The gas-liquid two-phase flow behaviors are always associated with its dynamic void fraction, such as flow resistance, heat transfer coefficient, phase distribution, critical heat flux etc. As regard to the commercial PWR and BWR, rod bundles are the typical geometry, which contains many sub-channels for coolant flowing. In present study, the sub-channel void fraction was measured in 5×5 rod bundles with the sub-channel impedance void meter consisting of 12 strip electrodes. Based on the measured void fraction in different sub-channels, the void fraction dynamics, PDF (probability distribution function) and CDF (cumulative distribution function) curves were analyzed to make clear the effect of superficial gas and liquid velocity, flow development and casing tube. The effect of superficial gas and liquid velocity on dynamic sub-channel void fraction has been analyzed, which mainly affect the averaged void fraction, fluctuating amplitude and frequency by changing bubble size and flow turbulence. The sub-channel void fraction characteristics are also influenced by L/D and casing tube, which plays an important role in the secondary flow velocity, lateral movement of bubbles and flow field on the whole cross-section. The empirical correlation for PDF of dynamic sub-channel void fraction has developed, which showed good fitness with PDF and CDF curves and satisfying accuracy of averaged void fraction. 


Experimental Study on the Sub-Channel Void Fraction Characteristics of Bubbly Flow in Rod Bundles

Division / Sponsors: 
Power Division & Nuclear Engineering Division (NED)

Power Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2020/volume/83747

International Conference on Nuclear Engineering
Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE2020/volume/83761

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