阶梯溢洪道不同坡比消能研究

针对实际工程中难以确定阶梯坡比的问题,通过4个水利工程、5个阶梯坡比的模型实验,得出了对工程设计最实用的坡比范围1∶2～1∶3。在相同条件下对4种坡比的阶梯水流进行了数值模拟,进一步论证了上述阶梯坡比的合理性,计算结果直观再现了滑移流中的顺时针水流旋滚,以及旋滚下游水体在剩余阶梯平面长度范围内的贴壁运动,提出的速度分析有助于了解阶梯旋滚消能的成因。研究成果反映出,阶梯坡比小于1∶2,水流旋滚已得到充分发展。在坡比范围1∶2～1∶3内,阶梯消能能够达到60%。坡比超过1∶2,阶梯消能率将明显下降;坡比低于1∶3,消能率增长空间不大。

Energy Dissipation of Skimming Flow over Stepped Chutes with Different Slopes

Based on experimental data of four hydraulic projects, the slops ranging from 1/2 to 1/3 of stepped chutes were proposed in this paper, which has direct implications for the practical design. The simulation on the stepped flow with four slopes under the same condition was performed to verify further the rationality of the step slope. The simulated results predicted the clockwise recirculating vortices and the movement of the wall-attached flow downstream. The velocity analysis proposed was helpful for understanding the energy loss caused by vortices. The vortices are fully developed when the slope is below 1:2. Based on the laboratory data and the simulation results, the energy dissipation rate reaches 60% in the slope range from 1/2 to 1/3, which drops down with a slope exceeding 1/2 and increases slowly with a slope below 1/3.