不同高径比下气液两相流流场结构的实验研究
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摘要
气液两相流是好氧曝气过程中产生的一种复杂的气液流动形态,其流型、流态对曝气反应器的运行效率具有重要的影响。本研究使用高速摄影机获得气泡羽流的流场图像,再经图像处理和数值计算来研究气泡羽流的空隙率参数,测得空隙率值在气泡羽流中的分布,并结合羽流摆动频率对不同纵横比下的羽流运动情况进行分析。研究结果表明,当曝气装置纵横比为1.0时,气液两相流的流场分布均匀,频谱稳定,能形成稳定的气液环流,使气泡在液相中的停留时间变长,可以有效地提高氧传质的效率,改善曝气效果。
The gas liquid two-phase flow is a kind of complex gas-liquid flow morphology produced in the process of oxygen-bearing aeration,whose flow type and flow morphology are of important effect upon the operation of aerating reactor.In this study,the high-speed camera is used to obtain the original images of bubble plume flow field and then the void fraction parameters of the bubble plume flow are studied through the image processing and numerical calculation to measure the distribution of void fraction value in bubble plume flow and in combination with plume swing frequency,the plume flow movement condition under the different aspect ratios are analyzed.The research result indicate that when the aspect ratio of aeration device is 1.0,the flow field distribution of gas-liquid two-phase flow is even with stable frequency spectrum so as to form the stable gas-liquid circulation,whereby making the bubbles study longer in the liquid phase in such a way that oxygen transmission efficiency can be effectively raised and aeration performance can be improved greatly.
The gas liquid two-phase flow is a kind of complex gas-liquid flow morphology produced in the process of oxygen-bearing aeration,whose flow type and flow morphology are of important effect upon the operation of aerating reactor.In this study,the high-speed camera is used to obtain the original images of bubble plume flow field and then the void fraction parameters of the bubble plume flow are studied through the image processing and numerical calculation to measure the distribution of void fraction value in bubble plume flow and in combination with plume swing frequency,the plume flow movement condition under the different aspect ratios are analyzed.The research result indicate that when the aspect ratio of aeration device is 1.0,the flow field distribution of gas-liquid two-phase flow is even with stable frequency spectrum so as to form the stable gas-liquid circulation,whereby making the bubbles study longer in the liquid phase in such a way that oxygen transmission efficiency can be effectively raised and aeration performance can be improved greatly.
引文
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[2]陈冬,陶豫萍.不同污水处理工艺对水质净化效果的比较[J].环境科学导刊,2013,27(20):69-70.Chen Dong,Tao Yuping.Comparison of water quality purification effect by different wastewater treatment process[J].Environmental Science Survey,2013,27(20):69-70.
[3]Vandu C O,Krishna R.Influence of scale on the volumetric mass transfer coefficients in bubble columns[J].Chemical Engineering&Processing,2004,43(4):575-579.
[4]侯和平,郭凯铭,刘凯,等.基于Radon变换与灰度投影积分极值方法的矩形检测[J].西安理工大学学报,2014,30(2):133-138.Hou Heping,Guo Kaiming,Liu Kai,et al.Rectangle detection based on radon transform and gray projection integral extreme value method[J].Journal of Xi’an University of Technology,2014,30(2):133-138.
[5]田道贵,孙立成,高菲,等.光学探针在气液两相流动局部参数测量中的应用研究[J].实验流体力学,2012,26(6):91-95.Tian Daogui,Sun Licheng,Gao Fei,et al.A study on application of optical probes for the measurement of local parameters in two-phase flow[J].Journal of Experiments in Fluid Mechanics,2012,26(6):91-95.
[6]刘文洪,万甜,程文娟,等.基于图像二值化处理的气液两相流不稳定结构分析[J].水利学报,2009,40(11):1369-1373.Liu Wenhong,Wan Tian,Cheng Wenjuan,et al.Analysis on steady structure of gas liquid two-phase flow in the basis of Image binarization[J].Journal of Hydraulic Engineering,2009,40(11):1369-1373.
[7]王秀英.气液两相流含气率图像检测方法[J].计算机工程与应用,2013,49(5):36-39.Wang Xiuying.Method to measure void fraction of gasliquid two-phase flow based on imaged processing[J].Computer Engineering and Applications,2013,49(5):36-39.
[8]张月皓,董峰,许聪,等.气液两相流含气率超声测试方法研究[J].仪器仪表学报,2014,35(9):2094-2101.Zhang Yuehao,Dong Feng,Xu Cong,et al.Ultrasonic method for gas-liquid two phase flow void fraction measurement[J].Chinese Journal of Scientific Instrument,2014,35(9):2094-2101.
[9]吴云,郭幸斐,张宏伟,等.气液两相流对气升式管式MBR膜污染的影响[J].中国给水排水,2013,29(9):120-124.Wu Yun,Guo Xingfei,Zhang Hongwei,et al.Impact of gas-liquid two-phase flow on membrane fouling in air-lift tubular MBR[J].China Water&Wastewater,2013,29(9):120-124.
[10]崔燕平,姚秉华.SMF-MBR工艺对UV254表征的有机污染物处理效果研究[J].西安理工大学学报,2014,30(1):40-45.Cui Yanping,Yao Binghua.A study of removal efficiency of UV254characterized organic pollutions with SMF-MBR process[J].Journal of Xi’an University of Technology,2014,30(1):40-45.
[11]裴烨青,陈东辉,周恭明,等.MBBR工艺中不同曝气方式充氧效率的比较及工程应用[J].环境工程,2011,29(1):5-9.Pei Yeqing,Chen Donghui,Zhou Gongming,et al.A comparison of aeration efficiency among various aeration modes for MBBR and its application[J].Environmental Engineering,2011,29(1):5-9.