堰-底孔组合式鱼道堰顶布置优化研究

Research on the Optimization of Weir Layout of the Weir-Bottom Hole Combined Fishway

堰-底孔组合式鱼道的隔板将鱼道槽身分割成连续的阶梯级水池,增加了池中水流的能量耗散,并创造了鱼类上溯的流态,但堰顶和底孔不同的形状、尺寸和布置方式均会带来水流特征的变化,其布置方式是需要仔细考虑的重要特征。以某工程堰-底孔组合式鱼道为研究对象,建立三维数学模型,对不同隔板布置型式下的鱼道池室水流特征进行了研究,通过改变堰顶缺口相对位置p/B对鱼道内流速分布和水流结构进行了优化。结果表明:在鱼道内水深为2 m时,不同的堰顶布置方式对池室的水流结构影响较大;与原方案左右交错布置的堰顶缺口相比,p/B=0.6时,鱼道池室内主流明确,回流区范围相对较小,堰和底孔处最大流速小于1.0 m/s,最大紊动能0.06 m^(2)/s^(2),基本满足四大家鱼等经济鱼类上溯要求,实际应用时可根据工程实际寻求p/B的最优解。

The baffle of the Weir-bottom hole combined fishway divides the Fishway into a continuous stepped pool,which increases the energy dissipation of the water in the pool and creates the upstream flow pattern of fishes.However,the different shapes,size and layout of weir and bottom hole will lead to the change of flow characteristics,and the layout of weir is an important feature that needs to be carefully considered.Taking a weir-hole combined fishway as the research object,a three-dimensional mathematical model is established to study the characteristics of the partitions of the Fishway pool room.The velocity distribution and flow structure in the fishway are optimized by changing the relative position p/B of weir.The results show that when the water depth in the fishway is 2 m,different weir layouts have a great influence on the flow structure of the pool room.Compared with the weir crest gaps staggered left and right in the original plan,when p/B=0.6,the main stream in the pool room is clear,the range of return zone is relatively small,the maximum velocity at the weir and bottom hole is less than 1.0 m/s,and the maximum turbulent kinetic energy is 0.06 m^(2)/s^(2),which can basically meet the upstream requirements of four major fishes and other cash fishes.In practical application,the optimal solution to P/B can be found according to the engineering practice.