Boiling dynamics on earth is heavily affected by gravity. The purpose of this work is to investigate the feasibility of a replacement of gravity when it lacks: an external electric field can promote an efficient and reliable bubble removal system for space applications. To this intent, different experiments running in normal gravity, reverse gravity and microgravity (via parabolic flights) have been performed. The experiments were executed in adiabatic conditions (injecting air through an orifice) and in quasi-static conditions. This option was chosen in order to investigate only the dynamics terms of momentum balance, neglecting, at this stage, all the terms involving heat and mass transfer (which are in turn promoted by the electric field, i.e.: electroconvection). An experimental electric force has been calculated, as the unbalanced component of the force balance, and, thanks to the FEM software COMSOL Multiphysics, compared to the numerical integration of Maxwell stress tensor. Furthermore, a simple model based on the electrohydrodynamics of an oblate ellipsoid (Landau and Lifšitz 1984) has been compared to the results of the three sets of experiments.
Electrohydrodynamics and boiling: Experiments, numerical calculation and modeling of Maxwell stress tensor and electric force acting on bubbles
Saccone, G.;Garivalis, A. I.;Di Marco, P.
2020-01-01
Abstract
Boiling dynamics on earth is heavily affected by gravity. The purpose of this work is to investigate the feasibility of a replacement of gravity when it lacks: an external electric field can promote an efficient and reliable bubble removal system for space applications. To this intent, different experiments running in normal gravity, reverse gravity and microgravity (via parabolic flights) have been performed. The experiments were executed in adiabatic conditions (injecting air through an orifice) and in quasi-static conditions. This option was chosen in order to investigate only the dynamics terms of momentum balance, neglecting, at this stage, all the terms involving heat and mass transfer (which are in turn promoted by the electric field, i.e.: electroconvection). An experimental electric force has been calculated, as the unbalanced component of the force balance, and, thanks to the FEM software COMSOL Multiphysics, compared to the numerical integration of Maxwell stress tensor. Furthermore, a simple model based on the electrohydrodynamics of an oblate ellipsoid (Landau and Lifšitz 1984) has been compared to the results of the three sets of experiments.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
