Study On Optimization Of Hydraulic Characteristics Of Fish Passing Facilities In Dipanzi Hydropower Station

Water retaining structures destroy the connectivity of river flow and the integrity of river ecology,increase the difficulty of upstream migration of fish in the river,and endanger the survival and reproduction of fish.It is of great significance to build a fishway to provide a safe and effective migration channel for migratory fish to protect the ecological integrity of the river basin and the ecological diversity of the river where the project is located?In this paper,the example of fish passing facilities in Dipanzi hydropower station in Qinghai Province is given,and ANSYS Fluent is used to carry on the modeling calculation to the structure section fishway between 3#rest pool and 5#rest pool in the preliminary design scheme,and has carried on the analysis research to the water flow structure of the vertical slot fishway with the bottom slope of I%,2%-5%based on the structure size of the conventional fishway chamber in the structure section of the Dipanzi fishway,and then has studied and analyzed the end of the structure section of the fishway on the basis of the previous research the optimization effect of the end structure improvement scheme and the velocity field distribution at the entrance of fishway and its vicinity under different jet layout schemes.The main conclusions are as follows:(1)When the bottom slope of vertical slot fishway is in the range of 1%?5%and the velocity at the entrance of fishway meets the requirement of passing through fish,the bottom slope of fishway has no obvious influence on the velocity distribution of vertical cross section,the position and distribution of maximum velocity in the main flow area,the influence range of return area and the maximum and minimum velocity in the interior of the conventional pool,which shows that the vertical fishway has good adaptability to the terrain;(2)Increasing the number of vertical joints at the outlet of the end tank chamber of vertical fishway can form a flow pattern with high and low outlet velocity,which can effectively solve the problem of excessive vertical joint velocity in the end tank chamber under the condition of low downstream water level;(3)When the flow velocity of a single jet exceeds 4 m/s,the high-speed flow belt formed by the combination of the single jet and the fishway flow closes the fishway inlet,which makes it impossible for fish to enter the fishway through the high-speed flow;(4)When the upstream jet velocity is 4 m/s,the incidence angle is 90°?120°,the downstream jet velocity is 3 m/s,and the incidence angle is 30°,the water body will diverge obviously from the two jet pipe sections.The high-speed velocity will form a water wall at the entrance of the fishway to prevent the migratory fish from going upstream along the river,and the low-speed jet and the fishway flow will converge at the downstream of the entrance of the fishway and the high-speed jet,and the main stream will converge The road is winding,and most of the velocity is in the range of 0.6-0.8m/s,which is preferred by migratory fish,forming a good fish passage.