Auxiliary facility and method for recovering fish resources in an open water intake channel

Abstract

The present invention relates to an auxiliary facility and method for recovering fish resources in an open water intake channel, comprising: an inlet of an attracting flow channel arranged on a side wall of one side of the open water intake channel, a slope arranged inside the attracting flow channel, the lower end of the slope being inside the open water intake channel, and the upper end of the slope being outside the open water intake channel; an inducing water flow flowing into the attracting flow channel is arranged at the upper end of the slope; the outlet of the attracting flow channel is connected to a steady flow water area, and a releasing device is arranged in the steady flow water area. The present invention guides a large number of fish that mistakenly enter the open water intake channel out of the open channel by induction, which protects the fish and prevents the open water intake channel from being blocked due to the inhalation of a large number of fish, causing a shutdown accident of the power station, thereby avoiding huge economic losses, and more importantly, ensuring the safe operation of the power plant.

Description

Technical Field

[0001] The present invention relates to an auxiliary facility and method for recovering fish resources in an open water intake channel, a hydraulic project and method for protecting fish ecology in the process of water intake in a power plant, a measure for reducing the impact of open channel water intake on fish resources, reducing the risks of water intake roll load, roll blockage and nuclear power cold source, so as to improve the safety and environmental friendliness of water intake project operation, and an auxiliary facility and method for recovering fish resources in an environment-friendly open water intake channel that takes into account factors such as fish behavior characteristics and water intake flow field distribution laws. Background Art

[0002] In recent years, there have been many cases of blockages in water intakes at nuclear power plants. Organisms causing blockages include economic fish, jellyfish, algae, etc. Such incidents have forced nuclear power plants to shut down, stop reactors, or operate at reduced power, causing huge economic losses. More importantly, they have seriously threatened the safety of nuclear power operations. At the same time, against the backdrop of the vigorous development of ecological civilization construction, the ecological impact of nuclear power operations has become a focus of widespread concern in the development of the industry. The damage caused by nuclear power water intake to organisms, especially fish resources, has affected the harmonious development of nuclear power and the marine environment. Research on the impact of nuclear power water intake on fish began in the 1970s. Studies have shown that after fish enter the nuclear power water intake system, their survival rate is low and their mortality rate is high, which directly leads to the loss of fish resources caused by water intake. For example, the total operating power of the Bay Shore Nuclear Power Plant in the United States is 631MW, and the water intake is 33m 3 / s, and monitoring results show that the power plant entrains 4.6×10 adult fish per year. 7 At present, the main measures to reduce the impact of water intake on fish resources are to reduce the flow rate of water intake, reduce the amount of water intake, and set up barrier nets around the water intake. However, there are no corresponding facilities in the open water channel to recycle the fish resources that have entered the open channel to reduce the impact of water intake on fish.

[0003] While ensuring the safety of the cooling source, nuclear power plants need to protect marine life during the water intake process and reduce biological losses caused by water intake. At present, most of the existing nuclear power plants have ignored the impact of water intake facilities on fish. Some nuclear power plants have gradually started to record the biomass of fish in water intake rolls, but the existing nuclear power plants have not built fish resource recovery facilities. It is urgent to consider the setting of fish resource recovery facilities in water intake facilities. How to recycle and protect fish entering the water intake open channel, reduce water intake rolls, and prevent water intake blockage is a problem that needs to be solved. Summary of the invention

[0004] In order to overcome the problems of the prior art, the present invention proposes an auxiliary facility and method for recovering fish resources in an open water intake channel. The facility and method set an attracting flow channel and an inducing water flow on one side of the water inlet of the open water intake channel to attract fish that have mistakenly entered the open water intake channel to the specially set attracting flow channel, and use the attracting flow channel to guide the fish to the stable flow water area outside the open water intake channel, and then guide or catch the fish in the stable flow water area and release them into natural waters.

[0005] The objective of the present invention is achieved as follows: an auxiliary facility for recovering fish resources in an open water intake channel, comprising: an inlet of an attracting flow channel arranged on the side wall of one side of the open water intake channel, the interior of the attracting flow channel being arranged as a slope, the lower end of the slope being in the open water intake channel, and the higher end of the slope being outside the open water intake channel; an induced water flow flowing into the attracting flow channel being arranged at the higher end of the slope; the outlet of the attracting flow channel being connected to a steady flow water area, a release device being arranged in the steady flow water area, and an interception net being arranged downstream of the inlet of the attracting flow channel.

[0006] Furthermore, the direction of the induced water flow is greater than or equal to 90 degrees to the direction of the water flow in the open water intake channel.

