宁夏引黄灌区干渠直开口出流流态及流量分析

Analysis on Flow Pattern and Discharge of Trunk Straight Opening Flow in Yellow River Irrigation Area of Ningxia

宁夏引黄灌区干渠直开口(斗口)结构是闸门加涵洞的结合体,水流通过闸孔在涵洞中呈现极为复杂的流态,有自由出流、淹没出流以及有压管流流态,并且交替变化。通过试验提出,当闸后某断面水深较小,且下游水深小于水跃的第二共轭水深时,可以按自由出流计算流量;当此水深小于或等于涵洞高度,且下游水深大于水跃的第二共轭水深时,可以按淹没出流计算流量;当此水深大于涵洞高度,且下游水深大于水跃的第二共轭水深时,可按有压管流计算流量。同时,提出了相应的流量计算公式,可供工程设计和管理使用。

Trunk straight opening（funnel mouth） structure in Yellow River Irrigation Area of Ningxia is a combination of the gate and culvert,the flow presents a very complex flow pattern in the culvert,including free outflow,submerged outflow and pressure flow.The test results show that,when the water depth after gate is smaller,and the downstream water depth is less than the jump of the second conjugate depth,we can calculate the discharge with free outflow;when the water depth is less than or equal to the height of the culvert,and downstream water depth is greater than the jump of the second conjugate depth,we can calculate the discharge according to submerge outflow;when the water depth is greater than the culvert height,and the downstream water depth is greater than the second water jump conjugate depth,we can calculate the pipe flow with pressure flow.Meanwhile,we make the corresponding discharge calculation formulas,which could be used for engineering design and management.