Experimental investigation of the effect of droplet size on the vaporization process in ambient turbulence

Stochastic models for the droplet motion and evaporation in under-resolved turbulent flows at a large Reynolds number

“…Two modes of turbulent evaporation were observed: the internal group slow evaporation in a droplet cluster, typically near the spray centre, and the single droplet intense evaporation, typically near the spray boundary. These experimental studies, along with the experimental study of Verwey & Birouk (2017), also support the earlier conclusion from experiments in Wu, Liu & Sheen (2001), Hiromitsu & Kawaguchi (1995) and Birouk & Gökalp (2006) that increasing the turbulence intensity promotes evaporation of droplets. In De Rivas & Villermaux (2016) and Villermaux et al (2017), the evaporation rate in layers of liquid droplets at very small Stokes number is described through analogy with scalar mixing (Villermaux 2019).…”

An analysis of the droplet support fiber effect on the evaporation process

“…Additional experiments at standard atmospheric pressure are performed to acquire data at the lower end of the ambient temperature in normal gravity conditions; that is, between approximately 300 K and 473 K using the test rig at the University of Manitoba. Detailed description of this experimental setup is reported elsewhere [21,22]. Essentially, the thermally-insulated spherical chamber has 2-pair of large windows arranged along the horizontal equator.…”

“…However, the effect of droplet size under the test conditions explored in these studies is considered negligible. Verwey and Birouk [21,22] demonstrated that the evaporation rate of n-heptane droplets, ranging between approximately 300 and 800 µm, changes only at elevated ambient pressure or in convective flow environments or both combined, while it remains nearly constant at standard ambient pressure. Morin [30] also demonstrated that, within her explored range of droplet sizes (810 and 1330 µm), the evaporation rate in a hot environment remains practically constant at ambient atmospheric pressure.…”

“…This is exactly what is observed when using the classical fiber suspending technique where the d 2 -law does not hold towards the end of the droplet lifetime; that is, a clear acceleration of the temporal variation of d 2 can be witnessed (e.g., [15]). This, of course, is not the case when using the cross-fiber technique (e.g., [21,22]) where tiny fibers are used. In this case, the 2 -law tends to hold until the complete depletion of the liquid or at least such an acceleration does not manifest (e.g., [21,22]).…”

“…This, of course, is not the case when using the cross-fiber technique (e.g., [21,22]) where tiny fibers are used. In this case, the 2 -law tends to hold until the complete depletion of the liquid or at least such an acceleration does not manifest (e.g., [21,22]).…”