Abstract
In industrial applications involving spray-cooling, combustion, and so on, prediction of the maximum spreading diameter of a droplet impinging on a solid surface permits a quantitative estimation of heat removal and energy consumption. However, although there are many experimental studies regarding droplet impingement behaviour, theoretical models have an applicability limit for predicting the maximum spreading diameter. In the present study, we have developed an analytical model for droplet impingement based on energy conservation that considers adhesion energy in both horizontal and vertical directions at the contact line. The theory is validated by our experiment and existing experimental data possessing a wide range of Weber numbers. We demonstrate that our model can predict βm (i.e., the maximum spreading diameter normalised in terms of initial droplet diameter) for various Newtonian liquids ranging from micro- to millimetre-sized droplets on different solid surfaces and can determine the transition between capillary and viscous regimes. Furthermore, theoretical relations for scaling laws observed by many researchers are derived.
Highlights
Droplet impingement on solid surfaces is of great importance to ink-jet printing[1], spray-cooling[2, 3], combustion[4], and coating processes[5]
We have presented experimental and theoretical considerations of droplet impingement on solid surfaces
Our model accurately predicts the impinging behaviour of several kinds of liquids on various solid surfaces
Summary
Droplet impingement on solid surfaces is of great importance to ink-jet printing[1], spray-cooling[2, 3], combustion[4], and coating processes[5]. Droplet impingement is especially important for spray-cooling and combustion applications, whereby heat transfer from solid surfaces to droplets influences their impingement behaviour. The maximum spreading diameter (dmax) depends on the impinging velocity of the droplet, as well as the properties of the liquid and solid This behaviour is mainly governed by the inertia of the droplet and the capillary and viscous forces. We validate our model by comparing it to existing experimental data that employ micro- to millimetre-sized droplets[8, 17, 22, 30, 31] In addition to these results, the transition point from the capillary regime to the viscous regime is theoretically determined. The importance of the work done by the adhesion force at the contact line, in the horizontal direction, and in the vertical direction[29] is revealed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
