自然循环条件下的气泡行为研究
|
摘要
本文以去离子水为工质,对常压条件下的环形通道内过冷沸腾中的气泡行为进行了摄像可视化观察与实验研究。
对于摄像可视化,基于图像处理技术,实验中进行了测试并对管道弧面的光学影响进行了校正计算讨论。结果表明,在低空泡份额下,该方法与采用快速截止阀法测量有着良好的吻合性。在中高空泡份额的情况中,由于气泡数量过多,形状任意,且存在重叠的情况,使得图形处理难以进行,误差极大。而必要的光学校正,有助于提高空泡份额的测量准确性。在单气泡方面,实验结果表明,滑移气泡的持续生长规律符合热力控制区Mihic方程。这说明滑移气泡在核化点处的生长符合Mihic惯性控制方程。气泡脱离频率与脱离直径,在本文实验条件下,不符合Ivey分区关系。
根据实验数据采用对频率的隐格式得到了高度相关的拟合关系式。在理论和实验上证明气泡的上升速度正比于气泡直径的平方根值,且与工况参数无关。对阻力系数,验证了小雷诺数流动中主要的两个计算公式。对比值表明,阻力系数计算时应该考虑工质流动速度,并将其从气泡上升速度中扣除。
气泡的形态主要受粘性与表面张力的影响,粘性与表面张力越小气泡的变形程度越大。
在多气泡间行为方面,本文主要研究了两气泡之间的垂直追赶聚合现象和管道轴向空泡份额分布。
相比于Fortes确定的聚合过程,实验中观察到在绕过上侧气泡之后还存在一个短暂的分离过程。气泡之间的聚合是大部分气泡从小气泡到大气泡的主要生长形式,也是壁面附近换热强化的主要方式。管道轴向空泡份额,在形式上与已知的理论与实验值一致。
In this paper, by using the de-ionized water as the working fluid, photographic method and experiment are used to research the bubble behaviors in annular channel under subcooling natural circulation in low pressure.
On the basis of photographic method, an experiment is designed to test the void fraction with photographic method and some optical corrections are discussed to the bubbles. Experimental results show that the method has the capacity of measuring of volumetric quality and section void fraction at low fraction, and match the valve cut-off method. At high fraction, bubbles are existing in great amount with random shapes and overlap each other. Thus, it’s hard to differentiate a single bubble in admissible error, and emendation would improve the measuring precision.
On single bubble, the results show that growing sliding bubbles are accord to the Mihic function, which is belong to thermal phase. This means the growth at nucleate sites belong to the inertial phase. In the conditions of this paper, Ivey relationships gave higher results than experiment. Compared with experiment data, an implicit function for frequency is gotten, which is fit to the data well. Theoretical and experimental analysis proved that the rising velocity is in proportion to bubble diameter’s square root and independent of conditions. About resistance coefficient, two formulas of low Reynolds number flow are tested. Compared with data, the flow velocity should be minus by rising velocity in calculation of coefficient.
The main factors which influence bubble shape are viscosity and surface tension. The viscosity and surface tension are lower, the bubble distortion is higher.
On bubbles behaviors, aggregation and void distribution in axial direction are main research contents. In experiment, a departure phase is observed after tumbling phase, which is different from Fortes chart. From the experiment, the process of big bubbles coalesced small bubbles is the main mode of bubble growing to big bubble, and a way to enhance the heat transfer near the heat rod. As a whole, the axial distribution of void fraction is the same as the existing theory and experiment.
