Stability and Oscillations in an Evaporating Corner Meniscus

Abstract

A Constrained Vapor Bubble Loop Thermosyphon, CVBLT, made of quartz was used to study the stability and oscillations of an evaporating curved wetting film of pentane in a corner. The film thickness profile was measured as a function of heat input, time, and axial position using image analyzing interferometry. The curvatures and apparent contact angles for the evaporating film under various operating conditions were obtained from the measured film thickness profiles. Instability (oscillation) of the liquid film was observed at relatively higher values of the heat input. The behavior of the curvature and the apparent contact angle of an oscillating film with changes in heat input was evaluated. Moving velocities of the oscillating film were calculated from the measured values of the liquid-wall wetted lengths and were found to be directly proportional to the difference between the instantaneous force acting on the curved film and the reference force. Using an augmented Young-Laplace pressure jump model, the effect of the excess free energy at the contact line on the oscillations was demonstrated.