Measurement of Multi-Dimensional Distribution of Local Bubble Parameters in a Vertical Annulus under Subcooled Boiling Conditions

At near-atmospheric pressure, the vapor bubbles exhibit complicated behaviors since they have various size including large ones over a few millimeters, generally not formed at high pressure conditions. Then the magnitude and even the direction, in some cases, of non-drag forces are changed compared to those at high pressure. In this study, an experimental investigation was performed to measure the local bubble parameters in steam-water subcooled boiling flow in a vertical channel at low heat and mass flux conditions. The optical fiber probe is applied to measure the multidimensional distribution of local bubble parameters, so that an integrated database for the two-phase flow variables in the boiling flow channel can be obtained. In this study, the local bubble parameters in steamwater subcooled boiling flow were measured in a vertical channel at low heat and mass flux conditions. An experimental DB for bubble parameters were obtained through four sets of test program. These test data can be used to validate the physical model of wall boiling and non-drag forces for vapor phase in a CFD scale codes.