跌坎型底流消能工跌坎深度在工程优化设计中的应用

以某工程导流泄洪隧洞底流消能工为试验研究对象,原方案试验中,在闸门半开工况下,下泄水流出现脱离泄槽底板现象,不利于下泄水流的消能,经研究,改变压坡段底板坡度,同时将泄槽的两个坡段改成一个坡段;原方案底流消能工消力池内均发生远驱式水跃,消能效果差,通过研究采用以最大临底流速为控制目标的最小跌坎深度计算公式,确定消力池底板高程。经两次优化试验后,消除了闸后水流脱离泄槽底板的现象,下泄水流流态稳定,消力池内形成稳定的淹没水跃消能,出池水流与下游水流衔接较好,消力池内临底流速和时均动水压强均明显降低,消能效果好。

Application of falling-sill depth of the falling-sill bottom-flow energy dissipator in engineering optimization design

This paper took the bottom-flow energy dissipator of a diversion spillway tunnel of a project as the object of study. In the original test scheme, when the gate was half open, the discharged flow was off the bottom of the discharge chute, which was not conducive to dissipating the energy of the discharged flow. In this study, we altered the slope of the floor in the pressing slope section, and reduced the two slope sections of the discharge chute into one slope section. In the original scheme, there were repelled hydraulic jumps in the stilling pool, resulting in poor energy dissipation. To tackle this problem, we adopted a calculation formula of the minimum falling-sill depth that was aimed at controlling the maximum underflow speed, and determined the elevation of the floor of the stilling pool. After two optimization experiments, we eliminated the phenomenon in which the flow out of the gate was off the bottom of the discharge chute. The discharged flow was in a steady regime. There were stable submerged jumps to dissipate the energy in the stilling pool. The water flow out of the stilling pool connected well with the downstream flow. The underflow speed and time-averaged dynamic water pressure in the stilling pool were significantly reduced. The dissipation effect was good.