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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-472-4

ISBN Online: 978-1-56700-471-7

3rd Thermal and Fluids Engineering Conference (TFEC)
March, 4–7, 2018, Fort Lauderdale, FL, USA

HYDRODYNAMIC AND HEAT TRANSFER CHARACTERISTICS OF SPREADING-SPLASHING TRANSITION UPON DROPLET TRAIN IMPINGEMENT

Get access (open in a dialog) pages 1215-1224
DOI: 10.1615/TFEC2018.fnd.021623

Resumo

In this study, heat transfer and hydrodynamic characteristics of droplet-induced impinged liquid film spreading-splashing transition have been investigated experimentally and numerically. The effects of droplet parameters such as droplet impingement frequency, droplet diameter and droplet impingement velocity on hydrodynamics and heat transfer have been evaluated experimentally. Numerically, ANSYS-Fluent was employed to simulate the droplet impingement process using Volume of Fluid model coupled with the Level Set method (CLS-VOF). A dynamic mesh adaption was used in the simulations, which is capable of capturing the propagation of droplet-induced crown with high spatial and temporal resolutions. A good agreement was reached between experimental and numerical data in terms of droplet-induced crown morphology and surface temperatures. It was observed that low Weber number (< 280) droplet impingements resulted in smooth spreading of the droplet-induced crown while splashing was observed at high Weber number (> 489) cases. The effect of spreading-splashing transition on surface heat transfer has also been investigated for fixed flow rate conditions. Time-averaged temperature measurements indicate that heat flux-surface temperature curves are linear at low surface temperature and before the onset of dry-out. However, a sharp increase in surface temperature was observed when dry-out appears on the heater surface. It was also found that strong splashing is unfavorable for heat transfer at high surface temperatures. In summary, the results indicate that droplet Weber number is a significant factor in spreading-splashing transition and droplet-induced liquid film heat transfer.