The effect of electric field on the formation and fragmentation of condensate film on the walls of a capillary in a flow of steam

An experimental investigation is performed of the effect of electric field on the parameters of a condensate film forming on the walls of a capillary in which hot steam flows. The increase in the field intensity in the vicinity of the capillary exit section causes a variation of the two-phase mode of flow in the capillary from annular to slug; the shape of the film surface varies from smooth to wavy; and the formation of large droplets at the capillary exit section changes to pulsating fragmentation of the film. With continuing increase in the intensity, the slug flow changes back to annular, water forms steady-state projections at the capillary exit section, the fragmentation of the film becomes monotonic, and an unsteady corona discharge arises on the projections. The variation of the capillary orientation from horizontal to vertical results in an increase in the intensity required for the development of the slug mode of flow. A mechanism of monotonic fragmentation of film is suggested, within which the characteristics of resultant fragments are assessed.