西安建筑科技大学学报(自然科学版)

为探析扬水曝气器内部流动特性,本文采用VOF(Volume of Fluid)法对扬水曝气器流场进行数值模拟,通过比对模拟和实验结果验证了模型的可靠性,详细分析了扬水曝气器内部气弹形成和释放过程及其流动特征,讨论了不同曝气速率和气室体积大小对扬水曝气器提水性能的影响.研究结果表明:数值模拟和试验结果间的误差在6%以内,该方法可靠; 利用VOF方法有效模拟了气室中气体的聚集、气弹形成及释放过程,并发现气体进入上升筒中所形成的并不是一个整体气弹,气弹后还尾随许多中小气泡,研究加深了对扬水曝气器内部流动特性的认识; 出口平均流速随着曝气速率的增大而增大,随着气室体积的减小而增大,并在参数的计算范围内给出了其拟合关系式; 其规律与丛海兵给出的结论一致,进一步印证了本文方法在扬水曝气器性能研究中的适用性,为后续扬水曝气器各项参数的优化设计提供了可靠的分析手段,具有较大的工程应用价值.

In order to analyze the internal flow characteristic of the water-lifting aerator, VOF(volume of fluid)method was used to simulate the flow field of the water-lifting aerator, the reliability of the VOF model was verified by comparing the simulation results with the experimental results, the formation and release process and flow characteristics of the air piston in the water-lifting aerator were analyzed in detail, the effects of different aeration rates and air chamber volume on the water lifting performance of the water-lifting aerator were discussed.The results show that: the error between numerical simulation and experimental results is less than 6%, so the method is reliable; VOF method is used to effectively simulate the process of gas accumulation, gas formation and release in the gas chamber, and it is found that the gas entering the ascending tube is not a whole piston, and many small and medium bubbles are also followed after the piston, which deepens the understanding on the flow characteristics of the internal flow in the water-lifting aerator The results show that: the average outlet velocity increases with the increase of aeration rate, and increases with the decrease of air chamber volume, and its fitting relationship is given within the calculation range of parameters; the law is consistent with the conclusion given by Cong Haibing, which further verifies the applicability of the method in the performance study of the water-lifting aerator, and provides a reference for the optimization design of various parameters of the water-lifting aerator, has great engineering application value.

引言
1 数值模拟方法
2 模拟结果与分析
4 结论

图1 扬水曝气器结构图<br/>Fig.1 Diagram of the water-lifting aerator's configuration

图1 扬水曝气器结构图
Fig.1 Diagram of the water-lifting aerator's configuration

图2 计算模型网格及相位图<br/>Fig.2 Computational domain grids and phase diagram

图2 计算模型网格及相位图
Fig.2 Computational domain grids and phase diagram

图3 上升筒流速实测值[6]与计算结果对比<br/>Fig.3 Comparison of computational and experimental results of the velocity in the ascending tube

图3 上升筒流速实测值[6]与计算结果对比
Fig.3 Comparison of computational and experimental results of the velocity in the ascending tube

图4 计算模型对比<br/>Fig.4 Comparison of computational model

图4 计算模型对比
Fig.4 Comparison of computational model

表1 计算工况表<br/>Tab.1 Simulation conditions

表1 计算工况表
Tab.1 Simulation conditions

图5 上升筒流速周期变化情况<br/>Fig.5 Water flow velocity with time in the ascending tube

图5 上升筒流速周期变化情况
Fig.5 Water flow velocity with time in the ascending tube

图6 气弹生成释放过程<br/>Fig.6 The generation process of the air piston

图6 气弹生成释放过程
Fig.6 The generation process of the air piston

图7 不同工况相同气室条件下上升筒出口流速变化特征<br/>Fig.7 Distributions of the velocity in the outlet of ascending tube for case two to case five

图7 不同工况相同气室条件下上升筒出口流速变化特征
Fig.7 Distributions of the velocity in the outlet of ascending tube for case two to case five

表2 不同曝气速率条件下提水性能数值模拟结果<br/>Tab.2 Computational results of the water lifting performance with different aeration rate

表2 不同曝气速率条件下提水性能数值模拟结果
Tab.2 Computational results of the water lifting performance with different aeration rate

图8 相同工况不同气室条件下上升筒出口流速变化特征<br/>Fig.8 Distributions of the velocity in the outlet ofascending tube for case two and case six to case eight

图8 相同工况不同气室条件下上升筒出口流速变化特征
Fig.8 Distributions of the velocity in the outlet ofascending tube for case two and case six to case eight

