Impingement of a gas-in-liquid compound drop on a heated flat plate

Phenomena of a gas-in-liquid compound drop hitting a flat plate with a temperature greater than the Leidenfrost temperature were experimentally observed with a high speed video camera. The collision phenomena were found to depend strongly on the Weber number as well as the relative size and position of the gas core within the compound drop. For a gas core of diameter greater than half the compound drop diameter, the collision created a central jet which would penetrate the gas core to form a donut-shaped bubble if the gas core was near the bottom. If the gas core was near the top, the whole process took much longer dimensionless time to complete and the gas core may rupture before it was penetrated by the central jet. A distinct feature of the gas-in-liquid compound drop collision was the relatively large amount of liquid that was left near the center (the contact point). In the range of Weber number studied, the spread of the liquid on the hot plate produced a crown disintegration.