Investigation of droplet drying characteristics using an acoustic-aerodynamic levitator

The evaporation of liquid drops levitated in an acoustic-aerodynamic levitator is studied both theoretically and experimentally. The theoretical description takes the deformed drop shapes into account and is applicable for arbitrary ratios λ/2πα₀₀ of sound wavelength to drop circumference. The experimental technique is based on the processing of video images to measure the evaporation rates of the levitated drops. Results consist mainly in the function d² = f(t) of the squared volume-equivalent drop diameter, the drop shapes and the drop displacement from the pressure node as functions of time. The agreement between experiment and theory for small times is encouraging, the disagreement for larger times indicates liquid impurities which must be avoided in the future.