Modeling and analysis of condensation induced water hammer

Abstract

Direct contact of steam and subcooled water under certain situations may cause immense steam condensation at the two-phase interface and can lead to the generation of fast and violent pressure surges which is often termed as condensation induced water hammer (CIWH) or direct contact condensation (DCC) driven water hammer. The present work aims at the exploration of the underlying physics of the CIWH phenomenon in a horizontal two-phase flow scenario using a dedicated 1D, compressible in-house code which is formulated based on the two-fluid modeling approach (six-equation based model). The developed code is verified against the benchmark two-phase shock tube problem (Reimann problem) and it is observed that it is capable to capture the shock wave, rarefaction wave and contact discontinuity satisfactorily. A comparative assessment between present in-house code, RELAP5 and WAHA3 against the PMK-2 CIWH experimental data shows that the pressure peak amplitude predicted by our in-house code is more accurate in comparison to WAHA3 and RELAP5 simulation. In this work, emphasis is also given on the detailed investigation to study the effect of inlet water subcooling (20–80 °C), water inflow rate (corresponding = 0.1 and 0.7) on the pressure peak amplitude (along with its occurrence time and location), phase distribution, temperature history and interfacial condensation rate during CIWH. Observation reveals that with the decrease in inlet water temperature, pressure peak magnitude increases. It is also found that the pressure peak amplitude increases with the increase in inlet water flow rate.