An Experimental Study Of Turbulent Structures And Fish Movement In Combined Fishway Of Rectangular Central Orifice And Vertical Slot

With the rapid development of economy and society,the impact of engineering construction on the ecological environment has attracted more and more attention.Water conservancy projects as infrastructure provide necessary renewable energy for economic and social development,and have functions such as flood prevention and drainage,urban water supply,farmland irrigation,and shipping,and will definitely be further developed.China’s coastal and riverine fish resources are abundant,and there are many migratory fishes.According to the living environment,they can be divided into river-feeding migratory fishes living in the ocean and river-feeding migratory fishes living in fresh water.In addition,there are semi-migratory fish in rivers and lakes,main and tributaries.In order to communicate with fish migration channels and maintain biodiversity,fish passages are usually set up in water conservancy hubs such as tide barriers,drainage sluices,flood diversion sluices,and dams to achieve the harmonious development of water conservancy projects and ecological environment.Existing studies have shown that less than half of the fishways that fish can pass through have been built in the world! Therefore,it is of great practical significance to further study the hydraulic characteristics of fishways.The experimental research was carried out in a large-scale fishway tank in the Harbor Channel and Coastal Engineering Laboratory of Zhejiang University of Technology.Using acoustic Doppler velocimeter(ADV),automatic water level measuring system and other testing instruments to measure the three-dimensional instantaneous flow velocity and water level in the fishway pool,analyzed the flow characteristics of different horizontal planes,longitudinal sections,cross sections,The three-dimensional time-averaged velocity distribution and the mainstream along the way,the three-dimensional turbulence intensity distribution,the three-dimensional Reynolds stress distribution,the three-dimensional spectral characteristics,the three-dimensional autocorrelation coefficient,and the three-dimensional turbulence scale.The research shows that:(1)The jets at the orifice position and the jets at the vertical slit position will form a confluence,and a large clockwise vortex will be formed in the center of the entire sink.The jets at the orifice position on the same side are divergent,starting from the orifice.The positions diverge to both sides,each forming a small vortex.(2)There are two mainstream zones in the rectangular and vertical seam combined fishway designed on the opposite side and the same side.In the free jet area of the orifice and the jet wall area of the vertical seam,the three-dimensional time-averaged flow velocity has a maximum value;(3)three-dimensional The maximum value of the turbulence intensity appears at the upstream orifice and the junction of the two jets,and the three-dimensional Renault has a maximum value at the junction of the two jets;(4)The correlation of the flow point will gradually weaken and stabilize at Fluctuations within a small range,the fluctuations become larger after 9s;the vertical spectrum pulsation energy of the aperture position on the opposite side is the largest,the vertical spectrum pulsation energy is the largest on the vertical seam position,and the vertical spectrum pulsation energy is the largest on the same side;in the three-dimensional integration scale analysis In the three-dimensional differential scale analysis,the fluctuations in the three directions on the opposite side are smaller,and the amplitudes on the same side are larger in the vertical direction.At the same time,through the fish release experiment,the effect of the rectangular middle-hole-vertical seam combined fishway on the migratory habits of fish is analyzed,and the behavior of fish in the water tank can be observed more closely by using a high-speed camera.