燕尾挑坎近端水流挑射特性试验研究

通过物理模型试验,对不同来流条件下燕尾形挑坎近端水流挑射特性进行了研究,分析了挑坎前的断面平均流速、断面水深对近端水流挑射特性的影响,获得了近端水流挑射特性,尤其是近端水流出射角的变化规律。结果表明：燕尾坎近端水流出射角随断面流速降低而减小；随出出挑断面水深增加而减小。并由上述影响因素,分析了出口断面佛汝德数改变对内缘水流出射角的影响,得到了计算燕尾坎内缘水流出射角的经验公式,依据计算的水流出射角,采用自由抛体空中运动原理得出的内缘抛距与试验结果符合较好,为燕尾形挑坎的工程应用和下游水垫消能设计提供了必要的参考。

Experimental Research on the Characteristics of Water Jets at the Proximal End of the Dovetail-shaped Flip Bucket

The experimental study investigates the takeoff characteristics of lower jet trajectory from the dovetail-shaped flip bucket under different inlet conditions. The experiment analyzes the influences of velocity and water depth on lower takeoff characteristics, especially the variation of takeoff angle of lower jet trajectory. The following items are addressed:(1) relation between takeoff angle of lower jet trajectory and inlet velocity as well as inlet water depth; (2)characteristics of the takeoff angle as a function of changes of inlet Fr0;(3)the empirical formulas for calculating takeoff angle of lower jet trajectory. The results indicate that the effects of inlet conditions are significant on lower takeoff characteristics. Additionally, with the established empirical formulas, calculated values of horizontal distance of lower nappe profile are in good agreement with experimental values.