对于摄像可视化,基于图像处理技术,实验中进行了测试并对管道弧面的光学影响进行了校正计算讨论。结果表明,在低空泡份额下,该方法与采用快速截止阀法测量有着良好的吻合性。在中高空泡份额的情况中,由于气泡数量过多,形状任意,且存在重叠的情况,使得图形处理难以进行,误差极大。而必要的光学校正,有助于提高空泡份额的测量准确性。在单气泡方面,实验结果表明,滑移气泡的持续生长规律符合热力控制区Mihic方程。这说明滑移气泡在核化点处的生长符合Mihic惯性控制方程。气泡脱离频率与脱离直径,在本文实验条件下,不符合Ivey分区关系。
根据实验数据采用对频率的隐格式得到了高度相关的拟合关系式。在理论和实验上证明气泡的上升速度正比于气泡直径的平方根值,且与工况参数无关。对阻力系数,验证了小雷诺数流动中主要的两个计算公式。对比值表明,阻力系数计算时应该考虑工质流动速度,并将其从气泡上升速度中扣除。
气泡的形态主要受粘性与表面张力的影响,粘性与表面张力越小气泡的变形程度越大。
在多气泡间行为方面,本文主要研究了两气泡之间的垂直追赶聚合现象和管道轴向空泡份额分布。
相比于Fortes确定的聚合过程,实验中观察到在绕过上侧气泡之后还存在一个短暂的分离过程。气泡之间的聚合是大部分气泡从小气泡到大气泡的主要生长形式,也是壁面附近换热强化的主要方式。管道轴向空泡份额,在形式上与已知的理论与实验值一致。
In this paper, by using the de-ionized water as the working fluid, photographic method and experiment are used to research the bubble behaviors in annular channel under subcooling natural circulation in low pressure.
On the basis of photographic method, an experiment is designed to test the void fraction with photographic method and some optical corrections are discussed to the bubbles. Experimental results show that the method has the capacity of measuring of volumetric quality and section void fraction at low fraction, and match the valve cut-off method. At high fraction, bubbles are existing in great amount with random shapes and overlap each other. Thus, it’s hard to differentiate a single bubble in admissible error, and emendation would improve the measuring precision.
On single bubble, the results show that growing sliding bubbles are accord to the Mihic function, which is belong to thermal phase. This means the growth at nucleate sites belong to the inertial phase. In the conditions of this paper, Ivey relationships gave higher results than experiment. Compared with experiment data, an implicit function for frequency is gotten, which is fit to the data well. Theoretical and experimental analysis proved that the rising velocity is in proportion to bubble diameter’s square root and independent of conditions. About resistance coefficient, two formulas of low Reynolds number flow are tested. Compared with data, the flow velocity should be minus by rising velocity in calculation of coefficient.
The main factors which influence bubble shape are viscosity and surface tension. The viscosity and surface tension are lower, the bubble distortion is higher.
On bubbles behaviors, aggregation and void distribution in axial direction are main research contents. In experiment, a departure phase is observed after tumbling phase, which is different from Fortes chart. From the experiment, the process of big bubbles coalesced small bubbles is the main mode of bubble growing to big bubble, and a way to enhance the heat transfer near the heat rod. As a whole, the axial distribution of void fraction is the same as the existing theory and experiment.
