This PhD was carried out under the supervision of Samuel SIEDEL (SIMaP) and funded by the CNES and the MESR.
Bubble dynamics are critical for boiling heat transfer in thermal management, especially in microgravity environments where buoyancy is absent. While static DC electric fields have been used to enhance bubble detachment via electrohydrodynamics (EHD), the shift to modern "leaky dielectric" fluids (with non-negligible conductivity) has created a knowledge gap: the interplay between polarization forces and the polarity-dependent Coulomb force is poorly understood, leading to contradictory results. This thesis deconstructs these competing forces using adiabatic gas injection. An initial ground-based study found that DC fields induced polarity-dependent instabilities (attributed to the Coulomb force), whereas high-frequency AC fields isolated the stable elongating effect of the polarization force.
A second phase utilized a flight-certified platform for terrestrial and parabolic flight (microgravity) experiments. These tests confirmed a profound polarity dependence, revealing that negative DC fields are significantly more efficient and stable for triggering bubble detachment. In microgravity, EHD was proven to be an effective substitute for buoyancy, and unipolar periodic fields enabled precise phase-locking control of the bubbles. These findings establish that for leaky dielectric fluids, the transient Coulomb force is the critical mechanism governing system stability and control, while the polarization forces allow for the obtainment of resonance oscillations. This provides a new physical framework for designing advanced EHD-based thermal systems for both terrestrial and space applications.