摘要
为探究T形微细通道内蒸汽直接接触间歇凝结汽液相界面的运动特性,利用高速摄像机(帧率为5000帧/s)获取过冷水温33℃、过冷水质量流量6.325g/min、蒸汽温度100℃及蒸汽质量流量0.25g/min工况下的可视化图像。在此基础上定性分析汽液相界面的瞬时演变特征,进一步应用图像批处理技术定量分析相界面的前端运动规律,包括相界面位置及速度的瞬时波动特性。研究发现,不同凝结周期内的汽液相界面在蒸汽泡生成直至最大时的形貌、蒸汽泡的溃灭特性等方面有很大差异,主要体现在气泡溃灭时是否发生“局部收缩”和“内爆”等。此外,对于一个典型相界面运动周期而言,蒸汽泡消失阶段所占时间比例最小约为12%。通过分析相界面前端瞬时位置波动曲线,发现利用该曲线获得该工况下的凝结频率为23Hz,且该曲线的峰值分布具有较强周期振荡特性。通过分析相界面前端瞬时速度波动曲线,发现在多个极短时间内出现了速度的瞬时转变以及较为剧烈的多次振荡,速度峰值最大可达11m/s。结合可视化图像,详细描述了相界面速度振荡时的界面演变情况,并揭示“局部收缩”和“内爆”导致速度振荡的机理。
In order to explore the motion characteristics of vapor-liquid interface in a T-shaped micro channel when steam direct contact condensation the visual images under the conditions of subcooled water temperature 33℃and mass flow 6.325g/min and steam temperature 100℃and mass flow 0.25g/min were obtained through high-speed camera(5000fps).On this basis,the instantaneous evolution characteristics of vapor-liquid phase interface were qualitatively analyzed.Afterwards,the motion law of the front end of phase interface was quantified by using image batch processing technology,including the instantaneous fluctuation characteristics of phase interface position and velocity.Results showed that the vapor-liquid interface in different condensation cycles exhibited great differences in the morphology when steam bubble was generated to the maximum and the collapse characteristics of steam bubble,which was mainly reflected in“local shrinkage”and“implosion”.In addition,for a typical phase interface movement cycle,the time proportion of steam bubble disappearance stage was the smallest,about 12%.By analyzing the instantaneous position fluctuation curve at the front end of the phase boundary,it was found that the condensation frequency under this working condition was 23Hz,and the peak distribution of the curve had strong periodic oscillation characteristics.By analyzing the instantaneous velocity fluctuation curve at the front of phase boundary,it was found that the instantaneous transformation of velocity and violent multiple oscillations occur,and the maximum velocity peak reached 11m/s.Combined with the visual image,the interface evolution during phase interface velocity oscillation was further described in detail,and the mechanism of velocity oscillation caused by“local contraction”and“implosion”was revealed.
作者
张猛
李树谦
张东
马坤茹
ZHANG Meng;LI Shuqian;ZHANG Dong;MA Kunru(The Construction Engineering College,Hebei University of Science and Technology,Shijiazhuang 050018,Hebei,China;The Civil Engineering College,Hebei University of Water Resources and Electric Engineering,Cangzhou 061001,Hebei,China;Hebei Technology Innovation Center of Phase Change Thermal Management of Internet Data Center,Cangzhou 061001,Hebei,China;Cangzhou Technology Innovation Center of Thermal Storage and Low-grade Waste Heat Utilization of Electromagnetic Heating,Cangzhou 061001,Hebei,China)
出处
《化工进展》
EI
CAS
CSCD
北大核心
2022年第9期4644-4652,共9页
Chemical Industry and Engineering Progress
基金
国家自然科学基金(51976052)
河北省自然科学基金(E2020412176)
2020年河北省高等学校基本科研业务费研究项目(SYKY2001)。
关键词
微通道
气液两相流
界面
间歇凝结
相界面运动
microchannels
gas-liquid flow
interface
chugging
phase boundary movements
