CIESC Journal ›› 2016, Vol. 67 ›› Issue (6): 2211-2217.DOI: 10.11949/j.issn.0438-1157.20151549

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Characteristic analyses of boiling phenomena in process of drops impingement on heated surfaces

LIANG Gangtao1,2, MU Xingsen1, GUO Yali1, SHEN Shengqiang1, ZHANG Jili2   

  1. 1. Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China;
    2. School of Civil Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China
  • Received:2015-10-13 Revised:2016-02-18 Online:2016-06-05 Published:2016-06-05
  • Supported by:

    supported by the National Natural Science Foundation of China (51506023, 51336001), the China Postdoctoral Science Foundation (2015M571303) and the Fundamental Research Funds for the Central Universities of Ministry of Education of China (DUT14RC(3)159).

液滴冲击加热壁面沸腾现象特征分析

梁刚涛1,2, 牟兴森1, 郭亚丽1, 沈胜强1, 张吉礼2   

  1. 1. 大连理工大学能源与动力学院, 海洋能源利用与节能教育部重点实验室, 辽宁 大连 116024;
    2. 大连理工大学土木工程学院, 辽宁 大连 116024
  • 通讯作者: 沈胜强
  • 基金资助:

    国家自然科学基金项目(51506023,51336001);中国博士后科学基金项目(2015M571303);中央高校基本科研业务费专项资金项目(DUT14RC(3)159)。

Abstract:

An experimental process of liquid drops impingement on heated surfaces was observed using a high-speed digital camera, for which characteristics of boiling phenomena with different fluids were analyzed, and formation mechanisms of the central jet and pagoda-like bubbles were also discussed. At the surface temperature above the Leidenfrost point when the water drops impingement on the surfaces, a phenomenon of explosive boiling occurred, while that of the central jet happened for the drops of sodium chloride solution due to bubble entrainment with dramatic nucleation, and that of alcohol drops rebound entirely appeared. Otherwise, at the surface temperature below the Leidenfrost point, bubbly boiling was observed, for which different from hemispherical bubbles, pagoda-like bubbles appeared at the thicker film region. Moreover, the maximum spreading factor during drop rebound on heated surfaces was investigated quantitatively, which only can be influenced by the Weber number. Compared with the literatures, the empirical correlation of the spreading factor in this study can well predict the drop spreading scale on heated surfaces.

Key words: drop impact, heated surface, boiling, spreading factor, bubble, tomography, measurement

摘要:

采用高速摄像仪对液滴冲击加热壁面过程进行实验观测,分析了不同实验流体的沸腾现象特征,探讨了中间射流及宝塔状气泡的形成机理。观测发现,壁温高于液体对应的Leidenfrost温度时水滴撞击后会出现暴沸现象,由于气泡夹带伴随强烈的核化作用,氯化钠溶液液滴撞击后可以观察到中间射流的产生,醇类液滴则发生完全反弹;壁温低于Leidenfrost温度时液滴在加热壁面会出现泡状沸腾现象,与半球形气泡不同,宝塔状气泡出现在液膜厚度较大的区域。此外定量考察了液滴在加热壁面完全反弹时的最大铺展因子,发现铺展因子仅受Weber数影响,与文献结果比较表明本研究得出的铺展因子经验公式可较好地预测液滴在加热壁面的铺展尺度。

关键词: 液滴撞击, 加热壁面, 沸腾, 铺展因子, 气泡, 成像, 测量

CLC Number: