CN110130471B - Wedge-shaped flow guiding pier for coping with large diffusion angle of front pool of pump station and research method thereof - Google Patents
Wedge-shaped flow guiding pier for coping with large diffusion angle of front pool of pump station and research method thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of hydraulic engineering, and particularly relates to a wedge-shaped flow guiding pier for coping with a large diffusion angle of a front pool of a pump station and a research method thereof. And the position 4D (D is the diameter of the impeller) away from the inlet of the front pool is provided with the flow guide pier, so that bad flow states such as backflow, vortex and the like can be effectively avoided. The invention has the advantages of arranging the flow guiding piers into a wedge shape, having good flow guiding effect, saving materials and the like. The wedge-shaped flow guiding pier can effectively solve the problems of main flow concentration, uneven water flow distribution, flow state disturbance and the like of the front pool.
Description
Technical Field
The invention belongs to the technical field of hydraulic engineering, and particularly relates to a wedge-shaped flow guiding pier for coping with a large diffusion angle of a front pool of a pump station and a research method thereof.
Background
The front pool is used as a hydraulic building for connecting the water inlet pool and the canal and mainly plays a role in smoothly diffusing water flow, wherein the size of the diffusion angle of the front pool directly influences the water flow state in the front pool. Poor flow states such as backflow and vortex are generated easily due to unreasonable diffusion angle setting. According to the specification, the value of the diffusion angle alpha of the front pool is within 20-40 degrees. Due to the reasons of site arrangement and engineering structural characteristics, the main flow is concentrated due to the fact that the pressurized culvert pipes are filled with water, the problem that the flow distribution is uneven due to the fact that the wall-falling backflow is caused due to the fact that the diffusion angle is too large and difficult to avoid in projects such as urban drainage pump stations is caused.
At present, CFD technology is developed rapidly, can efficiently simulate a fine flow field, and has a pushing effect on researching the flow characteristics of water flow. According to the structural characteristics of the front pool, a method combining numerical simulation and model test is adopted, a wedge-shaped flow guiding pier is provided, and a proper flow guiding included angle beta and a proper flow guiding length L are designed. The forward water flow state of the front pool of the urban drainage pump station is improved, the wall-falling backflow is restrained, the inlet condition of the water pump is improved, and the efficiency of the water inlet flow channel is further improved.
Disclosure of Invention
The invention aims at overcoming the defects of the prior art, and provides a wedge-shaped flow guiding pier for coping with a large diffusion angle of a front pool of a pump station and a research method thereof. The method aims at improving the forward water flow state of the front pool of the urban drainage pump station, adding a wedge-shaped flow guide pier in the forward water inlet front pool of the urban drainage pump station, inhibiting the generation of wall-falling backflow, improving the inlet condition of the water pump and further improving the efficiency of the water inlet flow channel.
The purpose of the invention is realized in the following way:
the wedge-shaped flow guiding pier is characterized in that the wedge-shaped flow guiding pier is of a triangular prism structure with a top surface obliquely arranged and is arranged in a forward water inlet front pool.
Preferably, the wedge-shaped flow guiding pier is arranged at a position 4D from the front pool inlet, and D is the diameter of the impeller of the water pump.
Preferably, the top surface of the wedge-shaped flow guiding pier is an isosceles triangle, the vertex angle of the isosceles triangle is lower than the bottom edge of the isosceles triangle, the vertex angle of the isosceles triangle faces the front pool inlet, and the bottom edge of the isosceles triangle faces the water inlet pool.
Preferably, the apex angle of the isosceles triangle is 90 degrees, the waist length is 2.5D, and D is the diameter of the impeller of the water pump.
Preferably, the vertex corresponding to the vertex angle of the isosceles triangle has a height of 0.3 times of the water depth of the section of the water inlet tank, and the ratio of the height to the height of the bottom edge of the isosceles triangle is 1:1.38.
preferably, the base of the isosceles triangle is perpendicular to the water flow direction.
