<p>Two-phase flow is widely involved in reactor design and is directly relevant to the reactor safety. However, the flow regime in narrow rectangular channels still needs further study due to the considerably difference from tube and bundle channels. In order to investigate two-phase flow regime and interfacial structure characteristics, the air-water experiment with adiabatic vertical channel of 4×66×1800, 6×66×1800 mm have been conducted under atmosphere pressure condition. The impedance void meter was used to measure the global void fraction in narrow rectangular channels. High speed camera was used to record the profiles of the flow regime. The flow regime was identified by the random forest clustering algorithm based on a training sample. The profiles of different parameters including void fraction, pressure loss at Z/D=150 were analyzed in this paper. Furthermore, based on the distribution of parameters, the regime transition criteria in narrow rectangular channels was discussed. It is shown that the transition from bubble to slug flow always occurred when average void fraction is 0.17-0.2. The transition value is 0.57-0.62 when slug flow change to churn-turbulent flow and 0.78-0.8 from churn-turbulent to annular flow. The constant used in&nbsp;Lockhart and Martinelli corelation is found to calculate the frictional pressure drop in rectangular channel. Furthermore, the drift-model applied to rectangular channel is verified.</p>

Research on the Air-Water Flow Regime and Characteristics in Rectangular Channel

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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