[0007] Furthermore, the water intake open channel includes two parallel side walls forming a straight segment channel, and a 90-degree elbow is provided at the end of the straight segment channel so that the inlet of the water intake open channel is parallel to one side of the side wall, and the inlet of the induced flow channel is arranged on one side of the recirculation area of ​​the water intake open channel at a position 2-3 inlet widths away from the inlet of the water intake open channel, and the induced water flow perpendicular to the water intake open channel can penetrate the recirculation area in the water intake open channel.

[0008] Furthermore, the slope of the attracting channel should be less than 1:10, the width should not exceed 5m, and the water depth should not be less than 0.5m.

[0009] Furthermore, the flow rate of the induced water flow is 1 / 15 of the flow rate of the water in the water intake open channel.

[0010] Furthermore, the release device is a guiding fishway.

[0011] Furthermore, the releasing device is a fishing device.

[0012] An auxiliary method for recovering fish resources in an open water intake channel using the above-mentioned facility, the steps of the method are as follows:

[0013] Step 1, establish a three-dimensional flow field model of the water intake water area: establish a three-dimensional flow field model of the water intake water area including the water intake open channel, obtain the water intake water area topography, environmental water flow conditions, shoreline characteristics, and the design size, water intake flow rate, water intake flow rate, and water intake depth of the water intake open channel, establish the water intake flow field model, divide the calculation grid, determine the boundary conditions and initial conditions of the flow field simulation, and select appropriate calculation parameters to simulate the flow field changes including the water intake open channel and the water area affected by the water intake; the flow field calculation control equation is as follows:

[0014]

[0015] Where: u is the time-averaged velocity, t is time, p is pressure, ρ is water density, μ eff is the turbulent effective viscosity, k is the turbulent kinetic energy, I is the second-order unit tensor, α k is the turbulent kinetic energy Prandtl number, ε is the turbulent dissipation rate, α ε is the turbulent dissipation rate Prandtl number, G k is the term for turbulent kinetic energy caused by the average velocity gradient, C 1ε and C 2ε is a constant coefficient;

[0016] Step 2: Verify the flow field model based on the experimental results of the physical model: Establish a corresponding normal scale physical model indoors, measure the flow velocity and direction of each characteristic section or characteristic point, and compare and verify with the simulation results of the mathematical model. The calculated values ​​are in good agreement with the measured values, that is, the constructed mathematical model can reflect the basic characteristics of the flow field distribution in the water intake open channel, and the location of the fish resource recovery facility in the open channel, the induced water flow rate and the configuration size can be determined accordingly;

[0017] Step 3, selection of the location of the attracting channel: Based on the flow field distribution analysis and combined with the swimming ability and behavioral characteristics of the fish entering the open channel, the inlet of the attracting channel is arranged near the shore where the flow velocity is low and the return flow is weak in the center of the recirculation area in the open channel. The outlet of the attracting channel can be set in the steady flow area with slow flow velocity and stable water flow outside the open channel near the shore, so as to serve as a temporary storage location for the fish before release;

[0018] Step 4, configuration, size and induced water flow rate of the luring channel: Based on the flow field distribution analysis, combined with the swimming ability and behavioral characteristics of the fish entering the open channel, the flow velocity and flow pattern in the luring channel, the configuration, size and induced water flow rate of the luring channel are comprehensively determined;

[0019] Step 5: Modify the physical model test to further verify the flow field: According to the recommended scheme of the attractant flow channel proposed in step 4, modify the physical model in step 2, add an attractant flow channel and a water supply system at the corresponding position in the open channel, use the physical model test to further conduct flow field research and analysis, and verify the suitability of the fish resource recovery facility;

[0020] Step 6, setting up auxiliary interception facilities: according to the results of the flow field analysis in the open channel, add auxiliary interception nets at the downstream of the entrance of the attracting channel in the open channel, where the water flow is more uniform and the flow velocity is lower. The interception nets should be arranged in full section to make it easier for fish to find the entrance of the attracting channel when swimming along the nets;

[0021] Step 7, fish luring and recovery process: open the luring flow channel, form a jet at the entrance of the luring flow channel that penetrates the water recirculation area in the open channel to the mainstream area, use the fish's countercurrent swimming characteristics to guide the fish in the mainstream area and the recirculation area to gather at the entrance of the luring flow channel, and then enter the luring flow channel, and use the slope in the luring flow channel to form a stable reverse flow field with a uniform and gradual flow rate, lure the fish to go upstream into the steady flow water area at the outlet of the luring flow channel, and then release the fish in the steady flow water area to the natural water area outside the open channel through the release device.