The research method of the wedge-shaped flow guiding pier for coping with the large diffusion angle of the front pool of the pump station is characterized by comprising the following steps:
A. geometric modeling:
the method comprises the steps of establishing a geometric model of a large-diffusion-angle forward water inlet front pool by using UG NX software, wherein the model comprises four vertical water pump water outlets, the diffusion angle degree is 55 degrees, the top angle of a wedge-shaped flow guiding pier is beta, the waist length is L, and the height of the lowest point of the flow guiding pier is 0.3 times of the section water depth;
B. boundary conditions:
(1) Inlet conditions: the river-inducing water inlet section is selected as an inlet boundary, the mass flow is imported, the total flow is 11.48kg/s, and the turbulence intensity is moderate;
(2) Outlet boundary: the section of the suction pipe of the four vertical water pumps is selected as a water outlet boundary, the section is set as static pressure water outlet, a research area in the fluid domain is far away from the section of the outlet, the section is set as 1atm according to the past experience, and the free outflow is simulated;
(3) Free water surface: adopting a rigid cover assumption that the water surface is set as a symmetrical surface without considering the water surface shearing force;
(4) Solid side wall: the solid side wall is selected as a smooth wall surface without sliding, and the influence of water flow on the side wall is not considered;
C. meshing and independence analysis:
mesh software is adopted to divide grids of the whole calculation domain, tetrahedron unstructured grids are adopted, and partial encryption is carried out on the flow guiding pier component; meanwhile, considering the influence of the number of grids on the accuracy of numerical simulation, firstly exploring the range of 30-300 ten thousand grids and calculating the intra-domain head loss h f Is of a size of (2);
the head loss is calculated using formula (1):
h f ＝(P in -P out )/ρg (1)
wherein: h is a f Head loss based on mass average; p (P) in Is the total pressure of the inlet section; p (P) out Is the total pressure of the outlet section; ρ is the density of water at 4 ℃; g is gravity acceleration;
when the number of the grids reaches 170 ten thousand, the head loss is basically unchanged, so that the order of magnitude of the calculated and selected grids is 170 ten thousand;
D. original protocol flow regime analysis:
the water flow flows into the water inlet front pool from the approach channel in the forward direction, the water flow state is symmetrically distributed, and the flow lines are concentrated; the uneven distribution of flow velocity and flow rate caused by the large diffusion angle of the water inlet front pool is reflected;
E. adopts a wedge-shaped flow guiding pier flow state analysis and research scheme:
by adjusting the top angle of the wedge-shaped flow guiding pier to be 90 degrees and the waist length to be 2.5D, compared with the streamline distribution of the original scheme, the wedge-shaped flow guiding pier is additionally arranged, so that the diffusion of the main flow is accelerated to a certain extent, and the areas of the reflow areas at two sides are reduced;
F. comparison analysis of test results:
in order to verify the numerical calculation result of the optimal rectifying scheme in the step E, a model circulation test device with the same size as the numerical simulation is manufactured, and the optimal rectifying scheme is verified by observing the change of particle trails of the inner layer of the front pool and wires of the bottom layer, comparing the flow diagrams of the original scheme and the scheme of the additionally arranged flow pier;
through a model test, the flow distribution of the water inlet pool of each scheme is observed to be basically consistent with the CFD result, and the reliability of the numerical simulation result is higher;
by observing the flow state of water, the pressure distribution of the section and calculating the uniformity of flow distribution, the flow state of the forehearth is obviously improved, the reflux area is reduced, the problems of transverse water flow and bias flow are relieved, and the flow distribution is uniform.
The invention mainly aims at solving the problem that the front pool with a large diffusion angle has bad flow state such as large scale convolution, and adopts a numerical simulation method to research the water flow movement rule after the wedge-shaped flow guiding pier is additionally arranged on the slope section of the front pool. The influence of single factor changing the flow guiding included angle beta and the length L of the flow guiding pier on the bad flow state of the front pool is explored by taking the flow distribution uniformity of the water pump as an objective function, and model test verification is carried out. Studies have shown that: when no rectifying measure is adopted, the main flow in the front pool is too concentrated, and the vortex with symmetrical vertical faces appears, so that the diffusion of water flow in the front pool is seriously influenced, even the water flow is wrapped by the vortex, and the flow state in the water inlet pool is further influenced. After the diversion pier with the diversion angle beta of 90 degrees and the length of 2.5D is additionally arranged at the position 4D away from the inlet of the front pool, the flow state of the front pool can be obviously improved, and water flows uniformly enter each water inlet pool. The research results have reference significance for improving the flow state of the front pool with too concentrated main flow or large diffusion angle of the urban drainage pump station. The invention is beneficial to better improving the flow state of the water in the front pool of the urban sewage disposal pump station, improving the inlet condition of the water pump, and has reliable technology and easy implementation.
