ABSTRACT

Hydraulic characteristics of swirling flow at shaft spillways with an innovative inlet, namely the marguerite-shaped inlet, is investigated based on model experimentation. Detailed measurements of head–discharge relationship, flow regimes, water free-surface profiles, flow circulation, discharge coefficient and threshold and critical submergence depths were performed for shaft spillways with marguerite-shaped inlets. Results indicate that the strength of swirling flow through a marguerite-shaped inlet is significantly lower than that of a simple shaft and a morning glory spillway. Marguerite-shaped inlets increase the developed crest length by at least 6 times the global size of the original shaft spillway. Therefore, they produce exceptional hydraulic performances in increasing the weir overflow length without changing the global size of the shaft spillway, thereby increasing the flow discharge up to 6, 4 and 1.5 times the simple shaft, morning glory and circular piano-key spillways, respectively. Finally, based on the detailed experimental data, different empirical correlations are derived for estimating the threshold and critical submergence depths and discharge coefficient of the marguerite-shaped inlets for different flow regimes using regression analysis.

摘要

基于模型实验研究了具有创新入口，即玛格丽特形入口的轴溢洪道涡流的水力特性。对带有玛格丽特形入口的竖井溢洪道进行了水头-流量关系、流态、水自由表面轮廓、流动循环、流量系数和阈值以及临界淹没深度的详细测量。结果表明，通过玛格丽特形入口的旋流强度明显低于简单竖井和牵牛花溢洪道的强度。玛格丽特形入口将开发的顶部长度至少增加了原始井道溢洪道整体尺寸的 6 倍。所以，它们在增加堰溢流长度而不改变竖井溢洪道的整体尺寸方面产生了卓越的水力性能，从而将流量分别增加到简单竖井、牵牛花和圆形钢琴键溢洪道的 6、4 和 1.5 倍。最后，基于详细的实验数据，使用回归分析推导出不同的经验相关性，用于估计不同流态下玛格丽特形入口的阈值和临界淹没深度和流量系数。