[0022] The advantages and beneficial effects of the present invention are as follows: the present invention sets an attracting flow channel and a fish attracting water flow on one side of the water inlet of the water intake open channel, attracts the fish that mistakenly enter the water intake open channel to a specially set recovery auxiliary facility, uses the facility to guide the fish to the stable flow water area outside the water intake open channel, and guides or catches the fish in the stable flow water area to the natural water area outside the open channel. The present invention guides a large number of fish that mistakenly enter the water intake open channel out of the open channel by induction, which protects the fish and prevents the water intake open channel from being blocked due to the inhalation of a large number of fish, causing a power station shutdown accident, thereby avoiding huge economic losses, and more importantly, ensuring the safe operation of the power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 is a schematic structural plan view of the recycling facility according to the first embodiment of the present invention;

[0025] Figure 2 is a schematic diagram of the elevation structure of the induction flow channel of the recycling facility according to the first embodiment of the present invention, Figure 1 Enlarged image in the middle AA direction;

[0026] Figure 3 is a schematic diagram of the angle between the induced water flow and the open channel water flow of the recovery facility according to the second embodiment of the present invention, Figure 1 Enlarged view of point C in the middle;

[0027] Figure 4 is a flow field distribution diagram of the recovery facility described in the third embodiment of the present invention;

[0028] Figure 5 It is a flow chart of the method described in Embodiment 8 of the present invention. DETAILED DESCRIPTION

[0029] Embodiment 1:

[0030] This embodiment is an auxiliary facility for recovering fish resources in an open water intake channel. Figure 1 As shown. This embodiment includes: an inlet 201 of an attracting flow channel 2 is arranged on the side wall of one side of an open water intake channel 1, a slope 202 is arranged inside the attracting flow channel, the lower end of the slope is inside the open water intake channel, and the upper end of the slope is outside the open water intake channel; an inducing water flow B is arranged at the upper end of the slope to flow into the attracting flow channel, and the flow direction of the inducing water flow B is perpendicular or nearly perpendicular to the main water intake direction D in the open water intake channel; the outlet 203 of the attracting flow channel is connected to a steady flow water area 3, a release device 4 is arranged in the steady flow water area, and an interception net 5 is arranged downstream of the inlet of the attracting flow channel.

[0031] The basic idea of ​​this embodiment is to solve the problem of recycling fish resources entering the open channel for water intake, reduce the impact of the water intake operation of the power plant on fish resources, and realize the ecological operation of the water intake of the power plant. This embodiment tries to create a flow state inside the open channel that is conducive to the fish entering the open channel to find and enter the luring channel, such as: using the outflow of the luring channel to create a countercurrent environment based on the countercurrent habit of fish swimming, among which it is better to directly connect with the mainstream of the open channel, so as to induce fish to find and enter the inside of the luring channel; it is advisable to consider adding auxiliary interception nets at the section where the water flow is more uniform (and the flow rate is smaller) on the downstream side of the entrance of the luring channel, so that fish can easily find the luring channel while swimming along the net, that is, the flow direction near the outlet of the luring channel presents a certain countercurrent environment and the flow rate meets the fish's preference for flow rate. In order to effectively attract fish to gather at the entrance of the luring channel, the luring channel needs to use sufficient induced water flow, which will have a certain impact on the economy of the project operation.

[0032] The water intake open channel is an open channel set on the bank and composed of two parallel side walls. The top of the open channel usually adopts a curved section to adapt to the environmental water flow. Figure 1 The environmental current is the current along the shore 01 channel ( Figure 1 The direction of flow is indicated by the arrow E in the middle), and the curved section of the open channel side wall is 90 degrees, which is a typical open channel inlet. When the power plant is built on the riverside and uses river water as the cooling water source, E is a unidirectional flow; when the power plant is built on the seashore and uses seawater as the cooling water source, the direction of the environmental water flow is a two-way reciprocating tide along the coast, that is, there is flow in the direction of E (high tide) and there is also environmental flow in the opposite direction of E (i.e. low tide); but due to the influence of the open channel 103 structure on the external environmental flow barrier, the flow field distribution law of the straight embankment section in the open channel is similar under high tide, low tide and in the river, that is, the distribution law of the main water intake area and the return flow area in the open channel is consistent.

[0033] The location of the attracting channel needs to be determined through physical model and computer hydrodynamic mathematical model flow field analysis, such as Figure 1 For the elbow open channel, the attracting channel can be set at a position close to the shore from the entrance of the open channel. According to the flow field analysis, this is a backflow area with a small average flow rate. It is easier to create a jet environment that attracts fish by adding external water flow, thereby inducing fish to gather at the entrance of the attracting channel.

