天然河道中的水流,有急流、缓流、平流之分,一般属于缓流,单宽流量沿河宽方向分布均匀。当在河道中合适位置修建了闸、坝、溢洪道等泄水建筑物后,河道中水流条件发生了变化,因下泄水流流速很大,单位质量水体所具有的能量也比下游河道中正常水流的能量大很多,对下游河床具有明显的破坏能力。特别是为节约建造成本,常要求这类建筑物的泄水宽度比原河床小,单宽流量加大,形成高速水流下泄,能量就更为集中,破坏性也更大。因此,深入研究泄水建筑物下游的水流衔接与消能,对建筑物本身及下游建筑和河道安全有良好作用,同时,充分利用其下泄的余能也是至关重要的一点。 Natural rivers in the water, a rapids, slow flow, the advection of the points, generally belong to slow flow, single wide flow along the river width direction evenly. After the sluice structures such as gates, dams and spillways have been constructed in proper places in the riverway, the water flow conditions in the riverway have changed. Because of the large flow rate of discharge water, the energy per unit mass of water is also lower than that of the normal flow in the downstream river The energy is much larger, with obvious damage to the downstream riverbed. In particular, in order to save construction cost, it is often required that the discharge width of such buildings should be smaller than that of the original riverbed and the flow rate per unit width should be increased to form a high-speed water flow discharge. As a result, energy is more concentrated and destructive. Therefore, in-depth study on the convergence and dissipation of water flow downstream of the drainage structures has a good effect on the buildings themselves and on the safety of downstream buildings and waterways. At the same time, it is also crucial to make full use of the excess energy they vent.