Experimental investigation of interaction between rising vapor bubbles on a vertical heater in acetone

Interaction between the rising vapor bubbles was investigated. The experiment was carried out in acetone under natural convection on a vertical heater 2.5 mm in diameter. Overheating of the heater surface before boiling-up varied from 30 to 120 degrees at saturation pressure from 20 to 40 kPa. Experiments have shown that the field of velocity and pressure behind a rising bubble has a strong influence on the growth dynamics of vapor bubble located below. This influence depends on the distance between the bubbles and growth phase of the upper bubble. When bubbles coalescence, high acceleration (100 m/s2) of particular parts of the interphase surface are observed. When the lower bubble coalescences with the upper bubble, the vapor spreads like a jet, and as a result, a conical perturbation is formed on the opposite side of the upper bubble.