The invention relates to a wedge-shaped flow guiding pier for coping with a large diffusion angle of a front pool of an urban drainage pump station, which is arranged on a slope section of the front pool, and the flow guiding pier is arranged at a position 4D (D is the diameter of an impeller) from an inlet of the front pool and is opposite to a sill and an upright post, so that bad flow states such as backflow, vortex and the like can be effectively avoided. The invention has the innovation that the guide piers are arranged in a wedge shape, and compared with the traditional T-shaped guide piers, the Y-shaped guide piers have the advantages of simple construction, good guide effect, material saving and the like. In particular to a front pool with a large diffusion angle, and numerical simulation and model test prove that the addition of the wedge-shaped flow guiding pier can effectively solve the problems of main flow concentration, uneven water flow distribution, flow state disturbance and the like of the front pool. The flow distribution uniformity of the water pump can reach 99.77 percent. The uniformity is improved by 4.80 percent compared with the original scheme.
Drawings
FIG. 1 is a schematic view of a wedge-shaped pier according to the present invention;
FIGS. 2 and 3 show the plan dimensions of the water inlet portion of the forehearth and the three-dimensional model of the present invention;
FIG. 4 shows hydraulic losses at different orders of magnitude of the grid of the present invention;
FIG. 5 is a three-dimensional streamline projection of the original solution forehearth;
FIG. 6 is a cloud chart of the pressure distribution of each intake pool section 1 according to the original scheme;
FIG. 7 is a three-dimensional streamline projection of the front pool of the rectification scheme of the present invention;
FIG. 8 is a cloud chart of the pressure distribution of each inlet pool section 1 according to each scheme of the invention;
FIG. 9 is a model cycle test apparatus of the present invention;
FIG. 10 is a comparison of the experimental results of the inlet basin flow distribution model of the present invention with the CFD results;
in the figure: the top surface of the wedge-shaped flow guiding pier 1 and the bottom surface of the wedge-shaped flow guiding pier 2.
Detailed description of the preferred embodiments
The invention is suitable for various large-diffusion-angle forward water inlet forehearth projects, and the drawing is designed according to the design requirement. And determining the total length of the wedge-shaped flow guiding pier in the front pool along the water flow direction L (namely the waist length of the top surface of the wedge-shaped flow guiding pier), the flow guiding included angle of the flow guiding pier (namely the top angle of the top surface of the wedge-shaped flow guiding pier), and the height of the flow guiding pier.
As shown in FIG. 1, the height of the wedge-shaped flow guiding pier is 0.3 times of the section water depth of the point A at the top of the flow guiding pier. The height ratio of the top point A of the flow guiding pier to the top point B and C is 1:1.38.
the length L of the wedge-shaped flow guiding pier along the water flow direction is 2.5D, namely the waist length. The wedge-shaped flow guiding piers (D is the diameter of the water pump impeller) are arranged at the position 4D away from the front pool inlet (namely, the distance between the top point A of the flow guiding piers and the front pool inlet is 4D), and the distance between the flow guiding piers and the left wall and the right wall are equal. The bottom side BC is perpendicular to the water flow direction. The flow guide included angle of the wedge-shaped flow guide pier is 90 degrees.
The horizontal projection of the top surface of the wedge-shaped flow guiding pier is triangular, the head of the flow guiding pier is triangular, and the cross section of the tail of the flow guiding pier is rectangular.
