Research On The Upward Behavior Of Fish Based On The Velocity Field Of Vertical Slit Fishway

Water is a precious substance that sustains our lives.Because of the uneven distribution of water resources in our country,the original state of water in nature cannot meet the actual needs of people.In order to improve the uneven distribution of water resources,water conservancy workers have built many dams and dikes in the rivers to control the flow of water,which largely avoided the damage caused by floods to humans,and at the same time,they can also use water energy resources for power generation,irrigation,etc.,Thereby improving people's lives,but also causing serious damage to the ecosystem and water ecological environment of the river basin.It blocks the connectivity of primitive rivers,making it impossible for fish to go from downstream to upstream through the dam to forage and lay eggs,causing irreversible damage to certain migratory fishes,causing an imbalance in the river ecosystem and destroying the river.Ecological environment,so in order to avoid this phenomenon,more and more countries are constructing channels connecting upstream and downstream.As a kind of biological compensation project,fish pass can make migratory fishes return upstream through fish pass.However,according to the"Washington State Fish Pass Guidelines",the fish pass currently constructed is generally less than 50%.Therefore,it is urgent to improve and optimize fish passes.With the continuous research on fish passages,more and more problems have gradually been discovered.The main problem is that the fish passages are constructed only from the hydraulic structure,and are not combined with the swimming ability and behavior characteristics of the fish.As a result,only a few migratory fish can go upstream,and most migratory fish do not meet the demand for upstream because of the hydraulic characteristics of the fish channel.The fish pass of the fish pass is very poor.Based on this,this article takes crucian carp as the research object,studies its swimming ability and conducts an uptracking test.Through the coupling analysis of the crucian carp's uptracking process and hydrodynamic factors,the most suitable hydraulic characteristics data for the migration of the crucian carp are obtained.And use this to provide a research method for determining the relationship between other migratory fish and hydrodynamic factors,and obtain the hydraulic characteristic data of other migratory fish.Then improve and optimize the fishway.The main research contents and conclusions are as follows:(1)Experimental study on fish swimming ability.In the fish swimming ability test device,the index of the swimming ability of the fish is measured by the increasing velocity method,and the induced flow velocity of the test fish is 0.046 m/s-0.086 m/s,and the relationship between the critical swimming speed and the body length is:U_crit=2.9606BL+59.474.The relation between relative critical swimming speed and body length of crucian carp is:U _c?_rit=-.01088BL+.80824.The relationship between the speed of rushing swimming and body length is:U_burst=2.2012BL+98.719.The relationship between crucian carp relative swimming speed and body length is:U_b?_urst=-.02026BL+11.203.(2)Use the method of combining physical model and numerical simulation to analyze the flow velocity field,turbulent kinetic energy,mainstream curve,and the attenuation of the maximum flow velocity in the fishway.Numerical simulation can be used to study and analyze the water flow inside the fish channel.Velocity field:The flow velocity in the main flow zone is larger than that in the recirculation zone,and the streamline trajectory is in the shape of a reverse"S"curve;with the increase of flow,the shape of the flow velocity field in the main flow zone does not change,but the flow velocity in the pool increases.The place where the indoor velocity of the fishway pond is highest is downstream of the vertical seam.Turbulent kinetic energy:The turbulent kinetic energy is the largest at the position of the vertical seam in the pool room.As the flow rate increases,the turbulent kinetic energy at the same location in the pool chamber also increases.Main flow curve:Under different flow conditions,the main flow curve in the fish pass basically overlaps,indicating that changing the flow will not change the shape of the main flow inside the tank.Attenuation of the maximum flow velocity along the way:the attenuation rate of the mainstream flow velocity reaches30%,and the maximum flow velocity in the mainstream area attenuates significantly along the way,indicating that the energy dissipation effect of the pool is better.(3)Carry out the continuous upward-tracing test of crucian carp under the condition of vertical-slit fishway multi-level tanks to analyze the influence of hydraulic factors in the fishway tank on the upward-tracing behavior of crucian carp.The velocity range of the pool room for the crucian carp with a body length of 19 cm-27 cm is0.091m/s-0.524 m/s,and the turbulent kinetic energy of the water flow should not exceed 0.0210 m²/s².