阅读说明：本技术 一种鱼道进口补水消能结构及设计方法 (Fishway inlet water replenishing and energy dissipating structure and design method ) 是由 苏加林 路振刚 马军 李润伟 周炳昊 银佳男 张志福 刘亚莲 马志强 孙万光 李 于 2021-09-02 设计创作，主要内容包括：本发明公开了鱼道设计技术领域的一种鱼道进口补水消能结构及设计方法,包括补水管,消能池,牛腿,消能盖板与透水格栅；补水管为补水钢管,消能池为补水钢管出水聚集池,牛腿位于消能池顶部,且牛腿用于给消能盖板提供支撑作用,消能盖板位于牛腿上,消能盖板之间缝隙不同,使补水出流相对均匀,补水水流自消能盖板间的缝隙进入鱼道,强制将大尺度紊流涡团变成小尺度涡团；涡团尺度变小后,粘性切应力比较容易将紊动能转化成流体内能而耗散掉,使鱼道内的紊动能降低,透水格栅固定于消能盖板之上,补水水体从消能池经消能盖板二次消能进入鱼道,能最大限度减少补水对水体造成的紊乱,保障鱼类在鱼道内部顺利洄游。(The invention discloses a fishway inlet water supplementing and energy dissipating structure and a design method thereof, belonging to the technical field of fishway design, and the fishway inlet water supplementing and energy dissipating structure comprises a water supplementing pipe, an energy dissipating pool, brackets, an energy dissipating cover plate and a water permeable grid; the water replenishing pipe is a water replenishing steel pipe, the energy dissipation pool is a water outlet gathering pool of the water replenishing steel pipe, the bracket is positioned at the top of the energy dissipation pool and used for providing a supporting effect for the energy dissipation cover plate, the energy dissipation cover plate is positioned on the bracket, gaps among the energy dissipation cover plates are different, so that the water replenishing outflow is relatively uniform, the water replenishing water flow enters the fishway from the gaps among the energy dissipation cover plates, and the large-scale turbulent vortex group is forcibly converted into a small-scale vortex group; after the size of the vortex group is reduced, the viscous shear stress is easy to convert turbulent energy into fluid internal energy to be dissipated, so that the turbulent energy in the fishway is reduced, the water-permeable grating is fixed on the energy dissipation cover plate, and the water supplementing water body enters the fishway through the energy dissipation cover plate by secondary energy dissipation of the energy dissipation pool, so that the disorder of the water body caused by water supplementation can be reduced to the maximum extent, and the smooth migration of fishes in the fishway is ensured.)

1. The utility model provides a fishway import moisturizing dissipation structure which characterized in that: comprises a water replenishing pipe (1), an energy dissipation pool (2), brackets (3), an energy dissipation cover plate (4) and a water permeable grid (5); the water replenishing pipe (1) is a water replenishing steel pipe, the energy dissipation pool (2) is a water replenishing steel pipe outlet water gathering pool, the bracket (3) is located at the top of the energy dissipation pool (2), and the bracket (3) is used for providing a supporting effect for the energy dissipation cover plate (4).

2. The fishway inlet water supplementing and energy dissipating structure of claim 1, wherein: the energy dissipation cover plates (4) are positioned on the brackets (3), gaps among the energy dissipation cover plates (4) are different, so that water supplement outflow is relatively uniform, water supplement water flow enters a fishway from the gaps among the energy dissipation cover plates (4), and large-scale turbulent vortex masses are forcibly changed into small-scale vortex masses; after the size of the vortex group is reduced, the viscous shear stress is easier to convert turbulent energy into fluid internal energy to be dissipated, so that the turbulent energy in the fishway is reduced, and the water-permeable grating (5) is fixed on the energy dissipation cover plate (4).

3. The fishway inlet water supplementing and energy dissipating structure of claim 2, wherein: the energy dissipation cover plate (4) is distributed at unequal intervals, the slit width is adjusted to be an arrangement mode that the head side and the tail side of the energy dissipation pool (2) are narrow and the middle part of the energy dissipation pool is wide, the vertical flow velocity of each slit is uniform, the vortex size of the outflow section of each slit is relatively small, and the viscous shear stress is easy to convert the turbulent energy into the internal fluid energy to be dissipated, so that the turbulent energy in the fishway is reduced.

