高含沙水流脉动特性试验研究

以某工程的表孔为依托,建立1∶100单体模型。通过配置不同含沙量的水流,对水垫塘底板含沙水流的脉动压强进行试验。结果表明,在试验范围内,水流条件不同,含沙量对脉动强度的影响不同:水流条件较强时,脉动压强随着含沙量的增大,呈现先减小后又增大的趋势,含沙水流最大脉动压强比清水最多减小24.73%;水流条件较弱时,脉动压强随着含沙量的增大,呈现先增大后减小的趋势,含沙水流最大脉动压强比清水最大增加78.74%。冲击区含沙水流脉动压力分布比清水更接近正态分布,脉动压力能量大部分集中在0.4 Hz以内,功率谱无明显的优势频率,水流主要以低频大尺度漩涡为主。通过对高含沙水流水垫塘底板的脉动压强进行观测,总结分析了不同因素影响下高含沙水流脉动压强特性的变化规律,为相关工程提供参考。

Experimental study on fluctuation characteristics of high sediment-laden flow

Based on the surface outlet of a project, a model with the scale of 1∶100 is established, and then an experiment on the fluctuation pressure of the sediment-laden flow on the bottom slab of the water cushion pond is made through allocation of the flows with various sediment contents. The result shows that the impact from the sediment on the fluctuation intensity is different along with the different flow condition within the experimental range, i.e. when the flow condition is more strong, the fluctuation pressure shows a trend of that decreasing at first and then increasing along with the increase of the sediment content, for which the maximum fluctuation pressure of the sediment-laden flow is at most reduced by 24.73%, if compared with that of the clear water; when the flow condition is more weak, the fluctuation pressure shows a trend of that increasing at first and then decreasing along with the increase of the sediment content, for which the maximum fluctuation pressure of the sediment-laden flow is at most increased by 78.74%, if compared with that of the clear water, and the distribution of the fluctuation pressure of the sediment-laden flow in the flow impacting zone is more approached to the normal distribution, while the most of the energy of the fluctuation pressure is concentrated within a range of 0.4 Hz without obvious dominant frequency for the power spectrum and the flow is mainly the low-frequency large-scale eddy. Through the observation made on the fluctuation pressure of the high sediment-laden flow on the bottom slab of water cushion pond, the variation law of the characteristics of the fluctuation pressure of the high sediment-laden flow under the impacts of various factors are summarized and analyzed herein, so as to provide some references for the project concerned.