Abstract
When a valve opens rapidly in a hot water emergency dump line or in a closed piping system where the steam side is separated from the cold water side by a valve, pressure oscillation is induced. The oscillation mechanism and influential parameters of this phenomenon were investigated experimentally. It was found that the oscillation in the hot water emergency system was induced by transient two-phase flow due to self-flashing of hot water downstream of the valve, and that in the closed piping system it was induced by transient two-phase flow due to steam condensation caused by the contact between steam and cold water In order to prevent this phenomenon, it is most important to decrease the thermal non-equilibrium in the piping system.
