Behavior of bubbles in non-uniform fields is of great interest primarily to study the electrically enhanced boiling heat transfer, the electrical breakdown of dielectric liquid in the presence of thermally induced bubbles and electrically stabilized boiling within a vessel in the zero-gravity space environment. In the present work, to clarify the bubble behavior in cryogenic and dielectric liquid during quenching period of superconducting coils, the bubble motion is analyzed numerically with a cylinder-to-plane electrode system in liquid nitrogen/helium under d.c. applied voltages.
The main content of this paper may be summarized as the following. A set of differential equations which describes the motion of a spherical bubble in dielectric liquid under non-uniform electrostatic field is given. The equations are solved numerically with three arrangements of the electrode system in liquid nitrogen or helium and the some results are confirmed by experiments. The effects of bubble size, gap parameters and characteristics of liquid on the bubble behavior are newly found and the formation of bubble stagnation is discussed.