4. The design method of the fishway inlet water replenishing energy dissipation structure as claimed in claim 3, characterized by comprising the following steps:

s1: under two working conditions of an energy dissipation cover plate and an energy dissipation cover plate, a macroscopic flow field of a water compensation energy dissipation pool under the conditions of water compensation flow and water compensation pipe outlet flow velocity is preliminarily recognized through a local physical model test;

s2: on the basis of a local physical model test S1, a three-dimensional hydrodynamic mathematical model and a k-epsilon two-stroke model adopted by a turbulent model are constructed;

s3: aiming at the test working condition of unfavorable combination, the water supplementing and energy dissipating schemes of different energy dissipating cover plate types are further calculated by a numerical simulation technical means, namely a three-dimensional hydrodynamic force mathematical model; evaluating the water replenishing and energy dissipating effects by means of the uniformity of the distribution of the flow field inside the fishway and the turbulent kinetic energy parameter of the hydraulic factor of the fishway being lower than 0.035m2/s 2;

s4: and performing the physical model test again on the basis of S3, continuously refining the detailed structure of the water supplementing energy dissipation cover plate, and determining the final type of the energy dissipation cover plate.

5. The design method of the fishway inlet water replenishing energy dissipation structure as claimed in claim 4, wherein the design method comprises the following steps: and the water replenishing body enters the fishway through secondary energy dissipation of the energy dissipation cover plate from the energy dissipation pool.

6. The design method of the fishway inlet water replenishing energy dissipation structure as claimed in claim 4, wherein the design method comprises the following steps: in S1, preliminarily determining the length a of the energy dissipation pool to be 2H-3H, the height B to be 1B-2B, the height c of the water replenishing energy dissipation pipe from the pool bottom to be 1/3B-1/2B, wherein H is the normal operating water depth of the fishway, and B is the net width of the fishway pool chamber.

7. The design method of the fishway inlet water replenishing energy dissipation structure as claimed in claim 4, wherein the design method comprises the following steps: in S2, the physical model actual measurement result under the working condition of S1 is used for verifying the mathematical model, so that the water flow motion state is accurately reflected.

8. The design method of the fishway inlet water replenishing energy dissipation structure as claimed in claim 4, wherein the design method comprises the following steps: in S3, the turbulent energy may be the more direct hydraulic factor; the turbulent energy represents the kinetic energy carried by the fluid turbulence and reflects the intensity of the fluid turbulence; the turbulent energy expression is as follows:

wherein ui is the instantaneous velocity, m/s;is the time average velocity, m/s; u'_iIs the pulse velocity, m/s; u'_x、u′_y、u′_zThe pulse speeds along 3 different directions x, y and z are respectively, and the unit is m/s.

Technical Field

The invention relates to the technical field of fishway design, in particular to a fishway inlet water supplementing and energy dissipating structure and a design method.

Background

The success or failure of the fishway operation is mainly determined by two aspects: 1) whether the fish can find an entrance; 2) whether fish can pass through smoothly. The effectiveness of the fishway is therefore closely related to the swimming behavior of the target fish. Particularly, the flow-approaching characteristic of the fish is mainly used for designing a flow field at the inlet of a fishway; swimming indexes such as gram flow speed, fatigue time and the like of the fishes are mainly used for designing the flow speed of the fishway.

The selection of the fishway inlet position belongs to the cross research category of fish behavior and hydraulics, and the setting is proper or not to directly influence the fish passing effect of the fishway engineering. Biological indicators and hydrodynamic indicators of the fish passing objects are important factors which must be considered in the selection of the fishway entrance position. Theoretical studies have shown that the fishway entry and exit flow rates typically use a relatively high flow rate to attract fish. As long as the fishway inlet outflow flow rate is smaller than the outburst speed of the target fish, the larger the fishway inlet outflow flow rate and the corresponding downward discharge flow rate is, the better the fishway inlet outflow flow rate and the corresponding downward discharge flow rate are, the larger flow rate and the higher flow rate at the fishway inlet are easily discovered and distinguished by the fish, the more easily the fish are attracted from other discharge positions of the gate dam, the aggregation of the fish is facilitated, and therefore the fish can conveniently find the inlet of the fishway.

In the actual fishway operation process, the fishway internal flow variation range is small, the flow velocity is uniform, and the average flow velocity of the cross section is low, so that the flow velocity advantage is difficult to form near the inlet, and a good fish luring effect is achieved. When the water flow velocity of the water flow in the inlet area of the fishway is smaller than the induction flow velocity of the fishes, measures such as water replenishing and the like are taken to induce the fishes to enter the fishway.