引文
[1]王飞,聂常华,黄彦平.稳态自然循环特性计算分析.核科学与工程. 2005,25(1):61~65页
[2]杨祖毛,陈炳德,王飞,黄彦平,杨瑞昌.一维单相自然循环流量稳态解的型式及实验验证.核科学与工程.1999,19(3):248~253页
[3]谭思超,张红岩,庞凤阁,高璞珍.摇摆运动下单相自然循环流动特点.核动力工程.2005,26(6):559~563页
[4]谭思超,庞凤阁.摇摆运动引起的波动与自然循环密度波型脉动的叠加.核动力工程.2005,26(2):140~143页
[5]谭思超,庞凤阁,高璞珍.摇摆对自然循环传热特性影响的实验研究.核动力工程.2006,27(5):33~36页,69页
[6]谭思超,高璞珍,苏光辉.摇摆运动条件下自然循环流动的实验和理论研究.哈尔滨工程大学学报.2007,28(11):1213~1217页
[7] S.N.DAS, S.N.DKS. Determination of coupled sway, roll, and yaw motions of a floating body in regular waves. IJMMS.2004:41, 2181~2197P
[8]杨春信,吴玉庭,袁修干,马重芳.核态池沸腾中气泡生长和脱离的动力学特征——气泡动力学研究回顾.热能动力工程.1999,14(82):246~249页,322页
[9] Michael D. Bartel, Mamoru Ishii, Takuyki Masukawa, Ye Mi, Rong Situ. Interfacial area measurements in subcooled flow boiling. Nuclear Engineering and Design. 2001 (210):135~155P
[10] V. Prodanovic, D. Fraser, M. Salcudean. A unified model for the prediction of bubble detachment diameters in boiling systems. I. Pool boiling. International Journal of Multiphase Flow. 2002 (28):1~19P
[11]杨春信,吴玉庭,袁修干,马重芳.核态池沸腾中气泡生长和脱离的动力学特征——气泡的脱离直径与脱离频率.热能动力工程.1999,14(83):330~333页
[12] Yao-Hua Zhao, Takashi Masuoka, Takaharu Tsuruta. Unified theoreticalprediction of fully developed nucleate boiling and critical heat flux based on a dynamic microlayer model. International Journal of Heat and Mass Transfer. 2002 (45):3189~3197P
[13]赵耀华,姬朝玥 .过冷沸腾气泡行为的实验研究.工程热物理学报.2004,25(1):109~111页
[14] McFadden, P.W. , Grassmann, P. The relation between bubble frequency and diameter during nucleate pool boiling. International Journal of Heat and Mass Transfer. 1962 (5):169~173P
[15] R.Cole, Bubble frequencies and departure volumes at subatmospheric pressures. American Institute of Chemical Engineers Journal. 1967(13): 779~783P
[16] H.J. Ivey. Relationships between bubble frequency, departure diameter and rise velocity in nucleate boiling. International Journal of Heat and Mass Transfer. 1967 (10):1023~1040P
[17]许卫新.单气泡在自由流场和边界层流场中运动的水动力计算及其空化行为.水动力学研究与进展.1987,2(3):19~32页
[18]刘胜,杨成渝,王平义.水中气泡运动规律的研究.重庆交通学院学报.2007,26(3):136~139页,152页
[19] Tomio Okawa, Tatsuhiro Ishida, Isao Kataoka, Michitsugu Mori. Bubble rise characteristics after the departure from a nucleation site in vertical up flow boiling of subcooled water. Nuclear Engineering and Design. 2005(235): 1149~1116P
[20] G. H. Yeoh, Sherman C. P. Cheung, J. Y. Tu, Mark K. M. Ho. Fundamental consideration of wall heat partition of vertical subcooled boiling flows. International Journal of Heat and Mass Transfer. 2008 (51):3840~3853P
[21] Rong Situ, Ye Mi, Mamoru Ishii, Michitsugu Mori. Photographic study of bubble behaviors in forced convection subcooled boiling. International Journal of Heat and Mass Transfer. 2004(47):3659~3667P
[22]李小明,冯全科,毕勤成,陈听宽.利用红外对管进行无干扰气泡上升速度测量的实验研究.西安交通大学学报.2004,38(11):1110~1113页,1118页
