窄缝消能工水力特性对比分析研究

以某大型水电站为例,基于RNG κ-ε和VOF相结合的数值模拟方法,对不同方案的窄缝消能工下游水垫塘内流态进行了对比分析研究,并与试验结果进行了对比,吻合较好。研究结果指出:(1)体型Ⅰ(3股纵向水舌消能方案)和体型Ⅱ(2股横向水舌+1股纵向水舌消能方案)条件下水垫塘内流态具有一定差异,但对水垫塘底板的冲刷效果基本一致;(2)两种体型条件下底板冲刷均由2~#表孔泄洪导致,而1~#和3~#表孔泄洪主流受到两侧回流及水体顶托作用下潜深度较小;(3)水垫塘首部基本为静压区,水垫塘桩号0+280 m下游底板压力较大,为主流冲刷区,2~#表孔下游为冲刷重点防护区域,而1~#和3~#表孔泄流方式对水垫塘底板冲刷较小。研究结果可为窄缝消能工的设计方案对比提供借鉴。

Comparative analysis on hydraulic characteristics of narrow slot energy dissipator

By taking a largescale hydropower station as the study case，a comparative analysis is made on the various schemes of the flow regimes in the downstream cushion pool of narrow slot energy dissipator，of which the result is compared with that of the relevant experiment and a better coincidence is obtained. The result indicates that ( 1) Certain difference is there between the flow regimes in the cushion pools under the conditions of the shape I ( the energy dissipation scheme with three longitudinal waterjets) and the shape II ( the energy dissipation scheme with two transverse waterjets + one longitudinal waterjet) ，but the scouring effects on the bottom slab of cushion pool are basically the same. ( 2) The scours on bottom slabs under the conditions of both the shapes are caused by the flood discharge from the No. 2 surface outlet，while the submerging depths of the main discharge flows of No. 1 and No. 3 outlets are smaller under the effects of both the side-backflows and the backwater. ( 3) The front-part of cushion pool is basically a zone of static pressure with larger pressure on the downstream slab at the stake number of 0 +280m of the cushion pool and is the mainflow scouring zone，while the main scouring prevention zone is at the downstream area of the No. 2 surface outlet，but the scouring on the bottom slab from the discharge modes of both the No. 1 and No. 3 surface outlet is smaller. The study result can provide a reference for the comparison of design alternative for narrow slot energy dissipator.