明渠交汇流分离区形态及二次流强度分析

采用基于雷诺应力模型与体积函数法的等宽明渠交汇流三维数值模型，对7种交汇角和3种流量比的21种组合工况进行了模拟计算；采用基于主流向流速的等值线法定义分离区，对分离区尺度及其三维形态进行了分析，并根据断面涡量值的计算结果对交汇口下游二次流强度沿程分布规律进行了归纳总结。结果表明:当流量比增大或交汇角减小时，分离区的水平尺寸变小，平面形态变狭长；分离区域平均水深随着流量比或交汇角的增大而降低；交汇口下游二次流强度随着流量比的增大而逐渐减弱；在交汇口附近二次流强度受交汇角影响较大，沿主流方向交汇角影响逐渐降低。

Analysis on separation zone shape and secondary current intensity in open-channel combining flows

Numerical simulations for open-channel combining flows with equal channel width were performed with a three-dimensional numerical model with RSM and VOF method. The results were analyzed for 21 cases, in which seven junction angles and three discharge ratios were combined. The separation zone is defined with the isoline method of longitudinal velocity. The sizes and the three-dimensional shape of the separation zone were analyzed. Meanwhile, the streamwise distribution of the secondary-current intensity downstream the junction was summarized in terms of the sectional vorticity. The results reveal that as the discharge ratio increases or the junction angle decreases, the horizontal sizes of the separation zone decrease, and its shape becomes long and narrow. The averaged depth of separation zone decreases while the discharge ratio or the junction angle increases. The intensity of the secondary currents downstream of the junction gradually reduces while the discharge ratio increases. The impact of the junction angle is significant near the junction and gradually reduces along the streamwise direction.