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为研究粗细颗粒间相互作用对非均匀沙输移的影响,采用推移质动态采集、图像识别和多普勒测速技术,实现了瞬时输沙量、颗粒组成与近壁脉动流速的实时同步监测。针对双峰型非均匀沙进行了211组推移质系列水槽试验,分析表明:推移质输移量与粗沙拣选度的随机波动与紊动猝发引起的流速脉动具有响应关系;推移质中细粒基本保持持续输移,而粗粒输移则具阵发性,并遵循促发、触发与失怙3种模式;颗粒组成结构对3种模式的实施过程有重要影响;它制约着泥沙中细粒对粗粒的激励、碰撞和解怙强度,使得推移质总沙、细沙和粗沙输移率随床沙组成的改变各自呈现出不同的变化规律;水流强度一定时,随床沙粗细比的减小,输沙率呈驼峰型曲线变化;只有适宜的粗细颗粒搭配(ηc)才能使非均匀推移质输沙率达到峰值,且大于该床沙组成中任一均匀沙的输沙率。
In order to study the influence of the interaction between coarse and fine particles on the transport of non-uniform sand, real-time synchronization monitoring of instantaneous sediment transport, particle composition and near-wall pulsation velocity was achieved by using dynamic collection of pluton, image recognition and Doppler velocimetry. A series of 211 pusher series of flume tests were carried out for the bimodal heterogeneous sand. The analysis shows that the random fluctuation of the pumped mass transfer and coarse sediment picking has a response to the pulsation caused by the turbulent burst; While the transport of coarse particles was paroxysmal and followed the patterns of triggering, triggering and losing. The structure of the particles had an important influence on the implementation of the three modes. It constrained the sediment The motivation, collision and solution strength of the fine particles to the coarse particles make the transport rates of total sand, fine sand and coarse sand vary with the composition of the bed sand. The change of sediment transport rate And the sediment discharge rate changes in a hump type curve. Only with the appropriate thickness of particles (ηc) in order to make the uneven bedrock sediment transport rate reached a peak, and more than the sediment composition of any sand sediment transport rate .