The wedge-shaped flow guiding pier is additionally arranged at the proper position of the forward water inlet front pool of the pump station, can well guide water flow from the river diversion, has a very good flow guiding effect, and effectively improves the flow state of the water flow of the water inlet flow channel of the pump station near the water inlet pool and the flow speed uniformity of the inlet section.
The invention is used for improving the diversion pier in the front pool of the urban drainage pump station, and the head of the diversion pier along the water flow direction is changed into a wedge shape. Before the water flow enters the water inlet flow channel after flowing through the flow guiding pier, the flowing water is guided by the wedge-shaped section of the flow guiding pier, the flow state of the water flow is improved, and the flow velocity distribution is uniform. The invention is suitable for various forward water inlet forehearth engineering, can effectively improve the flow state near the forward water inlet forehearth with a large diffusion angle, eliminates vortex, ensures smoother water flow and improves the flow velocity uniformity of the inlet of the water inlet flow passage of the water pump.
The flow guide pier is a common rectifying measure for improving the flow state of the front pool, is beneficial to better improving the flow state of water near the front pool with large diffusion angle and improves the inlet condition of the water pump, and has reliable technology, easy implementation and wide application prospect.
Geometric modeling:
and (3) establishing a large diffusion angle forward water inflow forehearth geometric model by using UG NX software (figures 1, 2 and 3). The model comprises four vertical water pumps for discharging water, the number is shown in the figure, and the diffusion angle degree is 55 degrees. In the model size schematic diagram of fig. 3, D is the diameter of the impeller of the water pump, the longitudinal length of the foretank is 12.8D, and the transverse length is 20D. In the three-dimensional model of fig. 2, a wedge-shaped flow-guiding pier model can be seen, the flow-guiding pier flow-guiding included angle BAC is beta, the length AB is L, and the height of the flow-guiding pier point A is 0.3 times of the section water depth.
Considering the symmetrical distribution of the flow patterns of the water tanks before forward water inflow, only the flow patterns of the water inflow tanks with the open type 1# and 2# are studied. Because the flow of the front pool with a large diffusion angle is complex, the flow state change of the front pool is indirectly reflected by quantitatively analyzing the typical sections in the water inlet pool, namely, four sections (section 1-1, section 1-2, section 2-1 and section 2-2) are respectively cut in the 1# and 2# open water inlet pool, and the characteristic values on the typical sections are compared at the positions which are respectively 4D and 8D away from the water inlet pool.
Boundary conditions:
(1) Inlet conditions: the water inlet section of the river is selected as an inlet boundary, the Mass flow inlet (Mass flow Inlet) has a total flow of 11.48kgs and a medium turbulence intensity, namely 5%.
(2) Outlet boundary: four vertical water pump suction pipe sections are selected as water outlet boundaries, are set as Static Pressure water outlet, and a research area in a fluid domain is far away from the outlet section, is set as 1atm according to the past experience, and simulates free outflow.
(3) Free water surface: with the rigid cover assumption, the water surface is set to be a Symmetry plane (Symmetry) irrespective of the water surface shear force.
(4) Solid side wall: the solid side wall is selected to be a smooth wall surface without sliding, and the influence of water flow on the side wall is not considered.
Meshing and independence analysis:
the invention adopts mesh software to divide the grid of the whole calculation domain, adopts tetrahedron unstructured grid, and carries out local encryption on the flow guiding pier component. Meanwhile, considering the influence of the number of grids on the accuracy of numerical simulation, firstly exploring the range of 30-300 ten thousand grids and calculating the intra-domain head loss h f Is larger (as in fig. 4).
The head loss is calculated using formula (1):
h f ＝(P in -P out )/ρg (1)
wherein: h is a f Head loss based on mass average; p (P) in Is the total pressure of the inlet section; po (Po) ut Is the total pressure of the outlet section; ρ is the density of water at 4 ℃; g is gravitational acceleration.
When the number of meshes reaches 170 ten thousand, the head loss remains substantially unchanged. The computational selection grid is on the order of 170 tens of thousands.
