挑流水舌泄洪雾化源形成过程研究

水利工程大功率泄洪引发的强降雨及雾流对工程运行安全和周围生态环境均可能产生较大影响。以往研究工作主要从工程安全出发,关注大坝下游两岸岸坡的泄洪雾化影响范围和雨强分布特性。由于泄洪雾化涉及复杂的水气两相流和高速水流运动问题,现阶段对雾化形成机理的研究尚不透彻。通过概化模型试验,利用高速摄影等测量手段,对不同水力条件下挑流水舌落水产生泄洪雾化的过程进行了观测分析,重点研究了落水点附近表面水体激溅反弹产生雾化源的过程,分析了泄洪雾化主要雾化源的组成和特点。研究表明泄洪雾化主要由水舌空中紊动掺气形成的抛洒雾源和水舌与下游水体碰撞反弹形成的激溅雾源组成,特别指出激溅雾源的形成与水舌入水导致的下游水体表面周期性壅水形成、破裂、消落的过程密切相关。

Formation of Atomization Source Caused by Flood Discharge Flow Nappe

The heavy rainfall and mist flow induced by flood discharge atomization of high dam projects may have negative effect on the hydropower project and its surrounding environment.Researchers have done much work on its influence region and rainfall intensity distribution on the downstream banks.Because of the complexity of this phe-nomenon,the formation mechanism of the flood discharge atomization is still not well revealed.Using high speed video technique in simplified hydraulic model tests,we observed the formation process of flood discharge atomiza-tion when a deflecting flow nappe drops into the downstream pool in different hydraulic conditions.We especially focused on the movement of the flow nappe and surface water around the drop area,and then analysed the compo-nents of different sources and their features.We obtain that the flood discharge atomization source could be divided into two types:dropping caused by the instability and aeration of nappe,and splashing caused by the collision be-tween nappe and downstream water.Specially,the formation of the splashing atomization source is closely related with the periodical formation and dissipation of water surface bulges in the nappe drop area.