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Deformation process of a droplet impinging on a hot oxide‐scaled surface above the Leidenfrost temperature
Author(s) -
Hatta Natsuo,
Fujimoto Hitoshi,
Takuda Hirohiko
Publication year - 1997
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199701771
Subject(s) - leidenfrost effect , collision , deformation (meteorology) , oxide , quenching (fluorescence) , rough surface , surface (topology) , mechanics , axial symmetry , materials science , weber number , composite material , chemistry , metallurgy , physics , heat transfer , optics , structural engineering , nucleate boiling , geometry , engineering , turbulence , heat transfer coefficient , computer security , mathematics , reynolds number , computer science , fluorescence
This paper is concerned with the collision dynamics of a water droplet impinging on a hot surface heated to above the Leidenfrost temperature, focusing upon the case where the impingement side is rough (oxide‐scaled) with an oxide film. The rough surface has been artificially made by rapidly quenching as‐rolled stainless steel by water spraying, after it has been heated to 1000°C in a furnace. A sequence of photographs showing the progressive stages of droplet deformation have been taken on several Weber number conditions. It has been found that the droplet configuration is not axially symmetric around the initial impact point even at an early stage immediately after collision and that the irregularity of the droplet configuration is amplified as the droplet deformation proceeds. With increasing Weber number, the irregularity has been seen to be more remarkable in the later stage and finally the droplet breaks up into some parts. Therefore, the critical Weber number to specify whether or not the droplet is disintegrated on the rough surface has been found to become small compared with the smooth surface case.