Corona splashes

Keywords Contact angle Corona splashes Disintegration Disintegration limits Droplet impact Drop surface energy Heat transfer regimes Leidenfrost point Molten metal droplet impact Rupture Secondary atomization Spread Surface topography Thermal induced atomization Wettability... 

Contrary to spreading, the disintegration mechanisms are not so well documented in the literature. Several disintegration mechanisms can be identified (a) prompt splash, (b) corona splash, (c) receding break-up (d) partial rebound, (e) finger break-up [10, 11]. 

Increase of Prompt splash Corona splash Receding break-up Finger break-up Partial rebound... 

Here we focus oti the impacts onto films with 5 <2 since this condition is often satisfied in most practical spray applications. Similarly to droplet impingement on dry targets, diverse outcomes may occur deposition and coalescence, bounce, formation of a crater, corraia splash or uprising of a central jet. Most studies reported in the Uterature consider corona splash and focus on three issues (1) characterization of crown morphology, (2) establishment of threshold criteria for disintegration and (3) characterization of secondary atomization. 

Many studies have been devoted to predicting when corona splashes will occur. Mundo, Sommerfeld, and Tropea [11] found that droplets splashed only if the... 

The air film trapped tmder the impacting droplet plays an important role in creating instabihties. Xu, Zhang, Nagel [18] demonstrated that if the pressure in the atmosphere surrotmding an impacting drop is reduced corona splashes are... 

The prompt splash (Figure 26(b)) is induced by an inaeased impact velocity and a rough surface, resulting in tiny droplets at the perimeter of the liquid lamellae. The corona splash (Figure 26(c)) occurs when the surface tension of the liquid is small enough to detach the liquid lamellae from the wall. It was found that the corona splash can be suppressed by reducing the surrounding atmosphere pressure. 

Fig. 18.15 (a) A snapshot of the splashing from zu et al. s exptaiment. (b) Formation of the rising corona and the subsequent splashed droplets, whose number is predicted by the vortex ring instabihty theory of Ponstein [58]. The impact conditirai at which this simulatirai was carried out is based on the operating condition of Xu et al. [83] expoiment impact speed, U = 3.74 m/s droplet radius, a = 1.7 nun Weber number, Wej = 838 Bond number. Bo = 0.998... 

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