贴壁射流形态对跌坎消能的水力特性影响试验研究

Tests for influence of wall jet on energy dissipation in a plunge pool

贴壁射流形态是影响跌坎型消力池消能效果和水力特性的重要因素之一。为研究贴壁射流形态对输水工程跌坎消能效果和水流特性的影响,通过1:20的水工模型试验对反弧贴壁射流和平抛贴壁射流情况下的跌坎消力特性进行试验观察和测试。获得不同射流形态下的主流形态、消力池底板脉动压力过程及水面波动时程曲线。试验结果表明:平抛型贴壁射流通过增加射流入水的俯角,使射流进入消力池后产生强烈紊动和翻滚,导致消力池底板的时均压力和脉动压力比反弧贴壁射流大,但平抛贴壁射流减小了消力池和稳水区的水面波动,能更好地满足输水工程下游隧洞稳定输水要求。

Wall jet has a great influence on hydraulic characteristics of energy dissipations in a plunge pool with sudden enlargement and bottom drop. In order to study influence of wall jet pattern on hydraulic properties of a plunge pool with sudden enlargement and bottom drop, a hydraulic model with scale 1：20 was established. The energy dissipations were presented respectively under anti-arc wall jet and level-throwing wall jet. The time-history process of the fluctuating pressure on the bottom and the water surface fluctuation were obtained with tests. It was shown that the level- throwing wall jet enlarges the depression angle, and the hydraulic pressure increases with intensive turbulence and impact; however, the water surface fluctuation is improved partly. The results showed that the level-throwing wall jet is better to improve hydraulic conditions of energy dissipation in a plunge pool for water transfer pipelines systems.