When the fishway is used for water replenishing, the water replenishing water body is mixed with the water body in the fishway pool chamber, obvious disturbance can be generated on the water body in the fishway, the current state in the fishway is disturbed, and adverse effects on the upstream migration of fishes are caused.

Disclosure of Invention

The invention aims to provide a fishway inlet water replenishing and energy dissipating structure and a design method thereof, so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a fishway inlet water supplementing and energy dissipating structure comprises a water supplementing pipe, an energy dissipating pool, brackets, an energy dissipating cover plate and a water permeable grid; the water replenishing pipe is a water replenishing steel pipe, the energy dissipation pool is a water replenishing steel pipe outlet water gathering pool, the bracket is located at the top of the energy dissipation pool, and the bracket is used for providing a supporting effect for the energy dissipation cover plate.

Preferably, the energy dissipation cover plates are positioned on the bracket, gaps between the energy dissipation cover plates are different, so that the water supplementing outflow is relatively uniform, the water supplementing water flow enters the fishway from the gaps between the energy dissipation cover plates, and the large-scale turbulent vortex group is forcibly changed into the small-scale vortex group; and after the size of the vortex group is reduced, the viscous shear stress is easier to convert turbulent energy into fluid internal energy to be dissipated, so that the turbulent energy in the fishway is reduced, and the water-permeable grating is fixed on the energy dissipation cover plate.

Preferably, an unequal-interval distribution scheme of the energy dissipation cover plates is adopted, the seam width is adjusted to be an arrangement mode that the head side and the tail side of the energy dissipation pool are narrow and the middle of the energy dissipation pool is wide, the vertical flow velocity of each seam is uniform, the vortex size of the outflow section of each seam is relatively small, the viscous shear stress is easy to convert turbulent energy into fluid internal energy to be dissipated, and the turbulent energy in the fishway is reduced.

A design method of a fishway inlet water supplementing and energy dissipating structure comprises the following steps:

s1: under two working conditions of an energy dissipation cover plate and an energy dissipation cover plate, a macroscopic flow field of a water compensation energy dissipation pool under the conditions of water compensation flow and water compensation pipe outlet flow velocity is preliminarily recognized through a local physical model test;

s2: on the basis of a local physical model test S1, a three-dimensional hydrodynamic mathematical model and a k-epsilon two-stroke model adopted by a turbulent model are constructed;

s3: aiming at the test working condition of unfavorable combination, the water supplementing and energy dissipating schemes of different energy dissipating cover plate types are further calculated by a numerical simulation technical means, namely a three-dimensional hydrodynamic force mathematical model; evaluating the water replenishing and energy dissipating effects by means of the uniformity of the distribution of the flow field inside the fishway and the turbulent kinetic energy parameter of the hydraulic factor of the fishway being lower than 0.035m2/s 2;

s4: performing the physical model test again on the basis of S3, continuously refining the detailed structure of the water replenishing energy dissipation cover plate, and determining the final type of the energy dissipation cover plate

Preferably, the water replenishing body enters the fishway through secondary energy dissipation of the energy dissipation cover plate from the energy dissipation pool.

Preferably, in S1, the length a of the energy dissipation pool is preliminarily determined to be 2H to 3H, the height B is determined to be 1B to 2B, the height c of the water replenishing energy dissipation pipe from the pool bottom is determined to be 1/3B to 1/2B, H is the normal operating water depth of the fishway, and B is the clear width of the fishway pool chamber.

Preferably, in S2, the physical model measurement result under the S1 condition is used to verify the mathematical model, so that the mathematical model accurately reflects the water flow motion state.

Preferably, in S3, the turbulent energy may be the more direct hydraulic factor; the turbulent energy represents the kinetic energy carried by the fluid turbulence and reflects the intensity of the fluid turbulence; the turbulent energy expression is as follows:

wherein ui is the instantaneous velocity, m/s;is the time average velocity, m/s; u'_iIs the pulse velocity, m/s; u'_x、u′_y、u′_zThe pulse speeds along 3 different directions x, y and z are respectively, and the unit is m/s.

