摘要
基于高速摄像方法,开展了28°C~350°C范围内不同温度的亲水性与超疏水性球体垂直入水实验研究,分析了表面润湿性、水温、球温和入水速度对入水空泡形态特性的影响。结果表明,在高温水中,核态沸腾阶段的汽泡扰动使亲水球体可以在较低入水速度下形成完整的粗糙空泡,超疏水球体受到核态沸腾和疏水性的耦合影响产生褶皱的光滑空泡,超疏水球体可以在较低温度下进入膜态沸腾阶段形成光滑的入水空泡,并且相比于亲水球体,随着入水速度的增加空泡壁面不易受到扰动;在低温水中,当球温较高时,稳定的蒸汽膜较难维持,超疏水球体可以产生比亲水球体更完整的空泡。
The vertical water-entry experiments of hydrophilic and super-hydrophobic hot spheres within the temperature range of 28°C-350°C were conducted and recorded with a high-speed video camera. The effects of surface wettability, water temperature, sphere body temperature and water-entry velocity on characteristics of cavitation morphology in water were analyzed. The results showed that in high temperature water, bubble disturbance in nucleate boiling stage can cause a hydrophilic sphere to form a complete rough cavitation at a lower water-entry rate, and a super-hydrophobic sphere affected by coupling of nucleate boiling and hydrophobicity can produce a smooth cavitation with folds, a super-hydrophobic sphere can enter a film boiling stage under a lower sphere temperature to form a smooth cavitation in water, the cavitation wall surface is not easy to be disturbed with increase in water-entry velocity compared with a hydrophilic sphere; in low temperature water, stable vapor film is not easy to keep when sphere temperature is higher, a super-hydrophobic sphere can produce a more complete cavitation than a hydrophilic one can.
引文
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