低弗劳德数水流二级消力池水力特性试验研究

Experimental study on the hydraulic characteristics of the two-stage energy dissipation in low Froude Number flow

  • 摘要: 针对低弗劳德数水流消能问题,在确定单级消力池和二级消力池体型的基础上,采用物理模型试验方法,分别研究了低弗劳德数水流单级和二级消力池的水力特性和消能结构特性。结果表明,在低弗劳德数水流条件下,二级消力池将原单级消力池出池水面较大波动区变成了适应区,对下游尾水位的适应区间显著增加,出池水面波动更小。同时,单级消力池内流线更加稀疏,流速梯度更小;消力池涡量大小明显低于二级消力池,而雷诺应力明显大于二级消力池;二级消力池内雷诺应力大小分区较单级消力池更明显,表面旋滚区明显大于底部旋滚区,水流更加稳定。相比单级消力池,二级消力池消能率显著提高,且有利于下游河床和岸边的防冲保护,工程应用更为有利。

     

    Abstract: In this study, the problem of energy dissipation under low Froude number flow conditions is investigated based on the shape of a single stage stilling basin vs. a two-stage stilling basin. Tests on a physical model were conducted to study the hydraulic and energy dissipation structure characteristics of these two types of basins in low Froude number flow. The results of these experiments reveal that under low Froude number flow conditions, the large fluctuation area of the original single stilling basin is changed in the two-stage stilling basin into an adaptive area, while the adaptive area of the downstream tail water level increases significantly, and the fluctuation of the outlet water level decreases. In addition, the streamline in the single stilling pool is sparser and the velocity gradient and vorticity smaller than those of the two-stage stilling basin, while the Reynolds stress is significantly larger. The flow in the two-stage stilling basin is more stable, and the Reynolds stress zoning is more obvious than that in the single stage stilling basin. The surface rolling zone is markedly larger than the bottom rolling zone as well. Compared with the single stage stilling basin, the energy dissipation rate of the two-stage stilling basin is significantly improved, which is beneficial to the anti-scour protection of downstream riverbeds and the shore.

     

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