Compared with the prior art, the invention has the beneficial effects that:

the fishway energy dissipation pool is disordered in water flow state of water supply, three-dimensional structural characteristics of a flow field are quite complex, the size of the turbulent flow field is small, and conventional propeller-type flow velocity meters are adopted in a physical model test, so that the capturing and measuring capacity of flow field information is limited, but macroscopic flow field structural information can be provided. A physical model test can preliminarily recognize a macroscopic flow field of the water supplementing and energy dissipating pool, but the method is a deficient technical means for optimizing a water supplementing and energy dissipating scheme.

The length a of the energy dissipation pool is 2H-3H, and the height B is 1B-2B, so that water in the water supply pipe can fully roll in the energy dissipation pool; 1/3 b-1/2 b are taken from the height c of the water supplementing energy dissipation pipe from the bottom of the energy dissipation pool, the purpose is to ensure that the water in the energy dissipation pool has a certain thickness, fully and oppositely rushes the water flow in the water supplementing pipe, and the purpose of primary energy dissipation in the energy dissipation pool is achieved.

The water replenishing and energy dissipating pool is a 'threshold' for migratory fish, and it is not enough to evaluate whether the requirement of fish migration is met by only depending on the flow field observation result. The requirement of fish migration on the turbulent kinetic energy factor of water flow is high, the turbulent kinetic energy is an index representing the impulse kinetic energy of water flow, and the value cannot be obtained by existing observation equipment.

Developing a three-dimensional hydrodynamic force numerical simulation technology, verifying a mathematical model through physical model test data, analyzing detailed structures of a flow field of the energy dissipation pool on the basis, solving parameters such as turbulent energy and the like, and preferably selecting an energy dissipation cover plate scheme; and finally determining the type of the energy dissipation cover plate through a physical model test by an optimal design scheme, and enabling the water replenishing water body to enter the fishway through secondary energy dissipation of the energy dissipation cover plate from the energy dissipation pool, so that the disorder of the water body caused by water replenishing can be reduced to the maximum extent, and the smooth migration of the fishes in the fishway is ensured.

Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a cross-sectional schematic view of the structure of the present invention;

FIG. 3 is a schematic view of measuring point arrangement of a working condition 1 energy-dissipation-free cover plate scheme in the embodiment of the invention;

FIG. 4 is a schematic view of measuring point arrangement of a working condition 2 energy dissipation cover plate scheme in the embodiment of the invention;

FIG. 5 is a schematic side view of a three-dimensional solid model according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of an operating mode 3 energy dissipation cover plate in the embodiment of the invention;

FIG. 7 is a schematic view of a working condition 4 energy dissipating cover plate according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a calculated flow velocity distribution under condition 3 in an embodiment of the present invention;

FIG. 9 is a schematic diagram of the distribution of the turbulence energy of the flow field calculated under the working condition 3 in the embodiment of the present invention;

FIG. 10 is a schematic illustration of a calculated flow velocity profile for condition 4 in an embodiment of the present invention;

FIG. 11 is a schematic diagram of the calculated flow field turbulence energy distribution under condition 4 in the embodiment of the present invention;

FIG. 12 is a schematic view of an operating condition 5 energy-dissipating cover plate according to an embodiment of the present invention;

figure 13 is a schematic diagram of a working condition 6 energy dissipation cover plate in the embodiment of the invention.

In the drawings, the components represented by the respective reference numerals are listed below:

1. a water replenishing pipe; 2. an energy dissipation pool; 3. a bracket; 4. energy dissipation cover plates; 5. a water permeable grid.

Detailed Description

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 only a part of the embodiments of the present invention, and not all of the embodiments. 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.

Referring to fig. 1 to 4, the present invention provides a fishway inlet water replenishing energy dissipation structure and a design method thereof: the energy dissipation device comprises a water replenishing pipe 1, an energy dissipation pool 2, brackets 3, an energy dissipation cover plate 4 and a water permeable grid 5. The clear width B of the fishway pool chamber is 2.5m, and the normal operation water depth H is 2.5 m. The pipe diameter of a water replenishing pipe 1 serving as a water replenishing flow source is 60cm, the maximum water replenishing flow is 1m3/s, the outlet flow speed is 1m/s, the pipe diameter is vertically downward, and water in the pipe is discharged into an energy dissipation pool; wherein the length a of the energy dissipation pool 2 is 7m from 2H to 3H, the height B is 3m from 1B to 2B, the distance c from the bottom surface of the energy dissipation pool 2 is 1/3B to 1/2B, and the width is the width of the fishway pool body; the bracket 3 is positioned at the top of the energy dissipation pool 2 and provides a supporting function for the energy dissipation cover plate 4; gaps among the energy dissipation cover plates 4 are different, so that the water supplementing outflow is relatively uniform, water supplementing water flow enters a fishway from the gaps among the cover plates, and large-scale turbulent vortex masses are forcibly changed into small-scale vortex masses. After the size of the vortex group is reduced, the viscous shear stress is easier to convert turbulent energy into fluid internal energy to be dissipated, so that the turbulent energy in the fishway is reduced, and the migration of fishes is facilitated. The size of the water-permeable grille 5 is 2.5cm multiplied by 2.5cm, and the water-permeable grille is fixed on the energy dissipation cover plate 4, so that the fish in the fishway body can be effectively prevented from swimming into the energy dissipation pool 2.