表3 不同气室体积条件下提水性能数值模拟结果<br/>Tab.3 Computational results of the water lifting performance with different effective volume of the aeration chamber

表3 不同气室体积条件下提水性能数值模拟结果
Tab.3 Computational results of the water lifting performance with different effective volume of the aeration chamber

[1]黄廷林. 水源水库水质污染原位控制与改善是饮用水水质安全保障的首要前提[J].给水排水,2017,43(1):1-3.
[2]丛海兵,黄廷林,缪晶广,等. 水体修复装置—扬水曝气器的开发[J].中国给水排水, 2005, 21(3): 41-45.
[3]丛海兵,黄廷林,缪晶广,等. 扬水曝气器的水质改善功能及提水、充氧性能研究[J].环境工程学报, 2007,(1): 7-13.
[4]丛海兵. 扬水曝气水源水质改善技术研究[D].西安:西安建筑科技大学, 2007.
[5]CONG Haibing, HUANG Tinglin, CHAI Beibei, et al. An new mixing-oxygenating technology for water quality improvement of urban water source and its implication in a reservoir. Renewable Energy[J],2009,34(9): 2054-2060
[6]黄廷林,丛海兵,柴蓓蓓. 饮用水水源水质污染控制[M].北京:中国建筑工业出版社, 2009.
[7]CONG Haibing, HUANG Tinglin, CHAI Beibei. A Water-Circulating Aerator: optimizing structure and predicting water flow rate and oxygen transfer[J].Journal of Hydraulic Engineering,2011,137(6):659-667.
[8]朱伟峰. 基于CFD的扬水曝气器外围流场及曝气室流场模拟[D].西安:西安建筑科技大学, 2008.
[9]王进行. 温度分层及水深对扬水曝气器流场影响的CFD模拟[D].西安:西安建筑科技大学, 2010.
[10]赵伟丽. 深水型水库扬水曝气混合原位控藻数值模拟[D].西安:西安建筑科技大学, 2013
[11]SUN Xin, ZHAO Weili, HUANG Tinglin. Effects of water depth on algae control in stratified reservoirs using in-situ water-lifting aeration technology[J].Advanced Materials Research, 2013,663: 977-981.
[12]SUN Xin, ZHAO Weili, HUANG Tinglin. Effects of temperature gradient on algae inhibition zone in source water reservoirs using in-situ water-lifting aeration technology[J].Advanced Materials Research,2013, 663: 870-875.
[13]龙圣海.峡谷分层型水源水库水质变化特征及水温结构模拟研究[D].西安:西安建筑科技大学,2017.
[14]LI Yang, HUANG Tinglin, ZHOU Zizhen, et al. Effects of reservoir operation and climate change on thermal stratification of a canyon-shaped reservoir, in northwest China[J].Water Science & Technology Water Supply, 2018, 18(2): 418-429.
[15]李扬.分层型水源水库水温模拟及扬水曝气系统运行优化研究[D].西安:西安建筑科技大学,2018.
[16]孙昕,张梦丹,黄廷林,等. 扬水曝气器类型对分层水库藻类控制效果的影响[J].环境科学研究,2014,(12): 1479-1485.
[17]张梦丹. 深水型水库扬水曝气系统优化[D].西安:西安建筑科技大学,2014.
[18]SUN X, LI X L, ZHANG M D, et al. Comparison of water-lifting aerator type for algae inhibition in stratified source water reservoirs[J].Ecological Engineering, 2014, 73: 624-634.
[19]HIRT C W,NICHOLS B D. Volume of fluid(VOF)method for dynamics of free boundaries[J].Journal of Computational Physics,1981,39(1):201-225.
[20]GUO F, CHEN B. Numerical study on Taylor bubble formation in a micro-channel T-junction using VOF method[J].Microgravity Science and Technology, 2009, 21(1): 51-58.
[21]WANG L J, JIA Y, YAN X K, et al. Gas-liquid numerical simulation on micro-bubble generator and optimization on the nozzle to throat spacing[J].Asia-Pacific Journal of Chemical Engineering, 2015, 10(6): 893-903.
[22]丁国栋,陈家庆,蔡小垒,等. 文丘里管式微气泡发生器内单气泡碎化行为的数值模拟[J].化工进展, 2020, 39(7): 2590-2598.
[23]BRACKBILL J U,KOTHE D B,ZEMACH C. A continuum method for modeling surface tension[J].Journal of computational physics, 1992, 100(2):335-354.

备注

引言

1 数值模拟方法

2 模拟结果与分析

4 结论

期刊信息