挺水植被环境中逆向射流和浮力射流近区稀释机理研究

It has been regards as an effective way that the wastewater is collected and primarily treated before being discharged to receiving waters through pipes. Every year, plenty of wastewaters are discharged to rivers and seas from cities of China along rivers and coasts. It is always a problem widely concerned by environment engineers how to effectively raise and improve the initial dilution near the neighbor of discharge outlet through designing discharge pattern and environment conditions of receiving waters. The project proposes the topics of opposed jet in an environment with emergent plants and dilution in the neighbor of buoyant jet to study environment parameters of the receiving waters and the effect of jet emission angle on the dilution near the outlet. The key point is to greatly improve the dilution efficiency through the drag effects on jet caused by emergent plants, expansion of jet due to opposed flow, initial moment of jet and buoyant effect, and fast dilution in the mixing zone formed by the jet entrainment and strong turbulence. This project is going to study the effects of emergent plants and opposed jet on the flow field and concentration field near the neighbor of outlet via theory, experiments and numerical simulations. The object is to complete the dilution theory in the environment of emergent plants and opposed jet flow near the neighbor of discharge outlet, which would be the basis of hydraulic designing wastewater discharge diffuser and environmental impact assessment.

污水集中后经过一级处理通过放流管排放到受纳水域是行之有效的废水排放方式。我国沿江沿海的城市每年有大量的废水排放到海洋或大江大河。如何优化设计废水排放的形式和受纳环境条件来有效地改善和提高污水排放近区的初始稀释一直是环境力学和环境工程界关注的问题。本项目提出的挺水植被环境中逆向射流和浮力射流近区稀释机理研究，就是针对受纳水体环境参数和射流排放角对废水排放近区稀释效应展开研究。其核心思想是利用挺水植被对射流的阻滞效应、逆流环境流体对射流的扩展作用、射流的初始动量和浮力效应，同时伴随射流的卷吸和强烈紊动可迅速形成强的混合区来达到污染物在近区的快速稀释，使得废水排放近区稀释得到大幅度提高。本研究从理论、试验和数值模拟等方面研究挺水植被和逆向来流两类环境因素对废水排放近区流场和浓度场的影响，形成挺水植被环境中逆向射流和浮力射流近区稀释理论，为废水排放扩散器水力设计和环境影响评价奠定理论基础。

我国沿江沿海的城市每年有大量的废水排放到海洋或大江大河。本项目主要针对废水排放的形式和受纳环境条件能有效地改善和提高污水排放近区的初始稀释这一论点开展了系列研究。获得挺水植被环境中射流、浮力射流、逆向射流和逆向浮力射流近区稀释特性，揭示了水流、植被和浮力通量之间的相互作用机理，形成了一整套基于试验研究、理论分析、数值解法的勾勒三者作用与效应的生态河道水力学体系；从植被与水流相互作用形成的阻力特性方面，提出了辅助河床概念，基于GP算法给出植被水流过流能力计算新的公式，统一了明渠水力学谢才公式；基于Chickwendu的N 区纵向离散模型，提出了非淹没植被河道纵向离散系数新公式；基于多孔介质流体动力学控制方程组，解析出复杂边界条件下湿地流动泰勒弥散分析解，完善了泰勒弥散理论。这些成果丰富了生态环境水力学的理论，对当前生态河道整治，生态河道环境影响评价具有直接的应用前景。