Jones Paul R, Chuang Chihpin Andrew, Sun Tao, Zhao Tom Y, Fezzaa Kamel, Takase Juan C, Singh Dileep, Patankar Neelesh A
Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, United States.
Argonne National Laboratory, Lemont, IL, 60439, United States.
Sci Rep. 2019 Feb 7;9(1):1598. doi: 10.1038/s41598-018-36603-w.
The Leidenfrost layer is characterized by an insulating vapor film between a heated surface and an ambient liquid. The collapse of this film has been canonically theorized to occur from an interfacial instability between the liquid and vapor phases. The interfacial instability alone, however, is insufficient to explain the known influence of the surface on the film collapse process. In this work, we provide visual evidence for two key mechanisms governing the film collapse: the interfacial instability, and the nucleation of vapor upon multiple non-terminal liquid-solid contacts. These results were obtained by implementing high-speed X-ray imaging of the film collapse on a heated sphere submerged in liquid-water. The X-ray images were synchronized with a second high-speed visible light camera and two thermocouples to provide insight into the film formation and film collapse processes. Lastly, the dynamic film thickness was quantified by analysis of the X-ray images. This helped assess the influence of surface roughness on the disruption of the film. The results of this work encourage further investigation into non-linear stability theory to consolidate the role of the surface on the liquid-vapor interface during the film collapse process.
莱顿弗罗斯特层的特征是在受热表面与周围液体之间存在一层绝缘蒸汽膜。该膜的破裂通常被理论化为是由液相和气相之间的界面不稳定性引起的。然而，仅界面不稳定性不足以解释表面对膜破裂过程的已知影响。在这项工作中，我们为控制膜破裂的两个关键机制提供了可视化证据：界面不稳定性以及在多个非终端液 - 固接触时蒸汽的成核。这些结果是通过对浸没在液态水中的加热球体上的膜破裂进行高速X射线成像获得的。X射线图像与第二台高速可见光相机和两个热电偶同步，以深入了解膜的形成和膜破裂过程。最后，通过对X射线图像的分析对动态膜厚度进行了量化。这有助于评估表面粗糙度对膜破裂的影响。这项工作的结果鼓励进一步研究非线性稳定性理论，以巩固表面在膜破裂过程中对液 - 气界面的作用。