[23]冀邦杰,严冰,胡巍,员晓辉,钱建平.实验室气泡大小的测量.舰船科学技术.2008,30(2):79~84页
[24]孙奇,杨瑞昌,赵华.低流速过冷沸腾净蒸汽产生点计算模型.核动力工程.2003,24(5):417~420页,444页
[25] M. Kureta, T. Hibiki, K. Mishima, H. Akimoto. Study on point of net vapor generation by neutron radiography in subcooled boiling flow along narrow rectangular channels with short heated length. International Journal of Heat and Mass Transfer. 2003(46):1171~1181P
[26]孙奇,杨瑞昌,王小军,郗昭,赵华.低流速过冷沸腾截面平均空泡率实验研究.原子能科学技术.2005,29(2):193~197页
[27]杨瑞昌,王彦武,唐虹,施德强,鲁钟琪.自然循环过冷沸腾流动不稳定性的实验研究.工程热物理学报.1999,20(2):228~232页
[28]杨星团,姜胜耀,张佑杰.低温堆和沸水堆流动不稳定因素比较分析.核动力工程.2002,23(2):5~9页
[29]杨瑞昌,唐虹,王彦武.自然循环过冷沸腾流动不稳定性的研究.工程热物理学报.2004,25(3):435~438页
[30]杨瑞昌,王彦武,唐虹,施德强,鲁钟琪.自然循环过冷沸腾流动不稳定性的实验研究.工程热物理学报.2005,26(4):317~321页
[31]谭思超,庞凤阁,高璞珍.自然循环过冷沸腾流动不稳定性实验研究.核动力工程.2006,27(1):18~21页,93页
[32]闫丽.气液两相流动中气泡行为3D测量关键技术研究.天津大学.硕士论文.2006,6
[33]邵建武.水中气泡运动图像测量方法研究.西安理工大学.硕士论文.2004:4-6页
[34]冈萨雷斯.数字图像处理MATLAB版.电子工业出版社,2009:315~320页
[35]郭烈锦.两相与多相流体动力学.西安交通大学出版社,2002:382页,387页, 388~390页,399页,401页,402页
[36]徐济鋆.沸腾传热与气液两相流.北京,原子能出版社,2001.6:231页
[37] B.Γ.列维奇.物理—化学流体动力学.上海科技出版社,1965.2:439页
[38]张鸣远,景思睿,李国君.高等工程流体动力学.西安交通大学出版社,2006:237页
[39] E. E. Michaelides. Particles, bubbles& drops:their motion heat and mass transfer. World Scientific Publishing Co.Pte.Ltd.2006:48P
[40] Fortes, A Joseph G.. G..& Lundgren T., Nonlinear mechanics of beds of spherical particles. J Fluid Mech. 1987,177:467~483P
[2]杨祖毛,陈炳德,王飞,黄彦平,杨瑞昌.一维单相自然循环流量稳态解的型式及实验验证.核科学与工程.1999,19(3):248~253页
[3]谭思超,张红岩,庞凤阁,高璞珍.摇摆运动下单相自然循环流动特点.核动力工程.2005,26(6):559~563页
[4]谭思超,庞凤阁.摇摆运动引起的波动与自然循环密度波型脉动的叠加.核动力工程.2005,26(2):140~143页
[5]谭思超,庞凤阁,高璞珍.摇摆对自然循环传热特性影响的实验研究.核动力工程.2006,27(5):33~36页,69页
[6]谭思超,高璞珍,苏光辉.摇摆运动条件下自然循环流动的实验和理论研究.哈尔滨工程大学学报.2007,28(11):1213~1217页
[7] S.N.DAS, S.N.DKS. Determination of coupled sway, roll, and yaw motions of a floating body in regular waves. IJMMS.2004:41, 2181~2197P
[8]杨春信,吴玉庭,袁修干,马重芳.核态池沸腾中气泡生长和脱离的动力学特征——气泡动力学研究回顾.热能动力工程.1999,14(82):246~249页,322页
[9] Michael D. Bartel, Mamoru Ishii, Takuyki Masukawa, Ye Mi, Rong Situ. Interfacial area measurements in subcooled flow boiling. Nuclear Engineering and Design. 2001 (210):135~155P
[10] V. Prodanovic, D. Fraser, M. Salcudean. A unified model for the prediction of bubble detachment diameters in boiling systems. I. Pool boiling. International Journal of Multiphase Flow. 2002 (28):1~19P
[11]杨春信,吴玉庭,袁修干,马重芳.核态池沸腾中气泡生长和脱离的动力学特征——气泡的脱离直径与脱离频率.热能动力工程.1999,14(83):330~333页
[12] Yao-Hua Zhao, Takashi Masuoka, Takaharu Tsuruta. Unified theoreticalprediction of fully developed nucleate boiling and critical heat flux based on a dynamic microlayer model. International Journal of Heat and Mass Transfer. 2002 (45):3189~3197P
[13]赵耀华,姬朝玥 .过冷沸腾气泡行为的实验研究.工程热物理学报.2004,25(1):109~111页