A design method of a fishway inlet water supplementing and energy dissipating structure comprises the following steps:

s1, carrying out local model test on two schemes of water flow conditions with and without energy dissipation cover plates, actually measuring the flow rate by using a propeller type flow meter, wherein the arrangement conditions of the measuring points of the design scheme are shown in figures 3 and 4, and the actually measured results of the flow rate along the water flow direction are shown in the following table:

under the working condition of the energy dissipation free cover plate:

and a #1 measuring point of the section 0+01.10 is positioned at the bottom of the water supplementing energy dissipation pool, the flow speed is high, and the influence of outflow of the water supplementing pipe is obvious. The flow velocity of other observation sections such as 0+02.80 section #1 and 0+04.90 section #1 in the water replenishing energy dissipation pool is the maximum value of the flow velocity of different sections and different water depths. The 0+04.90 section near the surface (points #4 and # 5) showed a reflow. This shows that after the water supply pipe outflows, the main flow moves close to the bottom of the energy dissipation pool, and is influenced by the rising ridge of the energy dissipation pool, and backflow with a certain scale is generated near the surface layer. The water flows out of the energy dissipation pool and enters a downstream fishway, the flow velocity near the bottom is relatively low, the flow velocity near the surface layer is relatively high (the section of 0+ 011.00), and the flow velocity distribution is basically consistent with that of a common fishway pool chamber.

Under the working condition of the energy dissipation cover plate:

the 3 measuring points of the 0+01.10 section are arranged in the fishway at the upper part of the cover plate, the section flow is mainly the fishway flow, and therefore, the flow speed is relatively small. The cross section 0+02.80 has reverse flow velocity at the point #2, which is near the front edge of the cover plate, and the point #2 is below the cover plate, so the flow of the fishway flows through the cover plate and generates a certain scale of backflow. The flow velocity of the surface layer of the section 0+02.80 and the flow velocity of the surface layer of the section 0+04.90 are both low, and the surface layer of the section 0+04.90 also has backflow, which is caused by the fact that the backflow generated by the upward movement of the replenishing water flow along the raised ridge is intersected with the water flow of the fishway. The water flows out of the energy dissipation pool and enters a downstream fishway, the flow velocity near the bottom is relatively low, the flow velocity near the surface layer is relatively high (the section of 0+ 011.00), and the flow velocity distribution is basically consistent with that of a common fishway pool chamber.

After the cover plate is added, the phenomenon of 'turning over' of the water replenishing flow under the working condition of the energy dissipation-free cover plate disappears, but the flow field structure is still very complex. The flow field structure of the water replenishing energy dissipation pool is mainly characterized by small scale and complex change, and the complete flow field structure is difficult to capture by an actual measurement means; in addition, the water replenishing and energy dissipating pool is a 'threshold' for migratory fish, and it is not enough to evaluate whether the requirement of fish migration is met by only depending on the flow field observation result.

In conclusion, for the water replenishing and outflow condition with certain flow and flow rate, a physical model test can preliminarily recognize the macroscopic flow field of the water replenishing and energy dissipating pool, but the method is deficient as a technical means for optimizing a water replenishing and energy dissipating scheme. Therefore, a three-dimensional hydrodynamic numerical simulation technology must be developed very much, the model is verified through physical model test data, the detailed structure of the flow field of the energy dissipation pool is analyzed on the basis, turbulent kinetic energy parameters are solved, and optimization work of a water supplementing and energy dissipating scheme is further carried out.

