Numerical Simulation of Condensation Induced Water Hammer

Abstract

A numerical model for the simulation and analyses of condensation induced water hammer is presented and applied to the prediction of intensive pressure waves propagation in a two-phase pipe system. The modelling approach is based on the one-dimensional homogeneous two-phase flow model, tracking of the water column - steam bubble interface and modelling of the direct steam condensation on the subcooled liquid. The mass, momentum and enthalpy conservation equations are solved with the method of characteristics. The explicit time integration is performed along the three characteristic paths, where two of them are determined with the pressure waves propagation and third by the fluid particle flow. Fluid particle and water-steam interface tracking is achieved through the third-order accurate solving of the energy equation in space, where the thermodynamic quality determines the presence of water, two-phase mixture or steam. The heat conduction term is included into the enthalpy equation with the appropriate effective heat conduction coefficient in the two-phase region. The model is applied to the simulation and analyses of condensation induced water hammer in laboratory test case.