A method to measure vapor concentration of droplet evaporation based on background oriented Schlieren

The direct visualization of vapor distribution and quantitative measurement of vapor concentration plays an important role in studying droplet evaporation. In this study, we propose a method to measure the vapor concentration field based on the modified background oriented Schlieren, inverse Radon transform, high-speed imaging, and image processing. The method is demonstrated for the measurement of the transient concentration field during the impact of volatile droplets on solid surfaces. The results show that the vapor distribution is remarkably different from the diffusion-limited model because of the strong convection. The complex structure of the vapor cloud is the result of the interplay among fluid inertia, fluid evaporation, vapor diffusion, vapor convection, and droplet shape evolution. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

A novel method to measure the vapor concentration field during the impact of volatile droplets on solid surfaces was proposed in this study, using modified background oriented Schlieren, inverse Radon transform, high-speed imaging, and image processing techniques. The results demonstrated a significant difference in vapor distribution from the diffusion-limited model due to strong convection during the impact process. The complex structure of the vapor cloud was attributed to the interplay among fluid inertia, fluid evaporation, vapor diffusion, vapor convection, and droplet shape evolution.