• Journal of ILASS-Korea
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• v.12 no.4
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• pp.198-203
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• 2007

In the present work, surface wetting effect on spread-splash regime and transition criterion of the water and ethanol droplets impacting an unheated dry wall has been experimentally investigated. The droplet was directed on a polished STS plate and a glass slide, and the impinging behavior was visualized and recorded using a CCD camera. Droplet diameter and velocity approaching the wall were measured as well. The critical Sommerfeld number representing the spread-splash boundary for the ethanol droplet impinging on the substrates turned out to be smaller compared to that for the water droplet impinging on the substrates with the surface roughness condition remained unchanged. The shift of the transition boundary is considered to be due to the effect of the surface wettability represented by static contact angle and surface tension of droplet.

• Journal of Mechanical Science and Technology
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• v.20 no.8
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• pp.1101-1117
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• 2006

In the present article, recent progress of spray-wall interaction research has been reviewed. Studies on the spray-wall interaction phenomena can be categorized mainly into three groups: experiments on single drop impact and spray (multiple-drop) impingement, and development of comprehensive models. The criteria of wall-impingement regimes (i.e., stick, rebound, spread, splash, boiling induced breakup, breakup, and rebound with breakup) and the post-impingement characteristics (mostly for splash and rebound) are the main subjects of the single-drop impingement studies. Experimental studies on spray-wall impingement phenomena cover examination of the outline shape and internal structure of a spray after the wall impact. Various prediction models for the spray-wall impingement phenomena have been developed based on the experiments on the single drop impact and the spray impingement. In the present article, details on the wall-impingement criteria and post-impingement characteristics of single drops, external and internal structures of the spray after the wall impact, and their prediction models are reviewed.

• Journal of Mechanical Science and Technology
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• v.15 no.3
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• pp.374-383
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• 2001

The spray/wall interaction is considered as an important phenomenon influencing air-fuel mixing in the internal combustion engines. In order to adequately represent the spray/wall interaction process, impingement regimes and post-impingement behavior have been modeled using experimental data and conservation constraints. The modeled regimes were stick, rebound, spread and splash. The tangential velocities of splashing droplets were obtained using a theoretical relationship. The continuous phase was modeled using the Eulerian conservation equations, and the dispersed phase was calculated using a discrete droplet model. The numerical simulations were compared to experimental results for spray impingement normal to the wall. The predictions for the secondary droplet velocities and droplet sizes were in good agreement with the experimental data.