水电站坝身沉冲沙系统试验研究与数值模拟

Experimental Research on the Dam-body Sand Flushing System for Hydropower Station and Numerical Simulation

水电站沉沙池按常规大多布置在枢纽首部,由于受地形地质条件限制,因此可将沉沙池同坝体相结合,以满足空间布置要求,而在此条件下对沉沙池的沉冲沙效果提出了更高的要求。通过模型试验发现了某水电站坝身式沉沙和冲沙系统设计中的水力学问题,提出了裁弯取直、加分流墩、增加整流池以及改变冲沙方式等措施,在此基础上,对沉沙和冲沙两种工况下沉沙池内的水流流态、断面流速分布等水力特性进行了模型试验和数值计算研究。结果表明,沉沙池优化后,沉沙和冲沙效果均能够满足设计要求;优化后的沉沙池在沉沙工况时其内水流流速较小、分布更加均匀,便于泥沙沉降,冲沙工况下水流能够集中在冲沙底孔进入沉沙池,水流流速较大,可以顺利将泥沙冲出沉沙池。

According to the conventional layout, most sand basins are set in the front of hydropower station hub. Due to the limitations of topography and geological conditions, sand basin can be combined with the dam to meet the requirements of space arrangement, in which it re- quires a higher efficiency of desihing and flushing for sand basin. In this study, firstly some hydraulic problems were found in the design of desihing and flushing system in a hydropower station through model tests, then some optimization measures, such as curve cutoff, adding diversion pier, increasing the rectifier pool, and changing the way of flushing, were put forward. Then to study the reliability of the new desilting system, numerical simulation was conducted to study the flow regime, velocity distribution and other hydraulic characteristics and then the results were compared with model test data. The results show that the desilting and flushing system can meet the design requirements by means of such optimization. The flow distribution is more uniform than before under desilting conditions, which makes sediment easy to deposit uniformly and the relatively high speed flow through the flushing bottom hole can flush the sediment out of the sand basin smoothly under flushing conditions.