Simultaneous grouping and evaporation of spray droplets in oscillating flow-theoretical analysis

Basic criteria are established for the phenomenon of travel grouping, both for the possibility of it to occur as well as for the associated characteristic time. These criteria are suggested to be incorporated in the rate of spray evaporation, thus enabling for the estimation of the effect of grouping due to periodic oscillation on the overall vapor production of a multisize spray. It is shown that the relatively small droplets tend to form groups and thus decrease their evaporation rate. On the other hand, the lager droplets tend not to group, thus maximizing their rate of evaporation. Hence, such travel grouping brings closer the evaporation rates of different droplet size ranges. With respect to the opposite effect, that is, the influence of evaporation on grouping, it is shown that once a grouping or a non-grouping mode of behavior has been established, evaporation does not change this behavior as time passes or, in other words, droplet's history determines a single mode of time-behavior.