amount of suspended sediment to the total amount of sediment above an initial bed surface according to a mass conservation law.
The device for determining the total amount of suspended sand in the pump station approach channel and the forebay, provided by the embodiment of the invention, considers the conservation of mass, carries out design calculation through the determined related phase difference parameters, can reflect the time response required by the total amount of suspended sand relative to water flow in the reciprocating flow process, reflects the phase residue of the total amount of suspended sand after the flow speed is reduced and the phase drift of the relative flow speed, and avoids underestimation of the mean value of the total amount of suspended sand.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (7)
1. A method for determining the total amount of suspended sand in a pump station approach channel and a forebay is characterized by comprising the following steps:
acquiring the flow velocity, the flow period, the sediment particle size, the ratio of sediment to water density and the motion viscosity coefficient of water of an outer boundary layer of a pump station approach channel and a front pool water body;
obtaining the maximum Sherz number and the friction factor of the sand-containing movable bed surface based on the maximum value of the flow velocity of the outer boundary layer, the flow period, the particle size of the sediment, the ratio of the sediment to the water density, the motion viscosity coefficient of the water and the gravity acceleration;
and obtaining the total amount of suspended sand on the sand-containing moving bed surface and the proportion of the total amount of the suspended sand in the total amount of the sand above the initial bed surface according to the law of conservation of mass, the flow velocity of the outer boundary layer, the flow period, the particle size of the sand, the ratio of the sand to the water density, the maximum Sierpitz number and the friction factor of the sand-containing moving bed surface.
2. The method of claim 1, wherein obtaining the total amount of suspended sand on the sand-containing moving bed and the ratio of the total amount of suspended sand to the total amount of sediment above the initial bed based on the mass conservation law, the outer boundary layer flow velocity, the flow period, the sediment particle size, the ratio of the sediment to the water density, the maximum siertes number, and the friction factor of the sand-containing moving bed comprises:
obtaining the ratio of the settling time of the silt in the sand conveying layer to the flow period and the settling velocity of the silt according to the particle size of the silt, the maximum Sherz number, the flow period, the maximum value of the flow velocity of the outer boundary layer, the ratio of the silt to the density of water, the gravitational acceleration and the motion viscosity coefficient of water;
obtaining the phase drift time of the erosion depth to the flow velocity and the residue of the sediment phase according to the ratio of the sedimentation time and the flow period of the sediment in the sediment transport layer and the flow period;
and obtaining the total amount of suspended sand on the sand-containing moving bed surface and the proportion of the total amount of the suspended sand to the total amount of the sediment above the initial bed surface according to the mass conservation law and all the parameters.
3. The method according to claim 2, wherein the maximum siertz number and the friction factor of the sand bed surface are obtained based on the maximum value of the outer boundary layer flow velocity, the flow period, the silt particle size, the ratio of the silt to the water density, and the gravitational acceleration, and specifically:
wherein, thetamRepresenting the maximum Sherz number, f representing the friction factor of the sand-containing moving bed surface, UmAnd the maximum value of the flow velocity of the outer boundary layer is represented, D represents the particle size of the silt, s represents the ratio of the silt to the density of water, g represents the gravitational acceleration, and T represents the flow period.
4. The method according to claim 3, wherein the obtaining of the ratio of the settling time of the sediment in the sediment transport layer to the flow period and the sediment settling velocity of the sediment is performed according to the sediment particle size, the maximum Sherz number, the flow period, the maximum value of the flow velocity of the outer boundary layer, the ratio of the sediment to the water density, the gravitational acceleration, and the kinetic viscosity coefficient of water, and specifically comprises:
where Ψ represents the ratio of the settling time of silt in the sediment transport layer to the flow period, w represents the settling velocity of the silt, and v represents the kinetic viscosity coefficient of the water.
5. The method according to claim 4, wherein the obtaining of the phase drift time of the erosion depth to the flow velocity and the residue of the sediment phase according to the ratio of the settling time of the sediment in the sediment transport layer to the flow period and the flow period comprises:
α＝exp(-0.2/Ψ)，
where ψ represents the phase drift time of the erosion depth against the flow velocity, and α represents the residue of the silt phase.
6. The method according to claim 5, wherein the obtaining of the total amount of suspended sand on the sand-bearing moving bed and the ratio of the total amount of suspended sand to the total amount of sediment above the initial bed surface according to the law of conservation of mass and all the parameters mentioned above comprises:
wherein U represents the outer boundary layerFlow rate, [ theta ]crDenotes the critical Sherz number, SmDelta represents the total volume of the sand above the surface of the saturated sand-containing layer satisfying the conservation of mass, SmThe maximum sediment volume concentration is shown, delta represents the depth of the sand-containing layer eroded by water flow, namely the distance from the surface of the saturated sand-containing layer to the initial bed surface, C represents the total amount of suspended sand on the sand-containing moving bed surface per unit area in terms of sediment volume, and P represents the proportion of the total amount of suspended sand to the total amount of sediment above the initial bed surface.
7. The utility model provides a pump station approach and forebay hang determination device of sand total amount which characterized in that includes:
the first module is used for acquiring the flow velocity, the flow period, the sediment particle size, the ratio of sediment to water density and the motion viscosity coefficient of water of an outer boundary layer of a pump station approach and a front pool water body;
the second module is used for obtaining the maximum Sherz number and the friction factor of the sand-containing moving bed surface based on the maximum value of the flow velocity of the outer boundary layer, the flow period, the grain size of the silt, the ratio of the silt to the density of water, the motion viscosity coefficient of the water and the gravity acceleration;
and the third module is used for acquiring the total amount of suspended sand on the sand-containing movable bed surface and the proportion of the total amount of the suspended sand in the total amount of the sand above the initial bed surface according to the law of conservation of mass, the flow velocity of the outer boundary layer, the flow period, the particle size of the sand, the ratio of the sand to the water density, the maximum Sierpitz number and the friction factor of the sand-containing movable bed surface.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113486806A (en) * | 2021-07-07 | 2021-10-08 | 西安交通大学 | Suspended sand monitoring method based on one-dimensional residual error neural network |
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Application publication date: 20200623 |