多级侧坎式螺旋泄水道竖井水力特性研究

Study on Hydraulic Characteristics of Helicoidal-Ramp Dropshaft with Side Sills

针对螺旋滑道式竖井入流条件要求低、排气稳定但消能不足的特点,该文提出了一种多级侧坎式螺旋泄水道竖井,即在竖井螺旋泄水道外壁沿程设置多级侧坎以达到消能效果。试验中可以观察到:在螺旋泄水道水流流动时,部分水流受侧坎作用形成折射水流,折向泄水道内侧,部分水流未受侧坎影响,在离心力作用下发展为贴壁流动;两股水流在侧坎后交汇,交汇处产生了强烈的紊动剪切,降低了水流动能。结果表明,侧坎螺旋滑道式竖井的消能率与螺旋阶梯式竖井的消能率相近,与传统螺旋滑道式竖井相比,其消能率可提高20%~30%。此外,还试验研究了不同侧坎宽度下的竖井水力特性,包括流态、压强、消能和水面线等,总结了侧坎宽度对竖井流动的影响规律。

Focus on the problem of increasing energy dissipation for helicoidal-ramp drop shaft,this paper develops a new form of helicoidal-ramp dropshaft with side sills.The side sills may generate the unique flow regimes of dropshaft,which increase energy dissipation remarkably.It is found from experiment observation that a part of flow is deflected by side sills and the jets are generated.Meantime,another part of the flow bypasses the side sills and becomes the wall pressing flow attaching the wall of the shaft.The jet and the wall pressing flow impact each other downstream of the side sill,thus a strong turbulent zone is generated.As a result,kinetic energy of flow is dissipated effectively.The experiment results demonstrate that the energy dissipation of helicoidal-ramp drop shaft with side sills is similar to that of stepped helicoidal-ramp drop shafts,but is larger than that of traditional helicoidal-ramp shaft about 20%~30%.Further,the hydraulics of the present drop shaft,including the flow regimes,pressure,energy dissipation and flow profiles are experimentally invested and the effect of side sill width on drop shaft flow is summarized in this paper.