| 高温壁面上静止液滴的Leidenfrost温度模型研究 |
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| 引用本文： | 蔡畅,刘红,奚溪,Issam Mudawar.高温壁面上静止液滴的Leidenfrost温度模型研究[J].工程热物理学报,2021,42(3):732-739. |
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| 作者姓名： | 蔡畅 刘红 奚溪 Issam Mudawar |
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| 作者单位： | 海洋能源利用与节能教育部重点实验室,大连理工大学能源与动力学院,大连 116024;沸腾与两相流动实验室,普渡大学机械工程学院,西拉法叶,美国,IN 47907 |
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| 基金项目： | 国家重点研发计划(No.2017YFA0700300);国家自然科学基金项目(No.51961135105,No.91641117);天津大学内燃机燃烧学国家重点实验室开放项目(No.K2018-04)。 |
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| 摘 要： | 本文以高温壁面上的静止液滴为研究对象,对其蒸发特性开展了理论研究。不同计算工况下得到的液滴蒸发过程中半径和蒸汽膜厚度变化与实验值吻合良好。结果表明随着壁面温度的降低,蒸汽膜厚度逐渐减小。结合表面粗糙度的影响,研究中提出了Leidenfrost温度的触发机制:当蒸汽膜厚度足够小时,会极易被加热表面的不平整突起贯穿,蒸汽膜的稳定性遭到破坏,从而导致液滴-壁面的直接接触,最终结束膜态沸腾状态。利用此模型预测的Leidenfrost温度与实验值吻合良好,并从理论角度解释了环境压力对Leidenfrost温度的影响机制。
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| 关 键 词： | Leidenfrost温度 液滴蒸发 蒸汽膜厚度 表面粗糙度 环境压力 |
Study on the Theoretical Model of Leidenfrost Temperature for a Sessile Droplet on a High-temperature Wall |
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| Institution: | (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,P.R.China;Boiling and Two-Phase Flow Laboratory,School of Mechanical Engineering,Purdue University,Lafayette,IN 47907,USA) |
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| Abstract: | Evaporation characteristics of a sessile droplet on a high-temperature wall are theoretically studied through shape analysis.The calculated droplet radius and vapor layer thickness under various conditions using the present model agree well with available data.The results show that the vapor layer thickness gradually decreases with decreased wall temperature.A new triggering mechanism for the Leidenfrost temperature is proposed by combining the surface roughness effect.A thin enough vapor film is extremely vulnerable to be penetrated by the surface irregularities.As the vapor film stability is destroyed,direct liquid-solid contact occurs,which terminates the film boiling.The predicted Leidenfrost temperatures using correlated surface roughness relations compare satisfactorily with experimental data,and theoretical explanations are also provided for the influencing mechanism of ambient pressure. |
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| Keywords: | Leidenfrost temperature droplet evaporation vapor film thickness surface roughness ambient pressure |
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