[0034] The induction channel is a ramp to induce fish to swim upstream into the stable flow area. Figure 2 As shown in the figure, the lower end of the ramp is the fish inlet and the higher end is the fish outlet. Therefore, water needs to flow from high to low in the ramp and form a jet toward the open channel ( Figure 1 , 2 In order to generate this jet, it is necessary to use artificial means such as water pumps to extract the induced flow from the end of the open channel and inject water into the induced flow channel to generate induced water flow, so that after entering the open channel through the induced flow channel, it can form a horizontal flow that penetrates the open channel recirculation area to the mainstream ( Figure 1 The water flow of the arrow D in the middle, under normal circumstances, the induced water flow can be one-fifteenth of the open channel water intake flow, or a little larger. The induced water flow entering the open channel can be perpendicular to the mainstream direction of water intake, which plays a better guiding role, or it can be biased to a certain angle in the mainstream direction, but the angle should be close to 90°, and it should not be too biased, otherwise the fish attracting effect will be easily weakened. A steady flow pool is specially set at the outlet of the attracting channel.

[0035] The release device can be a device specifically used for catching fish, which is used to collect fish that enter the stable water area and send them back to the natural water area to form an ecological balance. A special fish pump can also be used to pump the fish back to the natural water area.

[0036] A full-section interception facility is provided in the open channel downstream of the entrance of the attracting channel to intercept and assist fishes to gather at the entrance of the attracting channel. The interception net is used to guide the fishes that miss the entrance of the attracting channel to swim along the net, gather at the entrance of the attracting channel, and then enter the attracting channel. The interception net itself is a standard configuration of the water intake open channel, but it has a special meaning in this embodiment, that is, to intercept the fishes that miss the attracting channel and encourage the fishes to swim along the net to the entrance of the attracting channel under the guidance of the countercurrent water flow.

[0037] It should be noted that the attracting channel is a channel for leading fish that have mistakenly entered the open water intake channel out of the open water intake channel. It can be called a fishway, but it is not a fishway in the traditional sense set up to solve the problem of dams blocking migratory fish. Therefore, this embodiment is called an attracting channel. The attracting channel takes fish as the main consideration, so the definition of the entrance and exit is determined by the swimming direction of the fish. The end where the fish enters the attracting channel is called the entrance, and the other end is called the exit. This title is opposite to the direction of water flow in the attracting channel. The water flows out at the entrance (lower end of the ramp) of the attracting channel and flows in at the exit (higher end of the ramp).

[0038] The left and right described in this embodiment and the following embodiments are determined according to the direction of water flow in hydraulics, that is, in hydraulics, facing the downstream of the water flow is the positive direction. For a river, the left hand is the left bank of the river, and the right hand is the right bank of the river. The left and right descriptions of this embodiment still follow this principle.

[0039] Embodiment 2:

[0040] This embodiment is an improvement of the first embodiment and is a refinement of the first embodiment regarding the induced water flow. The angle α between the induced water flow direction B described in this embodiment and the water flow direction D in the water intake open channel is greater than or equal to 90 degrees. Figure 3 shown.

[0041] The jet direction of the induced water flow is mainly related to the direction of the outlet of the induced flow channel. Therefore, after the induced flow channel is built, the direction of the induced water flow is basically determined. Therefore, experiments should be carried out in advance on a certain size and a certain type of fish to determine the best angle.

[0042] Embodiment three:

[0043] This embodiment is an improvement of the above embodiment and is a refinement of the above embodiment regarding the water intake open channel. The water intake open channel described in this embodiment includes two parallel side walls 101 and 102 forming a straight channel segment, and a 90-degree elbow 103 is provided at the end of the straight channel segment ( Figure 1 The left side wall where the middle elbow is actually connected) makes the inlet of the water intake open channel parallel to one side wall, and the 90-degree elbow makes the water flow entering the water intake open channel form a mainstream area and a recirculation area in the straight channel segment. The inlet of the induced flow channel is set at a position 2-3 inlet widths away from the inlet of the water intake open channel on one side of the recirculation area of ​​the water intake open channel. The induced water flow perpendicular to the water intake open channel can penetrate the recirculation area in the water intake open channel. Figure 1 As shown, d is the inlet width of the water intake open channel, and l is the distance between the inlet of the inducement channel and the inlet of the water intake open channel. For example: the inlet width d = 200m, and the flow channel is located at about l = 400m in the middle of the open channel.

[0044] The embodiment used Figure 1 The water intake open channel with a 90-degree elbow at the top is shown in the figure. By building a 1:100 physical model and a computer flow field simulation model, the internal and external water flows of this open channel are simulated to form the internal and external flow field distribution diagram of the open channel, as shown in Figure 1. Figure 4As shown in the figure. Through the analysis of the flow field distribution map, the attracting channel is arranged on the left side of the water intake open channel and in the nearshore area. This area is located in the recirculation area on the left side of the open channel, and the entrance of the attracting channel is located in the shore area of ​​the recirculation center. The recirculation area has a weak flow velocity, and the right side is the mainstream area, which has a high flow velocity and a stable flow direction and is not suitable for fish to stay. Fish with certain swimming ability may swim along the mainstream to the outside of the open channel driven by the countercurrent habit. Some fish with relatively weak flow ability are more inclined to swim in the suitable flow velocity area near the recirculation area based on their preference for flow velocity. Therefore, the attracting channel is arranged in the nearshore position of the weak area in the center of the recirculation area, and a certain flow rate is set upstream of the attracting channel to create a countercurrent and more suitable flow velocity environment for fish, inducing fish to actively swim to this area, so as to induce fish to gather here, and cooperate with subsequent collection measures (such as fish pumps, etc.) to guide fish out of the open channel, so as to reduce the damage to marine organisms caused by rolling and clogging, and thus protect marine biological resources.