Original protocol flow regime analysis:
fig. 5 shows a projection view of a three-dimensional streamline of a front pool without adding any rectifying measure, the streamline is displayed by adopting an equal flow speed principle, the flow speed is represented by the density degree and the color of the streamline, the flow speed of a region with denser color and brighter streamline is higher, and the flow speed of a region which is not displayed by the streamline is lower, namely a backflow region.
As can be seen from the figure: the water flow flows into the water inlet front pool from the approach channel in the forward direction, the water flow state is symmetrically distributed, and the flow lines are concentrated; two wall-falling backflow areas with larger areas appear at the positions of the side walls at the two sides of the front pool due to larger diffusion angle of the front pool, so as to press the main flow; the front pool bottom slope is designed as a forward water slope, water flow inertial clamping is additionally added, the main flow cannot be effectively diffused, and countercurrent and transverse water flow are indirectly caused at the inlets of the 2# and 3# water inlet pools; because of the existence of the backflow area, the inflow bias flows of the No. 1 water inflow pool and the No. 4 water inflow pool are serious, the flow distribution is uneven, and the inflow flow state is disordered. The comparison of the model test and the numerical simulation shows that the flow state of the water flow is similar, the backflow area is obvious, and the simulation result is true and credible. Fig. 6 shows a cloud image of the pressure distribution of each inlet tank section 1 in the original scheme, four inlet tank sections (section 1) are cut at the position of the section 1-1, and the pressure distribution of water flowing through the sections is compared. Because the main flow is concentrated, the pressure distribution on each section is uneven, and the section pressure of the 2# and 3# water inlet tanks is larger. The pressure distribution on the same section of the water inlet tanks No. 2 and No. 3 is still uneven, which indirectly reflects the uneven flow velocity and flow distribution caused by the large diffusion angle of the water inlet front tank.
The flow state analysis and research scheme of the invention:
the diversion pier is a common rectifying measure in the front pool and the water inlet pool and mainly plays a role in adjusting the flow direction of water flow. By combining the characteristic of overlarge diffusion angle of the front pool in the flow-guiding device, the wedge-shaped flow-guiding piers are arranged on the slope section, so that the flow direction of water flow is changed, the main flow is accelerated to diffuse, and the flow distribution is further regulated.
By adjusting the flow guide angle beta and the length L of the wedge-shaped flow guide pier, 6 different rectification schemes are designed. FIG. 6 is a three-dimensional streamline projection of a forehearth using different schemes. By comparing the streamline distribution of each scheme with that of the original scheme and adding the flow guiding piers, the diffusion of the main flow is accelerated to a certain extent, and the areas of the reflow areas at the two sides are reduced.
Table 1 rectification scheme
| Scheme for the production of a semiconductor device | β/° | L/cm |
| 1 | 45 | 10.0 |
| 2 | 75 | 10.0 |
| 3 | 90 | 10.0 |
| 4 | 120 | 10.0 |
| 5 | 120 | 7.5 |
| 6 | 90 | 12.5 |
As can be seen by comparing the flow charts of fig. 7 (a), (b) and (c): by adjusting the flow guide angle of the flow guide pier, the size of the backflow areas at the two sides of the front pool can be reduced, but the backflow areas cannot be effectively eliminated. The shape of the backflow area is compressed into a thin strip shape closely attached to the side wall from the original ellipse shape, so that water flows into the No. 1 water inlet tank and the No. 4 water inlet tank in an inclined manner, water flows are easily formed in the water inlet tank in a folding manner, and the safe operation of the water pump is endangered. As can be seen from fig. 7 (d), the size of the backflow area at both sides of the front pool can be effectively controlled due to the overlarge angle of the flow guiding pier, but the water flow after the pier is disturbed to form a secondary vortex, so that the flow state of the water flow in the water inlet pool is directly influenced, and the rectifying effect is poor.
In view of the characteristic that the size of the backflow area can be well controlled in the scheme 4, the scheme 5 is obtained by reducing the length of the flow guiding piers on the basis of the scheme 4, and the streamline distribution is good as seen in the streamline in the figure 7 (e), so that the problem of secondary backflow after piers is relieved, and the rectifying effect is good.
