The effect of temperature at the nozzle exit under superheated condition on the condensation characteristics of a superheated steam jet

Abstract

During a severe power plant accident, steam condensation mitigates containment pressurization in a postulated nuclear accident. Understanding the condensation process of the steam jet is essential to prevent structural damage and accidents. This study investigated the effect of temperature at the nozzle exit under superheated conditions on the steam jet velocity and temperature distribution, and the condensation characteristics of the steam jet released from the orifice nozzle. The steam jet discharged from the orifice nozzle exhibited the vena-contracta effect, resulting in an increase in velocity along the centerline and a decrease from the exit to the near field. In experiments, the temperature of the exit nozzle was adjusted to 100.4 °C, 106.3 °C, and 112 °C, sequentially. It was found that as the steam jet moves downstream, it undergoes condensation as it mixes with the surrounding air. As the temperature at the exit becomes lower, the condensation becomes more significant, resulting in smaller temperature and velocity spread rates, and larger Liquid Water Content (LWC) and Total Number Concentration (TNC) values, due to the condensation process.