S2: on the basis of a local physical model test S1, a three-dimensional hydrodynamic mathematical model and a k-epsilon two-stroke model adopted by a turbulent model are constructed. Dispersing by adopting a finite difference method; the simulation range is mainly a water-replenishing energy-dissipating pool with the length of 7.0m, the depth of 3.0m and the clear width of 2.5m, the upstream and downstream of the energy-dissipating pool are connected with a fishway pool chamber, and a three-dimensional solid model is shown in figure 5.

The calculation results of the flow velocity along the water flow direction of 4 sections such as 0+01.10, 0+02.80, 0+04.90, 0+07.00 and the like under the two schemes are respectively compared with the actual measurement results of a physical model test, the trend of the flow velocity of a digital model and an object model along the vertical distribution is basically consistent, and particularly, the simulation of the backflow is relatively accurate. The flow velocity difference along the water flow direction on the same vertical line is very large, the complexity of the flow field structure of the energy dissipation pool is verified, and a certain error between the calculation result of the flow velocity distribution of the vertical lines of part of the sections and an actually measured value can be accepted. In summary, the three-dimensional hydrodynamic mathematical model established by the invention can accurately depict the flow field structure of the energy dissipation pool and can be used as a technical means for optimizing a water replenishing and energy dissipating scheme.

S3: selecting the most unfavorable working condition of the combination of the running water depth and the water replenishing flow of the fishway: the water replenishing flow of the water replenishing pipe is close to the upper limit water replenishing capacity (the value is obtained according to 2.0m 3/s), meanwhile, the running water depth of the fishway is relatively small, and the flow combination working condition is the most unfavorable combination working condition. And based on the working condition, the fishway water supplementing and energy dissipating cover plate scheme is continuously optimized through a numerical simulation technology.

Meter digital-to-analog calculation condition selection

The calculated flow field distribution and turbulent energy distribution under various working conditions are shown in the figures 8-11:

in the aspect of a fishway section flow field, the working condition 4 is compared with the working condition 3, the water outlet seam of the cover plate at the tail part of the energy dissipation water replenishing pool is narrowed or even cancelled, and the outflow flow rate of each water outlet seam is forced to be relatively uniform. Under the working condition 4, a channel suitable for fish migration is arranged in the plane flow field, more importantly, the larger area turbulence energy is still less than 0.035m2/s2 near the side wall within the range of 0.875H-0.225H of the water depth of the fishway, the water replenishing outflow is relatively uniform by adjusting the seam width of the cover plate, and the turbulence energy of the water replenishing flow of the fishway can also be reduced.

S4: and performing the physical model test again on the basis of S3, continuously refining the detailed structure of the water supplementing energy dissipation cover plate, and determining the final type of the energy dissipation cover plate.

Working condition 5: the cover plate is 7.00m long, 2.50m wide and 17.5m2 in total area. The widths of the left side edge strip and the right side edge strip are respectively 0.45 m; the cover plate strips are 21 blocks, the width of each cover plate strip is 0.2m (20 blocks), and the width of each cover plate strip is 0.46m (1 block); 17 slits with width of 0.30m (1), 0.14m (16), water passing area of 4.06m2, accounting for 23.22% of the total area, see fig. 12. The measured vertical flow rates are shown in the table below.

Under the scheme, the vertical flow velocity distribution of each seam is uneven, the vertical flow velocity of the seams at the head and the tail of the energy dissipation pool is larger, and the vertical flow velocity of the seam at the middle part of the energy dissipation pool is smaller. The width of the seam at the head and the tail of the energy dissipation pool needs to be further reduced, and the seam width of the cover plate in the middle of the energy dissipation pool is increased.

Working condition 6: namely, the cover plate strip 21, 0.20m (20 pieces) wide and 0.46m (1 piece) wide; 17 slits with width of 0.05m (2), 0.29m (5) and 0.10m (11), water passing area of 4.06m2 and total area of 23.22%, see fig. 12, and measured vertical flow rate as shown in the following table.

The cover plate unequal interval distribution scheme is adopted, the seam width is adjusted to be an arrangement mode that the head side and the tail side of the energy dissipation pool are narrow and the middle is wide, the vertical flow velocity of each seam is uniform, the vortex size of the outflow section of each seam is relatively small, the viscous shear stress is easy to convert turbulent energy into internal fluid energy to be dissipated, the turbulent energy in the fishway is reduced, and the migration of fishes is facilitated.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.