Aiming at the problem that the flow guide angles of the flow guide piers in the schemes 1 to 5 can not effectively control the countercurrent and transverse water flow at the water inlet pool opening piers, the length of the flow guide piers is further increased on the basis of the scheme 3. As can be seen by comparing the flow charts of fig. 7 (c) and (f): by increasing the length of the flow guiding piers, the backflow area is further reduced, the backflow and transverse water flow at the position of the block piers are relieved, and streamline distribution is uniform. The deflection angle of the water flowing into the No. 1 water inlet tank and the No. 4 water inlet tank is reduced, and the rectifying effect is good.
Fig. 8 is a cloud of pressure distribution of the section 1 of the water intake pool according to each scheme. Comparing fig. 8 (a), (b) and (c), although the flow-guiding piers are added in the water inlet front pool, the pressure difference on each section is aggravated due to the unreasonable size of the flow-guiding piers. In the schemes (4) and (5), a local high-pressure area appears on the cross section of the middle water inlet tank, the pressure distribution of other cross sections is reasonable, but the side surface reflects the problem of uneven flow distribution of the cross section. Compared with other schemes, the scheme (6) has the most reasonable pressure distribution and is the optimal scheme.
From the above, the comparison analysis of the flow lines and pressure distribution of the original scheme and each rectification scheme can be seen as follows: scheme 5 and scheme 6 are that the rectification effect is better, can effective control reflux zone size. A typical section is selected hereinafter, and the change of the characteristic value on the section is quantitatively analyzed and verified by a model test.
Quantitative analysis of the calculation result:
numerical calculations the inlet pool flow distribution for each scheme is shown in table 2. The large difference of different water inflow pool flow distribution due to the fact that the diffusion angle is too large and water flow cannot be effectively diffused, indicates that the water flow state in the front pool directly influences the water inflow pool flow state, and secondary backflow formed in the water inflow pool influences the water pump flow distribution.
Table 2 under various schemes inlet pool flow distribution
As can be seen from table 2, the variation trend of the uniformity of the flow distribution of the water pump in each scheme is consistent with the streamline distribution rule. The size of the flow guiding piers arranged in the scheme 1 is unreasonable, the main flow diffusion effect is not obvious, and poor flow state is generated after piers, so that uniformity is reduced by 2 percent. Other schemes except scheme 1 have improved uniformity, the optimal scheme is scheme 6, the uniformity is improved by 4.80 percent compared with the uniformity of the original scheme (scheme 0), the suboptimal scheme is scheme 5, and the uniformity is improved by 4.63 percent compared with the uniformity of the original scheme.
Comparative analysis of the test results of the invention:
in order to verify the numerical calculation result of the optimal rectification scheme, a model circulation test device (as shown in fig. 9. By observing the change of particle trace and bottom thread in the inner surface layer of the front pool, the flow charts of the original scheme and the additional flow pier scheme are compared, and the optimal rectification scheme is verified.
Through model tests, the flow distribution of the water inlet pool of each scheme is observed to be basically consistent with the CFD result, and the reliability of the numerical simulation result is higher (as shown in figure 10).
By observing the flow state of water, the pressure distribution of the section and calculating the uniformity of flow distribution, the flow state of the forehearth is obviously improved, the reflux area is reduced, the problems of transverse water flow and bias flow are relieved, and the flow distribution is uniform.
Claims (2)
1. Wedge-shaped flow guiding piers for coping with large diffusion angle of front pool of pump station, wherein the degree of diffusion angle is 55 degrees; the water inlet front pool is characterized in that the wedge-shaped flow guiding pier is of a triangular prism structure with the top surface obliquely arranged and is arranged in the forward water inlet front pool;
the wedge-shaped flow guiding pier is arranged at a position 4D away from an inlet of a front pool, the longitudinal length of the front pool is 12.8D, the transverse length of the front pool is 20D, and D is the diameter of a water pump impeller;
the top surface of the wedge-shaped flow guiding pier is an isosceles triangle, the vertex angle of the isosceles triangle is lower than the bottom edge of the isosceles triangle, the vertex angle of the isosceles triangle faces to the front pool inlet, and the bottom edge of the isosceles triangle faces to the water inlet pool;
the vertex angle of the isosceles triangle is 90 degrees, and the waist length is 2.5D;
the vertex corresponding to the vertex angle of the isosceles triangle is 0.3 times of the water depth of the section of the water inlet tank, and the height ratio of the height to the bottom edge of the isosceles triangle is 1:1.38;
the bottom side of the isosceles triangle is perpendicular to the water flow direction.
