A Study on Steam Explosion (The Influence of the Falling Condition of the Melted Metal)

蒸汽爆炸是热熔物质落入水中所引起的爆炸现象之一。快速相变是由熔化物质与水的直接接触热传递所控制的。通常，当融化的物质落入水中时，它会伴随着空气。蒸汽混合物中的空气成分降低了传热能力。重要的是要研究，如果空气被排除在水面以上的空间，这些现象是如何变化的。即使水没有处于过冷状态，是否会发生爆炸也是一个值得关注的问题。有必要判断这种现象是否真的是蒸汽爆炸。它们碰巧出现的地方，靠近水面，或在中心，或在底部，也是重要的特征。为了这些目的，测试水容器应该通过用透明材料建造侧壁来可视化。同时，容器内的空间可以保持在20托左右，并且热熔物质的流入必须易于控制。压力变化由压电传感器检测，并记录下来，与高速摄像机拍摄的照片同步。对锡和焊料（Sn63%Pb37i%）进行了测试，并与我们以往的数据进行了比较。在水饱和压力为30℃的条件下，未发生蒸汽爆炸。在200托的压力下产生。纯金属和合金之间的区别似乎是存在的，但仍然是未来的一个问题。在此基础上，对蒸汽爆炸的结构进行了改造。

The steam explosion is one of the explosive phenomena excited by the fall of the hot melted substance into the water. Rapid phase change is governed by the direct contact heat transfer of melted substance and water. Usually the melted substance accompanies air, when it falls into the water. The air component in the steam mixture reduces the heat transfer capacity. It is important to investigate, how the phenomena change if the air is excluded from the space above the water. Whether the explosion occurs even if the water is not at the state of subcooling, is also a matter of interest. It is necessary to judge whether the phenomena are really steam explosion or not. Where they happen to emerge, near the surface, or in the center, or at the bottom, is also important characteristics. For these purposes the test water vessel should be visualized by building the sidewall with transparent material. At the same time the space in the vessel can be kept at about 20 Torr, and the inflow of the hot melted substance have to be controlled easily.Pressure variations are detected by a Piezo sensor, and is recorded, synchronized with the pictures taken by high speed video camera. The tin and solder (Sn63%Pb37i%)were tested, and the results were compared with our data in the past. Under the condition of the saturated pressure for the water of 30℃, the steam explosion didn't occur. Under the pressure 200 Torr it is generated. The difference between the pure metal and the alloy seems to exist, but remains as a problem for the future. Based on these results, the structure of steam explosion is to be remodeled.