| Abstract: | The time scale for measuring the heat transfer phenomena, such as the Leidenfrost phenomenon, is much longer than the hydrodynamic transient period of a droplet impinging onto a heated surface. However, the Leidenfrost temperature has been long since taken as the criterion to classify characteristic regimes for not only heat transfer but also hydrodynamic impact patterns of liquid‐solid‐interface problems in the literature. The impingement phenomena of a single droplet onto a heated plate for We <200 were experimentally classified as five different characteristic patterns in this paper. They are [I] completely wet, [II] wet film boiling, [III] transition, [IV] dry rebounding, and [V] satellite dry rebounding impact patterns. The former two patterns belong to wet impact, while the latter two are dry impact. This work reveals that the hydrodynamic impact parameter does influence the classification of characteristic impact patterns, especially for the dry impact patterns. For high impact Weber numbers, the dry impact happens to the plate surface temperature much lower than the commonly believed Leidenfrost temperature due to the squeeze film effect. The evolutions that impact changes from one to another characteristic patterns are also discussed. This paper offers a systematic and reliable database for future numerical simulations. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(8): 579–594, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20089 |