2. The method for researching a wedge-shaped flow guiding pier for coping with a large diffusion angle of a front pool of a pump station according to claim 1, which is characterized by comprising the following steps:
A. geometric modeling:
the method comprises the steps of establishing a geometric model of a large-diffusion-angle forward water inlet front pool by using UG NX software, wherein the model comprises four vertical water pump water outlets, the diffusion angle degree is 55 degrees, the top angle of a wedge-shaped flow guiding pier is beta, the waist length is L, and the height of the lowest point of the flow guiding pier is 0.3 times of the water depth of the section of the water inlet pool;
B. boundary conditions:
(1) Inlet conditions: the river-inducing water inlet section is selected as an inlet boundary, the mass flow is imported, the total flow is 11.48kg/s, and the turbulence intensity is moderate;
(2) Outlet boundary: the section of the suction pipe of the four vertical water pumps is selected as a water outlet boundary, the section is set as static pressure water outlet, a research area in the fluid domain is far away from the section of the outlet, the section is set as 1atm, and the free outflow is simulated;
(3) Free water surface: adopting a rigid cover assumption that the water surface is set as a symmetrical surface without considering the water surface shearing force;
(4) Solid side wall: the solid side wall is selected as a smooth wall surface without sliding, and the influence of water flow on the side wall is not considered;
C. meshing and independence analysis:
mesh software is adopted to divide grids of the whole calculation domain, tetrahedron unstructured grids are adopted to carry out local encryption on the flow guiding pier components; meanwhile, considering the influence of the number of grids on the accuracy of numerical simulation, firstly exploring the range of 30-300 ten thousand grids and calculating the intra-domain head loss h f Is of a size of (2);
the head loss is calculated using formula (1):
h f ＝(P in -P out )/ρg (1)
wherein: h is a f Head loss based on mass average; p (P) in Is the total pressure of the inlet section; p (P) out Is the total pressure of the outlet section; ρ is the density of water at 4 ℃; g is gravity acceleration;
the order of magnitude of the calculation selection grid is 170 ten thousand;
D. original protocol flow regime analysis:
the water flow flows into the water inlet front pool from the approach channel in the forward direction, the water flow state is symmetrically distributed, and the flow lines are concentrated; the uneven distribution of flow velocity and flow rate caused by the large diffusion angle of the water inlet front pool is reflected;
E. adopts a wedge-shaped flow guiding pier flow state analysis and research scheme:
the apex angle of the top surface of the wedge-shaped flow guiding pier is adjusted to be 90 degrees, the waist length is 2.5D, and the flow line distribution of the wedge-shaped flow guiding pier is compared with that of the original scheme;
F. comparison analysis of test results:
in order to verify the numerical calculation result of the optimal rectifying scheme in the step E, a model circulation test device with the same size as the numerical simulation is manufactured, and the optimal rectifying scheme is verified by observing the change of particle trails of the inner layer of the front pool and wires of the bottom layer, comparing the flow patterns of the original scheme and the scheme of the additionally arranged flow pier.
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| KR20190045477A (en) * | 2017-10-24 | 2019-05-03 | 구재삭 | The method and system for tide gate design and water flow control of tidal power plant which minimized the influence of bending angle of input water flow and which uniform the electricity output between each turbine generator and which keep the falling height by fast discharge of water |
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| KR20190045477A (en) * | 2017-10-24 | 2019-05-03 | 구재삭 | The method and system for tide gate design and water flow control of tidal power plant which minimized the influence of bending angle of input water flow and which uniform the electricity output between each turbine generator and which keep the falling height by fast discharge of water |
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