Multiphase Flow Measurements with Superhydrophobic Surfaces in Constrained Geometries*

Superhydrophobic surfaces are a novel way of influencing the behavior in multiphase flow regimes. While their effects have been previously studied in bubble columns, these types of surfaces have yet to be studied in flow loops. This research seeks to characterize the effects of superhydrophobic surfaces in a flow loop setting to better understand how various changes in geometries using superhydrophobic surfaces can affect the multiphase flow regime characteristics. Using a high-speed camera and event based camera we measured key flow characteristics to include bubble rise velocity, void fraction, and slip ratio for various geometries and layouts using superhydrophobic surfaces. The results obtained highlight the similarities between multiphase bubble columns and flow loops for which superhydrophobic surfaces are present. These results demonstrate that with superhydrophobic surfaces in the multiphase flow loop system, void fraction will decrease and the bubble rise velocity will increase with varying degrees depending on the geometry set up of each case. This presentation demonstrates that the concepts seen previously in bubble columns case can be applied to flow loops, leading to new, innovative ways of incorporating superhydrophobic surfaces into important engineering flow applications, such as pressurized water reactors, to enhance the heat transfer within the system, and chemical reactor plants to enhance mixing.