Numerical Simulation of Condensation Induced Water Hammer

A numerical model for the simulation and analysis of the water hammer in the pipe two-phase flow is developed. The modelling is based on one-dimensional homogeneous model of two-phase flow, tracking of the interface between steam volume and water column and modelling of the direct condensation of steam on subcooled liquid. The mass, momentum and energy conservation equations are solved by the method of characteristics. For these three equations, there are three characteristic directions: two of them are determined by the pressure wave propagation and the third one by the fluid particle propagation. The fluid particle and the steam-water interface tracking are obtained through the energy conservation equation solving in space, with the accuracy of the third degree. The value of thermodynamic quality is used to determine whether the observed computational region is filled with water, two-phase mixture or steam. The term in the energy conservation equation, which contains information about the heat exchanged between steam and liquid phase through condensation, is determined by integration of superficial heat flux over steam-water interface. The model is applied to the simulation and analysis of the air-water interface propagation in the experimental apparatus of oscillating manometer and the condensation induced water hammer in a vertical pipe for draining of steam into the pool filled with subcooled water.