[2G08-12] Thermal Hydraulics Experiment/Analysis 2

[2G09] Flow Characteristics in Vertical Pipes under Flooding Conditions at the Top End

*TAKAKI Toshiya¹, GODA Raito², SHIMAMURA Takeyuki², MURASE Michio¹, TOMIYAMA Akio² (1. Institute of Nuclear Safety System, Incorporated , 2. Kobe University)

Keywords:Vertical pipe, Countercurrent flow, Flooding, Countercurrent flow limitation, Wall friction factor

Flooding occurs at the square top end of the vertical pipe in a pressurizer surge line under countercurrent flow conditions. In this study, we measured the pressure gradient dp/dz, countercurrent flow limitation (i.e. the falling water velocity J_L for a given gas velocity J_G) and void fraction α in a vertical pipe (with the square top end, the diameter of D = 40 mm, and working fluids of air and water) under flooding conditions, evaluated the wall friction factor f_w and interfacial friction factor f_i by using the annular flow model, and compared them with flow characteristics previously measured with D = 20 mm.