Abstract
Pre-breakdown analysis of dielectric liquids is important in many power system applications. The electric field effect is important as well in pool boiling as it improves the boiling process. This physical phenomenon combined with the pre-breakdown condition in a dielectric liquid has been investigated using a single artificial air bubble immersed in the dielectric liquid and attached to a high voltage electrode. The Level Set coupled with Volume of Fluid numerical method is used to simulate the behaviour of the air bubble in the dielectric liquid. This approach combined with considering the electrical stresses accounts for both the electrical and mechanical (Electrohydrodynamic) stresses on the bubble-liquid interface. Laplace's equation is used to solve the electric field distribution, while the fluid is solved by using Navier–Stokes equations. The electric force effect on the fluid is considered as a source term in the momentum equation. The simulation results show good agreement with the experimental data. It is observed that high-velocity eddies in the order of 22.88 mm/ss are generated inside the air bubble. These eddies are caused by high-pressure gradients near the bubble boundaries caused by the electric field. This high velocity improves the heat and mass transfer between the two fluids.