An experimental shock wave study of aerosol droplet evaporation in the transition regime

The evaporation rate of submicron aerosol droplets suspended in argon was studied behind incident shock waves at initial droplet Knudsen numbers 0.1≤KnG≤0.9. In this case the Knudsen number is formulated with the mean free path of the surrounding carrier gas and the droplet radius. The reduction in the size of the particles in the post-shock relaxation zone was measured by laser light scattering, simultaneously recorded under four fixed angles. Mie theory was applied to determine the time-dependent droplet size during the evaporation process. By comparison with an analytical description of the transfer process of a single droplet with the surrounding gas, a physical interpretation of the measurements could be established. The experimental results are consistent with analytical first-order correction terms of the mass flux in the transition regime.