跌坎对消力池水力特性影响的试验研究

Experiment on influence of falling- still on hydraulic characteristics in dissipation basin

为研究跌坎在底流消能中的作用,依托某工程水力学模型,研究了跌坎对消力池内水流流态、临底流速及脉动压强的影响。结果表明:在来流量一定的情况下,随着跌坎高度的增加,消力池内流态会由底流依次演变为淹没混合流及淹没面流流态。加设跌坎可显著降低消力池前半段的临底流速,且跌坎越高,最大临底流速降幅越大,跌坎对消力池后半段的临底流速基本无影响;跌坎对脉动压强影响较大,随跌坎高度的增加,最大脉动压强先增大后减小;加设跌坎后,脉动压强和临底流速沿程先增大后减小,且脉动压力和临底流速的最大值位置基本在同一区域。

In order to study the effect of falling -still in dissipation of bottom flow ,the paper studied the influence of falling -still on flow pattern , underflow velocity and fluctuating pressure based on a hydraulic model test from a project .Results show that when the flow is constant , the flow pattern in the dissipation basin would evolve from bottom flow to submerged admixture flow as well as surface flow with the increase of falling-still height.The falling-still can reduce the underflow velocity in first half of the stilling ba-sin, and the higher the height of falling -still, the more the decrease of maximum underflow velocity;and in the second half of the stilling basin , the falling-still has hardly effect on underflow velocity .The falling-still also has a crucial influence on fluctuating pressure , with the increase of falling -still hieght , the maximum fluctuating pressure increases first and then decreases .Along the flow direction of stilling basin , the fluctuating pressure and the underflow velocity increase first and then decrease and the position of their maximum values is in the same region .