Abstract
The dominant frequency of pressure oscillation caused by unstable steam jet in subcooled water flow in a narrow channel was experimentally investigated. In this study, a visualized test section with rectangular channel, steam nozzle and water nozzle was designed. A high speed camera was employed to record flow patterns. In order to investigate the characteristics of pressure oscillation in the channel, several high frequency dynamic pressure transducers were arranged on the wall of the channel. The main inlet parameters, including steam mass flux, water mass flux and inlet water temperature were tested in the range of 150-400kg/(m^2s), 6-18×10^3kg/(m^2s) and 15-40℃. Two different unstable flow patterns were observed as bubble flow and oscillation jet. The dominant frequency of pressure oscillation under various test conditions was obtained by fast Fourier transform (FFT) method. The results indicated that the dominant frequency was dependent on the variation of condensation length of the steam jet. The longer the condensation length, the lower the dominant frequency. The influence of steam mass flux, water mass flux and inlet water temperature on dominant frequency was discussed. The dominant frequency would decrease with the increase of steam mass flux and inlet water temperature, but increase with the water mass flux.
