跌坎型消力池底板脉动压强试验研究及体型优化

Experimental study on fluctuating pressure of stilling pool slab with bottom drop and shape optimization

脉动压强是衡量消力池底板安全稳定的重要指标,当泄槽末端与跌坎型消力池进口采用突扩或渐扩衔接时,消力池内脉动压强分布较为复杂。为了深入研究跌坎型消力池的脉动压强分布特性,基于金沙江梨园水电站构建了1∶50的物理模型,对高水头、大单宽流量下跌坎型消力池底板脉动压强分布开展系统研究。研究结果表明:跌坎突扩型消力池底板的前中部与泄槽延长线附近脉动压强普遍较大;将突扩调整为渐扩后,减轻了立轴漩涡对底板的作用,脉动压强系数最大值降低16.4%,但仍然超过安全阈值;将入射角由-10°优化为-8°后,各工况下脉动压强系数最大值降幅分别为37.4%,23.6%,62.1%,该优化体型在各工况下的脉动压强均为低频振动,不易对消力池底板产生共振破坏。

The fluctuating pressure is an important indicator of the safety and stability of the stilling pool slab.When the end of a discharge chute is connected with stilling pool with sudden expansion or gradual expansion,the fluctuating pressure distribution in the stilling pool is complicated.In order to study the fluctuating pressure distribution characteristics in the stilling pool,based on the physical model test with a scale of 1∶50 of Liyuan Hydropower Station on Jinsha River,a systematic study was carried out for the stilling pool with bottom drop under high head and large single-width flow.The study found that the fluctuating pressure was generally higher at the front and middle position of the bottom slab of the sudden expansion type stilling pool and near the extension line of the discharge chute;after adjusting the sudden expansion to gradual expansion,the effect of the vertical axis vortex on the bottom slab was reduced,and the maximum fluctuating pressure coefficient decreased to 16.4%,which exceeded the safety threshold;after optimizing the incident angle from-10°to-8°,the maximum fluctuating pressure coefficients under different conditions decreased to 37.4%,23.6%,and 62.1%respectively.The fluctuating pressure of each condition was low-frequency vibration,which was not easy to produce resonance damage to slab.