Mechanical Engineering, Washington State University, Vancouver, Washington 98686, USA.
Sci Rep. 2012;2:797. doi: 10.1038/srep00797. Epub 2012 Nov 12.
Friction is a major inhibitor in almost every mechanical system. Enlightened by the Leidenfrost effect - a droplet can be levitated by its own vapor layer on a sufficiently hot surface - we demonstrate for the first time that a small cart can also be levitated by Leidenfrost vapor. The levitated cart can carry certain amount of load and move frictionlessly over the hot surface. The maximum load that the cart can carry is experimentally tested over a range of surface temperatures. We show that the levitated cart can be propelled not only by gravitational force over a slanted flat surface, but also self-propelled over a ratchet shaped horizontal surface. In the end, we experimentally tested water consumption rate for sustaining the levitated cart, and compared the results to theoretical calculations. If perfected, this frictionless Leidenfrost cart could be used in numerous engineering applications where relative motion exists between surfaces.
摩擦几乎是每一个机械系统的主要阻力。受莱顿弗罗斯特效应的启发——当一个足够热的表面上方存在一层蒸汽时，液滴可以被蒸汽层托起——我们首次证明，一个小推车也可以被莱顿弗罗斯特蒸汽托起。被托起的小推车可以承载一定的负载，并在热表面上无摩擦地移动。我们通过实验测试了在不同表面温度范围内小推车能够承载的最大负载。我们发现，被托起的小推车不仅可以在倾斜的平面上通过重力推动，还可以在棘轮状的水平表面上自行移动。最后，我们还实验测试了维持小推车悬浮所需的耗水量，并将结果与理论计算进行了比较。如果得到完善，这种无摩擦的莱顿弗罗斯特推车可以用于许多存在表面相对运动的工程应用中。
