液滴規模の自発的蒸気爆発の開始段階の観察(熱工学,内燃機関,動力など)  [in Japanese] Observations of Initiation Stage of Spontaneous Vapor Explosions for Droplet Scale(Thermal Engineering)  [in Japanese]

In the present study, the initiation stage of spontaneous vapor explosions generated by single droplets of molten tin submerged in water has been investigated using a high speed video camera operated with reflected light system. The photographs of the formulating process of vapor film, the process of vapor film disturbance and initiation process of the vapor explosions for different mass of molten tin and different diameter of nozzle were obtained. The results show that partial thermal interaction between tin and water does not bring to vapor explosion with fragmentation, and vapor film locally disappears during the formulation term of vapor film around a hot liquid droplet. Direct contact between hot molten tin surface and water is generated in a consequence. However, the local disappearance of vapor film does not progress and the vapor film is reconstructed. A spontaneous vapor explosion begins to vaper film collapse at the local area of the bottom or edge of the disk-shaped droplet.