| Hydropower development not only brings huge economic and social benefits,but also has a series of impacts on river ecosystem.Hydraulic structures hinder the upstream passage of migratory fish,resulting in a decrease in fish population.In order to ensure the successful migration of migratory fish,it is necessary to strengthen the research on fishways.The vertical slot fishway has been widely used in engineering at home and abroad because of its technical advantages such as high fish passing efficiency and strong adaptability to water level changes.In this paper,the vertical slot fishway of Dongfei Sluice is taken as the research object.On the basis of prototype observation test,the detailed data of flow field,water level and field photos are collected by using Acoustic-Doppler Velocimeter(ADV)and other measuring instruments.Further,the numerical simulation method is used to study the hydraulic characteristics of the conventional pool room,rest pool and 140°turning section of fishway based on RNG k-εmodel and VOF model.The optimization research is carried out on the unfavorable flow pattern in the rest pool and turning section of fishway,focusing on the influence of three different schemes on the flow pattern,velocity and turbulent kinetic energy in the fishway pool.Better than the selected hydraulic indicators of the program.The main conclusions are as follows:(1)In the fishway prototype observation test,the flow velocity in the fishway was low,and the maximum flow velocity near the vertical slot was 0.25 m/s.The recirculation zone on both sides of the mainstream was compressed by the mainstream.The velocity values of the upper,middle and lower layers of the fishway are not much different,and the velocity of the bottom layer is small.The flow field presents two-dimensional characteristics.The water surface line along the fishway changes little,and the water flow continues;Under the design flow scenario,the numerical simulation shows that the mainstream in the conventional pool of the fishway is’C’shaped,and the area of the recirculation zone on both sides of the mainstream is similar.The mainstream position is distributed on the right side of the pool chamber,and the velocity attenuation effect in the mainstream area is obvious.The velocity value of the vertical slot section is between 0.6to 0.9 m/s.The surface velocity value is high,and the velocity value is not much different as a whole.The range of Turbulent Kinetic Energy(TKE)value in the conventional pool is 0～0.05 m~2/s~2,and the TKE value shows an increasing trend from the bottom to the surface.(2)The simulation results show that the hydraulic characteristics of the rest pool and the turning section are similar,and the flow pattern of the pool is as follows:There is a large area of adherent flow in the mainstream,and the scale of the right recirculation zone is much larger than that of the left recirculation zone.The flow velocity characteristics are summarized as follows:The mainstream flow velocity is in the range of 0.3 to 0.9m/s,and the energy dissipation effect along the mainstream is good.The flow velocity in the recirculation zone is basically lower than that of fish induction,and the maximum flow velocity in the recirculation zone decreases from the bottom to the surface.The vertical velocity increases first and then decreases from the bottom to the surface.The TKE value is lower than 0.06 m~2/s~2,and the variation of TKE in the water depth direction is consistent with that of the conventional pool.(3)Although the baffle structure of the rest pool optimization scheme 1 has improved the flow state,the flow velocity value and shows an increasing trend.The improvement effect of scheme 2 and scheme 3 on the flow state is more obvious,and the maximum flow velocity value and TKE value also show a decreasing trend.It is concluded that the hydraulic indexes of the rest pool in scheme 2(the ratio of long and short baffles is about3.3:1)are more traced by fish;The optimization scheme 1 and scheme 2 of the turning section significantly improve the area of the right recirculation zone,and the internal flow velocity value is lower than the initial scheme.In scheme 3,the main flow in the lower half of the main flow is adhered to the wall,and the number of recirculation zones increases,which increases the velocity of the recirculation zone.Scheme 1 is obtained by comparison,that is,the length of the baffle is within the range of 0.16～0.2 of the width of the pool,and the flow pattern and other hydraulic indexes of the turning section are more suitable for fish rest and migration.Figure[47]Table[9]Reference[125]... |
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