Graeber Gustav, Regulagadda Kartik, Hodel Pascal, Küttel Christian, Landolf Dominic, Schutzius Thomas M, Poulikakos Dimos
Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
Laboratory for Multiphase Thermofluidics and Surface Nanoengineering, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
Nat Commun. 2021 Mar 19;12(1):1727. doi: 10.1038/s41467-021-21981-z.
A liquid droplet dispensed over a sufficiently hot surface does not make contact but instead hovers on a cushion of its own self-generated vapor. Since its discovery in 1756, this so-called Leidenfrost effect has been intensively studied. Here we report a remarkable self-propulsion mechanism of Leidenfrost droplets against gravity, that we term Leidenfrost droplet trampolining. Leidenfrost droplets gently deposited on fully rigid surfaces experience self-induced spontaneous oscillations and start to gradually bounce from an initial resting altitude to increasing heights, thereby violating the traditionally accepted Leidenfrost equilibrium. We found that the continuously draining vapor cushion initiates and fuels Leidenfrost trampolining by inducing ripples on the droplet bottom surface, which translate into pressure oscillations and induce self-sustained periodic vertical droplet bouncing over a broad range of experimental conditions.
滴落在足够热的表面上的液滴不会接触表面，而是悬浮在其自身产生的蒸汽垫上。自1756年被发现以来，这种所谓的莱顿弗罗斯特效应一直受到深入研究。在此，我们报告了一种莱顿弗罗斯特液滴对抗重力的显著自推进机制，我们将其称为莱顿弗罗斯特液滴蹦床效应。轻轻放置在完全刚性表面上的莱顿弗罗斯特液滴会经历自激自发振荡，并开始从初始静止高度逐渐反弹至更高高度，从而打破了传统上所接受的莱顿弗罗斯特平衡。我们发现，持续排出的蒸汽垫通过在液滴底面引发涟漪来启动并推动莱顿弗罗斯特蹦床效应，这些涟漪转化为压力振荡，并在广泛的实验条件下诱导液滴进行自我维持的周期性垂直反弹。
