Appearance of gas phase just before a breakdown of dielectric liquids because of heterogeneous nucleation under the action of strong electric fields
In the earlier works, we proposed a new instability mechanism for dielectric liquid in strong electric fields: the anisotropic decay into a system of vapor channels in the liquid oriented along the field. Electrohydrodynamic flows with phase transitions are simulated using the lattice Boltzmann method (Lattice Boltzmann Equation, LBE). The critical values of electric field strength for a "pure" dielectric liquid obtained in LBE simulations are coincide well with the theoretical values obtained from the spinodal curve in the electric field. It was shown earlier that the critical field strength decrease significantly in the presence of gases dissolved in a dielectric liquid. However, these values are still noticeably higher than the ones observed in practice. In the present work, we propose a simple model of heterogeneous nucleation that can be used in LBE simulations. Influence of the heterogeneity centers together with dissolved gas leads to the further significant decrease of the critical electric field values down to 10–20 MV/cm that close to the experimental values observed in breakdowns of dielectric liquids.