推移质采样器模型试验与相似条件

Model Experiment of Bedload Samplers in Water Trough and Similar Requirement

通过MB—2、YZ—80和TR—2三种有代表性的推移质采样器模型试验,得出不同采样器口门断面中垂线流速分布规律,首次测出采样器绕流阻力系数随采样器雷诺数的变化规律,定量分析了采样器采样效率分别随模型相对边界宽度、相对淹没深度、采样器雷诺数、反映推移质运动强度的水流参数以及相对充盈度等因素变化的规律,并提出了采样器模型试验必须遵循的相似准则。

This paper introduces the research achievements of model experiment of bed loadsamplers in water trough. The vertical velocity distribution on the section of sampler nozzle isnot smooth. When sampler nold number is smaller than 10~5, the friction efficiency C_D of abedload sampler decreases with the increase of Re. After Re≥10~5, Change of Re won't resultin change of C_D again. when B/b≥10、H/h≥5 and Re≥10~5, Changes of B/b、H/h and Re willhave little effect on the sampling efficiency η_s of sampler, which is similar requirement ofmodel experiment of a bedload sampler in water trough. The efficiency of sampling increaseswith the increase of the stream parameter ψ for MB-2 or YZ-80 type samplers, but the efficiencyof sampling decreases with the increase of the stream parameter ψ for TR-2 typesampler. The efficiency of sampling is a function of dimention varicables W_*. In case the valuesof W_* are small, owing to the formation of a depositing delta in front of the entrace of thesampler, the efficiency of sampling η_5 increases with the increase of W_*. After η_s reachs itsmaximum value, η_5 decreases with the increase of W_* as the sampler is being filled with gravel.