EXPERIMENTAL INVESTIGATION ON RISING BEHAVIOR OF SINGLE BUBBLE UNDER THE EFFECT OF UNIFORM DC ELECTRIC FIELD

Bubbles in an electric field have a significant effect on enhancing heat transfer. The study of the dynamic characteristics of bubbles in an electric field is important for enhancing the efficiency of heat exchangers and improving energy efficiency. In order to obtain the dynamics of bubbles under an applied electric field, a visualization experiment was designed and built. A 50 kV high voltage direct current power supply was used to construct a uniform electric field and a high-definition camera was used to capture the experimental images. The electric field strength, bubble volume and dielectric constant of the solution were introduced as variables to investigate their effects on the dynamic properties of the bubbles. The rise of the bubble in a vertical and horizontal uniform electric field was observed and the variation of the bubble deformation and rise velocity for different variables was analyzed. The bubble aspect ratio L/D was used to represent the degree of bubble stretching and deformation, and the individual bubble rising process was captured in separate time periods to show the shape change process. The results show that the bubble elongates in the direction of the electric field, and the larger the electric field strength, the more obvious the deformation is; in the vertical electric field, the elongation of the bubble causes the rising speed to increase, while in the horizontal electric field, the rising speed decreases. As the size of the bubble increases, the buoyancy force on the bubble increases and the rate of rising bubbles increases. As the dielectric constant of the solution increases, the electric field force on the bubble increases significantly and the bubble deformation becomes more pronounced.