Advancement of compressible multi-phase flows and sodium-water reaction analysis program SERAPHIM. Validation of a numerical method for the simulation of highly underexpanded jets

Numerical analysis of highly underexpanded jets was performed by using the SERAPHIM program for compressible multi-phase flows with sodium-water chemical reaction to investigate its applicability. When the pressurized water leaks from a failed heat transfer tube in a steam generator of sodium cooled fast reactors, the underexpanded jet with the chemical reaction will be formed. The role of the SERAPHIM program is to predict the profiles of velocities, temperatures and concentrations under the sodium-water reaction accident. To achieve this, validation of the numerical method to the multi-phase flow including underexpanded jets must be conducted. A multi-fluid model considering compressibility and a second-order TVD scheme were used in the present analysis. In the case of the air jet into the air, numerical results agreed with the experimental data very well. Also in the case of the air jet into the water, the comparable numerical results were obtained by our method. (author)