水平旋流泄洪洞的基本流态与影响因素

通过模型试验,对上下游水位、通气孔直径、水平洞洞长和起旋器收缩断面面积比对水平旋流泄洪洞的流态的影响进行了研究。结果表明,在竖井为有压流的条件下,水平旋流泄洪洞的流态可分为自由流、吸吮流和淹没流3种基本流态,流态的分类与转变受各种因素的影响;通气时,水平旋流洞内旋流的空腔直径大而均匀,水流旋转的强度增大;不同的洞长,流态从吸吮流向淹没流转变时过渡区的相对上下游水位差相同,但洞长越大,吸吮流的范围越大,转变为自由流流态时所需要的起旋器出口的水流弗劳德数也越大;起旋器出口面积比不同时,流态分区的临界水力条件是不同的。

Basic flow pattern in horizontal rotary flow spillway tunnels and its influencing factors

Based on model tests,a study was performed on the influences of the upstream and downstream water levels,the diameter of vent hole,the length of spillway tunnels,and the area contraction ratio of rotary flow generator on the flow pattern in the horizontal rotary flow spillway tunnel.The result shows that,under the condition of pressure flow,the flow in the spillway tunnel can be divided into three patterns,i.e.the free flow pattern,the absorbing flow pattern,and the submerged flow pattern,and that classification and conversion of different flow patterns are influenced by many factors.Moreover,some conclusions are drawn as follows: in ventilation state,the cavity of rotary flow in the spillway tunnel is uniform with large diameter,and the intensity of flow rotation increases;for different lengths of the spillway tunnel,the relative difference between upstream and downstream water levels(H-h)/h in transitional zone where the absorbing flow pattern is converted to the submerged flow pattern is invariable;the longer the spillway tunnel,the wider the range of absorbing flow,and the greater the Froude number at the outlet of rotary flow generator needed for the conversion of the absorbing flow pattern into the free flow pattern;for different area contraction ratios at the outlet of rotary flow generator,the critical hydraulic conditions for flow pattern regionalization are different.