研究论文
曾立云,余昌全,常青.异波折板流场模拟分析与结构优化[J].环境科学学报,2011,31(12):2634-2641
异波折板流场模拟分析与结构优化
- Simulation analysis of flow field and structure optimization of asynchronous folded plates
- 基金项目：国家自然科学基金(No.50878102)
- 作者
- 单位
- 曾立云
- 兰州交通大学环境与市政工程学院,兰州 730070
- 余昌全
- 兰州交通大学环境与市政工程学院,兰州 730070
- 常青
- 兰州交通大学环境与市政工程学院,兰州 730070
- 摘要：基于FLUENT技术,以连续方程、Navier-Stokes方程及k-epsilon湍流方程作为流动基本控制方程,对异波折板絮凝反应流场进行了数值模拟,并通过网格独立性检验,保证了模拟结果的真实性.以流场速度分布、紊动动能、有效能耗作为评价标准,根据数值模拟提出了不同絮凝段的最优折板单元组合.结果表明,夹角90°的短折板适宜于絮凝前段,而夹角120°的长折板更适宜于后续絮凝段.在此基础上建议对絮凝前段的折板单元进行结构优化,在每个折板单元中心增设菱形扰流板,用以增强折板内流场紊动动能,提高有效能耗相对比例.优化后折板内的流场面积平均紊动动能可由2.75×10-3 m2·s-2提高到3.83×10-3 m2·s-2;面积平均有效能耗可由4.70×10-3 m2·s-3提高到7.74×10-3 m2·s-3.该优化将有利于营造更优越的水力条件从而提高絮凝效率.
- Abstract：Based on FLUENT technology,the numerical simulation of flow field of asynchronous folded-plate flocculation reactor was performed by using continuity equation,Navier-Stokes equations and k-epsilon turbulence equations as the basic fluid control equations,and the reliability of simulation results was confirmed through the test of grid independency. The optimum geometric structures of folded-plate units of different flocculation stages were determined, taking the distributions of flow velocity,turbulent kinetic energy and turbulent dissipation rate as evaluation standards. It turned out that short folded plates with 90° included angle are more applicable to the preceding flocculation stage,while long folded plates with 120° included angle are more applicable to the subsequent flocculation stage. On that basis,appropriate suggestion that rhombic spoilers should be added in the centre of each folded-plate unit was proposed,which contributed to intensifying turbulent kinetic energy and enhancing the ratio of turbulent dissipation rate in the flow field of folded-plate flocculation units, thus the structure of units of the preceding flocculation stage was optimized. Area-weighted average turbulent kinetic energy raise from 2.75×10-3 m2·s-2 to 3.83×10-3m2·s-2,and area-weighted average turbulent dissipation rate raise from 4.70×10-3m2·s-3 to 7.74×10-3m2·s-3 respectively after the optimization. This structure optimization will lead more to favorable hydrodynamic conditions and improve flocculation efficiency.
- Key words：folded-plate flocculation FLUENT turbulent kinetic energy turbulent dissipation rate rhombic spoiler
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