[0045] Figure 4 It is a schematic diagram of the flow field distribution of the open water intake channel described in this embodiment. The right side of the open channel is the mainstream area, and the left side is the recirculation area. A channel with a slope passes through the side wall of the open channel to form an induced flow channel, and an enclosed steady flow pool is built. A fishing device or fish suction equipment is set in the pool, and a water pump is added at the outlet of the induced flow channel to extract the induced flow from the end of the open channel to form a complete fish resource recovery system.

[0046] Embodiment 4:

[0047] This embodiment is an improvement of the above embodiment and a refinement of the above embodiment regarding the attracting flow channel. The attracting flow channel described in this embodiment has a slope gradient less than 1:10, a width less than 5m, and a water depth greater than 0.5m.

[0048] The slope gradient of the luring channel is related to the ability of fish to swim and should be selected based on the species, size, growth period, swimming ability and flow velocity preference of the main fish in the local environment. The swimming ability and flow velocity preference of fish can be obtained through existing research or by conducting indoor experiments on fish swimming ability and flow velocity preference.

[0049] Embodiment five:

[0050] This embodiment is an improvement of the above embodiment and a refinement of the above embodiment regarding the induced water flow. The flow rate of the induced water flow described in this embodiment is 1 / 15 of the flow rate of the water flow in the water intake open channel.

[0051] The flow rate of the induced water flow should not be too large or too small, and should be adapted to the flow rate in the water intake open channel. If it is too large, it will increase the water intake and operation costs of the power plant and reduce the economic efficiency of power generation; if it is too small, it will not be possible to form a fish-attracting water flow that runs through the recirculation area to the mainstream. In this embodiment, the flow rate of the induced flow channel is 1 / 15, for example: the water intake flow rate is 300m3 / s, flow rate of the induced flow channel is 20m 3 / s to avoid affecting the normal operation of the open water intake channel and achieve a better fish attracting effect.

[0052] Embodiment six:

[0053] This embodiment is an improvement of the above embodiment and a refinement of the release device of the above embodiment. The release device described in this embodiment is a guide fishway.

[0054] A special stabilizing pool is set up at the outlet of the luring channel, and a small canal is used as a fishway to guide the fish entering the stabilizing water area to a location away from the open water intake channel in order to protect the ecological environment.

[0055] Embodiment seven:

[0056] This embodiment is an improvement of the above embodiment and a refinement of the release device of the above embodiment. The release device described in this embodiment is a fishing device.

[0057] Fish traps are set up in the steady-flow waters to catch the fish stranded in these waters and then transport them to natural waters far away from the open water intake channel so that the fish can continue to survive. Fish traps can be fishing nets, fish pumps and other facilities.

[0058] Embodiment eight:

[0059] This embodiment is an auxiliary method for recovering fish resources in an open water intake channel using the recovery facilities described in the above embodiments.

[0060] The steps of the method are as follows: Figure 5 As shown:

[0061] Step 1, establish a three-dimensional flow field model of the water intake area: establish a three-dimensional flow field model of the water intake area including the water intake open channel, obtain the water intake area topography, environmental water flow conditions, shoreline characteristics, and the design size, water intake flow, water intake flow rate, and water intake depth of the water intake open channel, establish the water intake flow field model, divide the calculation grid, determine the boundary conditions and initial conditions of the flow field simulation, and select appropriate calculation parameters to simulate the flow field changes including the water intake open channel and the water intake affected area. The flow field calculation control equation is as follows:

[0062]

[0063]

[0064] Where: u is the time-averaged velocity, t is time, p is pressure, ρ is water density, μ eff is the turbulent effective viscosity, k is the turbulent kinetic energy, I is the second-order unit tensor, α k is the turbulent kinetic energy Prandtl number, ε is the turbulent dissipation rate, αε is the turbulent dissipation rate Prandtl number, G k is the term for turbulent kinetic energy caused by the average velocity gradient, C 1ε and C 2ε are constant coefficients, which are 1.42 and 1.68 respectively.

