摘要
通过水槽试验分别研究在沉水植物水蕨和挺水植物富贵竹两种植被作用下的突扩式明渠水流特性,采用声学多普勒测速仪,测量突扩前后不同垂线、不同测点的瞬时流速,计算得出时均流速分布,分析其变化特征,探讨突扩明渠中植物对水流内部结构的影响.试验发现:在种植植被前,中垂线上突扩前后流速均呈半对数分布,而种植植被后,水流受两种不同植物的影响而产生不同的变化趋势,有沉水植物的情况流速分布可分为3层,即植被冠层内、植被层之上和过渡层,且过渡层有随流逐渐增大的趋势,有挺水植物情况由于植物不同部位阻水效应的差异,使得流速呈现'3'型分布.位于扩散段回流区内的左垂线流速分布更加复杂,不服从半对数关系.种植植被后,同一垂线不同流量下水流的流速分布有很大变化,并且流速分布的变化率随流量的增大而增大.
Vegetated sudden-expansion open channel flow with the submerged plant of floating fern or emerging plant of lucky bamboo beds was studied in a laboratory flume. An acoustic doppler velocimeter was employed to measure the instantaneous flow velocity at different measure points of different vertical lines before and after the sudden expansion. The distribution of the mean flow velocity was ealculated in order to analyze its charaeteristic and discuss the influence of plants in open channel on the internal structure of water flow. The experiment revealed that before vegetating, the middle current cmwe before and after sudden-expansion was semi-logarithmically distributed; after vegetating, because of the influence of two different plants, the distribution of flow velocity under submerged plant condition was classified into three levels： the canopy, the vegetable layer, and the intermediate bed. The intermediate bed was increasingly enlarged. Due to the different water-blocking effects on the different positions of emerging plant, the flow veloeity assumes ＂3＂ style distribution. The velocity distribution of left vertical line located at the return flow region was more complex and was not semi-logarithmically distributed. After vegetating, the veloeity distribution of the identieal vertical line under different discharge has a great ehange. And the variance ratio of velocity distribution was increased along with the discharge increased.
出处
《排灌机械工程学报》
EI
2011年第1期45-49,共5页
Journal of Drainage and Irrigation Machinery Engineering
基金
国家973计划项目(2008CB418203)
关键词
明渠水流
突扩
植被
声学多普勒测速仪
流速分布
open channel flow
sudden expansion
vegetation
acoustic doppler velocimeter
velocity distribution
