A DIFFERENT APPROACH TO FRAGMENTATION IN STEAM EXPLOSIONS

摘要

Fragmentation of a high temperature liquid, which is embedded in a film boiling state within a low temperature liquid, has been the subject of numerous studies. For explosive interactions the fragmentation and subsequent energy transfer must be sufficiently rapid to support the formation of a shock wave. In previous studies, the principal interest was the rate at which these capillary size high temperature droplets could be fragmented and rapidly mixed with the surrounding liquid to cause heat transfer and vaporization on explosive timescales (generally less than milliseconds). Recent experiments have, shown that such rapid fragmentation and mixing is difficult to achieve. This paper proposes a different approach to fragmentation, namely that the principal fragmentation process is in the low temperature liquid and that the capillary size high temperature droplets do not substantially alter their dimensions during the propagation of the shock wave. Furthermore, if the hot material dimensions are altered, it is postulated that no substantive rapid mixing of the high temperature and low temperature liquids occurs. This approach to the detailed heat transfer mechanism during physical explosions results in a simple expression for the efficiency of such interactions that is consistent with large scale data. Furthermore, the mechanism for rapid fragmentation and the resulting rapid energy transfer rates are consistent with the small scale separate effects data from the spontaneous nucleation literature.