[0065] Step 2, verify the flow field model based on the experimental results of the physical model: establish the corresponding normal scale physical model indoors, measure the flow velocity and direction of each characteristic section or characteristic point, and compare and verify with the simulation results of the mathematical model. The calculated values ​​are in good agreement with the measured values, that is, the constructed mathematical model can reflect the basic characteristics of the flow field distribution in the open water intake channel, and can be used to determine the location of the fish resource recovery facility in the open channel, the induced water flow rate and the configuration size.

[0066] The physical model established in the laboratory must comply with the following principles: it must meet the requirements of flow field similarity, and the inlet and outlet sections of the model must have sufficient transition areas to ensure similarity of inlet and outlet flows. The model design should focus on gravity similarity, taking into account the requirements of resistance similarity and water buoyancy similarity. In order to ensure that the model flow pattern is similar to the prototype, it is necessary to ensure that the model water flow Reynolds number is greater than the critical Reynolds number and that the model water body enters the self-simulation area. A large-scale normal physical model of 1:100 is usually used to mainly simulate environmental flows and flow field distribution in open water intake channels.

[0067] Due to the different environments around each power plant, there are various forms of water intake open channels set up on the seashore or riverbank. To build an effective attracting channel, you can first build a physical model in proportion (or directly map the flow field distribution inside and outside the open channel), and then build a computer-simulated hydrodynamic mathematical model (flow field simulation model) based on the data of the physical model or the actual environment measurement data, and then simulate and correct the flow field in the computer based on the flow field of the physical model. The purpose of establishing the physical model and the flow field simulation model is to find the appropriate location for setting up the attracting channel based on the flow field simulation results.

[0068] Figure 4 This is a typical flow field distribution of a seaside (or riverbank) water intake open channel. The water intake open channel is inserted vertically from the seashore coast into the sea. The flow direction of the sea current is perpendicular to the open channel. Therefore, a 90-degree elbow is set at the top of the open channel, and the opening faces the direction of the sea current. There are usually two types of environmental flow. One is the river bank, where the environmental flow is unidirectional, such as Figure 4 As shown, it flows from the right side of the figure to the left side of the figure. The other is the seaside, where the direction of the environmental water flow is reciprocating, that is, the direction of the water flow E is bidirectional, and the distribution of the flow field of the straight embankment section in the open channel in the reciprocating flow environment is approximate.

[0069] pass Figure 4It can be observed that: the water flow makes a 90-degree turn when entering the open channel, so that the water flow in the open channel forms a mainstream area on the right side (the mainstream facing downstream is positive, the same below; left and right are relative to the downstream direction). The flow velocity in the mainstream area is high and the flow direction is stable, which is not suitable for fish to stay. The left side of the open channel forms a recirculation area, where the flow velocity is weak. Fish with swimming ability tend to swim to the suitable flow velocity area near the recirculation area based on their preference for flow velocity.

[0070] Step 3, selection of the location of the luring channel: Based on the analysis of the flow field distribution and the swimming ability and behavioral characteristics of the fish entering the open channel, the fish of interest in this case are small fish such as anchovies and Conner's mullet, which have a certain swimming ability and a swimming speed greater than 0.2 m / s. They like to swim against the current and prefer a flow rate of 0.2 m / s-1.3 m / s. Select the nearshore location in the weak area of ​​the central backflow zone in the open channel ( Figure 4 The inlet of the attracting channel is arranged on the right side of the middle open channel, and the outlet of the attracting channel is arranged in a steady flow area with a slow flow velocity and stable water flow near the shore outside the open channel. A permeable enclosure can be set in the steady flow area to prevent the fish that enter the area from escaping and then mistakenly entering the open channel again. A certain flow rate (such as a water pump) is set at the outlet of the attracting channel, and a penetrating flow that is perpendicular or nearly perpendicular to the flow direction of the mainstream area in the open channel is formed at the inlet of the attracting channel to attract fish, and a countercurrent and more suitable flow velocity environment (uniform steady flow water area) is created for fish in the attracting channel, so as to induce fish to actively swim to the steady flow water area outside the outlet of the attracting channel as a temporary storage position for fish before releasing, and cooperate with other subsequent collection measures (fish pump, etc.) to guide the fish out of the open channel, so as to reduce the damage to fish caused by water intake, thereby protecting resources.

[0071] Step 4, the configuration, size and induced water flow rate of the luring channel are set: Based on the flow field distribution analysis, combined with the swimming ability and behavioral characteristics of fish entering the open channel, the flow velocity and flow state in the luring channel, the configuration, size and induced water flow rate of the luring channel are comprehensively determined.

