On the dynamics of bubble growth under time-dependent pressure field

The dynamics of bubble growth plays an important role in the analysis of transient two-phase flow during blowdown of a DWR or a BWR or the transient evaporation in LMFBR. It is shown how to develop the asymptotic analytical solution to time-dependent pressure field, which is expressed by simple formulation. The resulting equation is useful to predict the bubble growth rate in such slowly time-dependent pressure field such as blowdown in a water-cooled reactor. Analysis was made by considering the non-equilibrium state at vapor-liquid interface and without assuming a temperature profile in the thermal boundary layer around a bubble. The results are useful to predict the bubble growth rate in high superheated and high conductivity liquid such as transient boiling and vapor explosion in LMFBR. Criteria of the non-equilibrium state at the interface were examined. Numerical solutions of the asymptotic and non-equilibrium analyses were compared with other analyses and empirical results. (Mori, K.)