A Numerical Analysis Research on Earlier Behavior of Molten Droplet Covered with Vapor Film at the Stage of Triggering and Propagation in Steam Explosion

When the molten fuel with high temperature falls into the cavity water, it will be dispersed into droplets which are covered with vapor films due to the rapid heat transfer with phase transition. This situation cannot be simply described by liquid-liquid or gas-liquid systems. And there are no sufficient experimental studies on the behavior of droplet covered with vapor film because of the rapid reaction and the difficulty in capture of the film configuration. In this paper, a multiphase code with the volume of fluid (VOF) method is used to simulate the earlier behavior of droplet when vapor film exits. The earlier behavior is defined as behavior of the droplet before its disintegration. Thermal effect and pure hydrodynamic effect are, respectively, considered. The simulation results indicate that the film thickness and material density have significant effect on the earlier behavior of droplet. The situation assumed in Ciccarelli and Frost’s model (1994) is observed in current simulation of earlier thermal droplet behavior. The effect of triggering pressure pulse on earlier hydrodynamic behavior is also discussed and it indicates that vapor film has little effect on the hydrodynamic droplet deformation when the intensity of the pressure pulse is very high.

[1]  J. Brackbill,et al.  A continuum method for modeling surface tension , 1992 .

[2]  D. Joseph,et al.  Breakup of a liquid drop suddenly exposed to a high-speed airstream , 1999 .

[3]  Truc-Nam Dinh,et al.  Simultaneous high speed digital cinematographic and X-ray radiographic imaging of a intense multi-fluid interaction with rapid phase changes , 2007 .

[4]  Liangxing Li,et al.  A numerical analysis on hydrodynamic deformation of molten droplets in a water pool , 2013 .

[5]  Yoshiaki Oka,et al.  Numerical analysis of fragmentation mechanisms in vapor explosions , 1999 .

[6]  Matjaž Leskovar,et al.  Estimation of ex-vessel steam explosion pressure loads , 2009 .

[7]  L YoungsD,et al.  Time-dependent multi-material flow with large fluid distortion. , 1982 .

[8]  T. Dinh,et al.  Dynamics and Preconditioning in a Single-Droplet Vapor Explosion , 2009 .

[9]  Yanhua Yang,et al.  Numerical simulation of film boiling on a sphere with a volume of fluid interface tracking method , 2008 .

[10]  Yang Yanhua,et al.  Numerical simulation of molten droplet deformation and disintegration under sudden accelerations , 2014 .

[11]  M. Corradini,et al.  Modeling of Small-Scale Single Droplet Fuel/Coolant Interactions , 1988 .

[12]  S. V. Poplavski,et al.  On the dynamics of drop acceleration at the early stage of velocity relaxation in a shock wave , 2009 .

[13]  Nikolay Ivanov Kolev.  Film Boiling on Vertical Plates and Spheres , 1998 .

[14]  Nasser Ashgriz,et al.  FLAIR: fluz line-segment model for advection and interface reconstruction , 1991 .

[15]  S. J. Board,et al.  Detonation of fuel coolant explosions , 1975, Nature.

[16]  Fine fragmentation of molten droplet in highly subcooled water due to vapor explosion observed by X-ray radiography , 2005 .

[17]  Yutaka Abe,et al.  Fragmentation behavior during molten material and coolant interactions , 2006 .

[18]  Abraham M. Lenhoff,et al.  Drop formation in liquid-liquid systems before and after jetting , 1995 .

[19]  D. B. Kothe,et al.  RIPPLE: A NEW MODEL FOR INCOMPRESSIBLE FLOWS WITH FREE SURFACES , 1991 .

[20]  Yan Xiao,et al.  Numerical simulation of fragmentation of melt drop triggered by external pressure pulse in vapor explosions , 2013 .

[21]  D. Frost,et al.  Fragmentation mechanisms based on single drop steam explosion experiments using flash X-ray radiography , 1994 .

[23]  M. Pilch,et al.  Use of breakup time data and velocity history data to predict the maximum size of stable fragments for acceleration-induced breakup of a liquid drop , 1987 .