[0072] The attracting channel is set outside the water intake open channel and connected to the water intake open channel. The inlet of the attracting channel is connected to the side wall of one side of the open channel. The configuration of the attracting channel is: a water tank with a slope at the bottom, the lower end of the slope is in the water intake open channel, and the upper end of the slope is outside the water intake open channel. The slope of the attracting channel (i.e. the sloped water tank) should not exceed 1:10, the width should not exceed 5m, the water depth should not be less than 0.5m, and the length is determined comprehensively according to the construction conditions of the power plant. In this case, the length of the attracting channel is 50m. The outlet of the attracting channel is connected to a steady flow area.

[0073] An induced water flow rate is set at the outlet of the induced flow channel, and a penetrating flow that is perpendicular or nearly perpendicular to the flow direction of the mainstream area in the open channel is formed at the inlet of the induced flow channel to induce fish to actively swim to the induced flow channel, thereby inducing fish to gather here.

[0074] Select the flow rate of the induced flow channel: According to the characteristics of fish in the open channel environment, comprehensively consider the upstream swimming ability of several larger fish populations, and consider the slope of the induced flow channel and the flow velocity formed to determine the induced water flow rate of the induced flow channel.

[0075] That is, set the appropriate flow rate of the attracting channel to form a water flow velocity and flow pattern that can attract and attract fish. Because it involves the slope of the attracting channel, it also affects the location selection of the attracting channel: the attracting channel is arranged on the right side of the water intake channel and in the nearshore area. This area is located in the backflow area on the right side of the open channel, and the outlet of the attracting channel is located in the stable flow area formed by the side wall outside the open channel and a backflow along the coast, such as Figure 4 shown.

[0076] Different open channel forms and their surrounding environments can set different fish attracting flow rates to form different flow fields in local areas of the open channel. Figure 4 The flow field distribution formed by the elbow open channel and the surrounding environment flow is shown in the figure. Figure 1 The layout of the attractant flow channel depicted has a flow rate of 20m 3 / s, an induced water flow can be formed that runs through the backflow zone, luring fish to the vicinity of the entrance of the induced flow channel.

[0077] Step 5: Modify the physical model test to further verify the flow field: According to the recommended solution for the attractant flow channel proposed in step 4, modify the physical model in step 2, add attractant flow channels and water supply systems at the corresponding positions in the open channel, use physical model tests to further conduct flow field research and analysis, and verify the suitability of fish resource recovery facilities.

[0078] An attracting flow channel is established in the physical model, and a simulated fish attracting experiment is carried out based on the determined data. A flow field simulation model is used to perform auxiliary flow field analysis to verify its suitability.

[0079] Step 6, setting up auxiliary interception facilities: Based on the results of the flow field analysis in the open channel, an auxiliary interception net is added downstream of the entrance of the luring channel in the open channel, where the water flow is more uniform and the flow velocity is lower. The interception net is arranged in the full cross-section, that is, from the water surface to the bottom of the water, to enable fish to find the entrance of the luring channel more easily while swimming along the net.

[0080] The first consideration in setting up the interception net is to enable fish to quickly identify the entrance of the attracting channel. The flow direction near the entrance of the attracting channel presents a certain countercurrent environment and the flow rate meets the fish's preference for flow rate.

[0081] Step 7, fish luring and recovery process: open the luring flow channel, form a jet at the entrance of the luring flow channel that penetrates the water recirculation area in the open channel to the mainstream area, utilize the fish's countercurrent swimming characteristics and corresponding auxiliary facilities to induce the fish in the mainstream area and the recirculation area to swim toward the entrance of the luring flow channel, and utilize the slope in the luring flow channel to form a stable reverse flow field with a uniform and gradual flow rate, lure the fish to go upstream into the steady flow water area at the outlet of the luring flow channel, and then release the fish in the steady flow water area to the natural water area outside the open channel through the release device.

[0082] This step is the entire process of luring and releasing, so that the main fish populations that have entered the open channel due to water intake can be released back to natural waters through this facility, reducing the impact of water intake on fish resources and playing a role in protecting the ecological environment.

