Effect of boundary conditions on the propagation of a vapor explosion in stratified molten tin/water systems

The propagation of a vapor explosion in a stratified molten tin/water system has been investigated experimentally in two different geometrical configurations: (i) linear propagation within a narrow channel, and (ii) radial propagation in a cylindrical tank. In the narrow channel experiments, self-sustained spatial propagation of the interaction occurs with an average propagation speed of 40-50 m s-1 and with an effective mixing depth not more than 2 mm. A minimum degree of inertial confinement provided by the water above the tin as well as the confinement provided by the lateral walls are required to sustain a propagating interaction. If an interaction propagating within a narrow channel encounters a sudden increase in the channel width, it fails abruptly after a short distance. Interactions initiated in a relatively unconfined cylindrical geometry always fail to propagate after a certain distance. A comparison between the energetics of single molten tin drop interactions and interactions in the stratified systems suggests that similar dynamic processes occur during the first interaction cycle in each case. In both cases, the first interaction is an efficient method for mixing the tin and water and is often a precursor to a second, more violent interaction. (orig.)