RELAP5 Analysis of Two-Phase Decompression and Rarefaction Wave Propagation Under a Temperature Gradient

Abstract

The capability of RELAP5 to model single and two-phase acoustic waves is demonstrated with the use of fine temporal and spatial discretizations. Two cases were considered: a single phase air shock tube problem and pressure waves observed by Takeda and Toda in a two-phase decompression experiment in a pipe. Whereas the agreement for the single phase case is excellent, some discrepancies were observed in the two-phase case. However, RELAP5 produced markedly better results after adjusting the bubble size and the choked flow area. These results illustrate the need of a dynamic model for the interfacial area concentration (i.e., the bubble size).