Numerical analysis of two-phase jet impingement by homogeneous flow model

A two-dimensional homogeneous equilibrium model is developed in order to evaluate impingement load caused by discharge of a two-phase mixture in postulated pipe rupture accidents of light water reactors. The present analysis differs from previous studies mainly in that a backward expansion around the pipe exit is taken into account. As a result: (1) it is confirmed that the backward expansion occurs around the pipe exit in a supersonic two-phase flow; (2) when the dimensionless position of an impingement wall z/D is larger than 2.0, the present calculations predict the pressure distribution on the impingement wall within an error of 10 %, while the previous calculations, which did not take the backward expansion into account, overestimated the pressure by 25 %; (3) existence of jet core and occurrence of shock waves in the two-phase jet are obtained and (4) a supersonic state of the jet is illustrated by comparing the velocity with the sonic velocity. (author)