收缩墩与跌坎消力池联合消能工的试验研究

The experimental study of stilling basin with contraction bier combined with step-down floor

为探究解决跌坎型消力池在大单宽、低弗劳德数引起的振荡型水跃问题,本研究进行了跌坎型消力池和收缩墩与跌坎型消力池两类消能工试验,对比分析了试验的流态、流速和压强分布规律。试验结果表明:加设收缩墩后,入池射流破坏了表面水流与水垫层剪切形成的大幅度振荡波动,有效地解决了振荡型水跃问题,同时,按照收缩墩与跌坎消力池内水流的运动情况可以将其分为收缩射流区、交互区和底流水跃区三大区域。其中,收缩射流区,水流受收缩墩作用后,形成三元扩散射流,水流纵向扩散,在空中形成两翼交汇,并互相碰撞、混掺,动能损失增加;底流水跃区,底部水流扩散、跃起,在表面形成较大的回流漩滚,构成了典型的底流消能;交互区射流与回流漩滚相互碰撞、混掺,能量损失加剧,同时扩散射流破坏了池内间歇性漩涡,解决了池内大幅度振荡和波动问题。

Two types of experiments were carried to study the stilling basins with step-down floor and the stilling basins with contraction bier combined with step-down floor.Flow pattern,velocity and pressure on the stilling basin floor were obtained.The results show that the stilling basins with contraction bier combined with step-down floor could effectively solve the state of oscillating fluid and it can be divided into three regions:contraction jet region,interactive zone and energy dissipation by hydraulic jump region.The water surface vertically diffused,and the two wings were converging,then colliding and mixing with each other after setting the contraction pier.Bottom flow was in a form of a jet diffused and leaped along the bottom of the stilling basin,and form the larger rolling at the surface,in this time the energy dissipation rate was larger,the diffusion jet damaged the unstable large-scale vortexes.The oscillatory flow pattern was disappeared.