Abstract Capturing the dynamics of the triple contact line at the base of a vapor bubble is crucial to the development and validation of boiling heat transfer and boiling crisis models. To this end, laser-based techniques are the state-of-the-art. However, they have technical limitations, e.g., due to the presence of parasite interference patterns or laser speckle, and are often complicated to implement and operate. In this paper, we propose and discuss the rationale of alternative phase detection techniques based on LED lights. Colored LED lights have a coherence length of several micrometers, which is long enough to create interference patterns when reflected by the microlayer and short enough to prevent the formation of the parasite interference patterns caused by lasers. We show that, even with a simple optical setup, these LED-based techniques can create images of superior quality and uniformity, making it possible to resolve smaller boiling features, e.g., size and shape of bubble footprint at high-pressure conditions. Moreover, LED lights are much less expensive, safer, and easier to operate than lasers, which is an obvious advantage for researchers that want to either enter the field or expand their measurement capabilities. We demonstrate the use and the potential of these LED-based techniques with experimental results obtained in subcooled flow boiling of water, at both ambient and high-pressure conditions. We also demonstrate how this technique can be combined with infrared thermometry to study the formation and evaporation of the microlayer, other heat transfer mechanisms associated with the growth and departure of a vapor bubble, and the heat flux partitioning over the entire boiling surface.

中文翻译：

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LED 灯能否代替激光对沸腾现象进行详细研究？

摘要 捕获蒸汽泡底部三重接触线的动力学对于沸腾传热和沸腾危机模型的开发和验证至关重要。为此，基于激光的技术是最先进的。然而，它们具有技术限制，例如，由于寄生干涉图案或激光散斑的存在，并且实施和操作通常很复杂。在本文中，我们提出并讨论了基于 LED 灯的替代相位检测技术的基本原理。彩色 LED 灯的相干长度为几微米，足够长以在被微层反射时产生干涉图案，而足够短以防止形成由激光引起的寄生干涉图案。我们表明，即使使用简单的光学设置，这些基于 LED 的技术可以创建高质量和均匀性的图像，从而可以解决更小的沸腾特征，例如高压条件下气泡足迹的大小和形状。此外，LED 灯比激光更便宜、更安全且更易于操作，这对于想要进入该领域或扩展其测量能力的研究人员来说是一个明显的优势。我们展示了这些基于 LED 的技术的使用和潜力，并在环境和高压条件下在水的过冷流沸腾中获得了实验结果。我们还展示了如何将这种技术与红外测温相结合来研究微层的形成和蒸发，以及与蒸汽泡的生长和离开相关的其他传热机制，