[14] McFadden, P.W. , Grassmann, P. The relation between bubble frequency and diameter during nucleate pool boiling. International Journal of Heat and Mass Transfer. 1962 (5):169~173P
[15] R.Cole, Bubble frequencies and departure volumes at subatmospheric pressures. American Institute of Chemical Engineers Journal. 1967(13): 779~783P
[16] H.J. Ivey. Relationships between bubble frequency, departure diameter and rise velocity in nucleate boiling. International Journal of Heat and Mass Transfer. 1967 (10):1023~1040P
[17]许卫新.单气泡在自由流场和边界层流场中运动的水动力计算及其空化行为.水动力学研究与进展.1987,2(3):19~32页
[18]刘胜,杨成渝,王平义.水中气泡运动规律的研究.重庆交通学院学报.2007,26(3):136~139页,152页
[19] Tomio Okawa, Tatsuhiro Ishida, Isao Kataoka, Michitsugu Mori. Bubble rise characteristics after the departure from a nucleation site in vertical up flow boiling of subcooled water. Nuclear Engineering and Design. 2005(235): 1149~1116P
[20] G. H. Yeoh, Sherman C. P. Cheung, J. Y. Tu, Mark K. M. Ho. Fundamental consideration of wall heat partition of vertical subcooled boiling flows. International Journal of Heat and Mass Transfer. 2008 (51):3840~3853P
[21] Rong Situ, Ye Mi, Mamoru Ishii, Michitsugu Mori. Photographic study of bubble behaviors in forced convection subcooled boiling. International Journal of Heat and Mass Transfer. 2004(47):3659~3667P
[22]李小明,冯全科,毕勤成,陈听宽.利用红外对管进行无干扰气泡上升速度测量的实验研究.西安交通大学学报.2004,38(11):1110~1113页,1118页
[23]冀邦杰,严冰,胡巍,员晓辉,钱建平.实验室气泡大小的测量.舰船科学技术.2008,30(2):79~84页
[24]孙奇,杨瑞昌,赵华.低流速过冷沸腾净蒸汽产生点计算模型.核动力工程.2003,24(5):417~420页,444页
[25] M. Kureta, T. Hibiki, K. Mishima, H. Akimoto. Study on point of net vapor generation by neutron radiography in subcooled boiling flow along narrow rectangular channels with short heated length. International Journal of Heat and Mass Transfer. 2003(46):1171~1181P
[26]孙奇,杨瑞昌,王小军,郗昭,赵华.低流速过冷沸腾截面平均空泡率实验研究.原子能科学技术.2005,29(2):193~197页
[27]杨瑞昌,王彦武,唐虹,施德强,鲁钟琪.自然循环过冷沸腾流动不稳定性的实验研究.工程热物理学报.1999,20(2):228~232页
[28]杨星团,姜胜耀,张佑杰.低温堆和沸水堆流动不稳定因素比较分析.核动力工程.2002,23(2):5~9页
[29]杨瑞昌,唐虹,王彦武.自然循环过冷沸腾流动不稳定性的研究.工程热物理学报.2004,25(3):435~438页
[30]杨瑞昌,王彦武,唐虹,施德强,鲁钟琪.自然循环过冷沸腾流动不稳定性的实验研究.工程热物理学报.2005,26(4):317~321页
[31]谭思超,庞凤阁,高璞珍.自然循环过冷沸腾流动不稳定性实验研究.核动力工程.2006,27(1):18~21页,93页
[32]闫丽.气液两相流动中气泡行为3D测量关键技术研究.天津大学.硕士论文.2006,6
[33]邵建武.水中气泡运动图像测量方法研究.西安理工大学.硕士论文.2004:4-6页
[34]冈萨雷斯.数字图像处理MATLAB版.电子工业出版社,2009:315~320页
[35]郭烈锦.两相与多相流体动力学.西安交通大学出版社,2002:382页,387页, 388~390页,399页,401页,402页
[36]徐济鋆.沸腾传热与气液两相流.北京,原子能出版社,2001.6:231页
[37] B.Γ.列维奇.物理—化学流体动力学.上海科技出版社,1965.2:439页
[38]张鸣远,景思睿,李国君.高等工程流体动力学.西安交通大学出版社,2006:237页
[39] E. E. Michaelides. Particles, bubbles& drops:their motion heat and mass transfer. World Scientific Publishing Co.Pte.Ltd.2006:48P
[40] Fortes, A Joseph G.. G..& Lundgren T., Nonlinear mechanics of beds of spherical particles. J Fluid Mech. 1987,177:467~483P