Analysis of kinematic shocks with RELAP5
This thesis considers a uniform bubbly flow in a vertical column where a kinematic shock is induced. When the average flux is low, the kinematic shock speed is strongly dependant on the void fraction. As the liquid flux is increased, the strong coupling of shock speed and void fraction is reduced. The nuclear thermal-hydraulics code RELAP5/Mod3.3 will be used to assess the capability of a 1-D code to numerically model kinematic shocks. Also tested is the code’s ability to accurately describe the propagation changes from a strong kinematic shock to an infinitesimal kinematic wave. As the shock strength approaches zero we are able compare the numerical results with a semi-analytical wave speed, which is derived from the kinematic wave theory. A modification to the drift flux correlations available in the code will be proposed for RELAP5 and similar onedimensional codes where the bubble size is not predicted. The proposed modification allows for more accurate predictions of kinematic shock speed in the very low liquid flux region. ^
Martin A. Lopez de Bertodano, Purdue University.