Scaling analysis for the condensation induced water hammer effect in horizontal pipe

In nuclear power engineering, researchers pay significant attention to phenomena related to the condensation process involving direct contact between saturated steam and subcooled water, mainly the phenomenon known as Condensation Induced Water Hammer (CIWH). Within the steam pipes of the pressurized water reactor, when saturated steam comes into direct contact with subcooled water, it may form an isolated steam pocket surrounded by water. The condensation of steam within this pocket results in its subsequent collapse, accelerating the surrounding water column to collide with the pipe wall and causing a substantial pressure peak. In this paper, the scaling analysis was conducted on the CIWH phenomenon in the steam line of a small PWR. The research is rooted in a two-fluid, six-equation framework and employs equation-based analysis to investigate the non-dimensional number of CIWH occurring within horizontal pipelines. By analyzing the conservation equations, suitable non-dimensional criteria for thermohydraulic phenomena were determined. These criteria can be employed to ascertain experimental facilities' geometric dimensions and operating conditions, which can study the risks associated with CIWH phenomenon.