ABSTRACT:

Experimental observation has shown that the assumption of complete fuel
fragmentation in a vapor explosion by the shock adiabatic thermodynamic
model results in predicting upper bounds for the shock pressure, propagation
velocity, and work output.
We have modified this model by considering the condition where the
assumption of complete fragmentation of the fuel is relaxed.
We have adopted a methodology using experimental values of the
shock pressure and propagation velocity to estimate the initial mixture
conditions of the experiment and the mass fraction of the materials
participating in the explosion.
Analysis of a steady state subcritical vapor explosion in one dimension has
been carried out by applying the conservation laws of mass, momentum and
energy and the appropriate equation of state for a homogeneous mixture of
molten tin and water.
The KROTOS-21 experiment, conducted at the Joint Research Center at Ispra,
Italy, was used as our initial benchmark experiment in this analysis.
A quasi-steady explosion pressure of ~3 MPa and a propagation velocity
of ~200 m/sec were obtained in this experiment.
Using this model, the estimated minimum mass of the fragmented fuel was
found to be 0.21 kg (3.2%) of the total mass of the fuel. The predicted
work output by this model corresponding to the above fragmented fuel mass
was found to be 9.8 kJ. The estimated initial void fraction of the vapor
was found to be 11.5%.
In these analyses we have compared the various possible closure relations
applied to the detonation wave theory for a vapor explosion and associated
concerns of model stability in the two-phase region.