Abstract
Abstract
A gas bubble traveling in a liquid flow through a convergent nozzle will experience a rapidly decreasing pressure on the leading edge of the bubble. Thus, the bubble will dynamically deform while passing through the nozzle showing an elongation of the front of the bubble. This work reports on experimental studies with high-speed imaging in a refractive index matched axisymmetric nozzle and complementary volume of fluid numerical simulations conducted via ANSYS Fluent. In these studies, an individual bubble is tracked as it flows downward approaching and then passing through the nozzle. A digital image processing algorithm is used to obtain quantitative information about the bubbles from high-speed images. Experimental results are provided that detail the bubble leading and trailing edge trajectory and bubble deformation. Under certain conditions the bubble deformation can lead to the bubble pinching apart near the leading edge, a phenomenon that was found in both the experiments and simulations. Simulation results are compared with experimental data and additionally provide information on the time-varying exit void fraction and exit velocity as the bubble accelerates through the contraction. This study examines two different bubble diameters and two different liquid flow rates to identify their role in the deforming bubble dynamics.