Preliminary analysis of a fuel droplet in a convective field

The effect of the relative gas-droplet velocity on the droplet heating is considered. For typical cases, a gas-phase laminar boundary layer is found to be present on the droplet throughout its lifetime. The shearing effect causes a liquid-phase viscous boundary layer to exist and, subsequently, a recirculating liquid motion within the droplet. The characteristic time for recirculation is less than the droplet lifetime but not several orders of magnitude smaller. Therefore, the internal motion can very likely be the most important mechanism for droplet heating. Interesting speculations can be made concerning the effect of the internal motion in the multicomponent fuel case.