Investigation of bubble-top jet flow during subcooled boiling on wires

High-speed photography and laser PIV (particle image velocimetry) technology were employed to investigate subcooled boiling, particularly bubble dynamics on ultrathin platinum wires. Bubble-top jet flows were experimentally observed and theoretically analyzed. The flow field around bubbles and in the jet flows was obtained by PIV. Velocity of jet flows above bubbles in experiments ranged from 15 mm/s to 140 mm/s. A numerical model was proposed to simulate the bubble-top jet flows and agreed very well with the experimental data. The theoretical and experimental evidences indicate that Marangoni effect plays a very important role in forming and driving the jet flows, while both natural convection and vapor condensation are demonstrated to have very little effect.