底流消力池空化特性探讨

Discussion on cavitation characteristics of bottom flow stilling basin

本文以某高水头泄洪底孔为例,通过减压模型试验探讨分析了连续式底流消力池和跌坎式底流消力池的流态、临底流速、水下噪声和脉动压强等水力指标,成果表明:连续式底流消力池底板存在空蚀破坏的危险性较大;采用跌坎式消力池可以有效减免消力池底板空蚀破坏的危险性,但消力池边墙与闸墩内壁齐平或间距较小时,边墙空蚀破坏的可能性较大,当边墙与闸墩内壁侧扩一定距离时,边墙空蚀破坏的危险性会显著降低。

This paper presents results of vacuum tank model tests on two bottom flow stilling basins with consecutive floor and step-down floor downstream to a high water head bottom outlet, and discusses the hydraulic behaviors of these two basin flows, focusing on flow pattern, bottom flow velocity, underwater noises and pulse pressure. The results indicate that the consecutive floor basin has a risk of floor erosion caused by flow cavitation while the step-down floor design reduces the erosion significantly. For the latter, however, the erosion would develop on the side wails, particularly for designs with too small spacing between the side wall and internal pier wall or the side wall flushed with internal wall. Thus, an obvious reduction in erosion risk can be achieved by increasing the spacing beyond a certain threshold.