[0083] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention and is not a limitation. Although the present invention has been described in detail with reference to the preferred arrangement scheme, a person skilled in the art should understand that the technical solution of the present invention (such as the form of the open water intake channel, the configuration and shape of the inducement flow channel, the sequence of steps, etc.) may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. An auxiliary method for recovering fish resources in an open water intake channel, characterized in that: The auxiliary method uses auxiliary facilities for recovering fish resources in an open water intake channel, and the auxiliary facilities include: an inlet of an attracting flow channel arranged on a side wall of one side of the open water intake channel, a slope is arranged in the attracting flow channel, the lower end of the slope is in the open water intake channel, and the upper end of the slope is outside the open water intake channel; an induced water flow flowing into the attracting flow channel is arranged at the upper end of the slope; the outlet of the attracting flow channel is connected to a steady flow water area, a release device is arranged in the steady flow water area, and an interception net is arranged downstream of the inlet of the attracting flow channel; the steps of the auxiliary method are as follows: Step 1, establish a three-dimensional flow field model of the water intake water area: establish a three-dimensional flow field model of the water intake water area including the water intake open channel, obtain the water intake water area topography, environmental water flow conditions, shoreline characteristics, and the design size, water intake flow rate, water intake flow rate, and water intake depth of the water intake open channel, establish the water intake flow field model, divide the calculation grid, determine the boundary conditions and initial conditions of the flow field simulation, and select appropriate calculation parameters to simulate the flow field changes including the water intake open channel and the water area affected by the water intake; the flow field calculation control equation is as follows: in: u is the average speed, t For time, p For pressure, ρ is the water density, μ eff is the turbulent effective viscosity, k is the turbulent kinetic energy, I is the second-order unit tensor, α k is the turbulent kinetic energy Prandtl number, ε is the turbulent dissipation rate, α ε is the turbulent dissipation rate Prandtl number, G k is the term for turbulent kinetic energy caused by the mean velocity gradient, C 1ε and C 2ε is a constant coefficient; Step 2: Verify the flow field model based on the experimental results of the physical model: Establish a corresponding normal scale physical model indoors, measure the flow velocity and direction of each characteristic section or characteristic point, and compare and verify with the simulation results of the mathematical model. The calculated values ​​are in good agreement with the measured values, that is, the constructed mathematical model can reflect the basic characteristics of the flow field distribution in the water intake open channel, and the location of the fish resource recovery facility in the open channel, the induced water flow rate and the configuration size can be determined accordingly; Step 3, selection of the location of the attracting channel: Based on the flow field distribution analysis and combined with the swimming ability and behavioral characteristics of the fish entering the open channel, the inlet of the attracting channel is arranged near the shore where the flow velocity is low and the return flow is weak in the center of the recirculation area in the open channel. The outlet of the attracting channel is set in the steady flow area with slow flow velocity and stable water flow outside the open channel near the shore, so as to serve as a temporary storage location for the fish before release; Step 4, configuration, size and induced water flow rate of the luring channel: Based on the flow field distribution analysis, combined with the swimming ability and behavioral characteristics of the fish entering the open channel, the flow velocity and flow pattern in the luring channel, the configuration, size and induced water flow rate of the luring channel are comprehensively determined; Step 5: Modify the physical model test to further verify the flow field: According to the recommended scheme of the attractant flow channel proposed in step 4, modify the physical model in step 2, add an attractant flow channel and a water supply system at the corresponding position in the open channel, use the physical model test to further conduct flow field research and analysis, and verify the suitability of the fish resource recovery facility; Step 6, setting up auxiliary interception facilities: according to the results of the flow field analysis in the open channel, an auxiliary interception net is added downstream of the entrance of the attracting channel in the open channel, where the water flow is more uniform and the flow velocity is lower. The interception net is arranged in full section to make it easier for fish to find the entrance of the attracting channel when swimming along the net; Step 7, fish luring and recovery process: open the luring flow channel, form a jet at the entrance of the luring flow channel that penetrates the water recirculation area in the open channel to the mainstream area, utilize the fish's countercurrent swimming characteristics and corresponding auxiliary facilities to induce the fish in the mainstream area and the recirculation area to swim toward the entrance of the luring flow channel, and utilize the slope in the luring flow channel to form a stable reverse flow field with a uniform and gradual flow rate, lure the fish to go upstream into the steady flow water area at the outlet of the luring flow channel, and then release the fish in the steady flow water area to the natural water area outside the open channel through the release device.

2. The auxiliary method according to claim 1, characterized in that: The direction of the induced water flow is greater than or equal to 90 degrees to the direction of the water flow in the water intake open channel.

3. The auxiliary method according to claim 2, characterized in that: The water intake open channel includes two parallel side walls forming a straight segment channel. A 90-degree elbow is provided at the end of the straight segment channel so that the inlet of the water intake open channel is parallel to one side of the side wall. The inlet of the induced flow channel is arranged on one side of the recirculation area of ​​the water intake open channel at a position 2-3 inlet widths away from the inlet of the water intake open channel. The induced water flow perpendicular to the water intake open channel can penetrate the recirculation area in the water intake open channel.

4. The auxiliary method according to claim 3, characterized in that: The slope of the attracting channel is less than 1:10, the width should not exceed 5m, and the water depth should not be less than 0.5m.

5. The auxiliary method according to claim 4, characterized in that: The flow rate of the induced water flow is 1 / 15 of the flow rate of the water flow in the water intake open channel.

6. The auxiliary method according to claim 5, characterized in that: The releasing device is a guiding fishway.

7. The auxiliary method according to claim 5, characterized in that: The releasing device is a fishing device.

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