Abstract
The evaluation of nuclear reactor safety under seismic vibration has been an important issue. However the mechanics and the database of two-phase flow under vibration were still limited. In order to investigate the effect of seismic vibration, experimental tests of adiabatic air-water two-phase flow under vertical vibration were carried out in this study. To simulate the vibration, an eccentric cam vibration module which was operated at a low frequency (up to 2Hz) was connected to the rectangular test section. The range of two-phase flow operation conditions was Jf 0.04-1.0m/s and Jg 0.01-0.4m/s. Eight impedance sensors were utilized to measure the local void fraction. Some analysis tools including cumulative distribution function (CDF), standard deviation (STD) and neural network were used to present the vibration effect on local two-phase flow. According to the CDF and STD results, instantaneous void signal would change under specific flow rate and specific vibration conditions. And utilizing the neural network to identify the possible flow regime changes by an objective way. The possible reasons for the flow regime changes is that the vibration increases the bubble coalescence and changes the flow regime structure.