Determination of the Bubble-to-Slug flow regime transition based on the instability of void fraction waves

The flow developments were objectively characterized by the statistical analysis of the void fraction signals in vertical bubble flow. And the Bubble-to-Slug Flow Regime Transition (RSFRT) was investigated based upon the instabilities of the fraction waves. A series of test was performed in air-water two-plase flow for different flow conditions and by varyting the bubble size. The test loop was pressurized to avoid the gravity effect on the flow developments. The void fraction was measured by the Impedance Void Meter (IVM). The flow developments of bubble flow are dependent on the bubble size, and it was turned out that the BSFRT boundary can by objectively determined based on the instaility criteria of void fraction waves and it is sensitive to the initial bubble size. (Author)